,,heroes ,,of ,,science4 ,,heroes ,,of ,,science4 ,,physicists4 ,,by ,,william ,,garnett1 ,m4,a41 ,d4,c4,l41 ,,formerly ,,fellow ,,of ,,st4 ,,john',s ,,college1 ,,cambridge2 ,,principal ,,of ,,the ,,durham ,,college ,,of ,,science1 ,,newcastle-,,upon-,,tyne2 ,,hon4 ,,member ,,of ,,the ,,north ,,of ,,england ,,institute ,,of ,,mining ,,and ,,mechanical ,,engineers4 ,,published ,,under ,,the ,,direction ,,of ,,the ,,committee ,,of ,,general ,,literature ,,and ,,education ,,appointed ,,by ,,the ,,society ,,for ,,promoting ,,christian ,,knowledge4 ,,london3 ,,society ,,for ,,promoting ,,christian ,,knowledge1 ,,northumberland ,,avenue1 ,,charing ,,cross1 ,w4,c42 #dc1 ,,queen ,,victoria ,,street1 ,e4,c42 #bf1 ,,st4 ,,george',s ,,place1 ,,hyde ,,park ,,corner1 ,s4,w4 ,,brighton3 #ace1 ,,north ,,street4 ,,new ,,york3 ,e4 ,j4 ,b4 ,,young ,,and ,,co4 ,,preface4 ,the following pages claim no originality1 and no merits beyond that of bringing within reach of every boy and girl material which would otherwise be available only to those who had extensive libraries at their command1 and much time at their disposal4 ,in the schools and colleges in which the principles of physical science are well taught1 the history of the discoveries whereby those principles have been established has been too much neglected4 ,the series to which the present volume belongs is intended1 in some measure1 to meet this deficiency4 ,a complete history of physical science would1 if it could be written1 form a library of considerable dimensions4 ,the following pages deal only with the biographies of a few distinguished men1 who1 by birth1 were ,british subjects1 and incidental allusions only are made to living philosophers2 but1 notwithstanding these narrow restrictions1 the foundations of the ,royal ,society of ,london1 of the ,american ,philosophical ,society1 of the great ,library of ,pennsylvania1 and of the ,royal ,institution1 are events1 some account of which comes within the compass of the volume4 ,the gradual development of our knowledge of electricity1 of the mechanical theory of heat1 and of the undulatory theory of optics1 will be found delineated in the biographies selected1 though no continuous history is traced in the case of any one of these branches of physics4 ,the sources from which the matter contained in the following pages has been derived have been1 in addition to the published works of the subjects of the several sketches1 the following3-- ,the ,encyclopaedia ,britannica4 ,memoir of the ,honourable ,robert ,boyle1 by ,thomas ,birch1 ,m4,a41 prefixed to the folio edition of his works1 which was published in ,london in #agdc4 ,life of ,benjamin ,franklin1 from his own writings1 by ,john ,bigelow4 ,dr4 ,g4 ,wilson's ,life of ,cavendish1 which forms the first volume of the publications of the ,cavendish ,society2 and the ,electrical ,researches of the ,hon4 ,henry ,cavendish1 ,f4,r4,s41 edited by the late ,professor ,james ,clerk ,maxwell4 ,the ,life of ,sir ,benjamin ,thompson1 ,count ,rumford1 by ,george ,e4 ,ellis1 published by the ,american ,academy of ,arts and ,sciences1 in connection with the complete edition of his works4 ,memoir of ,thomas ,young1 by the late ,dean ,peacock4 ,dr4 ,bence ,jones's ,life of ,faraday2 and ,professor ,tyndall's ,faraday as a ,discoverer4 ,life of ,james ,clerk ,maxwell1 by ,professor ,lewis ,campbell and ,william ,garnett4 ,it is hoped that the perusal of the following sketches may prove as instructive to the reader as their preparation has been to the writer4 ,,wm4 ,,garnett4 ,,newcastle-,,upon-,,tyne1 ,december1 #ahhe4 ,,contents4 ,,page ,,introduction #a ,,robert ,,boyle #e ,,benjamin ,,franklin #ch ,,henry ,,cavendish #abe ,,count ,,rumford #adh ,,thomas ,,young #aid ,,michael ,,faraday #bcg ,,james ,,clerk ,,maxwell #bgh ,,conclusion #cji ,,heroes ,,of ,,science4 ,,introduction4 ,the dawn of true ideas respecting mechanics has been described in the volume of this series devoted to astronomers4 ,at the time when the first of the following biographies opens there were a few men who held sound views respecting the laws of motion and the principles of hydrostatics4 ,considerable advance had been made in the subject of geometrical optics2 the rectilinear propagation of light and the laws of reflection having been known to the ,greeks and ,arabians1 whilst ,willebrod ,snellius1 ,professor of ,mathematics at ,leyden1 had correctly enunciated the laws of refraction very early in the seventeenth century4 ,pliny mentions the action of a sphere of rock-crystal and of a glass globe filled with water in bringing light to a focus4 ,roger ,bacon used segments of a glass sphere as lenses2 and in the eleventh century ,alhazen made many measurements of the angles of incidence and refraction1 though he did not succeed in discovering the law4 ,huyghens developed to a great extent the undulatory theory2 while ,newton at the same time made great contributions to the subject of geometrical optics1 decomposed white light by means of a prism1 investigated the colours of thin plates1 and some cases of diffraction1 and speculated on the nature1 properties1 and functions of the ether1 which was equally necessary to the corpuscular as to the undulatory theory of light1 if any of the phenomena of interference were to be explained4 ,the velocity of light was first measured by ,roemer1 in #afgf4 ,the camera obscura was invented by ,baptista ,porta1 a wealthy ,neapolitan1 in #aefj2 and ,kepler explained the action of the eye as an optical instrument1 in #afjd4 ,antonio de ,dominis1 ,archbishop of ,spalatro1 discovered the fringe of colours produced by sunlight once reflected from the interior of a globe of water1 and this led1 in ,newton's hands1 to the complete explanation of the rainbow4 ,the germ of the mechanical theory of heat is to be found in the writings of ,lord ,bacon4 ,the first thermometers which were blown in glass with a bulb and tube hermetically sealed1 were made by a craftsman in ,florence1 in the time of ,torricelli4 ,the graduations on these thermometers were made by attaching little beads of coloured glass to their stems1 and they were carried about ,europe by members of the ,florentine ,academy1 in order to learn whether ice melted at the same temperature in all latitudes4 ,in electricity the attraction of light bodies by amber when rubbed1 was known at least six hundred years before the ,christian era1 and the shocks of the torpedo were described by ,pliny and by ,aristotle2 but the phenomena were not associated in men's minds until recent times4 ,dr4 ,gilbert1 of ,colchester1 ,physician to ,queen ,elizabeth1 may be regarded as the founder of the modern science4 ,he distinguished two classes of bodies1 viz4 electrics1 or those which would attract light bodies when rubbed2 and non-electrics1 or those which could not be so excited4 ,the first electric machine was constructed by ,otto von ,guericke1 the inventor of the ,magdeburg hemispheres1 who mounted a ball of sulphur so that it could be made rapidly to rotate while it was excited by the friction of the hand4 ,he observed the repulsion which generally follows the attraction of a light body by an electrified object after the two have come in contact4 ,he also noticed that certain bodies placed near to electrified bodies possessed similar powers of attraction to those of the electrified bodies themselves4 ,newton replaced the sulphur globe of ,otto von ,guericke by a globe of glass4 ,stephen ,gray discovered the conduction of electricity1 in #agbi1 when he succeeded in transmitting a charge to a distance of #hhf feet along a pack-thread suspended by silk strings so as to insulate it from the earth4 ,desaguliers showed that ,gilbert's electrics were simply those bodies which could not conduct electricity1 while all conductors were non-electrics2 and ,dufay showed that all bodies could be electrified by friction if supported on insulating stands4 ,he also showed that there were two kinds of electrification1 and called one vitreous1 the other resinous4 ,gray1 ,hawksbee1 and ,dr4 ,wall all noticed the similarity between lightning and the electric discharge4 ,the prime conductor was first added to the electric machine by ,boze1 of ,wittenberg2 and ,winkler1 of ,leipsic1 employed a cushion instead of the hand to produce friction against the glass4 ,the accumulation of electricity in the ,leyden jar was discovered accidentally by ,cuneus1 a pupil of ,muschenbroeck1 of ,leyden1 about #agde1 while attempting to electrify water in a bottle held in his hand4 ,a nail passed through the cork1 by which the electricity was communicated to the water4 ,on touching the nail after charging the water1 he received the shock of the ,leyden jar4 ,this brings the history of electrical discovery down to the time of ,franklin4 ,,robert ,,boyle4 ,robert ,boyle was descended from a family who1 in ,saxon times1 held land in the county of ,hereford1 and whose name in the ,doomsday ,book is written ,biuvile4 ,his father was ,richard ,boyle1 ,earl of ,cork1 to whom the fortunes of the family were largely due4 ,richard ,boyle was born in the city of ,canterbury1 ,october #c1 #aeff4 ,he was educated at ,bene't ,college 7now ,corpus ,christi ,college71 ,cambridge1 and afterwards became a member of the ,middle ,temple4 ,finding his means insufficient for the prosecution of his legal studies1 he determined to seek his fortune abroad4 ,in #aeie he married1 at ,limerick1 one of the daughters of ,william ,apsley1 who brought him land of the value of ,l#ejj per annum4 ,in his autobiography the ,earl of ,cork writes3-- ,when first ,i arrived at ,dublin1 in ,ireland1 the #bcrd of ,june #aehh1 all my wealth then was twenty-seven pounds three shillings in money1 and two tokens which my mother had given me1 viz4 a diamond ring1 which ,i have ever since and still do wear1 and a bracelet of gold worth about ten pounds2 a taffety doublet cut with and upon taffety1 a pair of black velvet breeches laced1 a new ,milan fustian suit laced and cut upon taffety1 two cloaks1 competent linen1 and necessaries1 with my rapier and dagger4 ,and since1 the blessing of ,god1 whose heavenly providence guided me hither1 hath enriched my weak estate1 in beginning with such a fortune1 as ,i need not envy any of my neighbours1 and added no care or burthen of my conscience thereunto4 ,and the #bcrd of ,june1 #afcb1 ,i have served my ,god1 ,queen ,elizabeth1 ,king ,james1 and ,king ,charles1 full forty-four years1 and so long after as it shall please ,god to enable me4 ,richard ,boyle's property in ,ireland increased so rapidly that he was accused to ,queen ,elizabeth of receiving pay from some foreign power4 ,when about to visit ,england in order to clear himself of this charge1 the rebellion in ,munster broke out2 his lands were wasted1 and his income for the time destroyed4 ,reaching ,london1 he returned to his old chambers in the ,middle ,temple1 until he entered the service of the ,earl of ,essex1 to whom the government of ,ireland had been entrusted4 ,the charges against him were then resumed1 and he was made a prisoner1 and kept in confinement until the ,earl of ,essex had gone over to ,ireland4 ,at length he obtained a hearing before the queen1 who fully acquitted him of the charges1 gave him her hand to kiss1 and promised to employ him in her own service2 at the same time she dismissed ,sir ,henry ,wallop1 who was ,treasurer for ,ireland1 and prominent among ,boyle's accusers1 from his office4 ,a few days afterwards1 ,richard ,boyle was appointed by the queen ,clerk to the ,council of ,munster1 and having purchased a ship of ,sir ,walter ,raleigh1 he returned to ,ireland with ammunition and provisions4 ,then1 as ,clerk of the ,council1 ,i attended the ,lord ,president in all his employments1 and waited upon him at the siege of ,kingsale1 and was employed by his ,lordship to her ,majesty1 with the news of that happy victory2 in which employment ,i made a speedy expedition to the court2 for ,i left my ,lord ,president at ,shannon ,castle1 near ,corke1 on the ,monday morning1 about two of the clock1 and the next day1 being ,tuesday1 ,i delivered my packet1 and supped with ,sir ,robert ,cecil1 being then principal ,secretary of ,state1 at his house in the ,strand2 who1 after supper1 held me in discourse till two of the clock in the morning2 and by seven that morning called upon me to attend him to the court1 where he presented me to her ,majesty in her bed-chamber1 who remembered me1 calling me by my name1 and giving me her hand to kiss1 telling me that she was glad that ,i was the happy man to bring the first news of that glorious victory 444 and so ,i was dismissed with grace and favour4 ,in reading of this journey from ,cork to ,london1 it is almost necessary to be reminded that it took place two hundred and fifty years before the introduction of steam-boats and railways4 ,at the close of the rebellion1 ,richard ,boyle purchased from ,sir ,walter ,raleigh all his lands in ,munster2 and on ,july #be1 #afjc1 he married his second wife1 ,catharine1 the only daughter of ,sir ,geoffrey ,fenton1 principal ,secretary of ,state1 and ,privy ,councillor in ,ireland1 with whom ,i never demanded any marriage portion1 neither promise of any1 it not being in my consideration2 yet her father1 after my marriage1 gave me one thousand pounds in gold with her4 ,but that gift of his daughter unto me ,i must ever thankfully acknowledge as the crown of all my blessings2 for she was a most religious1 virtuous1 loving1 and obedient wife unto me all the days of her life4 ,he was knighted by the ,lord ,deputy of ,ireland1 ,sir ,george ,carew1 on his wedding-day2 was sworn ,privy ,councillor of ,state of the ,kingdom of ,ireland in #afab2 created ,lord ,boyle1 ,baron of ,youghall1 ,september #bi1 #afaf2 ,lord ,viscount of ,dungarvon and ,earl of ,cork1 ,october #bf1 #afbj2 one of the ,lords ,justices of ,ireland1 with a salary of ,l#abjj per annum1 in #afbi2 and ,lord ,high ,treasurer of ,ireland1 ,november #i1 #afca4 ,robert ,boyle1 the seventh son of the ,earl of ,cork1 was born ,january #be1 #afbg4 ,his mother died ,february #af1 #afcj4 ,the earl lived in prosperity in ,ireland till the breaking out of the rebellion in #afda1 and died at ,youghall in ,september1 #afdc4 ,it is said that when ,cromwell saw the vast improvements which the earl had made on his estate in ,munster1 he declared that if there had been an ,earl of ,cork in every province1 it would have been impossible for the ,irish to have raised a rebellion4 ,at a very early age ,robert was sent by his father to a country nurse1 who1 by early inuring him1 by slow degrees1 to a coarse but cleanly diet1 and to the usual passion of the air1 gave him so vigorous a complexion that both hardships were made easy to him by custom1 and the delights of conveniences and ease were endeared to him by their rarity4 ,making the acquaintance of some children who stuttered in their speech1 he1 by imitation1 acquired the same habit1 so contagious and catching are men's faults1 and so dangerous is the familiar commerce of those condemnable customs1 that1 being imitated but in jest1 come to be learned and acquired in earnest4 ,before going to school he studied ,french and ,latin1 and showed considerable aptitude for scholarship4 ,he was then sent to ,eton1 where his master took much notice of him1 and would sometimes give him unasked play-days1 and oft bestow upon him such balls and tops and other implements of idleness as he had taken away from others that had unduly used them4 ,while at school1 in the early morning1 a part of the wall of the bedroom1 with the bed1 chairs1 books1 and furniture of the room above1 fell on him and his brother4 ,his brother had his band torn about his neck1 and his coat upon his back1 and his chair crushed and broken under him2 but by a lusty youth1 then accidentally in the room1 was snatched from out the ruins1 by which ,robert had1 in all probability1 been immediately oppressed1 had not his bed been curtained by a watchful ,providence1 which kept all heavy things from falling on it2 but the dust of the crumbled rubbish raised was so thick that he might there have been stifled had not he remembered to wrap his head in the sheet1 which served him as a strainer1 through which none but the purer air could find a passage4 ,at ,eton he spent nearly four years1 in the last of which he forgot much of that ,latin he had got1 for he was so addicted to more solid parts of knowledge that he hated the study of bare words naturally1 as something that relished too much of pedantry to consort with his disposition and designs4 ,on leaving ,eton he joined his father at ,stalbridge1 in ,dorsetshire1 and was sent to reside with ,mr4 ,w4 ,douch1 then parson of that place1 who took the supervision of his studies4 ,here he renewed his acquaintance with ,latin1 and devoted some attention to ,english verse1 spending some of his idle hours in composing verses1 most of which1 the day he came of age1 he sacrificed to ,vulcan1 with a design to make the rest perish by the same fate4 ,a little later he returned to his father's house in ,stalbridge1 and was placed under the tutelage of a ,french gentleman1 who had been tutor to two of his brothers4 ,in ,october1 #afch1 ,robert ,boyle and his brother were sent into ,france4 ,after a short stay at ,lyons1 they reached ,geneva1 where ,robert remained with his tutor for about a year and three quarters4 ,during his residence here an incident occurred which he regarded as the most important event of his life1 and which we therefore give in his own words4 ,to frame a right apprehension of this1 you must understand that1 though his inclinations were ever virtuous1 and his life free from scandal and inoffensive1 yet had the piety he was master of already so diverted him from aspiring unto more1 that ,christ1 who long had lain asleep in his conscience 7as ,he once did in the ship71 must now1 as then1 be waked by a storm4 ,for at a time which 7being the very heat of summer7 promised nothing less1 about the dead of night1 that adds most terror to such accidents1 he was suddenly waked in a fright with such loud claps of thunder 7which are oftentimes very terrible in those hot climes and seasons71 that he thought the earth would owe an ague to the air1 and every clap was both preceded and attended with flashes of lightning1 so frequent and so dazzling that he began to imagine them the sallies of that fire that must consume the world4 ,the long continuance of that dismal tempest1 where the winds were so loud as almost drowned the noise of the very thunder1 and the showers so hideous as almost quenched the lightning ere it could reach his eyes1 confirmed him in his apprehensions of the day of judgment's being at hand4 ,whereupon the consideration of his unpreparedness to welcome it1 and the hideousness of being surprised by it in an unfit condition1 made him resolve and vow that1 if his fears were that night disappointed1 all his further additions to his life should be more religiously and watchfully employed4 ,the morning came1 and a serene1 cloudless sky returned1 when he ratified his determinations so solemnly1 that from that day he dated his conversion1 renewing1 now he was past danger1 the vow he had made whilst he believed himself to be in it2 and though his fear was 7and he blushed it was so7 the occasion of his resolution of amendment1 yet at least he might not owe his more deliberate consecration of himself to piety to any less noble motive than that of its own excellence4 ,after leaving ,geneva1 he crossed the ,alps and travelled through ,northern ,italy4 ,here he spent much time in learning ,italian2 the rest of his spare hours he spent in reading the modern history in ,italian1 and the new paradoxes of the great stargazer ,galileo1 whose ingenious books1 perhaps because they could not be so otherwise1 were confuted by a decree from ,rome2 his highness the ,pope1 it seems1 presuming1 and that justly1 that the infallibility of his chair extended equally to determine points in philosophy as in religion1 and loth to have the stability of that earth questioned in which he had established his kingdom4 ,having visited ,rome1 he at length returned to ,france1 and was detained at ,marseilles1 awaiting a remittance from the earl to enable him to continue his travels4 ,through some miscarriage1 the money which the earl sent did not arrive1 and ,robert and his brother had to depend on the credit of the tutor to procure the means to enable them to return home4 ,they reached ,england in the summer of #afdd1 where we found things in such confusion that1 although the manor of ,stalbridge were1 by my father's decease1 descended unto me1 yet it was near four months before ,i could get thither4 ,on reaching ,london1 ,robert ,boyle resided for some time with his sister1 ,lady ,ranelagh1 and was thus prevented from entering the ,royalist ,army4 ,later on he returned for a short time to ,france2 visited ,cambridge in ,december1 #afde1 and then took up his residence at ,stalbridge till ,may1 #afej1 where he commenced the study of chemistry and natural philosophy4 ,it was in ,october1 #afdf1 that ,boyle first made mention of the invisible college1 which afterwards developed into the ,royal ,society4 ,writing to a ,fellow of ,magdalen ,college1 ,cambridge1 in ,february1 #afdg1 he says1 ,the corner-stones of the invisible1 or1 as they term themselves1 the philosophical college1 do now and then honour me with their company4 ,it appears that a desire to escape from the troubles of the times had induced several persons to take refuge in philosophical pursuits1 and1 meeting together to discuss the subjects of their study1 they formed the invisible college4 ,boyle says1 ,i will conclude their praises with the recital of their chiefest fault1 which is very incident to almost all good things1 and that is1 that there is not enough of them4 ,dr4 ,wallis1 one of the first members of the society1 states that ,mr4 ,theodore ,hooke1 a ,german of the ,palatinate1 then resident in ,london1 gave the first occasion and first suggested those meetings and many others4 ,these meetings we held sometimes at ,dr4 ,goddard's lodging1 in ,wood ,street 7or some convenient place near71 on occasion of his keeping an operator in his house1 for grinding glasses for telescopes and microscopes1 and sometimes at a convenient place in ,cheapside2 sometimes at ,gresham ,college1 or some place near adjoining4 ,our business was 7precluding theology and ,state affairs7 to discourse and consider of philosophical inquiries1 and such as related thereunto2 as physic1 anatomy1 geometry1 astronomy1 navigation1 statics1 magnetics1 chemics1 mechanics1 and natural experiments1 with the state of these studies as then cultivated at home and abroad4 ,about the year #afdh-di some of us being removed to ,oxford1 first ,dr4 ,wilkins1 then ,i1 and soon after ,dr4 ,goddard1 our company divided4 ,those in ,london continued to meet there as before1 and we with them when we had occasion to be there4 ,and those of us at ,oxford1 with ,dr4 ,ward1 since ,bishop of ,salisbury1 ,dr4 ,ralph ,bathurst1 now ,president of ,trinity ,college in ,oxford1 ,dr4 ,petty1 since ,sir ,william ,petty1 ,dr4 ,willis1 then an eminent physician in ,oxford1 and divers others1 continued such meetings in ,oxford1 and brought those studies into fashion there2 meeting first at ,dr4 ,petty's lodgings1 in an apothecary's house1 because of the convenience of inspecting drugs and the like1 as there was occasion2 and after his remove to ,ireland 7though not so constantly7 at the lodgings of ,dr4 ,wilkins1 then ,warden of ,wadham ,college2 and after his removal to ,trinity ,college in ,cambridge1 at the lodgings of the ,honourable ,mr4 ,robert ,boyle1 then resident for divers years in ,oxford4 ,these meetings in ,london continued1 and after the king's return1 in #affj1 were increased with the accession of divers worthy and honourable persons1 and were afterwards incorporated by the name of the ,royal ,society1 and so continue to this day4 ,boyle was only about twenty years of age when he wrote his ,free ,discourse against ,swearing2 his ,seraphic ,love2 or1 ,some ,motives and ,incentives to the ,love of ,god2 and his ,essay on ,mistaken ,modesty4 ,seraphic ,love was the last of a series of treatises on love1 but the only one of the series that he published1 as he considered the others too trifling to be published alone or in conjunction with it4 ,in a letter to ,lady ,ranelagh1 he refers to his laboratory as a kind of ,elysium1 and there were few things which gave him so much pleasure as his furnaces and philosophical experiments4 ,in #afeb he visited ,ireland1 returning in the following summer4 ,in the autumn he was again obliged to visit ,ireland1 and remained there till the summer of #afed1 though residence in that country was far from agreeable to him4 ,he styled it a barbarous country1 where chemical spirits were so misunderstood1 and chemical instruments so unprocurable1 that it was hard to have any hermetic thoughts in it4 ,on his return he settled in ,oxford1 and there his lodgings soon became the centre of the scientific life of the university4 ,boyle and his friends may be regarded as the pioneers of experimental philosophy in this country4 ,to ,boyle the methods of ,aristotle appeared little more than discussions on words2 for a long time he refused to study the philosophy of ,descartes1 lest he should be turned aside from reasoning based strictly on the results of experiment4 ,the method pursued by these philosophers had been fully discussed by ,lord ,bacon1 but at best his experimental methods1 though most complete and systematic1 existed only upon paper1 and it was reserved for ,boyle and his friends to put the ,baconian philosophy into actual practice4 ,it was during his residence at ,oxford that he invented the air-pump1 which was afterwards improved for him by ,hooke1 and with which he conducted most of those experiments on the spring and weight of the air1 which led up to the investigations that have rendered his name inseparably connected with the gaseous laws4 ,the experiments of ,galileo and of ,torricelli had shown that the pressure of the air was capable of supporting a column of water about thirty-four feet in height1 or a column of mercury nearly thirty inches high4 ,the younger ,pascal1 at the request of ,torricelli1 had carried a barometer to the summit of the ,puy de ,dome1 and demonstrated that the height of the column of mercury supported by the air diminishes as the altitude is increased4 ,otto von ,guericke had constructed the ,magdeburg hemispheres1 and shown that1 when exhausted1 they could not be separated by sixteen horses1 eight pulling one way and eight the other4 ,he was aware that the same traction could have been produced by eight horses if one of the hemispheres had been attached to a fixed obstacle2 but1 with the instincts of a popular lecturer1 he considered that the spectacle would thus be rendered less striking1 and it was prepared for the king's entertainment4 ,boyle wished for an air-pump with an aperture in the receiver sufficiently large for the introduction of various objects1 and an arrangement for exhausting it without filling the receiver with water or otherwise interfering with the objects placed therein4 ,his apparatus consisted of a large glass globe capable of containing about three gallons or thereabouts1 terminating in an open tube below1 and with an aperture of about four inches diameter at the top4 ,around this aperture was cemented a turned brass ring1 the inner surface being conical1 and into this conical seat was fitted a brass plate with a thick rim1 but drilled with a small hole in the centre4 ,to this hole1 which was also conical1 was fitted a brass stopper1 which could be turned round when the receiver was exhausted4 ,by attaching a string to this stopper1 which was so long as to enter the receiver to the depth of two or three inches1 and turning the stopper in its seat1 the string could be wound up1 and thus objects could be moved within the receiver4 ,the tube at the bottom of the receiver communicated with a stop-cock1 and this with the upper end of the pumpbarrel1 which was inverted1 so that this stop-cock1 which was at the top of the barrel1 took the place of the foot-valve4 ,the piston was solid1 made of wood1 and surrounded with sole leather1 which was kept well greased4 ,there being no valve in the piston1 it was necessary to place an exhaust-valve in the upper end of the cylinder4 ,this consisted of a small brass plug closing a conical hole so that it could be removed at pleasure4 ,the construction of the cylinder was1 therefore1 similar to that of an ordinary force-pump1 except that the valves had to be moved by hand 7as in the early forms of the steam-engine74 ,the piston was raised and depressed by means of a rack and pinion4 ,the pumps could be used either for exhausting the receiver or for forcing air into it1 according to the order in which the valves were opened4 ,if the stop-cock communicating with the receiver were open while the piston was being drawn down1 and the brass plug removed so as to open the exhaust-valve when the piston was being forced up1 the receiver would gradually be exhausted4 ,if the brass plug were removed during the descent of the piston1 and the stop-cock opened during its ascent1 air would be forced into the receiver4 ,in the latter case it was necessary to take special precautions to prevent the brass plate at the top of the receiver being raised from its seat4 ,all joints were made air-tight with diachylon1 and when1 through the bursting of a glass bulb within it1 the receiver became cracked1 the crack was rendered air-tight by the same means4 ,other receivers of smaller capacity were also provided1 on account of the greater readiness with which they could be exhausted4 ,with this apparatus ,boyle carried out a long series of experiments4 ,he could reduce the pressure in the large receiver to somewhat less than that corresponding to an inch of mercury1 or about a foot of water4 ,squeezing a bladder so as to expel nearly all the air1 tying the neck1 and then introducing it into the receiver1 he found1 on working the pump1 that the bladder swelled so that at length it became completely distended4 ,in order to account for this great expansibility1 ,boyle pictured the constitution of the air in the following way4 ,he supposed the air to consist of separate particles1 each resembling a spiral spring1 which became tightly wound when exposed to great pressure1 but which expanded so as to occupy a larger circle when the pressure was diminished4 ,each of these little spirals he supposed to rotate about a diameter so as to exclude every other body from the sphere in which it moved4 ,increasing the length of the diameter tenfold would increase the volume of one of these spheres1 and therefore the volume of the gas1 a thousandfold4 ,possibly this was only intended as a mental illustration1 exhibiting a mechanism by which very great expansion might conceivably be produced1 and scarcely pretending to be considered a theory of the constitution of the air4 ,boyle's first idea seems to have been derived from a lock of wool in which the elasticity of each fibre caused the lock to expand after it had been compressed in the hand4 ,in another passage he speaks of the air as consisting of a number of bodies capable of striking against a surface exposed to them4 ,he demonstrated the weight of the air by placing a delicate balance within the receiver1 suspending from one arm a bladder half filled with water1 and balancing it with brass weights4 ,on exhausting the air1 the bladder preponderated1 and1 by repeating the experiment with additional weights on the other arm until a balance was effected in the exhausted receiver1 he determined the amount of the preponderance4 ,in another experiment he compressed air in a bladder by tying a pack-thread round it1 balanced it from one arm of his balance in the open air2 then1 pricking the bladder so as to relieve the pressure1 he found that with the escape of the compressed air the weight diminished4 ,one of the most important of his experiments with the air-pump was the following4 ,he placed within the receiver the cistern of a mercurial barometer1 the tube of which was made to pass through the central hole in the brass plate1 from which the stopper had been removed4 ,the space around the tube was filled up with cement1 and the receiver exhausted4 ,at each stroke of the pump the mercury in the barometer tube descended1 but through successively diminishing distances1 until at length it stood only an inch above the mercury in the cistern4 ,the experiment was then repeated with a tube four feet long and filled with water4 ,this constituted the nineteenth experiment referred to later on4 ,a great many strokes of the pump had to be made before the water began to descend4 ,at length it fell till the surface in the tube stood only about a foot above that in the tank4 ,placing vessels of ordinary spring-water and of distilled rain-water in the receiver1 he found that1 after the exhaustion had reached a certain stage1 bubbles of gas were copiously evolved from the spring-water1 but not from the distilled water4 ,on another occasion he caused warm water to boil by a few strokes of the pump2 and1 continuing the exhaustion1 the water was made to boil at intervals until it became only lukewarm4 ,the experiment was repeated with several volatile liquids4 ,he also noticed the cloud formed in the receiver when the air was allowed rapidly to expand2 but the mechanical theory of heat had not then made sufficient progress to enable him to account for the condensation by the loss of heat due to the work done by the expanding air4 ,the very minute accuracy of his observations is conspicuous in the descriptions of most of his experiments4 ,that the air is the usual medium for the conveyance of sound was shown by suspending a watch by a linen thread within the receiver4 ,on exhausting the air1 the ticking of the watch ceased to be heard4 ,a pretty experiment consisted in placing a bottle of a certain fuming liquid within the receiver2 on exhausting the air1 the fumes fell over the neck of the bottle and poured over the stand on which it was placed like a stream of water4 ,another experiment1 the thirty-second1 is worthy of mention on account of the use to which it was afterwards applied in the controversy respecting the cause of suction4 ,the receiver1 having been exhausted1 was removed from the cylinder1 the stop-cock being turned off1 and a small brass valve1 to which a scale-pan was attached1 was placed just under the aperture of the tube below the stop-cock4 ,on turning the latter1 the stream of air raised the valve1 closing the aperture1 and the atmospheric pressure supported it until a considerable weight had been placed in the scale-pan4 ,because the receiver could not be exhausted so thoroughly as the pump-cylinder1 ,boyle attempted to measure the pressure of the air by determining what weight could be supported by the piston4 ,he found first that a weight of twenty-eight pounds suspended directly from the piston was sufficient to overcome friction when air was admitted above the piston4 ,when the access of air to the top of the piston was prevented1 more than one hundred pounds additional weight was required to draw down the piston4 ,the diameter of the cylinder was about three inches4 ,boyle's style of reasoning is well illustrated by the following from his paper on ,the ,spring of the ,air3-- ,in the next place1 these experiments may teach us what to judge of the vulgar axiom received for so many ages as an undoubted truth in the peripatetick schools1 that ,nature abhors and flieth a vacuum1 and that to such a degree that no human power 7to go no higher7 is able to make one in the universe2 wherein heaven and earth would change places1 and all its other bodies rather act contrary to their own nature than suffer it4444 ,it will not easily1 then1 be intelligibly made out how hatred or aversation1 which is a passion of the soul1 can either for a vacuum or any other object be supposed to be in water1 or such like inanimate body1 which cannot be presumed to know when a vacuum would ensue1 if they did not bestir themselves to prevent it2 nor to be so generous as to act contrary to what is most conducive to their own particular preservation for the public good of the universe4 ,as much1 then1 of intelligible and probable truth as is contained in this metaphorical expression seems to amount but to this--that by the wise ,author of nature 7who is justly said to have made all things in number1 weight1 and measure7 the universe1 and the parts of it1 are so contrived that it is hard to make a vacuum in it1 as if they studiously conspired to prevent it4 ,and how far this itself may be granted deserves to be further considered4 ,for1 in the next place1 our experiments seem to teach that the supposed aversation of ,nature to a vacuum is but accidental1 or in consequence1 partly of the weight and fluidity1 or1 at least1 fluxility of the bodies here below2 and partly1 and perhaps principally1 of the air1 whose restless endeavour to expand itself every way makes it either rush in itself or compel the interposed bodies into all spaces where it finds no greater resistance than it can surmount4 ,and that in those motions which are made ob fugam vacui 7as the common phrase is71 bodies act without such generosity and consideration as is wont to be ascribed to them1 is apparent enough in our thirty-second experiment1 where the torrent of air1 that seemed to strive to get into the emptied receiver1 did plainly prevent its own design1 by so impelling the valve as to make it shut the only orifice the air was to get in at4 ,and if afterwards either ,nature or the internal air had a design the external air should be attracted1 they seemed to prosecute it very unwisely by continuing to suck the valve so strongly1 when they found that by that suction the valve itself could not be drawn in2 whereas1 by forbearing to suck1 the valve would1 by its own weight1 have fallen down and suffered the excluded air to return freely1 and to fill again the exhausted vessel4444 ,and as for the care of the public good of the universe ascribed to dead and stupid bodies1 we shall only demand why1 in our nineteenth experiment1 upon the exsuction of the ambient air1 the water deserted the upper half of the glass tube1 and did not ascend to fill it up till the external air was let in upon it4 ,whereas1 by its easy and sudden rejoining that upper part of the tube1 it appeared both that there was then much space devoid of air1 and that the water might1 with small or no resistance1 have ascended into it1 if it could have done so without the impulsion of the readmitted air2 which1 it seems1 was necessary to mind the water of its formerly neglected duty to the universe4 ,boyle then goes on to explain the phenomena correctly by the pressure of the air4 ,elsewhere he accounts for the diminished pressure on the top of a mountain by the diminished weight of the superincumbent column of air4 ,the treatise on ,the ,spring of the ,air met with much opposition1 and ,boyle considered it necessary to defend his doctrine against the objections of ,franciscus ,linus and ,hobbes4 ,in this defence he described the experiment in connection with which he is most generally remembered4 ,linus had admitted that the air might possess a certain small amount of elasticity1 but maintained that the force with which mercury rose in a barometer tube was due mainly to a totally different action1 as though a string were pulling upon it from above4 ,this was his funicular hypothesis4 ,boyle undertook to show that the pressure of the air might be made to support a much higher column of mercury than that of the barometer4 ,to this end he took a glass tube several feet in length1 and bent so as to form two vertical legs connected below4 ,the shorter leg was little more than a foot long1 and hermetically closed at the top4 ,the longer leg was nearly eight feet in length1 and open at the top4 ,the tube was suspended by strings upon the staircase1 the bend at the bottom pressing lightly against the bottom of a box placed to receive the mercury employed in case of accident4 ,each leg of the tube was provided with a paper scale4 ,mercury was poured in at the open end1 the tube being tilted so as to allow some of the air to escape from the shorter limb until the mercury stood at the same level in both legs when the tube was vertical4 ,the length of the closed tube occupied by the air was then just twelve inches4 ,the height of the barometer was about #bi-a_/h inches4 ,mercury was gently poured into the open limb by one operator1 while another watched its height in the closed limb4 ,the results of the experiments are given in the table on the opposite page4 ,in this table the third column gives the result of adding to the second column the height of the barometer1 which expresses in inches of mercury the pressure of the air on the free surface of the mercury in the longer limb4 ,the fourth column gives the total pressure1 in inches of mercury1 on the hypothesis that the pressure of the air varies inversely as the volume4 ,the agreement between the third and fourth columns is very close1 considering the roughness of the experiment and that no trouble appears to have been taken to calibrate the shorter limb of the tube1 and justified ,boyle in concluding that the hypothesis referred to expresses the relation between the volume and pressure of a given mass of air4 ---------------------------------------- ---------------- ,length of ,height of ,total pressure ,total pressure closed tubemercury in openon air in inchesaccording to occupied tube above thatof mercury4 ,boyle's law4 by air4 in closed tube4 ---------------------------------------- ---------------- #ab #j #bi-b_/af #bi-b_/af #aa-a_/b #a-g_/af #cj-i_/af #cj-f_/af #aa #b-ac_/af #ca-ae_/af #ca-ab_/af #aj-a_/b #d-f_/af #cc-h_/af #cc-a_/g #aj #f-c_/af #ce-e_/af #ce #i-a_/b #g-ad_/af #cg #cf-ae_/ai #i #aj-a_/af #ci-c_/af #ch-g_/h #h-a_/b #ab-h_/af #da-aj_/af #da-b_/ag #h #ae-a_/af #dd-c_/af #dc-aa_/af #g-a_/b #ag-ae_/af #dg-a_/af #df-c_/e #g #ba-c_/af #ej-e_/af #ej #f-a_/b #be-c_/af #ed-e_/af #ec-aj_/ac #f #bi-aa_/af #eh-ac_/af #eh-b_/h #e-c_/d #cb-c_/af #fa-e_/af #fj-ac_/bc #e-a_/b #cd-ae_/af #fd-a_/af #fc-f_/aa #e-a_/d #cg-ae_/af #fg-a_/af #ff-d_/g #e #da-i_/af #gj-aa_/af #gj #d-c_/d #de #gd-b_/af #gc-aa_/ai #d-a_/b #dh-ab_/af #gg-ad_/af #gg-b_/c #d-a_/d #ec-aa_/af #hb-ac_/af #hb-d_/ag #d #eh-b_/af #hg-ad_/af #hg-a_/h #c-c_/d #fc-ae_/af #ic-a_/af #ic-a_/e #c-a_/b #ga-e_/af #ajj-g_/af #ii-f_/g #c-a_/d #gh-aa_/af #ajg-ac_/af #ajg-g_/ac #c #hh-g_/af #aag-i_/af #aaf-d_/h ---------------------------------------- ---------------- ,to extend the investigation so as to include expansion below atmospheric pressure1 a different apparatus was employed4 ,it consisted of a glass tube about six feet in length1 closed at the lower end and filled with mercury4 ,into this bath of mercury was plunged a length of quill tube1 and the upper end was sealed with wax4 ,when the wax and air in the tube had cooled1 a hot pin was passed through the wax1 making a small orifice by which the amount of air in the tube was adjusted so as to occupy exactly one inch of its length as measured by a paper scale attached thereto1 after again sealing the wax4 ,the quill tube was then raised1 and the height of the surface of the mercury in the tube above that in the bath noticed1 together with the length of the tube occupied by the air4 ,the difference between the height of the barometer and the height of the mercury in the tube above that in the bath gave the pressure on the imprisoned air in inches of mercury4 ,the result showed that the volume varied very nearly in the inverse ratio of the pressure4 ,a certain amount of air1 however1 clung to the sides of the quill tube when immersed in the mercury1 and no care was taken to remove it by boiling the mercury or otherwise2 in consequence of this1 as the mercury descended1 this air escaped and joined the rest of the air in the tube4 ,this made the pressure rather greater than it should have been towards the end of the experiment1 and when the tube was again pressed down into the bath it was found that1 when the surfaces of the mercury within and without the tube were at the same level1 the air occupied nearly #a-a_/h inch instead of one inch of the tube4 ,these experiments first established the truth of the great law known as ,boyle's law1 which states that the volume of a given mass of a perfect gas varies inversely as the pressure to which it is exposed4 ,another experiment1 to show that the pressure of the air was the cause of suction1 ,boyle succeeded in carrying out at a later date4 ,two discs of marble were carefully polished1 so that when a little spirit of turpentine was placed between them the lower disc1 with a pound weight suspended from it1 was supported by the upper one4 ,the apparatus was introduced into the air-pump1 and a considerable amount of shaking proved insufficient to separate the discs4 ,after sixteen strokes of the pump1 on opening the communication between the receiver and cylinder1 when no mechanical vibration occurred1 the discs separated4 ,upon the ,restoration in #affj1 the ,earl of ,clarendon1 who was ,lord ,chancellor of ,england1 endeavoured to persuade ,boyle to enter holy orders1 urging the interest of the ,church as the chief motive for the proceeding4 ,this made some impression upon ,boyle1 but he declined for two reasons--first1 because he thought that he would have a greater influence for good if he had no share in the patrimony of the ,church2 and next1 because he had never felt an inward motion to it by the ,holy ,ghost4 ,in #afdi an association was incorporated by ,parliament1 to be called the ,president and ,society for the ,propagation of the ,gospel in ,new ,england1 whose object should be to receive and dispose of moneys in such manner as shall best and principally conduce to the preaching and propagating the gospel among the natives1 and for the maintenance of schools and nurseries of learning for the education of the children of the natives2 for which purpose a general collection was appointed to be made in and through all the counties1 cities1 towns1 and parishes of ,england and ,wales1 for a charitable contribution1 to be as the foundation of so pious and great an undertaking4 ,the society was revived by special charter in #affa1 and ,boyle was appointed president1 an office he continued to hold until shortly before his death4 ,the society afterwards enlarged its sphere of operations1 and became the ,society for the ,propagation of the ,gospel in ,foreign ,parts4 ,in the same year 7#affa7 ,boyle published ,some ,considerations on the ,usefulness of ,experimental ,natural ,philosophy1 etc41 and in #affc an extremely interesting paper on ,experiments and ,considerations touching ,colours4 ,in the course of this paper he describes some very beautiful experiments with a tincture of ,lignum nephriticum1 wherein the dichroism of the extract is made apparent4 ,boyle found that by transmitted light it appeared of a bright golden colour1 but when viewed from the side from which it was illuminated the light emitted was sky blue1 and in some cases bright green4 ,by arranging experiments so that some parts of the liquid were seen by the transmitted light and some by the scattered light1 very beautiful effects were produced4 ,boyle endeavoured to learn something of the nature of colours by projecting spectra on differently coloured papers1 and observing the appearance of the papers when illuminated by the several spectral rays4 ,he also passed sunlight1 concentrated by a lens1 through plates of differently coloured glass superposed1 allowing the light to fall on a white paper screen1 and observing the tint of the light which passed through each combination4 ,but the most interesting of these experiments was the actual mixture of light of different colours by forming two spectra1 one by means of a fixed prism1 the other by a prism held in the hand1 and superposing the latter on the former so that different colours were made to coincide4 ,this experiment was repeated in a modified form1 nearly two hundred years later1 by ,helmholtz1 who found that the mixture of blue and yellow lights produced pink4 ,unfortunately1 ,boyle's spectra were far from pure1 for1 the source of light being of considerable dimensions1 the different colours overlapped one another1 as in ,newton's experiments1 and in consequence some of his conclusions were inaccurate4 ,thus blue paper in the yellow part of the spectrum appeared to ,boyle green instead of black1 but this was due to the admixture of green light with the yellow4 ,he concluded that bodies appear black because they damp the light so as to reflect very little to the eye1 but that the surfaces of white bodies consist of innumerable little facets which reflect the light in all directions4 ,in the same year he published some ,observations on a ,diamond1 which shines in the ,dark2 and an extensive treatise on ,some ,considerations touching the ,style of the ,holy ,scriptures4 ,next year appeared several papers from his pen1 the most important being ,occasional ,reflections upon ,several ,subjects1 the wide scope of which may be gathered from the title4 ,his ,new ,experiments and ,observations touching ,cold were printed in #affe4 ,in this paper he discussed the cause of the force exerted by water in freezing1 methods of measuring degrees of cold1 the action of freezing-mixtures1 and many other questions4 ,he contended that cold was probably only privative1 and not a positive existence4 ,lord ,bacon had asserted that the essential self of heat was probably motion and nothing more1 and had adduced several experiments and observations in support of this opinion4 ,in his paper on the mechanical origin of heat and cold1 ,boyle maintained that heat was motion1 but motion of the very small particles of bodies1 very intense1 and taking place in all directions2 and that heat could be produced by any means whatever by which the particles of bodies could be agitated4 ,on one occasion he caused two pieces of brass1 one convex and the other concave1 to be pressed against each other by a spring1 and then rubbed together in a vacuum by a rotary motion communicated by a shaft which passed air-tight through the hole in the cover of the receiver1 a little emery being inserted between them4 ,in the second experiment the brasses became so hot that he could not endure to hold his hand on either of them4 ,this experiment was intended1 like the rubbing of the blocks of ice in vacuo by ,davy1 to meet the objection that the heat developed by friction was due to the action of the air4 ,the following extract from a paper intended to show that the sense of touch cannot be relied upon for the estimation of temperature1 shows that ,boyle possessed a very clear insight into the question3--,the account upon which we judge a body to be cold seems to be that we feel its particles less vehemently agitated than those of our fingers or other parts of the organ of touching2 and1 consequently1 if the temper of that organ be changed1 the object will appear more or less cold to us1 though itself continue of one and the same temperature4 ,to determine the expansion of water in freezing1 he filled the bulb and part of the stem of a bulb tube1 or1 as it was then generally called1 a philosophical egg1 with water1 and applying a freezing-mixture1 at first to the bottom of the bulb1 he succeeded in freezing the water without injury to the glass1 and found that #hb volumes of water expanded to #ia-a_/h volumes of ice--an expansion of about #aa-a_/h per cent4 ,probably air-bubbles caused the ice to appear to have a greater volume than it really possessed1 the true expansion being about nine per cent4 of the volume of the water at #d deg4,c4 ,the expansion of water in freezing he employed in order to compress air to a greater extent than he had been able otherwise to compress it4 ,having nearly filled a tube with water1 but left a little air above1 and then having sealed the top of the tube1 he froze the water from the bottom upwards1 so that in expanding it compressed the air to one-tenth of its former volume4 ,magnetism and electricity came in for some share of ,boyle's attention4 ,he carried out a number of experiments on magnetic induction1 and found that lodestones1 as well as pieces of iron1 when heated and allowed to cool1 became magnetized by the induction of the earth4 ,his later experiments with exhausted receivers were not made with his first pump1 but with a two-barrelled pump1 in which the pistons were connected by a cord passing over a large fixed pulley1 so that1 when the receiver was nearly exhausted1 the pressure of the air on the descending piston during the greater part of the stroke nearly balanced that on the ascending piston4 ,in this respect the pump differed only from ,hawksbee's in having the pulley and cord instead of the pinion and two racks4 ,it also resembled ,hawksbee's pump in having self-closing valves in the pistons and at the bottom of the cylinders1 which1 in this pump1 had their open ends at the top4 ,the pistons were alternately raised and lowered by the feet of the operator1 which were placed in stirrups1 of which one was fixed on each piston4 ,the lower portions of the barrels were filled with water1 through which the air bubbled1 and this1 occupying the clearance1 enabled a much higher degree of exhaustion to be produced than could be obtained without its employment4 ,in #affe ,boyle was nominated ,provost of ,eton1 but declined to accept the appointment4 ,his ,hydrostatical ,paradoxes1 published about this time1 contain all the ordinary theorems respecting the pressure of fluids under the action of gravity demonstrated experimentally4 ,in #afgg ,boyle printed1 at his own expense1 five hundred copies of the four ,gospels and the ,acts of the ,apostles in the ,malayan tongue4 ,this was but one of his many contributions towards similar objects4 ,on ,november #cj1 #afhj1 the ,royal ,society chose ,boyle for ,president4 ,he1 however1 declined to accept the appointment1 because he had conscientious objections to taking the oath required of the ,president by the charter of the ,society4 ,it appears that very many of ,boyle's manuscripts1 which were written in bound books1 were taken away1 and others mutilated by corrosive liquors4 ,in ,may1 #afhh1 he made this known to his friends1 but1 though these losses put him on his guard1 he complained afterwards that all his care and circumspection had not prevented the loss of six centuries of matters of fact in one parcel1 besides many other smaller papers4 ,his works1 however1 which have been published are so numerous that it would take several pages for the bare enumeration of their titles1 many of them being devoted to medical subjects4 ,the edition published in ,london in #agdc comprises nearly three thousand pages of folio4 ,boyle always suffered from weak eyes1 and in consequence he declined to revise his proofs4 ,in the advertisement to the original edition of his works the publisher mentioned this1 and at the same time pleaded his own business engagements as an excuse for not revising the proofs himself6 ,it was partly on account of the injury to his manuscripts1 and partly through failing health1 that in #afhi he set apart two days in the week1 during which he declined to receive visitors1 that he might devote himself to his work1 and especially to the reparation of the injured writings4 ,about this time he succeeded in procuring the repeal of an ,act passed in the fifth year of ,henry ,,iv4 to the effect that none from thenceforth should use to multiply gold or silver1 or use the craft of multiplication2 and if any the same do1 they should incur the pain of felony4 ,by this repeal it was made legal to extract gold and silver from ores1 or from their mixtures with other metals1 in this country provided that the gold and silver so procured should be put to no other use than the increase of moneys4 ,it is curious that ,boyle seems always to have believed in the possibility of transmuting other metals into gold4 ,his sister1 ,lady ,ranelagh1 died on ,december #bc1 #afia1 and ,boyle survived her but a few days1 for he died on ,december #cj1 and his body was interred near his sister's grave in the chancel of ,st4 ,martin's-in-the-,fields4 ,dr4 ,shaw1 in his preface to ,boyle's works1 writes1 ,the men of wit and learning have1 in all ages1 busied themselves in explaining nature by words2 but it is ,mr4 ,boyle alone who has wholly laid himself out in showing philosophy in action4 ,the single point he perpetually keeps in view is to render his reader1 not a talkative or a speculative1 but an actual and practical philosopher4 ,himself sets the example2 he made all the experiments he possibly could upon natural bodies1 and communicated them with all desirable candour and fidelity4 ,the second part of his treatise on ,the ,christian ,virtuoso1 ,boyle concluded with a number of aphorisms1 of which the following well represent his views respecting science3-- ,i think it becomes ,christian philosophers rather to try whether they can investigate the final causes of things than1 without trial1 to take it for granted that they are undiscoverable4 ,the book of ,nature is a fine and large piece of tapestry rolled up1 which we are not able to see all at once1 but must be content to wait for the discovery of its beauty and symmetry1 little by little1 as it gradually comes to be more unfolded or displayed4 ,,benjamin ,,franklin4 ,among those whose contributions to physics have immortalized their names in the annals of science1 there is none that holds a more prominent position in the history of the world than ,benjamin ,franklin4 ,at one time a journeyman printer1 living in obscure lodgings in ,london1 he became1 during the ,american ,war of ,independence1 one of the most conspicuous figures in ,europe1 and among ,americans his reputation was probably second to none1 ,general ,washington not excepted4 ,professor ,laboulaye says of ,franklin3 ,no one ever started from a lower point than the poor apprentice of ,boston4 ,no one ever raised himself higher by his own unaided forces than the inventor of the lightning-rod4 ,no one has rendered greater service to his country than the diplomatist who signed the treaty of #aghc1 and assured the independence of the ,united ,states4 ,better than the biographies of ,plutarch1 this life1 so long and so well filled1 is a source of perpetual instruction to all men4 ,every one can there find counsel and example4 ,a great part of the history of his life was written by ,franklin himself1 at first for the edification of the members of his own family1 and afterwards at the pressing request of some of his friends in ,london and ,paris4 ,his autobiography does not1 however1 comprise much more than the first fifty years of his life4 ,the first part was written while he was the guest of the ,bishop of ,st4 ,asaph1 at ,twyford2 the second portion at ,passy1 in the house of ,m4 de ,chaumont2 and the last part in ,philadelphia1 when he was retiring from public life at the age of eighty-two4 ,the former part of this autobiography was translated into ,french1 and published in ,paris1 in #agic1 though it is not known how the manuscript came into the publisher's hands4 ,the ,french version was translated into ,english1 and published in ,england and ,america1 together with such other of ,franklin's works as could be collected1 before the latter part was given to the world by ,franklin's grandson1 to whom he had bequeathed his papers1 and who first published them in ,america in #ahag4 ,for a period of three hundred years at least ,franklin's family lived on a small freehold of about thirty acres1 in the village of ,ecton1 in ,northamptonshire1 the eldest son1 who inherited the property1 being always brought up to the trade of a smith4 ,franklin himself was the youngest son of the youngest son for five generations back4 ,his grandfather lived at ,ecton till he was too old to follow his business1 when he went to live with his second son1 ,john1 who was a dyer at ,banbury4 ,to this business ,franklin's father1 ,josiah1 was apprenticed4 ,the eldest son1 ,thomas1 was brought up a smith1 but afterwards became a solicitor2 the other son1 ,benjamin1 was a silk-dyer1 and followed ,josiah to ,america4 ,he was fond of writing poetry and sermons4 ,the latter he wrote in a shorthand of his own inventing1 which he taught to his nephew and namesake1 in order that he might utilize the sermons if1 as was proposed1 he became a ,presbyterian minister4 ,franklin's father1 ,josiah1 took his wife and three children to ,new ,england1 in #afhb1 where he practised the trade of a tallow-chandler and soap-boiler4 ,franklin was born in ,boston on ,january #f 7,o4,s471 #agjf1 and was the youngest of seventeen children1 of whom thirteen grew up and married4 ,benjamin being the youngest of ten sons1 his father intended him for the service of the ,church1 and sent him to the grammar school when eight years of age1 where he continued only a year1 although he made very rapid progress in the school2 for his father concluded that he could not afford the expense of a college education1 and at the end of the year removed him to a private commercial school4 ,at the age of ten young ,benjamin was taken home to assist in cutting the wicks of candles1 and otherwise to make himself useful in his father's business4 ,his enterprising character as a boy is shown by the following story1 which is in his own words3-- ,there was a salt marsh that bounded part of the mill-pond1 on the edge of which1 at high-water1 we used to stand to fish for minnows4 ,by much trampling we had made it a mere quagmire4 ,my proposal was to build a wharf there fit for us to stand upon1 and ,i showed my comrades a large heap of stones1 which were intended for a new house near the marsh1 and which would very well suit our purpose4 ,accordingly1 in the evening1 when the workmen were gone1 ,i assembled a number of my play-fellows1 and working with them diligently1 like so many emmets1 sometimes two or three to a stone1 we brought them all away and built our little wharf4 ,the next morning the workmen were surprised at missing the stones1 which were found in our wharf4 ,inquiry was made after the removers2 we were discovered and complained of2 several of us were corrected by our fathers2 and1 though ,i pleaded the usefulness of the work1 mine convinced me that nothing was useful which was not honest4 ,until twelve years of age ,benjamin continued in his father's business1 but as he manifested a great dislike for it1 and his parents feared that he might one day run away to sea1 they set about finding some trade which would be more congenial to his tastes4 ,with this view his father took him to see various artificers at their work1 that he might observe the tastes of the boy4 ,this experience was very valuable to him1 as it taught him to do many little jobs for himself when workmen could not readily be procured4 ,during this time ,benjamin spent most of his pocket-money in purchasing books1 some of which he sold when he had read them1 in order to buy others4 ,he read through most of the books in his father's very limited library4 ,these mainly consisted of works on theological controversy1 which ,franklin afterwards considered to have been not very profitable to him4 ,there was another bookish lad in the town1 ,john ,collins by name1 with whom ,i was intimately acquainted4 ,we sometimes disputed1 and very fond we were of argument1 and very desirous of confuting one another1 which disputatious turn1 by the way1 is apt to become a very bad habit1 making people often very disagreeable in company by the contradiction that is necessary to bring it into practice2 and thence1 besides souring and spoiling the conversation1 is productive of disgusts and perhaps enmities when you may have occasion for friendship4 ,i had caught it by reading my father's books of dispute about religion4 ,persons of good sense1 ,i have since observed1 seldom fall into it1 except lawyers1 university men1 and men of all sorts that have been bred at ,edinburgh4 ,at length ,franklin's fondness for books caused his father to decide to make him a printer4 ,his brother ,james had already entered that business1 and had set up in ,boston with a new press and types which he had brought from ,england4 ,he signed his indentures when only twelve years old1 thereby apprenticing himself to his brother until he should attain the age of twenty-one4 ,the acquaintance which he formed with booksellers through the printing business enabled him to borrow a better class of books than he had been accustomed to1 and he frequently sat up the greater part of the night to read a book which he had to return in the morning4 ,while working with his brother1 the young apprentice wrote two ballads1 which he printed and sold in the streets of ,boston4 ,his father1 however1 ridiculed the performance2 so he escaped being a poet4 ,he adopted at this time a somewhat original method to improve his prose writing4 ,meeting with an odd volume of the ,spectator1 he purchased it and read it over and over1 and wished to imitate the style4 ,making short notes of the sentiment in each sentence1 he laid them by1 and afterwards tried to write out the papers without looking at the original4 ,then on comparison he discovered his faults and corrected them4 ,finding his vocabulary deficient1 he turned some of the tales into verse1 then retranslated them into prose1 believing that the attempt to make verses would necessitate a search for several words of the same meaning4 ,i also sometimes jumbled my collection of hints into confusion1 and after some weeks endeavoured to reduce them into the best order1 before ,i began to form the full sentence and complete the paper4 ,this was to teach me method in the arrangement of my thoughts4 ,meeting with a book on vegetarianism1 ,franklin determined to give the system a trial4 ,this led to some inconvenience in his brother's house-keeping1 so ,franklin proposed to board himself if his brother would give him half the sum he paid for his board1 and out of this he was able to save a considerable amount for the purpose of buying books4 ,moreover1 the time required for meals was so short that the dinner hour afforded considerable leisure for reading4 ,it was on his journey from ,boston to ,philadelphia that he first violated vegetarian principles2 for1 a large cod having been caught by the sailors1 some small fishes were found in its stomach1 whereupon ,franklin argued that if fishes ate one another1 there could be no reason against eating them1 so he dined on cod during the rest of the journey4 ,after reading ,xenophon's ,memorabilia1 ,franklin took up strongly with the ,socratic method of discussion1 and became so artful and expert in drawing people1 even of superior knowledge1 into concessions1 the consequence of which they did not foresee1 that some time afterwards one of his employers1 before answering the most simple question1 would frequently ask what he intended to infer from the answer4 ,this practice he gradually gave up1 retaining only the habit of expressing his opinions with modest diffidence4 ,in #agbj or #agba ,james ,franklin began to print a newspaper1 the ,new ,england ,courant4 ,to this paper1 which he helped to compose and print1 ,benjamin became an anonymous contributor4 ,the members of the staff spoke highly of his contributions1 but when the authorship became known1 ,james appears to have conceived a jealousy of his younger brother1 which ultimately led to their separation4 ,an article in the paper having offended the ,assembly1 ,james was imprisoned for a month and forbidden to print the paper4 ,he then freed ,benjamin from his indentures1 in order that the paper might be published in his name4 ,at length1 some disagreement arising1 ,benjamin took advantage of the cancelling of his indentures to quit his brother's service4 ,as he could get no employment in ,boston1 he obtained a passage to ,new ,york1 whence he was recommended to go to ,philadelphia1 which he reached after a very troublesome journey4 ,his whole stock of cash then consisted of a ,dutch dollar and about a shilling's worth of coppers4 ,the coppers he gave to the boatmen with whom he came across from ,burlington4 ,his first appearance in ,philadelphia1 about eight o'clock on a ,sunday morning1 was certainly striking4 ,a youth between seventeen and eighteen years of age1 dressed in his working clothes1 which were dirty through his journey1 with his pockets stuffed out with stockings and shirts1 his aspect was not calculated to command respect4 ,then ,i walked up the street1 gazing about till near the market-house ,i met a boy with bread4 ,i had made many a meal on bread1 and1 inquiring where he got it1 ,i went immediately to the baker's he directed me to1 in ,second ,street1 and ask'd for bisket1 intending such as we had in ,boston2 but they1 it seems1 were not made in ,philadelphia4 ,then ,i asked for a threepenny loaf1 and was told they had none such4 ,so1 not considering or knowing the difference of money1 and the greater cheapness1 nor the name of his bread1 ,i bad him give me three-penny-worth of any sort4 ,he gave me1 accordingly1 three great puffy rolls4 ,i was surpriz'd at the quantity1 but took it1 and having no room in my pockets1 walk'd off with a roll under each arm1 and eating the other4 ,thus ,i went up ,market ,street as far as ,fourth ,street1 passing by the door of ,mr4 ,read1 my future wife's father2 when she1 standing at the door1 saw me1 and thought ,i made1 as ,i certainly did1 a most awkward1 ridiculous appearance4 ,then ,i turned and went down ,chestnut ,street and part of ,walnut ,street1 eating my roll all the way1 and1 coming round1 found myself again at ,market ,street ,wharf1 near the boat ,i came in1 to which ,i went for a draught of the river water2 and1 being filled out with one of my rolls1 gave the other two to a woman and her child that came down the river in the boat with us1 and were waiting to go further4 ,in ,philadelphia ,franklin obtained an introduction1 through a gentleman he had met at ,new ,york1 to a printer1 named ,keimer1 who had just set up business with an old press which he appeared not to know how to use1 and one pair of cases of ,english type4 ,here ,franklin obtained employment when the business on hand would permit1 and he put the press in order and worked it4 ,keimer obtained lodgings for him at the house of ,mr4 ,read1 and1 by industry and economical living1 ,franklin found himself in easy circumstances4 ,sir ,william ,keith was then ,governor of ,pennsylvania1 and hearing of ,franklin1 he called upon him at ,keimer's printing-office1 invited him to take wine at a neighbouring tavern1 and promised to obtain for him the ,government printing if he would set up for himself4 ,it was then arranged that ,franklin should return to ,boston by the first ship1 in order to see what help his father would give towards setting him up in business4 ,in the mean while he was frequently invited to dine at the governor's house4 ,notwithstanding ,sir ,william ,keith's recommendation1 ,josiah ,franklin thought his son too young to take the responsibility of a business1 and would only promise to assist him if1 when he was twenty-one1 he had himself saved sufficient to purchase most of the requisite plant4 ,on his return to ,philadelphia1 he delivered his father's letter to ,sir ,william ,keith1 whereon the governor1 stating that he was determined to have a good printer there1 promised to find the means of equipping the printing-office himself1 and suggested the desirability of ,franklin's making a journey to ,england in order to purchase the plant4 ,he promised letters of introduction to various persons in ,england1 as well as a letter of credit to furnish the money for the purchase of the printing-plant4 ,these letters ,franklin was to call for1 but there was always some excuse for their not being ready4 ,at last they were to be sent on board the ship1 and ,franklin1 having gone on board1 awaited the letters4 ,when the governor's despatches came1 they were all put into a bag together1 and the captain promised to let ,franklin have his letters before landing4 ,on opening the bag off ,plymouth1 there were no letters of the kind promised1 and ,franklin was left without introductions and almost without money1 to make his own way in the world4 ,in ,london he learned that ,governor ,keith was well known as a man in whom no dependence could be placed1 and as to his giving a letter of credit1 he had no credit to give4 ,a friend of ,franklin's1 named ,ralph1 accompanied him from ,america1 and the two took lodgings together in ,little ,britain at three shillings and sixpence per week4 ,franklin immediately obtained employment at ,palmer's printing-office1 in ,bartholomew ,close2 but ,ralph1 who knew no trade1 but aimed at literature1 was unable to get any work4 ,he could not obtain employment1 even among the law stationers as a copying clerk1 so for some time the wages which ,franklin earned had to support the two4 ,at ,palmer's ,franklin was employed in composing ,wollaston's ,religion of ,nature4 ,on this he wrote a short critique1 which he printed4 it was entitled ,a ,dissertation on ,liberty and ,necessity1 ,pleasure and ,pain4 ,the publication of this he afterwards regretted1 but it obtained for him introductions to some literary persons in ,london4 ,subsequently he left ,palmer's and obtained work at ,watts's printing-office1 where he remained during the rest of his stay in ,london4 ,the beer-drinking capabilities of some of his fellow-workmen excited his astonishment4 ,he says3-- ,we had an alehouse boy who attended always in the house to supply the workmen4 ,my companion at the press drank every day a pint before breakfast1 a pint at breakfast with his bread and cheese1 a pint between breakfast and dinner1 a pint at dinner1 a pint in the afternoon about six o'clock1 and another when he had done his day's work4 ,i thought it a detestable custom1 but it was necessary1 he suppos'd1 to drink strong beer1 that he might be strong to labour4 ,i endeavoured to convince him that the bodily strength afforded by beer could only be in proportion to the grain or flour of the barley dissolved in the water of which it was made2 that there was more flour in a pennyworth of bread2 and therefore1 if he would eat that with a pint of water1 it would give him more strength than a quart of beer4 ,he drank on1 however1 and had four or five shillings to pay out of his wages every ,saturday night for that muddling liquor2 an expense ,i was free from4 ,and thus these poor devils keep themselves always under4 ,afterwards ,franklin succeeded in persuading several of the compositors to give up their muddling breakfast of beer and bread and cheese1 for a porringer of hot-water gruel1 with pepper1 breadcrumbs1 and butter1 which they obtained from a neighbouring house at a cost of three halfpence4 ,among ,franklin's fellow-passengers from ,philadelphia to ,england was an ,american merchant1 a ,mr4 ,denham1 who had formerly been in business in ,bristol1 but failed and compounded with his creditors4 ,he then went to ,america1 where he soon acquired a fortune1 and returned in ,franklin's ship4 ,he invited all his old creditors to dine with him4 ,at the dinner each guest found under his plate a cheque for the balance which had been due to him1 with interest to date4 ,this gentleman always remained a firm friend to ,franklin1 who1 during his stay in ,london1 sought his advice when any important questions arose4 ,when ,mr4 ,denham returned to ,philadelphia with a quantity of merchandise1 he offered ,franklin an appointment as clerk1 which was afterwards to develop into a commission agency4 ,the offer was accepted1 and1 after a voyage of nearly three months1 ,franklin reached ,philadelphia on ,october #aa1 #agbf4 ,here he found ,governor ,keith had been superseded by ,major ,gordon1 and1 what was of more importance to him1 that ,miss ,read1 to whom he had become engaged before leaving for ,england1 and to whom he had written only once during his absence1 had married4 ,shortly after starting in business1 ,mr4 ,denham died1 and thus left ,franklin to commence life again for himself4 ,keimer had by this time obtained a fairly extensive establishment1 and employed a number of hands1 but none of them were of much value2 and he made overtures to ,franklin to take the management of his printing-office1 apparently with the intention of getting his men taught their business1 so that he might afterwards be able to dispense with the manager4 ,franklin set the printing-house in order1 started type-founding1 made the ink1 and1 when necessary1 executed engravings4 ,as the other hands improved under his superintendence1 ,keimer began to treat his manager less civilly1 and apparently desired to curtail his stipend4 ,at length1 through an outbreak of temper on the part of ,keimer1 ,franklin left1 but was afterwards induced to return in order to prepare copper-plates and a press for printing paper money for ,new ,jersey4 ,while working for ,keimer1 ,franklin formed a club1 which was destined to exert considerable influence on ,american politics4 ,the club met on ,friday evenings1 and was called the ,junto4 ,it was essentially a debating society1 the subject for each evening's discussion being proposed at the preceding meeting4 ,one of the rules was that the existence of the club should remain a secret1 and that its members should be limited to twelve4 ,afterwards other similar clubs were formed by its members2 but the existence of the ,junto was kept a secret from them4 ,the club lasted for about forty years1 and became the nucleus of the ,american ,philosophical ,society1 of which ,franklin was the first president4 ,this1 and the fact that many of the great questions that arose previously to the ,declaration of ,independence were discussed in the ,junto in the first instance1 give to the club a special importance4 ,the following are specimens of subjects discussed by the club3-- ,is sound an entity or body8 ,how may the phenomena of vapours be explained8 ,is self-interest the rudder that steers mankind1 the universal monarch to whom all are tributaries8 ,which is the best form of government8 and what was that form which first prevailed among mankind8 ,can any one particular form of government suit all mankind8 ,what is the reason that the tides rise higher in the ,bay of ,fundy than the ,bay of ,delaware8 ,is the emission of paper money safe8 ,what is the reason that men of the greatest knowledge are not the most happy8 ,how may the possessions of the ,lakes be improved to our advantage8 ,why are tumultuous1 uneasy sensations united with our desires8 ,whether it ought to be the aim of philosophy to eradicate the passions4 ,how may smoky chimneys be best cured8 ,why does the flame of a candle tend upwards in a spire8 ,which is least criminal--a bad action joined with a good intention1 or a good action with a bad intention8 ,is it consistent with the principles of liberty in a free government to punish a man as a libeller when he speaks the truth8 ,on leaving ,keimer's1 ,franklin went into partnership with one of his fellow-workmen1 ,hugh ,meredith1 whose father found the necessary capital1 and a printing-office was started which soon excelled its two rivals in ,philadelphia4 ,franklin's industry attracted the attention of the townsfolk1 and inspired the merchants with confidence in the prospects of the new concern4 ,keimer started a newspaper1 which he had not the ability to carry on2 ,franklin purchased it from him for a trifle1 remodelled it1 and continued it in a very spirited manner under the title of the ,pennsylvania ,gazette4 ,his political articles soon attracted the attention of the principal men of the state2 the number of subscribers increased rapidly1 and the paper became a source of considerable profit4 ,soon after1 the printing for the ,house of ,representatives came into the hands of the firm4 ,meredith never took to the business1 and was seldom sober1 and at length was bought out by his partner1 on ,july #ad1 #agcj4 ,the discussion in the ,junto on paper currency induced ,franklin to publish a paper entitled ,the ,nature and ,necessity of a ,paper ,currency4 ,this was a prominent subject before the ,house1 but the introduction of paper money was opposed by the capitalists4 ,they were unable1 however1 to answer ,franklin's arguments2 the point was carried in the ,house1 and ,franklin was employed to print the money4 ,the amount of paper money in ,pennsylvania in #agci amounted to ,l#hj1jjj2 during the war it rose to more than ,l#cej1jjj4 ,in order to secure my credit and character as a tradesman1 ,i took care not only to be in reality industrious and frugal1 but to avoid all appearances to the contrary4 ,i drest plainly2 ,i was seen at no places of idle diversion4 ,i never went out a-fishing or shooting2 a book1 indeed1 sometimes debauch'd me from my work1 but that was seldom1 snug1 and gave no scandal2 and1 to show that ,i was not above my business1 ,i sometimes brought home the paper ,i purchas'd at the stores thro' the streets on a wheelbarrow4 ,thus being esteem'd an industrious1 thriving young man1 and paying duly for what ,i bought1 the merchants who imported stationery solicited my custom2 others proposed supplying me with books1 and ,i went on swimmingly4 ,in the mean time1 ,keimer's credit and business declining daily1 he was at last forc'd to sell his printing-house to satisfy his creditors4 ,on ,september #a1 #agcj1 ,franklin married his former fiancee1 whose previous husband had left her and was reported to have died in the ,west ,indies4 ,the marriage was a very happy one1 and continued over forty years1 ,mrs4 ,franklin living until the end of #aggd4 ,industry and frugality reigned in the household of the young printer4 ,mrs4 ,franklin not only managed the house1 but assisted in the business1 folding and stitching pamphlets1 and in other ways making herself useful4 ,the first part of ,franklin's autobiography concludes with an account of the foundation of the first subscription library4 ,by the co-operation of the members of the ,junto1 fifty subscribers were obtained1 who each paid in the first instance forty shillings1 and afterwards ten shillings per annum4 ,we afterwards obtained a charter1 the company being increased to one hundred4 ,this was the mother of all the ,north ,american subscription libraries1 now so numerous4 ,it is become a great thing itself1 and continually increasing4 ,these libraries have improved the general conversation of the ,americans1 made the common tradesmen and farmers as intelligent as most gentlemen from other countries1 and perhaps have contributed in some degree to the stand so generally made throughout the colonies in defence of their privileges4 ,ten years ago this library contained between seventy and eighty thousand volumes4 ,franklin's success in business was attributed by him largely to his early training4 ,my circumstances1 however1 grew daily easier4 ,my original habits of frugality continuing1 and my father having1 among his instructions to me when a boy1 frequently repeated a proverb of ,solomon1 ',seest thou a man diligent in his business8 he shall stand before kings2 he shall not stand before mean men1' ,i from thence considered industry as a means of obtaining wealth and distinction1 which encourag'd me1 tho' ,i did not think that ,i should ever literally stand before kings1 which1 however1 has since happened2 for ,i have stood before five1 and even had the honour of sitting down with one1 the ,king of ,denmark1 to dinner4 ,after his marriage1 ,franklin conceived the idea of obtaining moral perfection4 ,he was not altogether satisfied with the result1 but thought his method worthy of imitation4 ,assuming that he possessed complete knowledge of what was right or wrong1 he saw no reason why he should not always act in accordance therewith4 ,his principle was to devote his attention to one virtue only at first for a week1 at the end of which time he expected the practice of that virtue to have become a habit4 ,he then added another virtue to his list1 and devoted his attention to the same for the next week1 and so on1 until he had exhausted his list of virtues4 ,he then commenced again at the beginning4 ,as his moral code comprised thirteen virtues1 it was possible to go through the complete curriculum four times in a year4 ,afterwards he occupied a year in going once through the list1 and subsequently employed several years in one course4 ,a little book was ruled1 with a column for each day and a line for each virtue1 and in this a mark was made for every failure which could be remembered on examination at the end of the day4 ,it is easy to believe his statement3 ,i am surprised to find myself so much fuller of faults than ,i had imagined2 but ,i had the satisfaction of seeing them diminish4 ,this my little book had for its motto these lines from ,addison's ',cato'3-- ',here will ,i hold4 ,if there's a ,power above us 7,and that there is1 all ,nature cries aloud ,thro' all her work71 ,he must delight in virtue2 ,and that which ,he delights in must be happy4' ,another from ,cicero3-- ',o vitae ,philosophia dux6 ,o virtutum indagatrix expultrixque vitiorum6 ,unus dies ex praeceptis tuis actus1 peccanti immortalitati est anteponendus4' ,another from the ,proverbs of ,solomon1 speaking of wisdom and virtue3-- ',length of days is in her right hand2 and in her left hand riches and honour4 ,her ways are ways of pleasantness1 and all her paths are peace4' ,and conceiving ,god to be the fountain of wisdom1 ,i thought it right and necessary to solicit ,his assistance for obtaining it2 to this end ,i formed the following little prayer1 which was prefixed to my tables of examination1 for daily use3-- ',o powerful ,goodness6 bountiful ,father6 merciful ,guide6 increase in me that wisdom which discovers my truest interest4 ,strengthen my resolutions to perform what that wisdom dictates4 ,accept my kind offices to ,thy other children as the only return in my power for ,thy continual favours to me4' ,i used also sometimes a little prayer which ,i took from ,thomson's ,poems1 viz43-- ',father of light and life1 ,thou ,good ,supreme6 ,oh teach me what is good2 teach me ,thyself6 ,save me from folly1 vanity1 and vice1 ,from every low pursuit2 and fill my soul ,with knowledge1 conscious peace1 and virtue pure2 ,sacred1 substantial1 never-failing bliss6' ,the senses in which ,franklin's thirteen virtues were to be understood were explained by short precepts which followed them in his list4 ,the list was as follows3-- #a4 ,,temperance4 ,eat not to dulness2 drink not to elevation4 #b4 ,,silence4 ,speak not but what may benefit others or yourself2 avoid trifling conversation4 #c4 ,,order4 ,let all your things have their places2 let each part of your business have its time4 #d4 ,,resolution4 ,resolve to perform what you ought2 perform without fail what you resolve4 #e4 ,,frugality4 ,make no expense but to do good to others or yourself2 i4e4 waste nothing4 #f4 ,,industry4 ,lose no time2 be always employed in something useful2 cut off all unnecessary actions4 #g4 ,,sincerity4 ,use no hurtful deceit2 think innocently and justly2 and1 if you speak1 speak accordingly4 #h4 ,,justice4 ,wrong none by doing injuries1 or omitting the benefits that are your duty4 #i4 ,,moderation4 ,avoid extremes2 forbear resenting injuries so much as you think they deserve4 #aj4 ,,cleanliness4 ,tolerate no uncleanness in body1 clothes1 or habitation4 #aa4 ,,tranquillity4 ,be not disturbed at trifles1 or accidents common or unavoidable4 #ab4 ,,chastity4 #ac4 ,,humility4 ,imitate ,jesus and ,socrates4 ,the last of these was added to the list at the suggestion of a ,quaker friend4 ,franklin claims to have acquired a good deal of the appearance of it1 but concluded that in reality there was no passion so hard to subdue as pride4 ,for even if ,i could conceive that ,i had completely overcome it1 ,i should probably be proud of my humility4 ,the virtue which gave him most trouble1 however1 was order1 and this he never acquired4 ,in #agcb appeared the first copy of ,poor ,richard's ,almanack4 ,this was prepared1 printed1 and published by ,franklin for about twenty-five years in succession1 and nearly ten thousand copies were sold annually4 ,besides the usual astronomical information1 it contained a collection of entertaining anecdotes1 verses1 jests1 etc41 while the little spaces that occurred between the remarkable events in the calendar were filled with proverbial sayings1 inculcating industry and frugality as helps to virtue4 ,these sayings were collected and prefixed to the almanack of #ageg1 whence they were copied into the ,american newspapers1 and afterwards reprinted as a broad-sheet in ,england and in ,france4 ,in #agcc ,franklin commenced studying modern languages1 and acquired sufficient knowledge of ,french1 ,italian1 and ,spanish to be able to read books in those languages4 ,in #agcf he was chosen ,clerk to the ,general ,assembly1 an office to which he was annually re-elected until he became a member of the ,assembly about #agej4 ,there was one member who1 on the second occasion of his election1 made a long speech against him4 ,franklin determined to secure the friendship of this member4 ,accordingly he wrote to him to request the loan of a very scarce and curious book which was in his library4 ,the book was lent and returned in about a week1 with a note of thanks4 ,the member ever after manifested a readiness to serve ,franklin1 and they became great friends--,another instance of the truth of an old maxim ,i had learned1 which says1 ',he that has once done you a kindness will be more ready to do you another than he whom you yourself have obliged4' ,and it shows how much more profitable it is prudently to remove1 than to resent1 return1 and continue inimical proceedings4 ,in #agcg ,franklin was appointed ,deputy-,postmaster-,general for ,pennsylvania4 ,he was afterwards made ,postmaster-,general of the ,colonies4 ,he read a paper in the ,junto on the organization of the ,city watch1 and the propriety of rating the inhabitants on the value of their premises in order to support the same4 ,the subject was also discussed in the other clubs which had sprung from the ,junto1 and thus the way was prepared for the law which a few years afterwards carried ,franklin's proposals into effect4 ,his next scheme was the formation of a fire brigade1 in which he met with his usual success1 and other clubs followed1 until most of the men of property in the city were members of one club or another4 ,the original brigade1 known as the ,union ,fire ,company1 was formed ,december #g1 #agcf4 ,it was in active service in #agia4 ,franklin founded the ,american ,philosophical ,society in #agdc4 ,the head-quarters of the society were fixed in ,philadelphia1 where it was arranged that there should always be at least seven members1 viz4 a physician1 a botanist1 a mathematician1 a chemist1 a mechanician1 a geographer1 and a general natural philosopher1 besides a president1 treasurer1 and secretary4 ,the other members might be resident in any part of ,america4 ,correspondence was to be kept up with the ,royal ,society of ,london and the ,dublin ,society1 and abstracts of the communications were to be sent quarterly to all the members4 ,franklin became the first secretary4 ,spain1 having been for some years at war with ,england1 was joined at length by ,france4 ,this threatened danger to the ,american colonies1 as ,france then held ,canada1 and no organization for their defence existed4 ,franklin published a pamphlet entitled ,plain ,truth1 setting forth the unarmed condition of the colonies1 and recommending the formation of a volunteer force for defensive purposes4 ,the pamphlet excited much attention4 ,a public meeting was held and addressed by ,franklin2 at this meeting twelve hundred joined the association4 ,at length the number of members enrolled exceeded ten thousand4 ,these all provided themselves with arms1 formed regiments and companies1 elected their own officers1 and attended once a week for military drill4 ,franklin was elected colonel of the ,philadelphia ,regiment1 but declined the appointment1 and served as a private soldier4 ,the provision of war material was a difficulty with the ,assembly1 which consisted largely of ,quakers1 who1 though they appeared privately to be willing that the country should be put in a state of defence1 hesitated to vote in opposition to their peace principles4 ,hence it was that1 when the ,government of ,new ,england asked a grant of gunpowder from ,pennsylvania1 the ,assembly voted ,l#cjjj for the purchasing of bread1 flour1 wheat1 or other grain4 ,pebble-powder was not then in use4 ,when it was proposed to devote ,l#fj1 which was a balance in the hands of the ,union ,fire ,company1 as a contribution towards the erection of a battery below the town1 ,franklin suggested that it should be proposed that a fire-engine be purchased with the money1 and that the committee should buy a great gun1 which is certainly a fire-engine4 ,the ,pennsylvania fireplace was invented in #agdb4 ,a patent was offered to ,franklin by the ,governor of ,pennsylvania1 but he declined it on the principle that1 as we enjoy great advantages from the inventions of others1 we should be glad of an opportunity to serve others by any invention of ours2 and this we should do freely and generously4 ,an ironmonger in ,london made slight alterations1 which were not improvements1 in the design1 and took out a patent for the fireplace1 whereby he made a small fortune4 ,franklin never contested the patent1 having no desire of profiting by patents himself1 and hating disputes4 ,this fireplace was designed to burn wood1 but1 unlike the ,german stoves1 it was completely open in front1 though enclosed at the sides and top4 ,an air-chamber was formed in the middle of the stove1 so arranged that1 while the burning wood was in contact with the front of the chamber1 the flame passed above and behind it on its way to the flue4 ,through this chamber a constant current of air passed1 entering the room heated1 but not contaminated1 by the products of combustion4 ,in this way the stove furnished a constant supply of fresh warm air to the room1 while it possessed all the advantages of an open fireplace4 ,subsequently ,franklin contrived a special fireplace for the combustion of coal4 ,in the scientific thought which he devoted to the requirements of the domestic economist1 as in very many other particulars1 ,franklin strongly reminds us of ,count ,rumford4 ,the next important enterprise which ,franklin undertook1 partly through the medium of the ,junto1 was to establish an academy which soon developed into the ,university of ,philadelphia4 ,the members of the club having taken up the subject1 the next step was to enlist the sympathy of a wider constituency1 and this ,franklin effected1 in his usual way1 by the publication of a pamphlet4 ,he then set on foot a subscription1 the payments to extend over five years1 and thereby obtained about ,l#ejjj4 ,a house was taken and schools opened in #agdi4 ,the classes soon became too large for the house1 and the trustees of the academy then took over a large building1 or tabernacle1 which had been erected for ,george ,whitefield when he was preaching in ,philadelphia4 ,the hall was divided into stories1 and at a very small expense adapted to the requirements of the classes4 ,franklin1 having taken a partner in his printing business1 took the oversight of the work4 ,afterwards the funds were increased by ,english subscriptions1 by a grant from the ,assembly1 and by gifts of land from the proprietaries2 and thus was established the ,university of ,philadelphia4 ,having practically retired from business1 ,franklin intended to devote himself to philosophical studies1 having commenced his electrical researches some time before in conjunction with the other members of the ,library ,company4 ,public business1 however1 crowded upon him4 ,he was elected a member of the ,assembly1 a councillor and afterwards an alderman of the city1 and by the governor was made a justice of the peace4 ,as a member of the ,assembly1 he was largely concerned in providing the means for the erection of a hospital1 and in arranging for the paving and cleansing of the streets of the city4 ,in #agec he was appointed1 in conjunction with ,mr4 ,hunter1 ,postmaster-,general of ,america4 ,the post-office of the colonies had previously been conducted at a loss4 ,in a few years1 under ,franklin's management1 it not only paid the stipends of himself and ,mr4 ,hunter1 but yielded a considerable revenue to the ,crown4 ,but it was not only in the conduct of public business that ,franklin's merits were recognized4 ,by this time he had secured his reputation as an electrician1 and both ,yale ,college and ,cambridge ,university 7,new ,england7 conferred on him the honorary degree of ,master of ,arts4 ,in the same year that he was made ,postmaster-,general of ,america he was awarded the ,copley ,medal and elected a ,fellow of the ,royal ,society of ,london1 the usual fees being remitted in his case4 ,before his election as member1 ,franklin had for several years held the appointment of ,clerk to the ,assembly1 and he used to relieve the dulness of the debates by amusing himself in the construction of magic circles and squares1 and acquired such a knack at it that he could fill the cells of any magic square of reasonable size with a series of numbers as fast as he could write them4 ,many years afterwards ,mr4 ,logan showed ,franklin a ,french folio volume filled with magic squares1 and afterwards a magic square of #af1 which ,mr4 ,logan thought must have been a work of great labour1 though it possessed only the common properties of making #bjef in every row1 horizontal1 vertical1 and diagonal4 ,during the evening ,franklin made the square shown on the opposite page4 ,this ,i sent to our friend the next morning1 who1 after some days1 sent it back in a letter1 with these words3 ',i return to thee thy astonishing and most stupendous piece of the magical square1 in which----2' but the compliment is too extravagant1 and therefore1 for his sake as well as my own1 ,i ought not to repeat it4 ,nor is it necessary2 for ,i make no question that you will readily allow this square of #af to be the most magically magical of any magic square ever made by any magician4 ,the square has the following properties3--,every straight row of sixteen numbers1 whether vertical1 horizontal1 or diagonal1 makes #bjef4 ,every bent row of sixteen numbers1 as shown by the diagonal lines in the figure1 makes #bjef4 ,if a square hole be cut in a piece of paper1 so as to show through it just sixteen of the little squares1 and the paper be laid on the magic square1 then1 wherever the paper is placed1 the sum of the sixteen numbers visible through the hole will be #bjef4 ,illustration3 #bjj #bag #bcb #bdi #h #be #dj #eg #gb #hi #ajd #aba #acf #aec #afh #ahe #eh #ci #bf #g #bej #bca #bah #aii #ahf #afg #aed #ace #abb #ajc #ij #ga #aih #bai #bcj #bea #f #bg #ch #ei #gj #ia #ajb #abc #acd #aee #aff #ahg #fj #cg #bh #e #beb #bbi #bbj #aig #ahh #afe #aef #acc #abd #aja #ib #fi #bja #baf #bcc #bdh #i #bd #da #ef #gc #hh #aje #abj #acg #aeb #afi #ahd #ee #db #bc #aj #bdg #bcd #bae #bjb #ahc #agj #aea #ach #aai #ajf #hg #gd #bjc #bad #bce #bdf #aa #bb #dc #ed #ge #hf #ajg #aah #aci #aej #aga #ahb #ec #dd #ba #ab #bde #bcf #bac #bjd #aha #agb #adi #adj #aag #ajh #he #gf #bje #bab #bcg #bdd #ac #bj #de #eb #gg #hd #aji #aaf #ada #adh #agc #ahj #ea #df #ai #ad #bdc #bch #baa #bjf #agi #agd #adg #adb #aae #aaj #hc #gh #bjg #baj #bci #bdb #ae #ah #dg #ej #gi #hb #aaa #aad #adc #adf #age #agh #di #dh #ag #af #bda #bdj #bji #bjh #agg #agf #ade #add #aac #aab #ha #hj #aif #bba #bbh #bec #d #bi #cf #fa #fh #ic #ajj #abe #acb #aeg #afd #ahi #fb #ce #cj #c #bed #bbg #bbb #aie #aij #afc #aeh #aca #abf #ii #id #fg #aid #bbc #bbf #bee #b #ca #cd #fc #ff #ie #ih #abg #acj #aei #afb #aia #fd #cc #cb #a #bef #bbe #bbd #aic #aib #afa #afj #abi #abh #ig #if #fe ,in #aged war with ,france appeared to be again imminent1 and a ,congress of ,commissioners from the several colonies was arranged for4 ,of course1 ,franklin was one of the representatives of ,pennsylvania1 and was also one of the members who independently drew up a plan for the union of all the colonies under one government1 for defensive and other general purposes1 and his was the plan finally approved by ,congress for the union1 though it was not accepted by the ,assemblies or by the ,english ,government1 being regarded by the former as having too much of the prerogative in it1 by the latter as being too democratic4 ,franklin wrote respecting this scheme3 ,the different and contrary reasons of dislike to my plan makes me suspect that it was really the true medium2 and ,i am still of opinion that it would have been happy for both sides of the water if it had been adopted4 ,the colonies1 so united1 would have been sufficiently strong to have defended themselves2 there would then have been no need of troops from ,england2 of course1 the subsequent pretence for taxing ,america1 and the bloody contest it occasioned1 would have been avoided4 ,with this war against ,france began the struggle of the ,assemblies and the proprietaries on the question of taxing the estates of the latter4 ,the governors received strict instructions to approve no bills for the raising of money for the purposes of defence1 unless the estates of the proprietaries were specially exempted from the tax4 ,the ,assembly of ,pennsylvania resolved to contribute ,l#aj1jjj to assist the ,government of ,massachusetts ,bay in an attack upon ,crown ,point1 but the governor refused his assent to the bill for raising the money4 ,at this juncture ,franklin proposed a scheme by which the money could be raised without the consent of the governor4 ,his plan was successful1 and the difficulty was surmounted for the time1 but was destined to recur again and again during the progress of the war4 ,the ,british ,government1 not approving of the scheme of union1 whereby the colonies might have defended themselves1 sent ,general ,braddock to ,virginia1 with two regiments of regular troops4 ,on their arrival they found it impossible to obtain waggons for the conveyance of their baggage1 and the general commissioned ,franklin to provide them in ,pennsylvania4 ,by giving his private bond for their safety1 ,franklin succeeded in engaging one hundred and fifty four-horse waggons1 and two hundred and fifty-nine pack-horses4 ,his modest warnings against ,indian ambuscades were disregarded by the general1 the little army was cut to pieces1 and the remainder took to flight1 sacrificing the whole of their baggage and stores4 ,franklin was never fully recouped by the ,british ,government for the payments he had to make on account of provisions which the general had instructed him to procure for the use of the army4 ,after this1 ,franklin appeared for some time in a purely military capacity1 having yielded to the governor's persuasions to undertake the defence of the north-western frontier1 to raise troops1 and to build a line of forts4 ,after building and manning three wooden forts1 he was recalled by the ,assembly1 whose relations with the governor had become more and more strained4 ,at length the ,assembly determined to send ,franklin to ,england1 to present a petition to the king respecting the conduct of the proprietaries1 viz4 ,richard and ,thomas ,penn1 the successors of ,william ,penn4 ,a bill had been framed by the ,house to provide ,l#fj1jjj for the king's use in the defence of the province4 ,this the governor refused to pass1 because the proprietary estates were not exempted from the taxation4 ,the petition to the king was drawn up1 and ,franklin's baggage was on board the ship which was to convey him to ,england1 when ,general ,lord ,loudon endeavoured to make an arrangement between the parties4 ,the governor pleaded his instructions1 and the bond he had given for carrying them out1 and the ,assembly was prevailed upon to reconstruct the bill in accordance with the governor's wishes4 ,this was done under protest2 in the mean time ,franklin's ship had sailed1 carrying his baggage4 ,after a great deal of unnecessary delay on account of the general's inability to decide upon the despatch of the packet-boats1 ,franklin at last got away from ,new ,york1 and1 having narrowly escaped shipwreck off ,falmouth1 he reached ,london on ,july #bg1 #ageg4 ,on arriving in ,london1 ,franklin was introduced to ,lord ,granville1 who told him that the king's instructions were laws in the colonies4 ,franklin replied that he had always understood that the ,assemblies made the laws1 which then only required the king's consent4 ,i recollected that1 about twenty years before1 a clause in a bill brought into ,parliament by the ,ministry had proposed to make the king's instructions laws in the colonies1 but the clause was thrown out by the ,commons1 for which we adored them as our friends and the friends of liberty1 till1 by their conduct towards us in #agfe1 it seem'd that they had refus'd that point of sovereignty to the king only that they might reserve it for themselves4 ,a meeting was shortly afterwards arranged between ,franklin and the proprietaries at ,mr4 ,t4 ,penn's house2 but their views were so discordant that1 after some discussion1 ,franklin was requested to give them in writing the heads of his complaints1 and the whole question was submitted to the opinion of the attorney- and solicitor-general4 ,it was nearly a year before this opinion was given4 ,the proprietaries then communicated directly with the ,assembly1 but in the mean while ,governor ,denny had consented to a bill for raising ,l#ajj1jjj for the king's use1 in which it was provided that the proprietary estates should be taxed with the others4 ,when this bill reached ,england1 the proprietaries determined to oppose its receiving the royal assent4 ,franklin engaged counsel on behalf of the ,assembly1 and on his undertaking that the assessment should be fairly made between the estates of the proprietaries and others1 the bill was allowed to pass4 ,by this time ,franklin's career as a scientific investigator was practically at an end4 ,political business almost completely occupied his attention1 and in one sense the diplomatist replaced the philosopher4 ,his public scientific career was of short duration4 ,it may be said to have begun in #agdf1 when ,mr4 ,peter ,collinson presented an electrical tube to the ,library ,company in ,philadelphia1 which was some time after followed by a present of a complete set of electrical apparatus from the proprietaries1 but by #agee ,franklin's time was so much taken up by public business that there was very little opportunity for experimental work4 ,throughout his life he frequently expressed in his letters his strong desire to return to philosophy1 but the opportunity never came1 and when1 at the age of eighty-two1 he was liberated from public duty1 his strength was insufficient to enable him to complete even his autobiography4 ,it was on a visit to ,boston in #agdf that ,franklin met with ,dr4 ,spence1 a ,scotchman1 who exhibited some electrical experiments4 ,soon after his return to ,philadelphia the tube arrived from ,mr4 ,collinson1 and ,franklin acquired considerable dexterity in its use4 ,his house was continually full of visitors1 who came to see the experiments1 and1 to relieve the pressure upon his time1 he had a number of similar tubes blown at the glass-house1 and these he distributed to his friends1 so that there were soon a number of performers in ,philadelphia4 ,one of these was ,mr4 ,kinnersley1 who1 having no other employment1 was induced by ,franklin to become an itinerant lecturer4 ,franklin drew up a scheme for the lectures1 and ,kinnersley obtained several well-constructed instruments from ,franklin's rough and home-made models4 ,kinnersley and ,franklin appear to have worked together a good deal1 and when ,kinnersley was travelling on his lecture tour1 each communicated to the other the results of his experiments4 ,franklin sent his papers to ,mr4 ,collinson1 who presented them to the ,royal ,society1 but they were not at first judged worthy of a place in the ,transactions4 ,the paper on the identity of lightning and electricity was sent to ,dr4 ,mitchell1 who read it before the ,royal ,society1 when it was laughed at by the connoisseurs4 ,the papers were subsequently published in a pamphlet1 but did not at first receive much attention in ,england4 ,on the recommendation of ,count de ,buffon1 they were translated into ,french4 ,the ,abbe ,nollet1 who had previously published a theory of his own respecting electricity1 wrote and published a volume of letters defending his theory1 and denying the accuracy of some of ,franklin's experimental results4 ,to these letters ,franklin made no reply1 but they were answered by ,m4 le ,roy4 ,m4 de ,lor undertook to repeat in ,paris all ,franklin's experiments1 and they were performed before the king and court4 ,not content with the experiments which ,franklin had actually performed1 he tried those which had been only suggested1 and so was the first to obtain electricity from the clouds by means of the pointed rod4 ,this experiment produced a great sensation everywhere1 and was afterwards repeated by ,franklin at ,philadelphia4 ,franklin's papers were translated into ,italian1 ,german1 and ,latin2 his theory met with all but universal acceptance1 and great surprise was expressed that his papers had excited so little interest in ,england4 ,dr4 ,watson then drew up a summary of all ,franklin's papers1 and this was published in the ,philosophical ,transactions2 ,mr4 ,canton verified the experiment of procuring electricity from the clouds by means of a pointed rod1 and the ,royal ,society awarded to ,franklin the ,copley ,medal for #agec1 which was conveyed to him by ,governor ,denny4 ,we must now give a short account of ,franklin's contributions to electrical science4 ,the first is the wonderful effect of pointed bodies1 both in drawing off and throwing off the electrical fire4 ,it will be observed that this statement is made in the language of the one-fluid theory1 of which ,franklin may be regarded as the author4 ,this theory will be again referred to presently4 ,franklin electrified a cannon-ball so that it repelled a cork4 ,on bringing near it the point of a bodkin1 the repulsion disappeared4 ,a blunt body had to be brought near enough for a spark to pass in order to produce the same effect4 ,to prove that the electrical fire is drawn off by the point1 if you take the blade of the bodkin out of the wooden handle1 and fix it in a stick of sealing-wax1 and then present it at the distance aforesaid1 or if you bring it very near1 no such effect follows2 but sliding one finger along the wax till you touch the blade1 and the ball flies to the shot immediately4 ,if you present the point in the dark1 you will see1 sometimes at a foot distance or more1 a light gather upon it like that of a fire-fly or glow-worm2 the less sharp the point1 the nearer you must bring it to observe the light2 and at whatever distance you see the light1 you may draw off the electrical fire1 and destroy the repelling4 ,by laying a needle upon the shot1 ,franklin showed that points will throw off as well as draw off the electrical fire4 ,a candle-flame was found to be equally efficient with a sharp point in drawing off the electricity from a charged conductor4 ,the effect of the candle-flame ,franklin accounted for by supposing the particles separated from the candle to be first attracted and then repelled1 carrying off the electric matter with them4 ,the effect of points is a direct consequence of the law of electrical repulsion4 ,when a conductor is electrified1 the density of the electricity is greatest where the curvature is greatest4 ,thus1 if a number of spheres are electrified from the same source1 the density of the electricity on the different spheres will vary inversely as their diameters4 ,the force tending to drive the electricity off a conductor is everywhere proportional to the density1 and hence in the case of the spheres will be greatest for the smallest sphere4 ,on this principle1 the density of electricity on a perfectly sharp point1 if such could exist1 on a charged conductor1 would be infinite and the force tending to drive it off would be infinite also4 ,hence a moderately sharp point is sufficient to dissipate the electricity from a highly charged conductor1 or to neutralize it if the point is connected to earth and brought near the conductor so as to be electrified by induction4 ,franklin next found that1 if the person rubbing the electric tube stood upon a cake of resin1 and the person taking the charge from the tube stood also on an insulating stand1 a stronger spark would pass between these two persons than between either of them and the earth2 that1 after the spark had passed1 neither person was electrified1 though each had appeared electrified before4 ,these experiments suggested the idea of positive and negative electrification2 and ,franklin1 regarding the electric fluid as corresponding to positive electrification1 remarked that you may circulate it as ,mr4 ,watson has shown2 you may also accumulate or subtract it upon or from any body1 as you connect that body with the rubber or with the receiver1 the common stock being cut off4 ,thus ,franklin regarded electricity as a fluid1 of which everything in its normal state possesses a certain amount2 that1 by appropriate means1 some of the fluid may be removed from one body and given to another4 ,the former is then electrified negatively1 the latter positively1 and all processes by which bodies are electrified consist in the removal of electricity from one body or system and giving it to another4 ,he regarded the electric fluid as repelling itself and attracting matter4 ,a,epinus afterwards added the supposition that matter1 when devoid of electricity1 is self-repulsive1 and thus completed the one-fluid theory1 and accounted for the repulsion observed between negatively electrified bodies4 ,it had been usual to employ water for the interior armatures of ,leyden jars1 or phials1 as they were then generally called4 ,franklin substituted granulated lead for the water1 thereby improving the insulation by keeping the glass dry4 ,with these phials he contrived many ingenious experiments1 and imitated lightning by discharging them through the gilding of a mirror or the gold lines on the cover of a book4 ,he found that the inner and outer armatures of his ,leyden jars were oppositely electrified4 ,here we have a bottle containing at the same time a plenum of electrical fire and a vacuum of the same fire2 and yet the equilibrium cannot be restored between them but by a communication without6 though the plenum presses violently to expand1 and the hungry vacuum seems to attract as violently in order to be filled4 ,the charging of ,leyden jars by cascade1 that is by insulating all the jars except the last1 connecting the outer armature of the first with the inner armature of the second1 and so on throughout the series1 was well understood by ,franklin1 and he knew too that by this method the extent to which each jar could be charged from a given source varied inversely as the number of jars4 ,the discharge of the ,leyden jar by alternate contacts was also carried out by him2 and he found that1 if the jar is first placed on an insulating stand1 it may be held by the hook 7or knob7 without discharging it4 ,franklin1 in fact1 appears to have known almost as much about the ,leyden jar as is known to-day4 ,he found that1 when the armatures were removed from a jar1 no discharge would pass between them1 but when a fresh pair of armatures were supplied to the glass1 the jar could be discharged4 ,we are of opinion that there is really no more electrical fire in the phial after what is called its charging than before1 nor less after its discharging2 excepting only the small spark that might be given to and taken from the non-electric matter1 if separated from the bottle1 which spark may not be equal to a five-hundredth part of what is called the explosion4 ,the phial will not suffer what is called a charging unless as much fire can go out of it one way as is thrown in by another4 ,when a bottle is charged in the common way1 its inside and outside surfaces stand ready1 the one to give fire by the hook1 the other to receive it by the coating2 the one is full and ready to throw out1 the other empty and extremely hungry2 yet1 as the first will not give out unless the other can at the same time receive in1 so neither will the latter receive in unless the first can at the same time give out4 ,when both can be done at once1 it is done with inconceivable quickness and violence4 ,then follows a very beautiful illustration of the condition of the glass in the ,leyden jar4 ,so a straight spring 7though the comparison does not agree in every particular71 when forcibly bent1 must1 to restore itself1 contract that side which in the bending was extended1 and extend that which was contracted2 if either of these two operations be hindered1 the other cannot be done4 ,glass1 in like manner1 has1 within its substance1 always the same quantity of electrical fire1 and that a very great quantity in proportion to the mass of the glass1 as shall be shown hereafter4 ,this quantity proportioned to the glass it strongly and obstinately retains1 and will have neither more nor less1 though it will suffer a change to be made in its parts and situation2 i4e4 we may take away part of it from one of the sides1 provided we throw an equal quantity into the other4 ,the whole force of the bottle1 and power of giving a shock1 is in the ,,glass ,,itself2 the non-electrics in contact with the two surfaces serving only to give and receive to and from the several parts of the glass1 that is1 to give on one side and take away from the other4 ,all these statements were1 as far as possible1 fully substantiated by experiment4 ,they are perfectly consistent with the views held by ,cavendish and by ,clerk ,maxwell1 and1 though the phraseology is not that of the modern text-books1 the statements themselves can hardly be improved upon to-day4 ,one of ,franklin's early contrivances was an electro-motor1 which was driven by the alternate electrical attraction and repulsion of leaden bullets which discharged ,leyden jars by alternate contacts4 ,franklin concluded his account of these experiments as follows3-- ,chagrined a little that we have been hitherto able to produce nothing in this way of use to mankind1 and the hot weather coming on1 when electrical experiments are not so agreeable1 it is proposed to put an end to them for this season1 somewhat humorously1 in a party of pleasure1 on the banks of ,skuylkil4 ,spirits1 at the same time1 are to be fired by a spark sent from side to side through the river1 without any other conductor than the water--an experiment which we some time since performed1 to the amazement of many4 ,a turkey is to be killed for our dinner by the electrical shock1 and roasted by the electrical jack before a fire kindled by the electrified bottle1 when the healths of all the famous electricians in ,england1 ,holland1 ,france1 and ,germany1 are to be drunk in electrified bumpers1 under the discharge of guns from the electrical battery4 ,franklin's electrical battery consisted of eleven large panes of glass coated on each side with sheet lead4 ,the electrified bumper was a thin tumbler nearly filled with wine and electrified as a ,leyden jar1 so as to give a shock through the lips4 ,franklin's theory of the manner in which thunder-clouds become electrified he found to be not consistent with his subsequent experiments4 ,in the paper which he wrote explaining this theory1 however1 he shows some knowledge of the effects of bringing conductors into contact in diminishing their capacity4 ,he states that two gun-barrels electrified equally and then united1 will give a spark at a greater distance than one alone4 ,hence he asks1 ,to what a great distance may ten thousand acres of electrified cloud strike and give its fire1 and how loud must be that crack8 ,an electrical spark1 drawn from an irregular body at some distance1 is scarcely ever straight1 but shows crooked and waving in the air4 ,so do the flashes of lightning1 the clouds being very irregular bodies4 ,as electrified clouds pass over a country1 high hills and high trees1 lofty towers1 spires1 masts of ships1 chimneys1 etc41 as so many prominences and points1 draw the electrical fire1 and the whole cloud discharges there4 ,dangerous1 therefore1 is it to take shelter under a tree during a thunder-gust4 ,it has been fatal to many1 both men and beasts4 ,it is safer to be in the open field for another reason4 ,when the clothes are wet1 if a flash in its way to the ground should strike your head1 it may run in the water over the surface of your body2 whereas1 if your clothes were dry1 it would go through the body1 because the blood and other humours1 containing so much water1 are more ready conductors4 ,hence a wet rat cannot be killed by the exploding electrical bottle a quart jar1 while a dry rat may4 ,in the above quotations we see1 so to speak1 the germ of the lightning-rod4 ,this was developed in a letter addressed to ,mr4 ,collinson1 and dated ,july #bi1 #agej4 ,the following quotations will give an idea of its contents3-- ,the electrical matter consists of particles extremely subtile1 since it can permeate common matter1 even the densest metals1 with such ease and freedom as not to receive any perceptible resistance4#a ,footnote #a3 ,franklin was aware of the resistance of conductors 7see p4 #if74 ,if any one should doubt whether the electrical matter passes through the substance of bodies or only over and along their surfaces1 a shock from an electrified large glass jar1 taken through his own body1 will probably convince him4 ,common matter is a kind of sponge to the electrical fluid4 ,we know that the electrical fluid is in common matter1 because we can pump it out by the globe or tube4 ,we know that common matter has near as much as it can contain1 because when we add a little more to any portion of it1 the additional quantity does not enter1 but forms an electrical atmosphere4 ,to illustrate the action of a lightning-conductor on a thunder-cloud1 ,franklin suspended from the ceiling a pair of scales by a twisted string so that the beam revolved4 ,upon the floor1 in such a position that the scale-pans passed over it1 he placed a blunt steel punch4 ,the scale-pans were suspended by silk threads1 and one of them electrified4 ,when this passed over the punch it dipped towards it1 and sometimes discharged into it by a spark4 ,when a needle was placed with its point uppermost by the side of the punch1 no attraction was apparent1 for the needle discharged the scale-pan before it came near4 ,now1 if the fire of electricity and that of lightning be the same1 as ,i have endeavoured to show at large in a former paper 444 these scales may represent electrified clouds4444 ,the horizontal motion of the scales over the floor may represent the motion of the clouds over the earth1 and the erect iron punch a hill or high building2 and then we see how electrified clouds1 passing over hills or high buildings at too great a height to strike1 may be attracted lower till within their striking distance2 and lastly1 if a needle fixed on the punch1 with its point upright1 or even on the floor below the punch1 will draw the fire from the scale silently at a much greater than the striking distance1 and so prevent its descending towards the punch2 or if in its course it would have come nigh enough to strike1 yet1 being first deprived of its fire1 it cannot1 and the punch is thereby secured from its stroke2--,i say1 if these things are so1 may not the knowledge of this power of points be of use to mankind1 in preserving houses1 churches1 ships1 etc41 from the stroke of the lightning1 by directing us to fix1 on the highest parts of those edifices1 upright rods of iron made sharp as a needle1 and gilt to prevent rusting1 and from the foot of those rods a wire down the outside of the building into the ground1 or down round one of the shrouds of a ship1 and down her side till it reaches the water8 ,would not these pointed rods probably draw the electrical fire silently out of a cloud before it came nigh enough to strike1 and thereby secure us from that most sudden and terrible mischief8 ,franklin goes on to suggest the possibility of obtaining electricity from the clouds by means of a pointed rod fixed on the top of a high building and insulated4 ,such a rod he afterwards erected in his own house4 ,another rod connected to the earth he brought within six inches of it1 and1 attaching a small bell to each rod1 he suspended a little ball or clapper by a silk thread1 so that it could strike either bell when attracted to it4 ,on the approach of a thunder-cloud1 and occasionally when no clouds were near1 the bells would ring1 indicating that the rod had become strongly electrified4 ,on one occasion ,franklin was disturbed by a loud noise1 and1 coming out of his bedroom1 he found an apparently continuous and very luminous discharge taking place between the bells1 forming a stream of fire about as large as a pencil4 ,a very pretty experiment of ,franklin's was that of the golden fish4 ,a small piece of gold-leaf is cut into a quadrilateral having one of its angles about #aej deg41 the opposite angle about #cj deg41 and the other two right angles4 ,if you take it by the tail1 and hold it at a foot or greater horizontal distance from the prime conductor1 it will1 when let go1 fly to it with a brisk but wavering motion1 like that of an eel through the water2 it will then take place under the prime conductor1 at perhaps a quarter or half an inch distance1 and keep a continual shaking of its tail like a fish1 so that it seems animated4 ,turn its tail towards the prime conductor1 and then it flies to your finger1 and seems to nibble it4 ,and if you hold a pewter plate under it at six or eight inches distance1 and cease turning the globe1 when the electrical atmosphere of the conductor grows small it will descend to the plate and swim back again several times with the same fish-like motion2 greatly to the entertainment of spectators4 ,by a little practice in blunting or sharpening the heads or tails of these figures1 you may make them take place as desired1 nearer or further from the electrified plate4 ,by the discharge of the battery1 ,franklin succeeded in melting and volatilizing gold-leaf1 thin strips of tinfoil1 etc4 ,his views on the nature of light are best given in his own words4 ,i am not satisfied with the doctrine that supposes particles of matter called light1 continually driven off from the sun's surface1 with a swiftness so prodigious6 ,must not the smallest particle conceivable have1 with such a motion1 a force exceeding that of a twenty-four pounder discharged from a cannon8444 ,yet these particles1 with this amazing motion1 will not drive before them1 or remove1 the least and lightest dust they meet with4 ,may not all the phenomena of light be more conveniently solved by supposing universal space filled with a subtile elastic fluid1 which1 when at rest1 is not visible1 but whose vibrations affect that fine sense in the eye1 as those of air do the grosser organs of the ear8 ,we do not1 in the case of sound1 imagine that any sonorous particles are thrown off from a bell1 for instance1 and fly in straight lines to the ear2 why must we believe that luminous particles leave the sun and proceed to the eye8 ,some diamonds1 if rubbed1 shine in the dark without losing any part of their matter4 ,i can make an electrical spark as big as the flame of a candle1 much brighter1 and therefore visible further2 yet this is without fuel2 and ,i am persuaded no part of the electrical fluid flies off in such case to distant places1 but all goes directly and is to be found in the place to which ,i destine it4 ,may not different degrees of the vibration of the abovementioned universal medium occasion the appearances of different colours8 ,i think the electric fluid is always the same2 yet ,i find that weaker and stronger sparks differ in apparent colour1 some white1 blue1 purple1 red3 the strongest1 white2 weak ones1 red4 ,thus different degrees of vibration given to the air produce the seven different sounds in music1 analogous to the seven colours1 yet the medium1 air1 is the same4 ,mr4 ,kinnersley having called ,franklin's attention to the fact that a sulphur globe when rubbed produced electrification of an opposite kind from that produced by a glass globe1 ,franklin repeated the experiment1 and noticed that the discharge from the end of a wire connected with the conductor was different in the two cases1 being long1 large1 and much diverging when the glass globe is used1 and makes a snapping 7or rattling7 noise2 but when the sulphur one is used it is short1 small1 and makes a hissing noise2 and just the reverse of both happens when you hold the same wire in your hand and the globes are worked alternately4444 ,when the brush is long1 large1 and much diverging1 the body to which it is joined seems to be throwing the fire out2 and when the contrary appears it seems to be drinking in4 ,on ,october #ai1 #ageb1 ,franklin wrote to ,mr4 ,peter ,collinson as follows3-- ,as frequent mention is made in public papers from ,europe of the success of the ,philadelphia experiment for drawing the electric fire from clouds by means of pointed rods of iron erected on high buildings1 etc41 it may be agreeable to the curious to be informed that the same experiment has succeeded in ,philadelphia1 though made in a different and more easy manner1 which is as follows3-- ,make a small cross of two light strips of cedar1 the arms so long as to reach to the four corners of a large thin silk handkerchief when extended4 ,tie the corners of the handkerchief to the extremities of the cross1 so you have the body of a kite2 which1 being properly accommodated with a tail1 loop1 and string1 will rise in the air like those made of paper2 but this being of silk is fitter to bear the wet and wind of a thunder-gust without tearing4 ,to the top of the upright stick of the cross is to be fixed a very sharp-pointed wire1 rising a foot or more above the wood4 ,to the end of the twine1 next the hand1 is to be tied a silk ribbon1 and1 where the silk and twine join1 a key may be fastened4 ,this kite is to be raised when a thunder-gust appears to be coming on1 and the person who holds the string must stand within a door or window1 or under some cover so that the silk ribbon may not be wet1 and care must be taken that the twine does not touch the frame of the door or window4 ,as soon as any of the thunder-clouds come over the kite1 the pointed wire will draw the electric fire from them1 and the kite1 with all the twine1 will be electrified1 and the loose filaments of the twine will stand out every way1 and be attracted by an approaching finger4 ,and when the rain has wetted the kite and twine so that it can conduct the electric fire freely1 you will find it stream out plentifully from the key on the approach of your knuckle4 ,at this key the phial may be charged1 and from electric fire there obtained spirits may be kindled1 and all the other electric experiments be performed which are usually done by the help of a rubbed glass globe or tube1 and thereby the sameness of the electric matter with that of lightning completely demonstrated4 ,having1 in ,september1 #ageb1 erected the iron rod and bells in his own house1 as previously mentioned1 ,franklin succeeded1 in ,april1 #agec1 in charging a ,leyden jar from the rod1 and found its charge was negative4 ,on ,june #f1 however1 he obtained a positive charge from a cloud4 ,the results of his observations led him to the conclusion ,that the clouds of a thunder-gust are most commonly in a negative state of electricity1 but sometimes in a positive state4 ,in order to illustrate a theory respecting the electrification of clouds1 ,franklin placed a silver can on a wine-glass4 ,inside the can was placed a considerable length of chain1 which could be drawn out by means of a silk thread4 ,he electrified the can from a ,leyden jar until it would receive no more electricity4 ,then raising the silk thread1 he gradually drew the chain out of the can1 and found that the greater the length of chain drawn out the greater was the charge which the jar would give to the system1 and as the chain was raised1 spark after spark passed from the jar to the silver can1 thus showing that the capacity of the system was increased by increasing the amount of chain exposed4 ,in #agee ,franklin observed the effects of induction2 for1 having attached to his prime conductor a tassel made of damp threads and electrified the conductor1 he found that the threads repelled each other and stood out4 ,bringing an excited glass tube near the other end of the conductor1 the threads were found to diverge more1 because the atmosphere of the prime conductor is pressed by the atmosphere of the excited tube1 and driven towards the end where the threads are1 by which each thread acquires more atmosphere4 ,when the excited tube was brought near the threads1 they closed a little1 because the atmosphere of the glass tube repels their atmospheres1 and drives part of them back on the prime conductor4 ,a number of other experiments illustrating electrical induction were also carried out4 ,in writing to ,dr4 ,living1 of ,charlestown1 under date ,march #ah1 #agee1 ,franklin gave the following extracts of the minutes of his experiments as explaining the train of thought which led him to attempt to obtain electricity from the clouds3-- ,november #g1 #agdi4 ,electrical fluid agrees with lightning in these particulars3 #a4 ,giving light4 #b4 ,colour of the light4 #c4 ,crooked direction4 #d4 ,swift motion4 #e4 ,being conducted by metals4 #f4 ,crack or noise in exploding4 #g4 ,subsisting in water or ice4 #h4 ,rending bodies it passes through4 #i4 ,destroying animals4 #aj4 ,melting metals4 #aa4 ,firing inflammable substances4 #ab4 ,sulphureous smell4 ,the electric fluid is attracted by points4 ,we do not know whether this property is in lightning4 ,but since they agree in all the particulars wherein we can already compare them1 is it not probable they agree likewise in this8 ,let the experiment be made4 ,another experiment very important in its bearing on the theory of electricity was described by ,franklin in the same letter to ,dr4 ,living4 ,it was afterwards repeated in a much more complete form by ,cavendish1 who deduced from it the great law that electrical repulsion varies inversely as the square of the distance between the charges4 ,the same experiment was repeated in other forms by ,faraday1 who had no means of knowing what ,cavendish had done4 ,franklin writes3-- ,i electrified a silver fruit-can on an electric stand1 and then lowered into it a cork ball of about an inch in diameter1 hanging by a silk string1 till the cork touched the bottom of the can4 ,the cork was not attracted to the inside of the can1 as it would have been to the outside1 and though it touched the bottom1 yet1 when drawn out1 it was not found to be electrified by that touch1 as it would have been by touching the outside4 ,the fact is singular4 ,you require the reason8 ,i do not know it4 ,perhaps you may discover it1 and then you will be so good as to communicate it to me4 ,i find a frank acknowledgment of one's ignorance is not only the easiest way to get rid of a difficulty1 but the likeliest way to obtain information1 and therefore ,i practise it4 ,i think it is an honest policy4 ,a note appended to this letter runs as follows3-- ,mr4 ,f4 has since thought that1 possibly1 the mutual repulsion of the inner opposite sides of the electrized can may prevent the accumulating an electric atmosphere upon them1 and occasion it to stand chiefly on the outside4 ,but recommends it to the further examination of the curious4 ,the explanation in this note is the correct one1 and from the fact that in the case of a completely closed hollow conductor the charge is not only chiefly but wholly on the outside1 the law of inverse squares above referred to follows as a mathematical consequence4 ,on writing to ,m4 ,dalibard1 of ,paris1 on ,june #bi1 #agee1 ,franklin complained that1 though he always 7except once7 assigned to lightning-rods the alternative duty of either preventing a stroke or of conducting the lightning with safety to the ground1 yet in ,europe attention was paid only to the prevention of the stroke1 which was only a part of the duty assigned to the conductors4 ,this is followed by the description of the effect of a stroke upon a church-steeple at ,newbury1 in ,new ,england4 ,the spire was split all to pieces1 so that nothing remained above the bell4 ,the lightning then passed down a wire to the clock1 then down the pendulum1 without injury to the building4 ,from the end of the pendulum1 down quite to the ground1 the building was exceedingly rent and damaged1 and some stones in the foundation-wall torn out and thrown to the distance of twenty or thirty feet4 ,the pendulum-rod was uninjured1 but the fine wire leading from the bell to the clock was vaporized except for about two inches at each end4 ,mr4 ,james ,alexander1 of ,new ,york1 having proposed to ,franklin that the velocity of the electric discharge might be measured by discharging a jar through a long circuit of river-water1 ,franklin1 in his reply1 explained that such an experiment1 if successful1 would not determine the actual velocity of electricity in the conductor4 ,he compared the electricity in conductors to an incompressible fluid1 so that when a little additional fluid is injected at one end of a conductor1 an equal amount must be extruded at the other end--his view apparently being identical with that of ,maxwell1 who held that all electric displacements must take place in closed circuits4 ,suppose a tube of any length open at both ends4444 ,if the tube be filled with water1 and ,i inject an additional inch of water at one end1 ,i force out an equal quantity at the other in the very same instant4 ,and the water forced out at one end of the tube is not the very same water that was forced in at the other end at the same time2 it was only one motion at the same time4 ,the long wire1 made use of in the experiment to discover the velocity of the electric fluid1 is itself filled with what we call its natural quantity of that fluid1 before the hook of the ,leyden bottle is applied at one end of it4 ,the outside of the bottle being at the time of such application in contact with the other end of the wire1 the whole quantity of electric fluid contained in the wire is1 probably1 put in motion at once4 ,for at the instant the hook1 connected with the inside of the bottle1 gives out1 the coating or outside of the bottle draws in1 a portion of that fluid4444 ,so that this experiment only shows the extreme facility with which the electric fluid moves in metal2 it can never determine the velocity4 ,and1 therefore1 the proposed experiment 7though well imagined and very ingenious7 of sending the spark round through a vast length of space1 by the waters of ,susquehannah1 or ,potowmack1 and ,ohio1 would not afford the satisfaction desired1 though we could be sure that the motion of the electric fluid would be in that tract1 and not underground in the wet earth by the shortest way4 ,in his investigations of the source of electricity in thunder-clouds1 ,franklin tried an experiment which has been frequently repeated with various modifications4 ,having insulated a large brass plate which had been previously heated1 he sprinkled water upon it1 in order1 if possible1 to obtain electricity by the evaporation of the water1 but no trace of electrification could be detected4 ,during his visit to ,england1 ,franklin wrote many letters to ,mr4 ,kinnersley and others on philosophical questions1 but they consisted mainly of accounts of the work done by other experimenters in ,england1 his public business occupying too much of his attention to allow him to conduct investigations for himself4 ,in one of his letters1 speaking of ,lord ,charles ,cavendish1 he says3-- ,it were to be wished that this noble philosopher would communicate more of his experiments to the world1 as he makes many1 and with great accuracy4 ,when the controversy between the relative merits of points and knobs for the terminals of lightning-conductors arose1 ,franklin wrote to ,mr4 ,kinnersley3-- ,here are some electricians that recommend knobs instead of points on the upper end of the rods1 from a supposition that the points invite the stroke4 ,it is true that points draw electricity at greater distances in the gradual silent way2 but knobs will draw at the greatest distance a stroke4 ,there is an experiment which will settle this4 ,take a crooked wire of the thickness of a quill1 and of such a length as that1 one end of it being applied to the lower part of a charged bottle1 the upper may be brought near the ball on the top of the wire that is in the bottle4 ,let one end of this wire be furnished with a knob1 and the other may be gradually tapered to a fine point4 ,when the point is presented to discharge the bottle1 it must be brought much nearer before it will receive the stroke than the knob requires to be4 ,points1 besides1 tend to repel the fragments of an electrical cloud2 knobs draw them nearer4 ,an experiment1 which ,i believe ,i have shown you1 of cotton fleece hanging from an electrized body1 shows this clearly when a point or a knob is presented under it4 ,the following quotation from ,franklin's paper on the method of securing buildings and persons from the effects of lightning is worthy of attention1 for of late years a good deal of money has been wasted in providing insulators for lightning-rods4 ,a few years ago the vicar and churchwardens of a ,lincolnshire parish were strongly urged to go to the expense of insulating the conductor throughout the whole height of the very lofty tower and spire of their parish church4 ,happily they were wise enough to send the lightning-rod man about his business4 ,but this is not the only case which has come under the writer's notice1 showing that there is still a widespread impression that lightning-conductors should be carefully insulated4 ,franklin says3-- ,the rod may be fastened to the wall1 chimney1 etc41 with staples of iron4 ,the lightning will not leave the rod 7a good conductor7 to pass into the wall 7a bad conductor7 through these staples4 ,it would rather1 if any were in the wall1 pass out of it into the rod1 to get more readily by that conductor into the earth4#b ,footnote #b3 ,see p4 #ada4 ,the conditions to be secured in a lightning-conductor are1 firstly1 a sharp point projecting above the highest part of the building1 and gilded to prevent corrosion2 secondly1 metallic continuity from the point to the lower end of the conductor2 and1 thirdly1 a good earth-contact4 ,the last can frequently be secured by soldering the conductor to iron water-pipes underground4 ,where these are not available1 a copper plate1 two or three feet square1 imbedded in clay or other damp earth1 will serve the purpose4 ,the method of securing a building which is erected on granite or other foundation affording no good earth-connection1 will be referred to in a subsequent biographical sketch4 ,the controversy of points versus knobs was again revived in ,london when ,franklin was in ,paris1 and the ,war of ,independence had begun4 ,franklin was consulted on the subject1 the question having arisen in connection with the conductor at the palace4 ,his reply was characteristic4 ,as to my writing anything on the subject1 which you seem to desire1 ,i think it not necessary1 especially as ,i have nothing to add to what ,i have already said upon it in a paper read to the committee who ordered the conductors at ,purfleet1 which paper is printed in the last ,french edition of my writings4 ,i have never entered into any controversy in defence of my philosophical opinions4 ,i leave them to take their chance in the world4 ,if they are right1 truth and experience will support them2 if wrong1 they ought to be refuted and rejected4 ,disputes are apt to sour one's temper and disturb one's quiet4 ,i have no private interest in the reception of my inventions by the world1 having never made1 nor proposed to make1 the least profit by any of them4 ,the king's changing his pointed conductors for blunt ones is1 therefore1 a matter of small importance to me4 ,if ,i had a wish about it1 it would be that he had rejected them altogether as ineffectual4 ,for it is only since he thought himself and family safe from the thunder of ,heaven1 that he dared to use his own thunder in destroying his innocent subjects4 ,the paper referred to was read before the committee appointed to consider the erecting conductors to secure the magazines at ,purfleet1 on ,august #bg1 #aggb4 ,it described a variety of experiments clearly demonstrating the effect of points in discharging a conductor4 ,this was a committee of the ,royal ,society1 to whom the question had been referred on account of ,dr4 ,wilson's recommendation of a blunt conductor4 ,the committee decided in favour of ,franklin's view1 and when1 in #aggg1 the question was again raised and again referred to a committee of the ,royal ,society1 the decision of the former committee was confirmed1 conceiving that the experiments and reasons made and alleged to the contrary by ,mr4 ,wilson are inconclusive4 ,though ,franklin's scientific reputation rests mainly on his electrical researches1 he did not leave other branches of science untouched4 ,besides his work on atmospheric electricity1 he devoted a great deal of thought to meteorology1 especially to the vortical motion of waterspouts4 ,the ,gulf-stream received a share of his attention4 ,his improvements in fireplaces have already been noticed2 the cure of smoky chimneys was the subject of a long paper addressed to ,dr4 ,ingenhousz1 and of some other letters4 ,one of his experiments on the absorption of radiant energy has been deservedly remembered4 ,my experiment was this3 ,i took a number of little square pieces of broad-cloth from a tailor's pattern-card1 of various colours4 ,there were black1 deep blue1 lighter blue1 green1 purple1 red1 yellow1 white1 and other colours or shades of colours4 ,i laid them all out upon the snow in a bright1 sun-shiny morning4 ,in a few hours 7,i cannot now be exact as to the time7 the black1 being warmed most by the sun1 was sunk so low as to be below the stroke of the sun's rays2 the dark blue almost as low1 the lighter blue not quite so much as the dark1 the other colours less as they were lighter2 and the quite white remained on the surface of the snow1 not having entered it at all4 ,what signifies philosophy that does not apply to some use8 ,may we not learn from hence that black clothes are not so fit to wear in a hot1 sunny climate or season1 as white ones8 ,franklin knew much about electricity1 but his knowledge of human nature was deeper still4 ,this appears in all his transactions4 ,his political economy was1 perhaps1 not always sound1 but his judgment of men was seldom at fault4 ,finally1 there seem to be but three ways for a nation to acquire wealth4 ,the first is by war1 as the ,romans did1 in plundering their conquered neighbour3 this is robbery4 ,the second by commerce1 which is generally cheating4 ,the third by agriculture1 the only honest way1 wherein man receives a real increase of the seed thrown into the ground1 in a kind of continual miracle wrought by the hand of ,god in his favour1 as a reward for his innocent life and his virtuous industry4 ,when ,franklin reached ,london in #ageg he took up his abode with ,mrs4 ,margaret ,stevenson1 in ,craven ,street1 ,strand4 ,for ,mrs4 ,stevenson and her daughter ,mary1 then a young lady of eighteen1 he acquired a sincere affection1 which continued throughout their lives4 ,miss ,stevenson spent much of her time with an aunt in the country1 and some of ,franklin's letters to her respecting the conduct of her higher education are among the most interesting of his writings4 ,miss ,stevenson treated him as a father1 and consulted him on every question of importance in her life4 ,when she was a widow and ,franklin eighty years of age1 he urged upon her to come to ,philadelphia1 for the sake of the better prospects which the new country offered her boys4 ,in coming to ,england1 ,franklin brought with him his son ,william1 who entered the ,middle ,temple1 but he left behind his only daughter1 ,sarah1 in charge of her mother4 ,to his wife and daughter he frequently sent presents from ,london1 and his letters to ,mrs4 ,franklin give a pretty full account of all his doings while in ,england4 ,during his visit he received the honorary degrees of ,d4,c4,l4 from the ,university of ,oxford1 and ,,ll4,d4 from that of ,edinburgh4 ,at ,cambridge he was sumptuously entertained4 ,in ,august1 #agfb1 he started again for ,america1 and reached ,philadelphia on ,november #a1 after an absence of five years4 ,his son ,william had shortly before been appointed ,governor of ,new ,jersey4 ,from this time ,william ,franklin became very much the servant of the proprietaries and of the ,english ,government1 but no offer of patronage produced any effect on the father4 ,franklin's stay in ,america was of short duration1 but while there he was mainly instrumental in quelling an insurrection in ,pennsylvania4 ,he made a tour of inspection through the northern colonies in the summer of #agfc1 to regulate the post-offices4 ,the disorder just referred to in the province caused the governor1 as well as the ,assembly1 to determine on the formation of a militia4 ,a committee1 of which ,franklin was a member1 drew up the necessary bill4 ,the governor claimed the sole power of appointing officers1 and required that trials should be by court-martial1 some offences being punishable with death4 ,the ,assembly refused to agree to these considerations4 ,the ill feeling was increased by the governor insisting on taxing all proprietary lands at the same rate as uncultivated land belonging to other persons1 whether the proprietary lands were cultivated or not4 ,the ,assembly1 before adjourning1 expressed an opinion that peace and happiness would not be secured until the government was lodged directly in the ,crown4 ,when the ,assembly again met1 petitions to the king came in from more than three thousand inhabitants4 ,in the mean while the ,british ,ministry had proposed the ,stamp ,act1 which was similar in principle to the ,english ,stamp ,act1 which requires that all agreements1 receipts1 bills of exchange1 marriage and birth certificates1 and all other legal documents should be provided with an inland revenue stamp of a particular value1 in order that they might be valid4 ,as soon as the ,assembly was convened1 it determined to send ,franklin to ,england1 to take charge of a petition for a change of government4 ,the merchants subscribed ,l#aajj towards his expenses in a few hours1 and in twelve days he was on his journey1 being accompanied to the ship1 a distance of sixteen miles1 by a cavalcade of three hundred of his friends1 and in thirty days he reached ,london4 ,arrived in ,london1 he at once took up his abode in his old lodgings with ,mrs4 ,stevenson4 ,he was a master of satire1 equalled only by ,swift1 and during the quarrels which preceded the ,war of ,independence1 as well as during the war1 he made good use of his powers in this respect4 ,articles appeared in some of the ,english papers tending to raise an alarm respecting the competition of the colonies with ,english manufacturers4 ,franklin's contribution to the discussion was a caricature of the ,english press writers4 ,it is objected by superficial readers1 who yet pretend to some knowledge of those countries1 that such establishments manufactories for woollen goods1 etc4 are not only improbable1 but impossible1 for that their sheep have but little wool1 not in the whole sufficient for a pair of stockings a year to each inhabitant2 that1 from the universal dearness of labour among them1 the working of iron and other materials1 except in a few coarse instances1 is impracticable to any advantage4 ,dear sir1 do not let us suffer ourselves to be amused with such groundless objections4 ,the very tails of the ,american sheep are so laden with wool that each has a little car or waggon on four little wheels to support and keep it from trailing on the ground4 ,would they caulk their ships1 would they even litter their horses with wool1 if it were not both plenty and cheap8 ,and what signifies the dearness of labour1 when an ,english shilling passes for five and twenty8 ,their engaging three hundred silk throwsters here in one week for ,new ,york was treated as a fable1 because1 forsooth1 they have 'no silk there to throw6' ,those who make this objection perhaps do not know that1 at the same time1 the agents for the ,king of ,spain were at ,quebec1 to contract for one thousand pieces of cannon to be made there for the fortification of ,mexico1 and at ,new ,york engaging the usual supply of woollen floor-carpets for their ,west ,india houses4 ,other agents from the ,emperor of ,china were at ,boston1 treating about an exchange of raw silk for wool1 to be carried in ,chinese junks through the ,straits of ,magellan4 ,and yet all this is as certainly true as the account said to be from ,quebec in all the papers of last week1 that the inhabitants of ,canada are making preparations for a cod and whale fishery this summer in the upper ,lakes4 ,ignorant people may object that the upper ,lakes are fresh1 and that cod and whales are salt-water fish2 but let them know1 sir1 that cod1 like other fish when attacked by their enemies1 fly into any water where they can be safest2 that whales1 when they have a mind to eat cod1 pursue them wherever they fly2 and that the grand leap of the whale in the chase up the ,falls of ,niagara is esteemed1 by all who have seen it1 as one of the finest spectacles in nature4 ,one of ,franklin's chief objects in coming to ,england was to prevent the passing of ,mr4 ,grenville's bill1 previously referred to as the ,stamp ,act4 ,the colonists urged that they had always been liberal in their votes1 whenever money was required by the ,crown1 and that taxation and representation must1 in accordance with the ,british constitution1 go hand-in-hand1 so that the ,english ,parliament had no right to raise taxes in ,america1 so long as the colonists were unrepresented in ,parliament4 ,had ,mr4 ,grenville1 instead of that act1 applied to the king in ,council for such requisitional letters i4e4 requests to the ,assemblies for voluntary grants1 to be circulated by the ,secretary of ,state1 ,i am sure he would have obtained more money from the colonies by their voluntary grants than he himself expected from the sale of stamps4 ,but he chose compulsion rather than persuasion1 and would not receive from their good will what he thought he could obtain without it4 ,the ,stamp ,act was passed1 stamps were printed1 distributors were appointed1 but the colonists would have nothing to do with the stamps4 ,the distributors were compelled to resign their commissions1 and the captains of vessels were forbidden to land the stamped paper4 ,the cost of printing and distributing amounted to ,l#ab1jjj2 the whole return was about ,l#aejj1 from ,canada and the ,west ,indies4 ,the passing of the ,stamp ,act was soon followed by a change of ,ministry1 when the question again came before ,parliament4 ,franklin submitted to a long examination before a ,committee of the whole ,house4 ,the feeling prevalent in ,america respecting the ,stamp ,act may be inferred from some of his answers4 #ca4 ,q4 ,do you think the people of ,america would submit to pay the stamp duty if it was moderated8 ,a4 ,no1 never1 unless compelled by force of arms4 #cf4 ,q4 ,what was the temper of ,america towards ,great ,britain before the year #agfc8c ,footnote #c3 ,the date of the ,sugar ,act4 ,a4 ,the best in the world4 ,they submitted willingly to the government of the ,crown1 and paid1 in their courts1 obedience to the ,acts of ,parliament4 ,numerous as the people are in the several old provinces1 they cost you nothing in forts1 citadels1 garrisons1 or armies to keep them in subjection4 ,they were governed by this country at the expense only of a little pen1 ink1 and paper2 they were led by a thread4 ,they had not only a respect1 but an affection1 for ,great ,britain--for its laws1 its customs and manners1 and even a fondness for its fashions1 that greatly increased the commerce4 ,natives of ,britain were always treated with particular regard2 to be an ,old-,englandman was1 of itself1 a character of some respect1 and gave a kind of rank among us4 #cg4 ,q4 ,and what is their temper now8 ,a4 ,oh1 very much altered4 #ej4 ,q4 ,was it an opinion in ,america before #agfc that the ,parliament had no right to lay taxes and duties there8 ,a4 ,i never heard any objection to the right of laying duties to regulate commerce2 but a right to lay internal taxes was never supposed to be in ,parliament1 as we are not represented there4 #ei4 ,q4 ,you say the colonies have always submitted to external taxes1 and object to the right of ,parliament only in laying internal taxes2 now1 can you show that there is any kind of difference between the two taxes to the colony on which they may be laid8 ,a4 ,i think the difference is very great4 ,an external tax is a duty laid on commodities imported2 that duty is added to the first cost and other charges on the commodity1 and1 when it is offered to sale1 makes a part of the price4 ,if the people do not like it at that price1 they refuse it2 they are not obliged to pay it4 ,but an internal tax is forced upon the people without their consent1 if not laid by their own representatives4 ,the ,stamp ,act says we shall have no commerce1 make no exchange of property with each other1 neither purchase1 nor grant1 nor recover debts2 we shall neither marry nor make our wills1 unless we pay such and such sums2 and thus it is intended to extort our money from us1 or ruin us by the consequences of refusing to pay it4 #fa4 ,q4 ,don't you think cloth from ,england absolutely necessary to them8 ,a4 ,no1 by no means absolutely necessary2 with industry and good management they may very well supply themselves with all they want4 #fb4 ,q4 ,will it not take a long time to establish that manufacture among them8 and must they not in the mean while suffer greatly8 ,a4 ,i think not4 ,they have made a surprising progress already4 ,and ,i am of opinion that1 before their old clothes are worn out1 they will have new ones of their own making4 #hd4 ,q4 ,if the ,act is not repealed1 what do you think will be the consequence8 ,a4 ,a total loss of the respect and affection the people of ,america bear to this country1 and of all the commerce that depends on that respect and affection4 #he4 ,q4 ,how can the commerce be affected8 ,a4 ,you will find that1 if the ,act is not repealed1 they will take a very little of your manufactures in a short time4 #hf4 ,q4 ,is it in their power to do without them8 ,a4 ,i think they may very well do without them4 #hg4 ,q4 ,is it their interest not to take them8 ,a4 ,the goods they take from ,britain are either necessaries1 mere conveniences1 or superfluities4 ,the first1 as cloth1 etc41 with a little industry they can make at home2 the second they can do without till they are able to provide them among themselves2 and the last1 which are much the greatest part1 they will strike off immediately4 ,they are mere articles of fashion1 purchased and consumed because the fashion in a respected country2 but will now be detested and rejected4 ,the people have already struck off1 by general agreement1 the use of all goods fashionable in mournings1 and many thousand pounds' worth are sent back as unsaleable4 #agc4 ,q4 ,what used to be the pride of the ,americans8 ,a4 ,to indulge in the fashions and manufactures of ,great ,britain4 #agd4 ,q4 ,what is now their pride8 ,a4 ,to wear their old clothes over again till they can make new ones4 ,the month following ,franklin's examination1 the repeal of the ,stamp ,act received the royal assent4 ,thereupon ,franklin sent his wife and daughter new dresses1 and a number of other little luxuries 7or toilet necessaries74 ,in #agfg ,franklin visited ,paris4 ,in the same year his daughter married ,mr4 ,richard ,bache4 ,though ,parliament had repealed the ,stamp ,act1 it nevertheless insisted on its right to tax the colonies4 ,the ,duty ,act was scarcely less objectionable than its predecessor4 ,on ,franklin's return from the ,continent1 he heard of the retaliatory measures of the ,boston people1 who had assembled in town-meetings1 formally resolved to encourage home manufactures1 to abandon superfluities1 and1 after a certain time1 to give up the use of some articles of foreign manufacture4 ,these associations afterwards became very general in the colonies1 so that in one year the importations by the colonists of ,new ,york fell from ,l#dhb1jjj to ,l#gd1jjj1 and in ,pennsylvania from ,l#dcb1jjj to ,l#aai1jjj4 ,the effect of the ,duty ,act was to encourage the ,dutch and other nations to smuggle tea and probably other ,india produce into ,america4 ,the exclusion from the ,american markets of tea sent from ,england placed the ,east ,india ,company in great difficulties2 for while they were unable to meet their bills1 they had in stock two million pounds' worth of tea and other goods4 ,the balance of the revenue collected under the ,duty ,act1 after paying salaries1 etc41 amounted to only ,l#he for the year1 and for this a fleet had to be maintained1 to guard the fifteen hundred miles of ,american coast2 while the fall in ,east ,india ,stock deprived the revenue of ,l#djj1jjj per annum1 which the ,east ,india ,company would otherwise have paid4 ,at length a licence was granted to the ,east ,india ,company to carry tea into ,america1 duty free4 ,this1 of course1 excluded all other merchants from the ,american tea-trade4 ,a quantity of tea sent by the ,east ,india ,company to ,boston was destroyed by the people4 ,the ,british ,government then blockaded the port4 ,this soon led to open hostilities4 ,franklin worked hard to effect a reconciliation4 ,he drew up a scheme1 setting forth the conditions under which he conceived a reconciliation might be brought about1 and discussed it fully with ,mr4 ,daniel ,barclay and ,dr4 ,fothergill4 ,this scheme was shown to ,lord ,howe1 and afterwards brought before the ,ministry1 but was rejected4 ,other plans were considered1 and ,franklin offered to pay for the tea which had been destroyed at ,boston4 ,all his negotiations were1 however1 fruitless4 ,at last he addressed a memorial to the ,earl of ,dartmouth1 ,secretary of ,state1 complaining of the blockade of ,boston1 which had then continued for nine months1 and had during every week of its continuance done damage to that town1 equal to what was suffered there by the ,india ,company2 and claiming reparation for such injury beyond the value of the tea which had been destroyed4 ,the memorial also complained of the exclusion of the colonists from the ,newfoundland fisheries1 for which reparation would one day be required4 ,this memorial was returned to ,franklin by ,mr4 ,walpole1 and ,franklin shortly afterwards returned to ,philadelphia4 ,during this visit to ,england he had lost his wife1 who died on ,december #ai1 #aggd2 and his friend ,miss ,stevenson had married and been left a widow4 ,in ,april1 #agfh1 ,franklin was appointed ,agent for ,georgia1 in the following year for ,new ,jersey1 and in #aggj for ,massachusetts1 so that he was then the representative in ,england of four colonies1 with an income of ,l#abjj per annum4 ,in #agga he spent three weeks at ,twyford1 with the ,bishop of ,st4 ,asaph1 who remained a fast friend of ,franklin's until his death4 ,in #aggb he was nominated by the ,king of ,france as ,foreign ,associate of the ,academy of ,sciences4 ,during his negotiations with the ,british ,government ,franklin wrote two satirical pieces1 setting forth the treatment which the ,american colonists were receiving4 ,the first was entitled ,rules for ,reducing a ,great ,empire to a ,small ,one1 the rules being precisely those which1 in ,franklin's opinion1 had been followed by the ,british ,government in its dealings with ,america4 ,the other was ,an ,edict by the ,king of ,prussia1 in which the king claimed the right of taxing the ,british nation2 of forbidding ,english manufacture1 and compelling ,englishmen to purchase ,prussian goods2 of transporting prisoners to ,britain1 and generally of exercising all such controls over the ,english people as had been claimed over ,america by various ,acts of the ,english ,parliament1 on the ground that ,england was originally colonized by emigrants from ,prussia4 ,before ,franklin reached ,america1 the ,war of ,independence1 though not formally declared1 had fairly begun4 ,he was appointed a member of the second ,continental ,congress1 and one of a committee of three to confer with ,general ,washington respecting the support and regulation of the ,continental ,army4 ,this latter office necessitated his spending some time in the camp4 ,on ,october #c1 #agge1 he wrote to ,priestley3-- ,tell our dear good friend1 ,dr4 ,price1 who sometimes has his doubts and despondencies about our firmness1 that ,america is determined and unanimous2 a very few ,tories and placemen excepted1 who will probably soon export themselves4 ,britain1 at the expense of three millions1 has killed a hundred and fifty ,yankees this campaign1 which is ,l#bj1jjj a head2 and at ,bunker's ,hill she gained a mile of ground1 half of which she lost again by our taking the post on ,ploughed ,hill4 ,during the same time sixty thousand children have been born in ,america4 ,from these data his mathematical head will easily calculate the time and expense necessary to kill us all and conquer our whole territory4 ,in #aggf ,franklin1 then seventy years old1 was appointed one of three ,commissioners to visit ,canada1 in order1 if possible1 to promote a union between it and the ,states4 ,finding that only one ,canadian in five hundred could read1 and that the state of feeling in ,canada was fatal to the success of the ,commissioners1 they returned1 and ,franklin suggested that the next ,commission sent to ,canada should consist of schoolmasters4 ,on the #dth of ,july ,franklin took part in the signing of the ,declaration of ,independence4 ,when the document was about to be signed1 ,mr4 ,hancock remarked1 ,we must be unanimous2 there must be no pulling different ways2 we must all hang together4 ,franklin replied1 ,yes1 we must indeed all hang together1 or most assuredly we shall all hang separately4 ,in the autumn of #aggf ,franklin was unanimously chosen a ,special ,commissioner to the ,french ,court4 ,he took with him his two grandsons1 ,william ,temple ,franklin and ,benjamin ,franklin ,bache1 and leaving ,marcus ,hook on ,october #bh1 crossed the ,atlantic in a sloop of sixteen guns4 ,in ,paris he met with an enthusiastic reception4 ,m4 de ,chaumont placed at his disposal his house at ,passy1 then about a mile from ,paris1 but now within the city4 ,here he resided for nine years1 being a constant visitor at the ,french ,court1 and certainly one of the most conspicuous figures in ,paris4 ,he was obliged to serve in many capacities1 and was very much burdened with work4 ,not only were there his duties as ,commissioner at the ,french ,court1 but he was also made ,admiralty ,judge and ,financial ,agent1 so that all the coupons for the payment of interest on the money borrowed for the prosecution of the war1 as well as all financial negotiations1 either with the ,french ,government or contractors1 had to pass through his hands4 ,perhaps the most unpleasant part of his work was his continued applications to the ,french ,court for monetary advances4 ,the ,french ,government1 as is well known1 warmly espoused the cause of the ,americans1 and to the utmost of its ability assisted them with money1 material1 and men4 ,franklin was worried a good deal by applications from ,french officers for introductions to ,general ,washington1 that they might obtain employment in the ,american ,army4 ,at last he framed a model letter of recommendation1 which may be useful to many in this country in the present day4 ,it was as follows3-- ,,sir1 ,the bearer of this1 who is going to ,america1 presses me to give him a letter of recommendation1 though ,i know nothing of him1 not even his name4 ,this may seem extraordinary1 but ,i assure you it is not uncommon here4 ,sometimes1 indeed1 one unknown person brings another equally unknown1 to recommend him2 and sometimes they recommend one another6 ,as to this gentleman1 ,i must refer you to himself for his character and merits1 with which he is certainly better acquainted than ,i can possibly be4 ,i recommend him1 however1 to those civilities which every stranger1 of whom one knows no harm1 has a right to2 and ,i request you will do him all the good offices and show him all the favour that1 on further acquaintance1 you shall find him to deserve4 ,i have the honour to be1 etc4 ,captain ,wickes1 of the ,refusal1 having taken about a hundred ,british seamen prisoners1 ,franklin and ,silas ,deane1 one of the other ,commissioners1 wrote to ,lord ,stormont1 the ,british ambassador1 respecting an exchange4 ,receiving no answer1 they wrote again1 and ventured to complain of the treatment which the ,american prisoners were receiving in the ,english prisons1 and in being compelled to fight against their own countrymen4 ,to this communication ,lord ,stormont replied3-- ,the king's ambassador receives no applications from rebels1 unless they come to implore his ,majesty's mercy4 ,to this the ,commissioners rejoined3-- ,in answer to a letter1 which concerns some of the most material interests of humanity1 and of the two nations1 ,great ,britain and the ,united ,states of ,america1 now at war1 we received the enclosed indecent paper1 as coming from your ,lordship1 which we return for your ,lordship's more mature consideration4 ,at first the ,british ,government1 regarding the ,americans as rebels1 did not treat their prisoners as prisoners of war1 but threatened to try them for high treason4 ,their sufferings in the ,english prisons were very great4 ,mr4 ,david ,hartley did much to relieve them1 and ,franklin transmitted money for the purpose4 ,when a treaty had been formed between ,france and the ,states1 and ,france had engaged in the war1 and when fortune began to turn in favour of the united armies1 the ,american prisoners received better treatment from the ,english ,government1 and exchanges took place freely4 ,in ,april1 #aggh1 ,mr4 ,hartley visited ,franklin at ,passy1 apparently for the purpose of preventing1 if possible1 the offensive and defensive alliance between ,america and ,france4 ,very many attempts were made to produce a rupture between the ,french ,government and the ,american ,commissioners1 but ,franklin insisted that no treaty of peace could be made between ,england and ,america in which ,france was not included4 ,in #aggi the other ,commissioners were recalled1 and ,franklin was made ,minister ,plenipotentiary to the ,court of ,france4 ,in a letter to ,mr4 ,david ,hartley1 dated ,february #b1 #aghj1 ,franklin showed something of the feelings of the ,americans with respect to the ,english at that time3-- ,you may have heard that accounts upon oath have been taken in ,america1 by order of ,congress1 of the ,british barbarities committed there4 ,it is expected of me to make a school-book of them1 and to have thirty-five prints designed here by good artists1 and engraved1 each expressing one or more of the horrid facts1 in order to impress the minds of children and posterity with a deep sense of your bloody and insatiable malice and wickedness4 ,every kindness ,i hear of done by an ,englishman to an ,american prisoner makes me resolve not to proceed in the work4 ,while at ,passy1 ,franklin addressed to the ,journal of ,paris a paper on an economical project for diminishing the cost of light4 ,the proposal was to utilize the sunlight instead of candles1 and thereby save to the city of ,paris the sum of #if1jge1jjj livres per annum4 ,his reputation in ,paris is shown by the following quotation from a contemporary writer3-- ,i do not often speak of ,mr4 ,franklin1 because the gazettes tell you enough of him4 ,however1 ,i will say to you that our ,parisians are no more sensible in their attentions to him than they were towards ,voltaire1 of whom they have not spoken since the day following his death4 ,mr4 ,franklin is besieged1 followed1 admired1 adored1 wherever he shows himself1 with a fury1 a fanaticism1 capable no doubt of flattering him and of doing him honour1 but which at the same time proves that we shall never be reasonable1 and that the virtues and better qualities of our nation will always be balanced by a levity1 an inconsequence1 and an enthusiasm too excessive to be durable4 ,franklin always advocated free trade1 even in time of war4 ,he was of opinion that the merchant1 the agriculturist1 and the fisherman were benefactors to mankind4 ,he condemned privateering in every form1 and endeavoured to bring about an agreement between all the civilized powers against the fitting out of privateers4 ,he held that no merchantmen should be interfered with unless carrying war material4 ,he greatly lamented the horrors of the war1 but preferred anything to a dishonourable peace4 ,to ,priestley he wrote3-- ,perhaps as you grow older you may 444 repent of having murdered in mephitic air so many honest1 harmless mice1 and wish that1 to prevent mischief1 you had used boys and girls instead of them4 ,in what light we are viewed by superior beings may be gathered from a piece of late ,west ,india news1 which possibly has not yet reached you4 ,a young angel of distinction1 being sent down to this world on some business for the first time1 had an old courier-spirit assigned him as a guide4 ,they arrived over the seas of ,martinico1 in the middle of the long day of obstinate fight between the fleets of ,rodney and ,de ,grasse4 ,when1 through the clouds of smoke1 he saw the fire of the guns1 the decks covered with mangled limbs and bodies dead or dying2 the ships sinking1 burning1 or blown into the air2 and the quantity of pain1 misery1 and destruction the crews yet alive were thus with so much eagerness dealing round to one another1--he turned angrily to his guide1 and said1 ',you blundering blockhead1 you are ignorant of your business2 you undertook to conduct me to the earth1 and you have brought me into hell6' ',no1 sir1' says the guide1 ',i have made no mistake2 this is really the earth1 and these are men4 ,devils never treat one another in this cruel manner2 they have more sense and more of what men 7vainly7 call humanity4' ,franklin maintained that it would be far cheaper for a nation to extend its possessions by purchase from other nations than to pay the cost of war for the sake of conquest4 ,two ,british armies1 under ,general ,burgoyne and ,lord ,cornwallis1 having been wholly taken prisoners during the war1 at last1 after two years' negotiations1 a definitive treaty of peace was signed on ,september #c1 #aghb1 between ,great ,britain and the ,united ,states1 ,franklin being one of the ,commissioners for the latter1 and ,mr4 ,hartley for the former4 ,on the same day a treaty of peace between ,great ,britain and ,france was signed at ,versailles4 ,the ,united ,states ,treaty was ratified by the king on ,april #i1 and therewith terminated the seven years' ,war of ,independence4 ,franklin celebrated the surrender of the armies of ,burgoyne and ,cornwallis by a medal1 on which the infant ,hercules appears strangling two serpents4 ,when peace was at length realized1 a scheme was proposed for an hereditary knighthood of the order of ,cincinnatus1 to be bestowed upon the ,american officers who had distinguished themselves in the war4 ,franklin condemned the hereditary principle4 ,he pointed out that1 in the ninth generation1 the young noble would be only one five hundred and twelfth part of the present knight1 #ajbb men and women being counted among his ancestors1 reckoning only from the foundation of the knighthood4 ,posterity will have much reason to boast of the noble blood of the then existing set of ,chevaliers of ,cincinnatus4 ,on ,may #b1 #aghe1 ,franklin received from ,congress permission to return to ,america4 ,he was then in his eightieth year4 ,on ,july #ab he left ,passy for ,havre1 whence he crossed to ,southampton1 and there saw for the last time his old friend1 the ,bishop of ,st4 ,asaph1 and his family4 ,he reached his home in ,philadelphia early in ,september1 and the day after his arrival he received a congratulatory address from the ,assembly of ,pennsylvania4 ,in the following month he was elected ,president of the ,state1 and was twice re-elected to the same office1 it being contrary to the constitution for any president to be elected for more than three years in succession4 ,the following extract from a letter1 written most probably to ,tom ,paine1 is worthy of the attention of some writers3-- ,i have read your manuscript with some attention4 ,by the argument it contains against a particular ,providence1 though you allow a general ,providence1 you strike at the foundations of all religion4 ,for without the belief of a ,providence that takes cognizance of1 guards1 and guides1 and may favour particular persons1 there is no motive to worship a ,deity1 to fear ,his displeasure1 or to pray for ,his protection4 ,i will not enter into any discussion of your principles1 though you seem to desire it4 ,at present ,i shall only give you my opinion1 that1 though your reasonings are subtle1 and may prevail with some readers1 you will not succeed so as to change the general sentiments of mankind on that subject1 and the consequence of printing this piece will be a great deal of odium drawn upon yourself1 mischief to you1 and no benefit to others4 ,he that spits against the wind spits in his own face4 ,but were you to succeed1 do you imagine any good would be done by it8 ,you yourself may find it easy to live a virtuous life without the assistance afforded by religion2 you having a clear perception of the advantages of virtue and the disadvantages of vice1 and possessing strength of resolution sufficient to enable you to resist common temptations4 ,but think how great a portion of mankind consists of weak and ignorant men and women1 and of inexperienced1 inconsiderate youth of both sexes1 who have need of the motives of religion to restrain them from vice1 to support their virtue1 and retain them in the practice of it till it becomes habitual1 which is the great point for its security4 ,and perhaps you are indebted to her originally1 that is1 to your religious education1 for the habits of virtue upon which you now justly value yourself4 ,you might easily display your excellent talents of reasoning upon a less hazardous subject1 and thereby obtain a rank with our most distinguished authors4 ,for among us it is not necessary1 as among the ,hottentots1 that a youth1 to be raised into the company of men1 should prove his manhood by beating his mother4 ,i would advise you1 therefore1 not to attempt unchaining the tiger1 but to burn this piece before it is seen by any other person2 whereby you will save yourself a great deal of mortification by the enemies it may raise against you1 and perhaps a good deal of regret and repentance4 ,if men are so wicked with religion1 what would they be if without it8 ,i intend this letter itself as a proof of my friendship1 and therefore add no professions to it2 but subscribe simply yours4 ,during the last few years of his life ,franklin suffered from a painful disease1 which confined him to his bed and seriously interfered with his literary work1 preventing him from completing his biography4 ,during this time he was cared for by his daughter1 ,mrs4 ,bache1 who resided in the same house with him4 ,he died on ,april #ag1 #agij1 the immediate cause of death being an affection of the lungs4 ,he was buried beside his wife in the cemetery of ,christ ,church1 ,philadelphia1 the marble slab upon the grave bearing no other inscription than the name and date of death4 ,in his early days 7#agbh7 he had written the following epitaph for himself3-- ,,the ,,body ,,of ,,benjamin ,,franklin1 ,,printer1 7,,like ,,the ,,cover ,,of ,,an ,,old ,,book1 ,,its ,,contents ,,torn ,,out ,,and ,,stript ,,of ,,its ,,lettering ,,and ,,gilding17 ,,lies ,,here1 ,,food ,,for ,,worms4 ,,but ,,the ,,work ,,shall ,,not ,,be ,,lost1 ,,for ,,it ,,will 7,,as ,,he ,,believed7 ,,appear ,,once ,,more ,,in ,a ,,new ,,and ,,more ,,elegant ,,edition1 ,,revised ,,and ,,corrected ,,by ,,the ,,author4 ,when the news of his death reached the ,national ,assembly of ,france1 ,mirabeau rose and said3-- ,franklin is dead6 ,the genius1 which gave freedom to ,america1 and scattered torrents of light upon ,europe1 is returned to the bosom of the ,divinity4 ,the sage1 whom two worlds claim2 the man1 disputed by the history of the sciences and the history of empires1 holds1 most undoubtedly1 an elevated rank among the human species4 ,political cabinets have but too long notified the death of those who were never great but in their funeral orations2 the etiquette of courts has but too long sanctioned hypocritical grief4 ,nations ought only to mourn for their benefactors2 the representatives of free men ought never to recommend any other than the heroes of humanity to their homage4 ,the ,congress hath ordered a general mourning for one month throughout the fourteen confederated ,states on account of the death of ,franklin2 and ,america hath thus acquitted her tribute of admiration in behalf of one of the fathers of her constitution4 ,would it not be worthy of you1 fellow-legislators1 to unite yourselves in this religious act1 to participate in this homage rendered in the face of the universe to the rights of man1 and to the philosopher who has so eminently propagated the conquest of them throughout the world8 ,antiquity would have elevated altars to that mortal who1 for the advantage of the human race1 embracing both heaven and earth in his vast and extensive mind1 knew how to subdue thunder and tyranny4 ,enlightened and free1 ,europe at least owes its remembrance and its regret to one of the greatest men who has ever served the cause of philosophy and liberty4 ,i propose1 therefore1 that a decree do now pass1 enacting that the ,national ,assembly shall wear mourning during three days for ,benjamin ,franklin4 ,,henry ,,cavendish4 ,it would not be easy to mention two men between whom there was a greater contrast1 both in respect of their characters and lives1 than that which existed between ,benjamin ,franklin and the ,honourable ,henry ,cavendish4 ,the former of humble birth1 but of great public spirit1 possessed social qualities which were on a par with his scientific attainments1 and toward the close of his life was more renowned as a statesman than as a philosopher2 the latter1 a member of one of the most noble families of ,england1 and possessed of wealth far exceeding his own capacity for the enjoyment of it1 was known to very few1 was intimate with no one1 and devoted himself to scientific pursuits rather for the sake of the satisfaction which his results afforded to himself than from any hope that they might be useful to mankind1 or from any desire to secure a reputation by making them known1 and passed a long life1 the most uneventful that can be imagined4 ,though the records of his family may be traced to the ,norman ,conquest1 the famous ,elizabeth ,hardwicke1 the foundress of two ducal families and the builder of ,hardwicke ,hall and of ,chatsworth as it was before the erection of the present mansion1 was the most remarkable person in the genealogy4 ,her second son1 ,william1 was raised to the peerage by ,james ,i41 thus becoming ,baron ,cavendish1 and was subsequently created first ,earl of ,devonshire by the same monarch4 ,his great-grandson1 the fourth earl1 was created first ,duke of ,devonshire by ,william ,,iii41 to whom he had rendered valuable services4 ,he was succeeded by his eldest son in #agjg1 and the third son of the second duke was ,lord ,charles ,cavendish1 the father of ,henry and ,frederick1 of whom ,henry was the elder1 having been born at ,nice1 ,october #ac1 #agca4 ,his mother died when he was two years old1 and very little indeed is known respecting his early life4 ,in #agdb he entered ,dr4 ,newcome's school at ,hackney1 where he remained until he entered ,peterhouse1 in #agdi4 ,he remained at ,cambridge until ,february1 #agec1 when he left the university without taking his degree1 objecting1 most probably1 to the religious tests which were then required of all graduates4 ,in this respect his brother ,frederick followed his example4 ,on leaving ,cambridge ,cavendish appears to have resided with his father in ,marlborough ,street1 and to have occasionally assisted him in his scientific experiments1 but the investigations of the son soon eclipsed those of the father4 ,it is said that the rooms allotted to ,henry ,cavendish were a set of stables1 fitted up for his accommodation1 and here he carried out many of his experiments1 including all those electrical investigations in which he forestalled so much of the work of the present century4 ,during his father's life1 or1 at any rate1 till within a few years of its close1 ,henry ,cavendish appears to have enjoyed a very narrow income4 ,he frequently dined at the ,royal ,society ,club1 and on these occasions would come provided with the five shillings to be paid for the dinner1 but no more4 ,upon his father's death1 which took place in #aghc1 when ,henry was more than fifty years of age1 his circumstances were very much changed1 but it seems that the greater part of his wealth was left him by an uncle who had been an ,indian officer1 and this legacy may have come into his possession before his father's death4 ,he appears to have been very liberal when it was suggested to him that his assistance would be of service1 but it never occurred to him to offer a contribution towards any scientific or public undertaking1 and though at the time of his death he is said to have had more money in the funds than any other person in the country1 besides a balance of ,l#ej1jjj on his current account at his bank1 and various other property1 he bequeathed none to scientific societies or similar institutions4 ,throughout the latter part of his life he seems to have been quite careless about money1 and to have been satisfied if he could only avoid the trouble of attending to his own financial affairs4 ,hence he would allow enormous sums to accumulate at his banker's1 and on one occasion1 being present at a christening1 and hearing that it was customary for guests to give something to the nurse1 he drew from his pocket a handful of guineas1 and handed them to her without counting them4 ,after his father's death1 ,cavendish resided in his own house on ,clapham ,common4 ,here a few rooms at the top of the house were made habitable2 the rest were filled with apparatus of all descriptions1 among which the most numerous examples were thermometers of every kind4 ,he seldom entertained visitors1 but when1 on rare occasions1 a guest had to be entertained1 the repast invariably consisted of a leg of mutton4 ,his extreme shyness caused him to dislike all kinds of company1 and he had a special aversion to being addressed by a stranger4 ,on one occasion1 at a reception given by ,sir ,joseph ,banks1 ,dr4 ,ingenhousz introduced to him a distinguished ,austrian philosopher1 who professed that his main object in coming to ,england was to obtain a sight of so distinguished a man4 ,cavendish listened with his gaze fixed on the floor2 then1 observing a gap in the crowd1 he made a rush to the door1 nor did he pause till he had reached his carriage4 ,his aversion to women was still greater2 his orders for the day he would write out and leave at a stated time on the hall-table1 where his house-keeper1 at another stated time1 would find them4 ,servants were allowed access to the portion of the house which he occupied only at fixed times when he was away2 and having once met a servant on the stairs1 a back staircase was immediately erected4 ,his regular walk was down ,nightingale ,lane to ,wandsworth ,common1 and home by another route4 ,on one occasion1 as he was crossing a stile1 he saw that he was watched1 and thenceforth he took his walks in the evening1 but never along the same road4 ,there were only two occasions on which it is recorded that scientific men were admitted to ,cavendish's laboratory4 ,the first was in #agge1 when ,hunter1 ,priestley1 ,romayne1 ,lane1 and ,nairne were invited to see the experiments with the artificial torpedo4 ,the second was when his experiment on the formation of nitric acid by electric sparks in air had been unsuccessfully attempted by ,van ,marum1 ,lavoisier1 and ,monge1 and he thought it right to take some measures to authenticate the truth of it4 ,besides his house at ,clapham1 ,cavendish occupied 7by his instruments7 a house in ,bloomsbury1 near the ,british ,museum1 while a mansion in ,dean ,street1 ,soho1 was set apart as a library4 ,to this library a number of persons were admitted1 who could take out the books on depositing a receipt for them4 ,cavendish was perfectly methodical in all his actions1 and whenever he borrowed one of his own books he duly left the receipt in its place4 ,the only relief to his solitary life was afforded by the meetings of the ,royal ,society1 of which he was elected a ,fellow in #agfj2 by the occasional receptions at the residence of ,sir ,joseph ,banks1 ,p4,r4,s42 and by his not infrequent dinners with the ,royal ,society ,club at the ,crown and ,anchor2 and he may sometimes have joined the social gatherings of another club which met at the ,cat and ,bagpipes1 in ,downing ,street4 ,it was to his visits to the ,royal ,society ,club that we are indebted for the only portrait that exists of him4 ,alexander1 the draughtsman to the ,china ,embassy1 was bent upon procuring a portrait of ,cavendish1 and induced a friend to invite him to the club dinner1 where he could easily succeed1 by taking his seat near the end of the table1 from whence he could sketch the peculiar great-coat of a greyish-green colour1 and the remarkable three-cornered hat1 invariably worn by ,cavendish1 and obtain1 unobserved1 such an outline of the face as1 when inserted between the hat and coat1 would make1 he was quite sure1 a full-length portrait that no one could mistake4 ,it was so contrived1 and every one who saw it recognized it at once4 ,another incident is recorded of the ,royal ,society ,club which1 perhaps1 reflects as much credit upon ,cavendish as upon the ,society4 ,one evening we observed a very pretty girl looking out from an upper window on the opposite side of the street1 watching the philosophers at dinner4 ,she attracted notice1 and one by one we got up and mustered round the window to admire the fair one4 ,cavendish1 who thought we were looking at the moon1 hustled up to us in his odd way1 and when he saw the real object of our study1 turned away with intense disgust1 and grunted out1 ',pshaw6' ,in the spring and autumn of #aghe1 #aghf1 #aghg1 and #agic1 ,cavendish made tours through most of the southern1 midland1 and western counties1 and reached as far north as ,whitby4 ,the most memorable of these journeys was that undertaken in #aghe1 since during its course he visited ,james ,watt at the ,soho ,works1 and manifested great interest in ,watt's inventions4 ,this was only two years after the great controversy as to the discovery of the composition of water1 but the meeting of the philosophers was of the most friendly character4 ,on all these journeys considerable attention was paid to the geology of the country4 ,allusion has already been made to the two committees of the ,royal ,society to which the questions of the lightning-conductors at ,purfleet1 and of points versus knobs for the terminals of conductors1 were referred4 ,cavendish served on each of these committees1 and supported ,franklin's view against the recommendation of ,mr4 ,wilson4 ,on the first committee he probably came into personal communication with ,franklin himself4 ,cavendish's life consisted almost entirely of his philosophical experiments4 ,in other respects it was nearly without incident4 ,he appears to have been so constituted that he must subject everything to accurate measurement4 ,he rarely made experiments which were not quantitative2 and he may be regarded as the founder of quantitative philosophy4 ,the labour which he expended over some of his measurements must have been very great1 and the accuracy of many of his results is marvellous considering the appliances he had at disposal4 ,when he had satisfied himself with the result of an experiment1 he wrote out a full account and preserved it1 but very seldom gave it to the public1 and when he did publish accounts of any of his investigations it was usually a long time after the experiments had been completed4 ,one of the consequences of his reluctance to publish anything was the long controversy on the discovery of the composition of water1 which was revived many years afterwards by ,arago's eloge on ,james ,watt2 but a much more serious result was the loss to the world for so many years of discoveries and measurements which had to be made over again by ,faraday1 ,kohlrausch1 and others4 ,the papers he published appeared in the ,philosophical ,transactions of the ,royal ,society1 to which he began to communicate them in #agff4 ,on ,march #be1 #ahjc1 he was elected one of the eight ,foreign ,associates of the ,institute of ,france4 ,his eloge was pronounced by ,cuvier1 in #ahab1 who said1 ,his demeanour and the modest tone of his writings procured him the uncommon distinction of never having his repose disturbed either by jealousy or by criticism4 ,dr4 ,wilson says1 ,he was almost passionless4 ,all that needed for its apprehension more than the pure intellect1 or required the exercise of fancy1 imagination1 affection1 or faith1 was distasteful to ,cavendish4 ,an intellectual head thinking1 a pair of wonderfully acute eyes observing1 and a pair of very skilful hands experimenting or recording1 are all that ,i realize in reading his memorials4 ,he appeared to have no eye for beauty2 he cared nothing for natural scenery1 and his apparatus1 provided it were efficient1 might be clumsy in appearance and of the cheapest materials2 but he was extremely particular about accuracy of construction in all essential details4 ,he reminds us of one of our foremost men of science1 who1 when his attention was directed to the beautiful lantern tower of a cathedral1 behind which the full moon was shining1 remarked1 ,i see form and colour1 but ,i don't know what you mean by beauty4 ,the accounts of ,cavendish's death differ to some extent in their details1 but otherwise are very similar4 ,it appears that he requested his servant1 as he had something particular to engage his thoughts1 and did not wish to be disturbed by any one1 to leave him and not to return until a certain hour4 ,when the servant came back1 at the time appointed1 he found his master dead4 ,this was on ,february #bd1 #ahaj1 after an illness of only two or three days4 ,it is mainly on account of his researches in electricity that the biography of ,cavendish finds a place in this volume4 ,these investigations took place between the years #agfj and #aghc1 and1 as already stated1 were all conducted in the stables attached to his father's house in ,marlborough ,street4 ,it was by these experiments that electricity was first brought within the domain of measurement1 and many of the numerical results obtained far exceeded in accuracy those of any other observer until the instruments of ,sir ,w4 ,thomson rendered many electrical measurements a comparatively easy matter4 ,the near agreement of ,cavendish's results with those of the best modern electricians has made them a perpetual monument to the genius of their author4 ,it was at the request of ,sir ,w4 ,thomson1 ,mr4 ,charles ,tomlinson1 and others1 that ,cavendish's electrical researches might be given to the public1 that the ,duke of ,devonshire1 in #ahgd1 entrusted the manuscripts to the care of the late ,professor ,clerk ,maxwell4 ,they had previously been in the hands of ,sir ,william ,snow ,harris1 who reported upon them1 but after his death1 in #ahfg1 the report could not be found4 ,the papers1 with an introduction and a number of very valuable notes by the editor1 were published by the ,cambridge ,university ,press1 just before the death of ,clerk ,maxwell1 in #ahgi4 ,sir ,w4 ,thomson quotes the following illustration of the accuracy of ,cavendish's work3--,i find already that the capacity of a disc was determined experimentally by ,cavendish as #a_/a4eg of that of a sphere of the same radius4 ,now we have capacity of disc 7#b_/pi7a a_/#a4ega6 ,cavendish adopted ,franklin's theory of electricity1 treating it as an incompressible fluid pervading all bodies1 and admitting of displacement only in a closed circuit1 unless1 indeed1 the disturbance might extend to infinity4 ,this fluid he supposed1 with ,franklin1 to be self-repulsive1 but to attract matter1 while matter devoid of electricity1 and therefore in the highest possible condition of negative electrification1 he supposed1 with ,a,epinus1 to be1 like electricity1 self-repulsive4 ,one of ,cavendish's earliest experiments was the determination of the precise law according to which electrical action varies with the distance between the charges4 ,franklin had shown that there was no sensible amount of electricity on the interior of a deep hollow vessel1 however its exterior surface might be charged4 ,cavendish mounted a sphere of #ab4a inches in diameter1 so that it could be completely enclosed 7except where its insulating support passed through7 within two hemispheres of #ac4c inches diameter1 which were carried by hinged frames1 and could thus be allowed to close completely over the sphere1 or opened and removed altogether from its neighbourhood4 ,a piece of wire passed through one of the hemispheres so as to touch the inner sphere1 but could be removed at pleasure by means of a silk string4 ,the hemispheres being closed with the globe within them1 and the wire inserted so as to make communication between the inner and outer spheres1 the whole apparatus was electrified by a wire from a charged ,leyden jar4 ,this wire was then removed by means of a silken string and the same motion of the hand which drew away the wire by which the hemispheres were electrified1 immediately after that was done1 drew out the wire which made the communication between the hemispheres and the inner globe1 and1 immediately after that was drawn out1 separated the hemispheres from each other1 and applied the electrometer to the inner globe4 ,it was also contrived so that the electricity of the hemispheres and of the wire by which they were electrified was discharged as soon as they were separated from each other4444 ,the inner globe and hemispheres were also both coated with tinfoil to make them the more perfect conductors of electricity4 ,the electrometer consisted of a pair of pith-balls2 but1 though the experiment was several times repeated1 they shewed no signs of electrification4 ,from this it was clear that1 as there could have been no communication between the globe and hemispheres when the connecting wire was withdrawn1 there must have been no electrification on the globe while the hemispheres1 though themselves highly charged1 surrounded it4 ,to test the delicacy of the experiment1 a charge was given to the globe less than one-sixtieth of that previously given to the hemispheres1 and this was readily detected by the electrometer4 ,from the result ,cavendish inferred that there is no reason to think the inner globe to be at all charged during the experiment4 ,hence it follows that the electric attraction and repulsion must be inversely as the square of the distance1 and that1 when a globe is positively electrified1 the redundant fluid in it is lodged entirely on its surface4 ,this conclusion ,cavendish showed to be a mathematical consequence of the absence of electrification from the inner sphere2 for1 were the law otherwise1 the inner sphere must be electrified positively or negatively1 according as the inverse power were higher or lower than the second1 and that the accuracy of the experiment showed the law must lie between the #b-a_/ej and the #a-di_/ej power of the distance4 ,with his torsion-balance1 ,coulomb obtained the same law1 but ,cavendish's method is much easier to carry out1 and admits of much greater accuracy than that of ,coulomb4 ,cavendish's experiment was repeated by ,dr4 ,mac,alister1 under the superintendence of ,clerk ,maxwell1 in the ,cavendish ,laboratory1 the absence of electrification being tested by ,thomson's quadrant electrometer1 and it was shown that the deviation from the law of inverse squares could not exceed one in #gb1jjj4 ,the distinction between electrical charge or quantity of electricity and degree of electrification was first clearly made by ,cavendish4 ,the latter phrase was subsequently replaced by intensity1 but electric intensity is now used in another sense4 ,cavendish's phrase1 degree of electrification1 corresponds precisely with our notion of electric potential1 and is measured by the work done on a unit of electricity by the electric forces in removing it from the point in question to the earth or to infinity4 ,along with this notion ,cavendish introduced the further conception of the amount of electricity required to raise a conductor to a given degree of electrification1 that is1 the capacity of the conductor4 ,in modern language1 the capacity of a conductor is defined as the number of units of electricity required to raise it to unit potential2 and this definition is in precise accordance with the notion of ,cavendish1 who may be regarded as the founder of the mathematical theory of electricity4 ,finding that the capacities of similar conductors are proportional to their linear dimensions1 he adopted a sphere of one inch diameter as the unit of capacity1 and when he speaks of a capacity of so many inches of electricity1 he means a capacity so many times that of his one-inch sphere1 or equal to that of a sphere whose diameter is so many inches4 ,the modern unit of capacity in the electro-static system is that of a sphere of one centimetre radius1 and the capacity of any sphere is numerically equal to its radius expressed in centimetres4 ,cavendish determined the capacities of nearly all the pieces of apparatus he employed4 ,for this purpose he prepared plates of glass1 coated on each side with circles of tinfoil1 and arranged in three sets of three1 each plate of a set having the same capacity1 but each set having three times the capacity of the preceding4 ,there was also a tenth plate1 having a capacity equal to the whole of the largest set4 ,the capacity of the ten plates was thus sixty-six times that of one of the smallest set4 ,with these as standards of comparison1 he measured the capacities of his other apparatus1 and1 when possible1 modified his conductors so as to make them equal to one of his standards4 ,his large ,leyden battery he found to have a capacity of about #cba1jjj inches of electricity1 so that it was equivalent to a sphere more than five miles in diameter4 ,one of his instruments employed in the measurement of capacities was a trial plate1 consisting of a sheet of metal1 with a second sheet which could be made to slide upon it and to lie entirely on the top of the larger plate1 or to rest with any portion of its area extending over the edge of the former4 ,this was a conductor whose capacity could be varied at will within certain limits4 ,finding the capacity of two plates of tinfoil on glass much greater than his calculations led him to expect1 ,cavendish compared them with two equal plates having air between1 and found their capacity very much to exceed that of the air condenser4 ,the same was the case1 though in a less degree1 with condensers having shellac or bee's-wax for their dielectrics1 and thus ,cavendish not only discovered the property to which ,faraday afterwards gave the name of specific inductive capacity1 but determined its measure in these dielectrics4 ,he also discovered that the apparent capacity of a ,leyden jar increases at first for some time after it has been charged--a phenomenon connected with the so-called residual charge of the ,leyden jar4 ,another feature on which he laid some stress1 and which was brought to his notice by the comparison of his coated panes1 was the creeping of electricity over the surface of the glass beyond the edge of the tinfoil1 which had the same effect on the capacity as an increase in the dimensions of the tinfoil4 ,the electricity appeared to spread to a distance of #j4jg inch all round the tinfoil on glass plates whose thickness was #j4ba inch1 and #j4ji inch in the case of plates #j4jh inch thick4 ,his paper on the torpedo was read before the ,royal ,society in #aggf4 ,the experiments were undertaken in order to determine whether the phenomena observed by ,mr4 ,john ,walsh in connection with the torpedo could be so far imitated by electricity as to justify the conclusion that the shock of the torpedo is an electric discharge4 ,for this purpose ,cavendish constructed a wooden torpedo with electrical organs1 consisting of a pewter plate on each side1 covered with leather4 ,the plates were connected with a charged ,leyden battery1 by means of wires carried in glass tubes1 and thus the battery was discharged through the water in which the torpedo was immersed1 and which was rendered of about the same degree of saltness as the sea4 ,cavendish compared the shock given through the water with that given by the model fish in air1 and found the difference much greater than in the case of the real torpedo1 but1 by increasing the capacity of the battery and diminishing the potential to which it was charged1 this discrepancy was diminished1 and it was found to be very much less in the case of a second model having a leather1 instead of a wooden1 body1 so that the body of the fish itself offered less resistance to the discharge4 ,one of the chief difficulties lay in the fact that no one had succeeded in obtaining a visible spark from the discharge of the torpedo1 which will not pass through the smallest thickness of air4 ,cavendish accounted for this by supposing the quantity of electricity discharged to be very great1 and its potential very small1 and showed that the more the charge was increased and the potential diminished in his model1 the more closely did it imitate the behaviour of the torpedo4 ,but the main interest in this paper lies in the indications which it gives that ,cavendish was aware of the laws which regulate the flow of electricity through multiple conductors1 and in the comparisons of electrical resistance which are introduced4 ,it had been formerly believed that electricity would always select the shortest or best path1 and that the whole of the discharge would take place along that route4 ,franklin seems to have assumed this in the passage quoted#d respecting the discharge of the lightning down the uninsulated conductor instead of through the building4 ,the truth1 however1 is that1 when a number of paths are open to an electric current1 it will divide itself between them in the inverse ratios of their resistances1 or directly as their conductivities1 so that1 however great the resistance of one of the conductors1 some portion1 though it may be a very small fraction1 of the discharge will take place through it4 ,but this law does not hold in the case of insulators like the air1 through which electricity passes only by disruptive discharges1 and which completely prevent its passage unless the electro-motive force is sufficient to break through their substance4 ,in the case of the lightning-conductor1 however1 its resistance is generally so small in comparison with that of the building it is used to protect1 that ,franklin's conclusion is practically correct4 ,footnote #d3 ,page #if4 ,in his paper on the torpedo ,cavendish stated that some experiments had shown that iron wire conducted #djj1jjj1jjj times better than rain or distilled water1 sea-water #ajj times1 and saturated solution of sea-salt about #gbj times1 better than rain-water4 ,maxwell pointed out that this comparison of iron wire with sea-water would agree almost precisely with the measurements of ,matthiesen and ,kohlrausch at #aa deg4,c4 ,the records of the experiments which led to these results were found among ,cavendish's unpublished papers1 and the experiments also showed that the conductivity of saline solutions was very nearly proportional to the percentage of salt contained1 when this was not very large--a result also obtained long afterwards by ,kohlrausch4 ,in making these measurements ,cavendish was his own galvanometer4 ,the solutions were contained in glass tubes more than three feet long1 and a wire inserted to different distances into the solution2 thus the discharge could be made to pass through any length of the liquid column less than that of the tube itself4 ,from the ,leyden battery of forty-nine jars1 six jars of nearly equal capacity were selected and charged together1 and the charge of one jar only was employed for each shock4 ,the discharge passed through the column of liquid contained in the tube1 from a wire inserted at the further end1 until it reached the sliding wire1 when nearly the whole current betook itself to the wire on account of its smaller resistance1 and thence passed through the galvanometer1 which was ,cavendish himself4 ,two tubes were generally compared together1 and the jars discharged alternately through the tubes1 and the tube which gave the greatest shock was assumed to possess the least resistance4 ,the wires were then adjusted till the shocks were nearly equal1 and positions determined which made the first tube possess a greater and then a less resistance than the second4 ,from these positions the length of the column of liquid was estimated which would make the resistances of the two tubes exactly equal4 ,but the result which has the greatest theoretical interest was obtained by discharging the ,leyden jars through wide and narrow tubes containing the same solutions4 ,by these experiments ,cavendish found that the resistances of the conductors were independent of the strengths of the currents flowing in them2 that is to say1 he established ,ohm's law for electrolytes in a form which carried with it its full explanation4 ,this was in ,january1 #agha4 ,ohm's law was first formally stated in #ahbg4 ,the physical fact which is expressed by it is that the ratio of the electro-motive force to the current produced is the same for the same conductor1 otherwise under the same physical conditions1 however great or small that electro-motive force may be4 ,cavendish devoted considerable attention to the subject of heat1 especially thermometry4 ,in many of his investigations on latent and specific heat he worked on the same lines as ,black1 and at about the same time2 but it is difficult to determine the exact date of some of ,cavendish's work1 as he frequently did not publish it for a long time after its completion1 and most of ,black's results were made public only to his lecture audience4 ,cavendish1 however1 improved upon ,black in his mode of stating some of his results4 ,the heat1 for instance1 which is absorbed by a body in passing from the solid to the liquid1 or from the liquid to the gaseous1 condition1 ,black called latent heat1 and supposed it to become latent within the substance1 ready to reveal itself when the body returned to its original condition4 ,this heat ,cavendish spoke of as being destroyed or generated1 and this is in accordance with what we now know respecting the nature of heat1 for when a body passes from the solid to the liquid1 or from the liquid or solid to the gaseous1 condition1 a certain amount of work has to be done1 and a corresponding amount of heat is used up in the doing of it4 ,when the body returns to its original condition1 the heat is restored1 as when a heavy body falls to the ground1 or a bent spring returns to its original form4 ,cavendish's determination of the so-called latent heat of steam was very slightly in error4 ,about #agfj very extraordinary beliefs were current respecting the excessive degree of cold and the rapid variations of temperature which take place in the ,arctic regions4 ,braun1 of ,st4 ,petersburg1 had observed that mercury1 in solidifying in the tube of a thermometer1 descended through more than four hundred degrees1 and it was assumed that the melting point of mercury was about #djj deg4 below ,fahrenheit's zero4 ,it then became necessary to suppose that1 while the mercury in a thermometer was freezing1 there was a variation of temperature to this extent1 and thus these wild reports became current4 ,cavendish and ,black independently explained the anomaly1 and each suggested the same method of determining the freezing point of mercury4 ,cavendish1 however1 had a piece of apparatus prepared which he sent to ,governor ,hutchins1 at ,albany ,fort1 ,hudson's ,bay4 ,it consisted of an outer vessel1 in which the mercury was allowed to freeze1 but not throughout the whole of its mass1 and the bulb of the thermometer was kept immersed in the liquid metal in the interior4 ,in this way the mercury in the thermometer was cooled down to the melting point without commencing to solidify1 and the temperature was found to be between #ci deg4 and #dj deg4 below ,fahrenheit's zero4 ,as a chemist1 ,cavendish is renowned for his eudiometric analysis1 whereby he determined the percentage of oxygen in air with an amount of accuracy that would be creditable to a chemist of to-day1 and for his discovery of the composition of water2 but to the world generally he is perhaps best known by the famous ,cavendish experiment for determining the mass1 and hence the mean density1 of the earth4 ,the apparatus was originally suggested by the ,rev4 ,john ,michell1 but was first employed by ,cavendish1 who thereby determined the mean density of the earth to be #e4de4 ,at the request of the ,astronomical ,society1 the investigation was afterwards taken up by ,mr4 ,francis ,baily1 who1 after much labour1 discovered that the principal sources of error were due to radiation of heat1 and consequent variation of temperature of parts of the apparatus during the experiment4 ,to minimize the radiation and absorption1 he gilded the principal portions of the apparatus and the interior of the case in which it was contained1 and his results then became consistent4 ,cavendish had himself suggested the cause of the discrepancy1 but the gilding was proposed by ,principal ,forbes4 ,as a mean of many hundreds of experiments1 ,mr4 ,baily deduced for the mean density of the earth #e4ffjd4 ,cavendish's apparatus was a delicate torsion-balance1 whereby two leaden balls were supported upon the extremities of a wooden rod1 which was suspended by a thin wire4 ,these balls were about two inches in diameter1 and the experiment consisted in determining the deflection of the wooden arm by the attraction of two large solid spheres of lead brought very near the balls1 and so situated that the attraction of each tended to twist the rod horizontally in the same direction4 ,the force required to produce the observed deflection was calculated from the time of swing of the rod and balls when left to themselves4 ,the force exerted upon either ball by a known spherical mass of metal1 with its centre at a known distance1 being thus determined1 it was easy to calculate what mass1 having its centre at the centre of the earth1 would be required to attract one of the balls with the force with which the earth was known to attract it4 ,dr4 ,wilson sums up ,cavendish's view of life in these words3-- ,his theory of the universe seems to have been that it consisted solely of a multitude of objects which could be weighed1 numbered1 and measured2 and the vocation to which he considered himself called was to weigh1 number1 and measure as many of these objects as his allotted three score years and ten would permit4 ,this conviction biased all his doings--alike his great scientific enterprises and the petty details of his daily life4 ,greek3 ,panta metro1 kai arithmo1 kai stathmo1 was his motto2 and in the microcosm of his own nature he tried to reflect and repeat the subjection to inflexible rule and the necessitated harmony which are the appointed conditions of the macrocosm of ,god's universe4 ,,count ,,rumford4 ,benjamin ,thompson1 like ,franklin1 was a native of ,massachusetts1 his ancestors for several generations having been yeomen in that province1 and descendants of the first colonists of the ,bay4 ,in the diploma of arms granted him when he was knighted by ,george ,,iii41 he is described as son of ,benjamin ,thompson1 late of the province of ,massachusetts ,bay1 in ,new ,england1 gent4 ,he was born in the house of his grandfather1 ,ebenezer ,thompson1 at ,woburn1 ,massachusetts1 on ,march #bf1 #agec4 ,his father died at the age of twenty-six1 on ,november #g1 #aged1 leaving the infant ,benjamin and his mother to the care of the grandparents4 ,the widow married ,josiah ,pierce1 junior1 in ,march1 #agef1 and with her child1 now a boy of three1 went to live in a house but a short distance from her former residence4 ,young ,thompson appears to have received a sound elementary education at the village school4 ,from some remarks made by him in after years to his friend1 ,m4 ,pictet1 it has been inferred that he did not receive very kind treatment at the hands of his stepfather4 ,it is clear1 however1 that the most affectionate relationships always obtained between him and his mother1 and the latter appears to have had no cause to complain of the treatment she received from her second husband1 with whom she lived to a very good old age4 ,that ,thompson in early boyhood developed some tendencies which did not meet with ready sympathy from those around him is1 however1 equally clear4 ,his guardians destined him for a farmer1 like his ancestors1 and his experiments in mechanics1 which took up much of his playtime and in all probability not a few hours which should have been devoted to less interesting work1 were not regarded as tending towards the end in view4 ,hence he was probably looked upon as indolent1 flighty1 and unpromising4 ,later on he was sent to school in ,byfield1 and in #agfd1 at the age of eleven1 was put under the tuition of ,mr4 ,hill1 an able teacher in ,medford1 a town adjoining ,woburn4 ,at length1 his friends having given up all hope of ever making a farmer of the boy1 he was apprenticed1 on ,october #ad1 #agff1 to ,mr4 ,john ,appleton1 of ,salem1 an importer of ,british goods and dealer in miscellaneous articles4 ,he lived with his master1 and seems to have done his work in a manner satisfactory on the whole1 but there is evidence that he would1 during business hours1 occupy his spare moments with mechanical contrivances1 which he used to hide under the counter1 and even ventured occasionally to practise on his fiddle in the store4 ,he stayed with ,mr4 ,appleton till the autumn of #agfi1 and during this time he attended the ministry of the ,rev4 ,thomas ,barnard4 ,this gentleman seems to have taken great interest in the boy1 and to have taught him mathematics1 so that at the age of fifteen he was able to calculate an eclipse1 and was delighted when the eclipse commenced within six seconds of his calculated time4 ,thompson1 while an apprentice1 showed a great faculty for drawing and designing1 and used to carve devices for his friends on the handles of their knives or other implements4 ,it was at this time he constructed an elaborate contrivance to produce perpetual motion1 and on one evening it is said that he walked from ,salem to ,woburn1 to show it to ,loammi ,baldwin1 who was nine years older than himself1 but his most intimate friend4 ,like many other devices designed for the same purpose1 it had only one fault--it wouldn't go4 ,it was in #agfi1 while preparing fireworks for the illumination on the abolition of the ,stamp ,act1 that ,thompson was injured by a severe explosion as he was grinding his materials in a mortar4 ,his note-book contained many directions for the manufacture of fireworks4 ,during ,thompson's apprenticeship those questions were agitating the public mind which finally had their outcome in the ,war of ,independence4 ,mr4 ,appleton was one of those who signed the agreement refusing to import ,british goods1 and this so affected the trade of the store that he had no further need for the apprentice4 ,hence it was that1 in the autumn of #agfi1 ,thompson went to ,boston as apprentice-clerk in a dry goods store1 but had to leave after a few months1 through the depression in trade consequent on the non-importation agreement4 ,his note-book1 containing the entries made at this time1 comprised several comic sketches very well drawn1 and a quantity of business memoranda which show that he was very systematic in keeping his accounts4 ,his chief method of earning money1 or rather of making up the ,cr4 side of his accounts1 was by cutting and cording wood4 ,a series of entries made in ,july and ,august1 #agga1 show the expense he incurred in constructing an electrical machine4 ,it is not easy to determine1 from the list of items purchased1 the character of the machine he constructed2 but it is interesting to note that the price in ,america at that time of nitric acid was #bs4 #f;d4 per ounce2 of lacquer1 #djs4 per pint2 of shellac1 #es4 per ounce2 brass wire1 #djs4 per pound2 and iron wire1 #as4 #c;d4 per yard4 ,the nature of the problems which occupied his thoughts during the last year or two of his business life are apparent in the following letters3-- ,woburn1 ,august #af1 #agfi4 ,mr4 ,loammi ,baldwin1 ,,sir1 ,please to inform me in what manner fire operates upon clay to change the colour from the natural colour to red1 and from red to black1 etc42 and how it operates upon silver to change it to blue4 ,i am your most humble and obedient servant1 ,,benjamin ,,thompson ,god save the king4 ,woburn1 ,august1 #agfi4 ,mr4 ,loammi ,baldwin1 ,,sir1 ,please to give the nature1 essence1 beginning of existence1 and rise of the wind in general1 with the whole theory thereof1 so as to be able to answer all questions relative thereto4 ,yours1 ,,benjamin ,,thompson4 ,this was an extensive request1 and the reply was probably not altogether satisfactory to the inquirer4 ,on the back of the above letter was written3-- ,woburn1 ,august #ae1 #agfi4 ,,sir1 ,there was but few beings 7for inhabitants of this world7 created before the airy element was2 so it has not been transmitted down to us how the ,great ,creator formed the matter thereof4 ,so ,i shall leave it till ,i am asked only the ,natural ,cause1 and why it blows so many ways in so short a time as it does4 ,thompson appears now to have given up business and commenced the study of medicine under ,dr4 ,hay1 to whom for a year and a half he paid forty shillings per week for his board4 ,during this time he paid part of his expenses by keeping school for a few weeks consecutively at ,wilmington and ,bradford1 and another part was paid by cords of wood4 ,his business capacity1 as well as his dislike of ordinary work1 is shown by some arrangements which he made for getting wood cut and corded at prices considerably below those at which he was himself paid for it4 ,his note-book made at this time contains1 besides business entries1 several receipts for medicines and descriptions of surgical operations1 in some cases illustrated by sketches4 ,in his work he was methodical and industrious1 and the life of a medical student suited his genius far better than that of a clerk in a dry goods store4 ,when teaching at ,wilmington he seems to have attracted attention by the gymnastic performances with which he exercised both himself and his pupils4 ,while a student with ,dr4 ,hay1 he attended some of the scientific lectures at ,harvard ,college4 ,the pleasure and profit which he derived from these lectures are sufficiently indicated by the fact that forty years afterwards he made the college his residuary legatee4 ,thompson won such a reputation as a teacher during the few weeks that he taught in village schools in the course of his student life1 that he received an invitation from ,colonel ,timothy ,walker to come to ,concord1 in ,new ,hampshire1 on the ,merrimack1 and accept a permanent situation in a higher grade school4 ,it was from this place that he afterwards took his title1 for the early name of ,concord was ,rumford1 and the name was changed to ,concord to mark the restoration of harmony after a long period of agitation as to its provincial jurisdiction and its relation with its neighbours4 ,the young schoolmaster of ,concord was soon on very intimate terms with the minister of the town1 the ,rev4 ,timothy ,walker1#e a man who was so much respected that he had thrice been sent to ,britain on diplomatic business4 ,mr4 ,walker's daughter had been married to ,colonel ,rolfe1 a man of wealth and position1 and1 with the exception of the ,governor of ,portsmouth1 said to have been the first man in ,new ,hampshire to drive a curricle and pair of horses4 ,thompson soon married--or1 as he told ,pictet1 was married to--the young widow4 ,whatever may have been implied by this other way of putting the question1 there is no doubt that ,thompson always had the greatest possible respect for his father-in-law1 and ever remembered him with sincere gratitude4 ,the fortunes of the gallant young schoolmaster now appeared to be made2 when the engagement was settled1 the carriage and pair were brought out again1 and the youth was attired in his favourite scarlet as a man of wealth and position4 ,in this garb he drove to ,woburn1 and introduced his future wife to his mother1 whose surprise can be better imagined than described4 ,footnote #e3 ,father of the colonel4 ,the exact date of ,thompson's marriage is not known4 ,his daughter ,sarah1 afterwards ,countess of ,rumford1 was born in the ,rolfe mansion on ,october #ah1 #aggd4 ,it is needless to say that the engagement to ,mrs4 ,rolfe terminated the teaching at the school4 ,thompson now had a large estate and ample means to improve it4 ,he gave much attention to gardening1 and sent to ,england for garden seeds4 ,in some way he attracted the attention of ,governor ,wentworth1 the ,governor of ,portsmouth1 who invited him to the ,government ,house1 and was so taken with the former apprentice1 medical student1 and schoolmaster1 that he gave him at once a commission as major4 ,this appointment was the cause of the misfortunes which almost immediately began to overtake him4 ,he incurred the jealousy of his fellow-officers1 over whom he had been appointed1 and he failed to secure the confidence of the civilians of ,concord4 ,public feeling in ,new ,england was very much excited against the mother country4 ,representations were sent to the ,british ,government1 but appeared to be treated with contempt4 ,very many of these documents were found1 after the war was over1 unopened in drawers at the ,colonial ,office4 ,british ministers appeared to know little about the needs of their ,american dependencies1 and relations rapidly became more and more strained4 ,the patriots appointed committees to watch over the patriotism of their fellow-townsmen1 and thus the freedom of a free country was inaugurated by an institution bordering in character very closely upon the ,inquisition2 and the ,committees of ,correspondence and ,safety accepted evidence from every spy or eavesdropper who came before them with reports of suspected persons4 ,thompson was accused of ,toryism2 the only definite charge against him being that he had secured remission of punishment for some deserters from ,boston who had for some time worked upon his estate4 ,he was summoned before the ,committee of ,safety1 but refused to make any confession of acts injurious to his country1 on the ground that he had nothing to confess4 ,his whole after-life shows that his sympathies were very much on the side of monarchy and centralization1 but at this time there appears to have been no evidence that could be brought against him4 ,the populace1 however1 stormed his house1 and he owed his safety to the fact that he had received notice of their intentions1 and had made his escape a few hours before4 ,this was in ,november1 #aggd4 ,thompson then took refuge at ,woburn1 with his mother1 but the popular ill feeling troubled him here1 so that his life was one of great anxiety4 ,while at ,woburn1 his wife and child joined him1 and stayed there for some months4 ,at length he was arrested and confined in the town upon suspicion of being inimical to the interests of his country4 ,when he was brought before the ,committee of ,inquiry1 there was no evidence brought against him4 ,major ,thompson then petitioned to be heard before the ,committee of the ,provincial ,congress at ,washington4 ,this petition he entrusted to his friend ,colonel ,baldwin to present4 ,the petition was referred by the committee to ,congress1 by whom it was deferred for the sake of more pressing business4 ,at length he secured a hearing in his native town1 but the result was indecisive1 and he did not obtain the public acquittal that he desired1 though the ,committee of ,correspondence found that the said ,thompson had not in any one instance shown a disposition unfriendly to ,american liberty2 but that his general behaviour has evinced the direct contrary2 and as he has now given us the strongest assurances of his good intentions1 we recommend him to the friendship1 confidence1 and protection of all good people in this and the neighbouring provinces4 ,this decision1 however1 does not appear to have been made public2 and ,thompson1 on his release1 retired to ,charlestown1 near ,boston4 ,when the buildings of ,harvard ,college were converted into barracks1 ,major ,thompson assisted in the transfer of the books to ,concord4 ,it is said that1 after the battle of ,charlestown1 ,thompson was introduced to ,general ,washington1 and would probably have received a commission under him but for the opposition of some of the ,new ,hampshire officers4 ,he afterwards took refuge in ,boston1 and it does not appear that he ever again saw his wife or her father4 ,his daughter he did not see again till #agif1 when she was twenty-two years of age4 ,on ,march #bd1 #aggf1 ,general ,washington obliged the ,british troops to evacuate ,boston2 ,thompson was the first official bearer of this intelligence to ,london4 ,of course1 his property at ,concord was confiscated to the commonwealth of ,massachusetts1 and he himself was proscribed in the ,alienation ,act of ,new ,hampshire1 in #aggh4 ,when ,thompson reached ,london with the intelligence of the evacuation of ,boston1 ,lord ,george ,germaine1 the ,secretary for ,war1 saw that he could afford much information which would be of value to the ,government4 ,an appointment was soon found for him in the ,colonial ,office1 and afterwards he was made ,secretary of the ,province of ,georgia1 in which latter capacity1 however1 he had no duties to fulfil4 ,throughout his career in the ,colonial ,office he remained on very intimate terms with ,lord ,george ,germaine1 and generally breakfasted with him4 ,in ,july1 #aggh1 he was guest of ,lord ,george at ,stoneland ,lodge1 and here1 in company with ,mr4 ,ball1 the ,rector of ,withyham1 he undertook experiments to determine the most advantageous situation for the vent in firearms1 and to measure the velocities of bullets and the recoil under various circumstances4 ,the results of these investigations procured for him the friendship of ,sir ,joseph ,banks1 the ,president of the ,royal ,society1 and ,thompson was not the man to lose opportunities for want of making use of them4 ,in #aggi he was elected a ,fellow of the ,royal ,society1 as a gentleman well versed in natural knowledge and many branches of polite learning4 ,in the same year he went for a cruise in the ,victory with ,sir ,charles ,hardy1 in order to pursue his experiments on gunpowder with heavy guns4 ,here he studied the principles of naval artillery1 and devised a new code of marine signals4 ,in #aghj he was made ,under-,secretary of ,state for the ,northern ,department1 and in that capacity had the oversight of the transport and commissariat arrangements for the ,british forces4 ,on the defeat of ,cornwallis1 ,lord ,george ,germaine and his department had to bear the brunt of ,parliamentary dissatisfaction4 ,lord ,george resigned his position in the ,government1 and was created ,viscount ,sackville4 ,he had1 however1 previously conferred on ,thompson a commission as lieutenant-colonel in the ,british army1 and ,thompson1 probably foreseeing the outcome of events and its effect on the ,ministry1 was already in ,america when ,lord ,george resigned4 ,he had intended landing at ,new ,york1 but contrary winds drove him to ,charlestown4 ,it is needless to trace the sad events which preceded the end of the war4 ,it was to be expected that many bitter statements would be made by his countrymen respecting ,thompson's own actions as colonel commanding a ,british garrison1 for at length he succeeded in reaching ,long ,island1 and taking the command of the ,king's ,american ,dragoons1 who were there awaiting him4 ,the spirit of war always acts injuriously on those exposed to its influence1 and ,lieutenant-,colonel ,thompson in ,long ,island was doubtless a very different man from that which we find him to have been before and after2 nor were the months so spent very fruitful in scientific work4 ,in #aghc1 before the final disbanding of the ,british forces1 ,thompson returned to ,england1 and was promoted to the rank of colonel1 with half-pay for the rest of his life4 ,still anxious for military service1 he obtained permission to travel on the ,continent1 in hopes of serving in the ,austrian army against the ,turks4 ,he took with him three ,english horses1 which rendered themselves very objectionable to his fellow-travellers while crossing the ,channel in a small boat4 ,thompson went to ,strasbourg1 where he attracted the attention of the ,prince ,maximilian1 then ,field-,marshal of ,france1 but afterwards ,elector of ,bavaria4 ,on leaving ,strasbourg1 the prince gave him an introduction to his uncle1 the ,elector of ,bavaria4 ,he stayed some days at ,munich1 but on reaching ,vienna learned that the war against the ,turks would not be carried on1 so he returned to ,munich1 and thence to ,england4 ,m4 ,pictet gives the following as ,rumford's account of the manner in which he was cured of his passion for war3-- ',i owe it1' said he to me1 one day1 'to a beneficent ,deity1 that ,i was cured in season of this martial folly4 ,i met1 at the house of the ,prince de ,kaunitz1 a lady1 aged seventy years1 of infinite spirit and full of information4 ,she was the wife of ,general ,bourghausen4 ,the emperor1 ,joseph ,,ii41 came often to pass the evening with her4 ,this excellent person conceived a regard for me2 she gave me the wisest advice1 made my ideas take a new direction1 and opened my eyes to other kinds of glory than that of victory in battle4' ,if the course in life which ,colonel ,thompson afterwards took was due to the advice of this lady1 she deserves a ,european reputation4 ,the ,elector of ,bavaria1 ,charles ,theodore1 gave ,thompson a pressing invitation to enter his service in a sort of semi-military and semi-civil capacity1 to assist in reorganizing his dominions and removing the abuses which had crept in4 ,before accepting this appointment1 it was necessary to obtain the permission of ,george ,,iii4 ,the king not only approved of the arrangement1 but on ,february #bc1 #aghd1 conferred on the colonel the honour of knighthood4 ,sir ,benjamin then returned to ,bavaria1 and was appointed by the elector colonel of a regiment of cavalry and general aide-de-camp4 ,a palatial residence in ,munich was furnished for him1 and here he lived more as a prince than a soldier4 ,it was eleven years before he returned1 even on a visit1 to ,england1 and these years were spent by him in works of philanthropy and statesmanship1 to which it is difficult to find a parallel4 ,at one time he is found reorganizing the military system of the country1 arranging a complete system of military police1 erecting arsenals at ,mannheim and ,munich2 at another time he is carrying out scientific investigations in one of these arsenals2 and then he is cooking cheap dinners for the poor of the country4 ,one great evil of a standing army is the idleness which it develops in its members1 unfitting them for the business of life when their military service is ended4 ,thompson commenced by attacking this evil4 ,in #aghh he was made major-general of cavalry and ,privy ,councillor of ,state1 and was put at the head of the ,war ,department1 with instructions to carry out any schemes which he had developed for the reform of the army and the removal of mendicity4 ,four years after his arrival in ,munich he began to put some of his plans into operation4 ,the pay of the soldiers was only threepence per day1 and their quarters extremely uncomfortable1 while their drill and discipline were unnecessarily irksome4 ,thompson set to work to make soldiers citizens and citizens soldiers4 ,the soldier's pay1 uniform1 and quarters were improved2 the discipline rendered less irksome2 and schools in which the three ,r's were taught were connected with all the regiments1--and here not only the soldiers1 but their children as well as other children1 were taught gratuitously4 ,not only were the soldiers employed in public works1 and thus accustomed to habits of industry1 while they were enlivened in their work by the strains of their own military bands1 but they were supplied with raw material of various kinds1 and allowed1 when not on duty1 to manufacture various articles and sell them for their own benefit--an arrangement which in this country to-day would probably raise a storm of opposition from the various trades4 ,the garrisons were made permanent1 so that soldiers might all be near their homes and remain there1 and in time of peace only a small portion of the force was required to be in garrison at any time1 so that the great part of his life was spent by each soldier at home4 ,each soldier had a small garden appropriated to his use1 and its produce was his sole property4 ,garden seeds1 and especially seed potatoes1 were provided for the men1 for at that time the potato was almost unknown in ,bavaria4 ,under these circumstances a reform was quickly effected2 idle men began to take interest in their gardens1 and all looked on ,sir ,benjamin as a benefactor4 ,having thus secured the co-operation of the army1 ,thompson determined to attack the mendicants4 ,the number of beggars may be estimated from the fact that in ,munich1 with a population of sixty thousand1 no less than two thousand six hundred beggars were seized in a week4 ,in the towns1 they possessed a complete organization1 and positions of advantage were assigned in regular order1 or inherited according to definite customs4 ,in the country1 farm labourers begged of travellers1 and children were brought up to beggary from their infancy4 ,of course1 the evils did not cease with simple begging4 ,children were stolen and ill treated1 for the purpose of assisting in enlisting sympathy1 and the people had come to regard these evils as inevitable4 ,thompson organized a regular system of military patrol through every village of the country1 four regiments of cavalry being set apart for this work4 ,then on ,january #a1 #agij1 when the beggars were out in full force to keep their annual holiday1 ,thompson1 with the other field officers and the magistrates of the city1 gave the signal1 and all the beggars in ,munich were seized upon by the three regiments of infantry then in garrison4 ,the beggars were taken to the town hall1 and their names and addresses entered on lists prepared for the purpose4 ,they were ordered to present themselves next day at the military workhouse1 and a committee was appointed to inquire into the condition of each1 the city being divided into sixteen districts for that purpose4 ,relieved of an evil which they had regarded as inevitable1 the townspeople readily subscribed for the purpose of affording systematic relief1 while tradesmen sent articles of food and other requisites to the relief committee4 ,in the military workhouse the former mendicants made all the uniforms for the troops1 besides a great deal of clothes for sale in ,bavaria and other countries4 ,thompson himself fitted up and superintended the kitchen1 where food was daily cooked for between a thousand and fifteen hundred persons2 and1 under ,sir ,benjamin's management1 a dinner for a thousand was cooked at a cost for fuel of fourpence halfpenny--a result which has scarcely been surpassed in modern times1 even at ,gateshead4 ,that ,thompson's work was appreciated by those in whose interest it was undertaken is shown by the fact that when1 on one occasion1 he was dangerously ill1 the poor of ,munich went in public procession to the cathedral to pray for him1 though he was a foreigner and a ,protestant4 ,perhaps it may appear that his philanthropic work has little to do with physical science2 but with ,thompson everything was a scientific experiment1 conducted in a truly scientific manner4 ,for example1 the lighting of the military workhouse afforded matter for a long series of experiments1 described in his papers on photometry1 coloured shadows1 etc4 ,the investigations on the best methods of employing fuel for culinary purposes led to some of his most elaborate essays2 and his essay on food was welcomed alike in ,london and ,bavaria at a time of great scarcity1 and when famine seemed impending4 ,the ,emperor ,joseph was succeeded by ,leopold ,,ii41 but during the interregnum the ,elector of ,bavaria was ,vicar of the ,empire1 and he employed the power thus temporarily placed in his hands in raising ,sir ,benjamin to the dignity of ,count of the ,holy ,roman ,empire1 with the order of the ,white ,eagle1 and the title which the new count selected was the old name of the village in ,new ,england where he had spent the two or three years of his wedded life4 ,in #agie ,count ,rumford returned to ,england1 in order to publish his essays1 and to make known in this country something of the work in which he had been engaged4 ,soon after his arrival he was robbed of most of his manuscripts1 the trunk containing them being stolen from his carriage in ,st4 ,paul's ,churchyard4 ,on the invitation of ,lord ,pelham1 he visited ,dublin1 and carried out some of his improvements in the hospitals and other institutions of that city4 ,on his return to ,london he fitted up the kitchen of the ,foundling ,hospital4 ,lady ,thompson lived to hear of her husband's high position in ,bavaria1 but died on ,january #bi1 #agib4 ,when ,rumford came to ,london in #agie1 he wrote to his daughter1 who was then twenty-one years of age1 to meet him there1 and on ,january #bi1 #agif1 she started in the ,charlestown1 from ,boston4 ,she remained with her father for more than three years1 and her autobiography gives much information respecting the count's doings during this time4 ,while in ,london1 ,count ,rumford attained a high reputation as a curer of smoky chimneys4 ,one firm of builders found full employment in carrying out work in accordance with his instructions2 and in his hotel at ,pall ,mall he conducted experiments on fireplaces4 ,he concluded that the sides of a fireplace ought to make an angle of #ace deg4 with the back1 so as to throw the heat straight to the front2 and that the width of the back should be one-third of that of the front opening1 and be carried up perpendicularly till it joins the breast4 ,the ,rumford roaster gained a reputation not less than that earned by his open fireplace4 ,it was during this stay in ,london that ,rumford presented to the ,royal ,society of ,london1 and to the ,american ,academy of ,sciences ,l#ajjj ,three per ,cent4 ,stock1 for the purpose of endowing a medal to be called the ,rumford ,medal1 and to be given each alternate year for the best work done during the preceding two years in the subjects of heat and light4 ,he directed that two medals1 one in gold and the other in silver1 should be struck from the same die1 the value of the two together to amount to ,l#fj4 ,whenever no award was made1 the interest was to be added to the principal1 and the excess of the income for two years over ,l#fj was to be presented in cash to the recipient of the medal4 ,at present the amount thus presented is sufficient to pay the composition fee for life membership of the ,royal ,society4 ,the first award of the medal was made in #ahjb1 to ,rumford himself4 ,the other recipients have been ,john ,leslie1 ,william ,murdock1 ,etienne-,louis ,malus1 ,william ,charles ,wells1 ,humphry ,davy1 ,david ,brewster1 ,augustin ,jean ,fresnel1 ,macedonio ,melloni1 ,james ,david ,forbes1 ,jean ,baptiste ,biot1 ,henry ,fox ,talbot1 ,michael ,faraday1 ,m4 ,regnault1 ,f4 ,j4 ,d4 ,arago1 ,george ,gabriel ,stokes1 ,neil ,arnott1 ,m4 ,pasteur1 ,m4 ,jamin1 ,james ,clerk ,maxwell1 ,kirchoff1 ,john ,tyndall1 ,a4 ,h4 ,l4 ,fizeau1 ,balfour ,stewart1 ,a4 ,o4 des ,cloiseaux1 ,a4 ,j4 ,angstroem1 ,j4 ,norman ,lockyer1 ,p4 ,j4 ,c4 ,janssen1 ,w4 ,huggins1 ,captain ,abney4 ,in the summer of #agif ,rumford and his daughter left ,england to return to ,munich4 ,on account of the war1 they were obliged to go by sea to ,hamburg2 whence they drove to ,munich1 where the count was anxiously expected1 political troubles having compelled the elector to leave the city4 ,after the battle of ,friedburg1 the ,austrians retired to ,munich1 and1 finding the gates of the city closed1 they fortified themselves on an eminence overlooking the city1 and1 through some misunderstanding with the local authorities1 the ,austrian general threatened to attack the city if any ,frenchman should be allowed to enter4 ,rumford took supreme command of the ,bavarian forces1 and so gained the respect of the rival generals that neither the ,french nor the ,austrians made any attempt to enter the city4 ,the large number of soldiers now in ,munich gave ,rumford a good opportunity to exercise his skill in cooking on a large scale1 and this he did1 adding to the comfort of the soldiers and reducing the cost of the commissariat4 ,on the return of the elector1 ,miss ,sarah was made a countess1 and one-half of her father's pension was secured to her1 thus providing her with an income of about ,l#bjj per annum for life4 ,many of the details of the home life and social intercourse during this period of residence at ,munich are preserved in the autobiography of the countess1 as well as accounts of excursions1 including a trip by river to ,salzburg for the purpose of inspecting the salt-mines4 ,after two years' stay in ,munich1 the count was appointed ,minister ,plenipotentiary from ,bavaria to the ,court of ,great ,britain4 ,after an unpleasant and perilous journey1 he reached ,london1 via ,hamburg1 in ,september1 #agih1 but was terribly disappointed on learning that a ,british subject could not be accepted as an envoy from a ,foreign ,power4 ,as he did not then wish to return to ,bavaria1 he purchased a house in ,brompton ,row4 ,but he had been too much accustomed to great enterprises to be content with a quiet life1 and was bound to have some important scheme on hand4 ,pressing invitations were sent him to return to ,america1 but he preferred residence in ,london1 and devoted himself to the foundation of the ,royal ,institution1 though the countess returned to the ,states in ,august1 #agii4 ,a letter from ,colonel ,baldwin to her father shortly after her return contains the following passage3-- ,in the cask of fruit which your daughter and ,mr4 ,rolfe have sent you1 there is half a dozen apples of the growth of my farm1 wrapped up in papers1 with the name of ,baldwin's apples written upon them4444 ,it is 7,i believe7 a spontaneous production of this country2 that is1 it was not originally engrafted fruit4 ,the history of the remaining period of ,rumford's residence in ,london is the early history of the ,royal ,institution4 ,for many years ,rumford had had at his disposal for his philanthropic projects all the resources of the electorate of ,bavaria1 and he had done everything on a royal scale4 ,his original plan for the ,royal ,institution appears to embody to a very great extent the work of the ,science and ,art ,department1 the ,city and ,guilds ,institute for the ,advancement of ,technical ,education1 the ,national ,school of ,cookery1 the ,london ,society for the ,extension of ,university ,teaching1 and1 in addition to all this1 to have comprehended a sort of perpetual ,international ,health ,exhibition1 where every device for domestic purposes1 and especially for the improvement of the condition of the poor1 could be inspected4 ,how all this was to be carried out with the resources which the count expected to be able to devote to the purpose1 does not appear4 ,foremost among the objects of the institution was placed the management of fire2 for its promoter was convinced that more than half the fuel consumed in the country might be saved by proper arrangements4 ,the philanthropic objects with which the institution was started are apparent from the fact that it was the ,society for ,bettering the ,condition of the ,poor which appointed a committee to confer with ,rumford1 to report on the scheme1 and to raise the funds necessary for starting the project2 and one of ,rumford's hopes in connection with it was to make benevolence fashionable4 ,it was arranged that donors of fifty guineas each should be perpetual proprietors of the institution2 and that subscribers should be admitted at a subscription of two guineas per annum1 or ten guineas for life4 ,the price of a proprietor's share was raised to sixty guineas from ,may #a1 #ahjj1 and afterwards increased by ten guineas per annum up to one hundred guineas4 ,in a very short time there were fifty-eight fifty-guinea subscribers1 and to them ,rumford addressed a pamphlet1 setting forth his scheme in detail4 ,the following are specified as some of the contents of the future institution3--,cottage fireplaces and kitchen utensils for cottagers2 a farm-house kitchen with its furnishings2 a complete kitchen1 with its utensils1 for the house of a gentleman of fortune2 a laundry1 including boilers1 washing1 ironing1 and drying rooms1 for a gentleman's house1 or for a public hospital2 the most improved ,german1 ,swedish1 and ,russian stoves for heating rooms and passages4 ,as far as possible all these things were to be seen at work4 ,there were also to be ornamental open stoves with fires in them2 working models of steam-engines1 of brewers' boilers1 of distillers' coppers and condensers1 of large boilers for hospital kitchens1 and of ships' coppers with the requisite utensils2 models of ventilating apparatus1 spinning-wheels and looms adapted to the circumstances of the poor2 models of agricultural machinery and bridges1 and of all such other machines and useful instruments as the managers of the institution shall deem worthy of public notice4 ,all articles were to be provided with proper descriptions1 with the name and address of the maker1 and the price4 ,a lecture-room and laboratory were to be fitted up with all necessary philosophical apparatus1 and the most eminent expounders of science were to be engaged for the purpose of teaching the application of science to the useful purposes of life4 ,the lectures were to include warming and ventilation1 the preservation of food1 agricultural chemistry1 the chemistry of digestion1 of tanning1 of bleaching and dyeing1 and1 in general1 of all the mechanical arts as they apply to the various branches of manufacture4 ,the institution was to be governed by nine managers1 of whom three were to be elected each year by the proprietors2 and there was also to be a committee of visitors1 the members of which should not be the managers4 ,the king became patron of the institution1 and the first set of officers was nominated by him4 ,the ,earl of ,winchelsea and ,nottingham was ,president2 the ,earls of ,morton and of ,egremont and ,sir ,joseph ,banks1 ,vice-,presidents2 the ,earls of ,bessborough1 of ,egremont1 and of ,morton1 and ,count ,rumford1 were among the ,managers2 the ,duke of ,bridgewater1 ,viscount ,palmerston1 and ,earl ,spencer the ,visitors2 and ,dr4 ,thomas ,garnett was appointed first ,professor of ,physics and ,chemistry4 ,the royal charter of the institution was sealed on ,january #ac1 #ahjj4 ,the superintendence of the journals of the institution was entrusted to ,rumford's care4 ,for some time the count resided in the house in ,albemarle ,street1 which had been purchased by the institution1 and while there he superintended the workmen and servants4 ,dr4 ,thomas ,garnett1 the first professor at the institution1 was highly respected both as a man and a philosopher1 and seems to have been everywhere well spoken of4 ,but ,rumford and he could not work together1 and his connection with the institution was consequently a short one4 ,rumford was then authorized to engage ,dr4 ,young as ,professor of ,natural ,philosophy1 editor of the journals1 and general superintendent of the house1 at a salary of ,l#cjj per annum4 ,shortly before this the count's attention had been directed to the experiments on heat1 made by ,humphry ,davy1 and on ,february #af1 #ahja1 it was resolved that ,mr4 ,humphry ,davy be engaged in the service of the ,royal ,institution1 in the capacity of ,assistant-,lecturer in ,chemistry1 ,director of the ,chemical ,laboratory1 and ,assistant-,editor of the ,journals of the ,institution2 and that he be allowed to occupy a room in the house1 and be furnished with coals and candles1 and that he be paid a salary of one hundred guineas per annum4 ,in his personal appearance1 ,davy is said to have been at first somewhat uncouth1 and the count was by no means charmed with him at their first interview4 ,it was not till he had heard him lecture in private that ,rumford would allow ,davy to lecture in the theatre of the institution2 but he afterwards showed his complete confidence in the young chemist by ordering that all the resources of the institution should be at his service4 ,davy dined with ,rumford at the count's house in ,auteuil1 when he visited ,paris with ,lady ,davy and ,faraday1 in #ahac4 ,he commenced his duties at the institution on ,march #aa1 #ahja4 ,it was on ,june #ae1 in the same year1 that the managers having objected to the syllabus of his lectures1 ,dr4 ,garnett's resignation was accepted2 and on ,july #f ,dr4 ,young was appointed in his stead4 ,dr4 ,young resigned after holding the appointment only two years1 as he found the duties incompatible with his work as a physician4 ,rumford's life in ,london now became daily more unpleasant to himself4 ,accustomed1 as he had been in ,bavaria1 to carry out all his projects like an emperor1 it was difficult for him to work as one member of a body of managers4 ,one by one he quarrelled with his colleagues1 and at length left ,england1 in ,may1 #ahjb1 never to return4 ,when distinguished men of science are placed at the head of an institution like that which ,rumford founded1 there is always a tendency for the technical teaching of the establishment to become gradually merged into scientific research2 and in this case1 after ,rumford's departure1 the genius of ,davy gradually converted the ,royal ,institution into the establishment for scientific research which it has been for more than three quarters of a century4 ,probably the man who has come nearest to realizing all that ,count ,rumford had planned for his institution is the late ,sir ,henry ,cole2 but he succeeded only through the resources of the ,treasury4 ,on leaving ,england in ,may1 #ahjb1 ,rumford went to ,paris1 where he stayed till ,july or ,august1 when he revisited ,bavaria and remained there till the following year1 when he returned to ,paris4 ,he was again at ,munich in #ahje2 but under the new elector1 though an old friend of the count1 relationships do not seem to have been all that they were with his uncle1 and at length the elector himself was compelled to leave ,munich1 and soon after the ,bavarian sovereign became a vassal of ,napoleon4 ,on ,october #bd1 #ahje1 ,rumford married ,madame ,lavoisier1 a lady of brilliant talents and ample fortune4 ,that his position might be nearly equal to hers1 the ,elector of ,bavaria raised his pension to ,l#abjj per annum4 ,a house1 ,rue d',anjou1 ,no4 #ci1 was purchased for six thousand guineas1 and ,rumford expended much thought and energy in making it1 with its garden of two acres1 all that he could desire4 ,but the union was not so happy as he anticipated4 ,the count loved quiet2 ,madame de ,rumford was fond of company3 to the former the pleasure of the table had no charms2 the latter took delight in sumptuous dinner-parties4 ,as time went on1 domestic affairs became more and more unpleasant1 and at length a friendly separation was agreed upon1 after they had lived together for about three years and a half4 ,the count then retired to a small estate which he hired at ,auteuil1 about four miles from ,paris4 ,the ,elector of ,bavaria was crowned king on ,january #a1 #ahjf1 and in #ahaj ,rumford was again at ,munich1 for the purpose of forming1 at the king's request1 an ,academy of ,arts and ,sciences4 ,at ,auteuil the count was joined by his daughter in ,december1 #ahaa1 her journey having been much delayed through the capture of the vessel in which she had taken her passage1 off ,bordeaux4 ,an engraving of the house at ,auteuil1 and the room in which ,rumford carried on his experiments1 was published in the ,illustrated ,london ,news of ,january #bb1 #ahgj4 ,while resident at ,auteuil1 ,rumford frequently read papers before the ,institute of ,france1 of which he was a member4 ,he complained very much of the jealousy exhibited by the other members with reference to any discoveries made by a foreigner4 ,he died in his house at ,auteuil1 on ,august #ba1 #ahad1 in the sixty-second year of his age4 ,in #ahjd he had made over1 by deed of gift to his mother1 the sum of ten thousand dollars1 that she might leave it by will to her younger children4 ,as before mentioned1 ,harvard ,college was his residuary legatee1 and the property so bequeathed founded the ,rumford ,professorship in that institution4 ,cuvier1 as ,secretary of the ,institute1 pronounced the customary eulogy over its late member4 ,the following passages throw some light on the reputation in which the count was held3-- ,he has constructed two singularly ingenious instruments of his own contriving4 ,one is a new calorimeter for measuring the amount of heat produced by the combustion of any body4 ,it is a receptacle containing a given quantity of water1 through which passes1 by a serpentine tube1 the product of the combustion2 and the heat that is generated is transmitted through the water1 which1 being raised by a fixed number of degrees1 serves as the basis of the calculations4 ,the manner in which the exterior heat is prevented from affecting the experiment is very simple and very ingenious4 ,he begins the operation at a certain number of degrees below the outside heat1 and terminates it at the same number of degrees above it4 ,the external air takes back during the second half of the experiment exactly what it gave up during the first4 ,the other instrument serves for noting the most trifling differences in the temperature of bodies1 or in the rapidity of its changes4 ,it consists of two glass bulbs filled with air1 united by a tube1 in the middle of which is a pellet of coloured spirits of wine2 the slightest increase of heat in one of the bulbs drives the pellet towards the other4 ,this instrument1 which he called a thermoscope1 was of especial service in making known to him the varied and powerful influence of different surfaces in the transmission of heat1 and also for indicating a variety of methods for retarding or hastening at will the processes of heating and freezing4444 ,he thought it was not wise or good to entrust to men1 in the mass1 the care of their own well-being4 ,the right1 which seems so natural to them1 of judging whether they are wisely governed1 appeared to him to be a fictitious fancy born of false notions of enlightenment4 ,his views of slavery were nearly the same as those of a plantation-owner4 ,he regarded the government of ,china as coming nearest to perfection1 because1 in giving over the people to the absolute control of their only intelligent men1 and in lifting each of those who belonged to this hierarchy on the scale according to the degree of his intelligence1 it made1 so to speak1 so many millions of arms the passive organs of the will of a few sound heads--a notion which ,i state without pretending in the slightest degree to approve it1 and which1 as we know1 would be poorly calculated to find prevalence among ,european nations4 ,as for the rest1 whatever were the sentiments of ,m4 ,rumford for men1 they in no way lessened his reverence for ,god4 ,he never omitted any opportunity in his works of expressing his religious admiration of ,providence1 and of proposing for that admiration by others1 the innumerable and varied provisions which are made for the preservation of all creatures2 indeed1 even his political views came from his firm persuasion that princes ought to imitate ,providence in this respect by taking charge of us without being amenable to us4 ,in front of the new ,government offices and the ,national ,museum in the ,maximilian ,strasse1 in ,munich1 stand1 on granite pedestals1 four bronze figures1 ten feet in height4 ,these represent ,general ,deroy1 ,fraunhofer1 ,schelling1 and ,count ,rumford4 ,the statue of ,rumford was erected in #ahfg1 at the king's private expense4 ,in the ,english garden which ,rumford planned and laid out is the monument erected during his absence in ,england in #agif1 and bearing allegorical figures of ,peace and ,plenty1 and a medallion of the count4 ,the bare enumeration of ,rumford's published papers would occupy considerable space1 but many of them have more to do with philanthropy and domestic economy than with physics4 ,we have seen that1 when guest of ,lord ,george ,germaine1 he was engaged in experiments on gunpowder4 ,the experiments were made in the usual manner by firing bullets into a ballistic pendulum1 and recording the swing of the pendulum4 ,thompson suggested a modification of the ballistic pendulum1 attaching the gun-barrel to the pendulum1 and observing the recoil1 and making allowance for the recoil due to the discharge from the gun of the products of combustion of the powder1 the excess enabled the velocity of the bullet to be calculated4 ,afterwards he made experiments on the maximum pressure produced by the explosion of powder1 and pointed out that the value of powder in ordnance does not depend simply on the whole amount of gas produced1 but also on the rapidity of combustion4 ,while superintending the arsenal at ,munich1 ,rumford exploded small charges of powder in a specially constructed receiver1 which was closed by a plug of well-greased leather1 and on this was placed a hemisphere of steel pressed down by a #bd-pounder brass cannon weighing #hjha pounds4 ,he found that the weight of the gun was lifted by the explosion of quantities of powder varying from twelve to fifteen grains1 and hence concluded that1 if the products of combustion of the powder were confined to the space actually occupied by the solid powder1 the initial pressure would exceed twenty thousand atmospheres4 ,rumford's calculation of the pressure1 based upon the bursting of a barrel1 which he had previously constructed1 is not satisfactory1 inasmuch as he takes no account of the fact that the inner portions of the metal would give way long before the outer layers exerted anything like their maximum tension4 ,when a hollow vessel with thick walls1 such as a gun-barrel or shell1 is burst by gaseous pressure from within1 the inner layers of material are stretched to their breaking tension before they receive much support from the outer layers2 a rift is thus made in the interior1 into which the gas enters1 and the surface on which the gas presses being thus increased1 the rift deepens till the fracture is complete4 ,in order to gain the full strength due to the material employed1 every portion of that material should be stretched simultaneously to the extent of its maximum safe load4 ,this principle was first practically adopted by ,sir ,w4 ,g4 ,armstrong1 who1 by building up the breech of the gun with cylinders shrunk on1 and so arranged that the tension increased towards the exterior1 availed himself of nearly the whole strength of the metal employed to resist the explosion4 ,had ,rumford's barrel been constructed on this principle1 he would have obtained a much more satisfactory result4 ,these investigations were followed by a very interesting series of experiments on the conducting power of fluids for heat1 and1 although he pushed his conclusions further than his experiments warranted1 he showed conclusively that convection currents are the principal means by which heat is transferred through the substance of fluids1 and described how1 when a vessel of water is heated1 there is generally an ascending current in the centre1 and a descending current all round the periphery4 ,hence it is only when a liquid expands by increase of temperature that a large mass can be readily heated from below4 ,water below #ci deg4 ,fahr4 contracts when heated4 ,rumford1 in his paper1 enlarges on the bearing of this fact on the economy of the universe1 and the following extracts afford a good specimen of his style1 and justify some of the statements made by ,cuvier in his eulogy3-- ,i feel the danger to which a mortal exposes himself who has the temerity to undertake to explain the designs of ,infinite ,wisdom4 ,the enterprise is adventurous1 but it cannot surely be improper4 ,the wonderful simplicity of the means employed by the ,creator of the world to produce the changes of the seasons1 with all the innumerable advantages to the inhabitants of the earth which flow from them1 cannot fail to make a very deep and lasting impression on every human being whose mind is not degraded and quite callous to every ingenuous and noble sentiment2 but the further we pursue our inquiries respecting the constitution of the universe1 and the more attentively we examine the effects produced by the various modifications of the active powers which we perceive1 the more we shall be disposed to admire1 adore1 and love that great ,first ,cause which brought all things into existence4 ,though winter and summer1 spring and autumn1 and all the variety of the seasons are produced in a manner at the same time the most simple and the most stupendous 7by the inclination of the axis of the earth to the plane of the ecliptic71 yet this mechanical contrivance alone would not have been sufficient 7as ,i shall endeavour to show7 to produce that gradual change of temperature in the various climates which we find to exist1 and which doubtless is indispensably necessary to the preservation of animal and vegetable life4444 ,but in very cold countries the ground is frozen and covered with snow1 and all the lakes and rivers are frozen over in the very beginning of winter4 ,the cold then first begins to be extreme1 and there appears to be no source of heat left which is sufficient to moderate it in any sensible degree4 ,let us see what must have happened if things had been left to what might be called their natural course--if the condensation of water1 on being deprived of its heat1 had followed the law which we find obtains in other fluids1 and even in water itself in some cases1 namely1 when it is mixed with certain bodies4 ,had not ,providence interfered on this occasion in a manner which may well be considered miraculous1 all the fresh water within the polar circle must inevitably have been frozen to a very great depth in one winter1 and every plant and tree destroyed2 and it is more than probable that the region of eternal frost would have spread on every side from the poles1 and1 advancing towards the equator1 would have extended its dreary and solitary reign over a great part of what are now the most fertile and most inhabited climates of the world6444 ,let us with becoming diffidence and awe endeavour to see what the means are which have been employed by an almighty and benevolent ,god to protect ,his fair creation4 ,he then goes on to explain how large bodies of water are prevented from freezing at great depths on account of the expansion which takes place on cooling below #ci deg4 ,fahr41 and the further expansion which occurs on freezing1 and mentions that in the ,lake of ,geneva1 at a depth of a thousand feet1 ,m4 ,pictet found the temperature to be #dj deg4 ,fahr4 ,we cannot sufficiently admire the simplicity of the contrivance by which all this heat is saved4 ,it well deserves to be compared with that by which the seasons are produced2 and ,i must think that every candid inquirer who will begin by divesting himself of all unreasonable prejudice will agree with me in attributing them both ,,to ,,the ,,same ,,author4444 ,but ,i must take care not to tire my reader by pursuing these speculations too far4 ,if ,i have persisted in them1 if ,i have dwelt on them with peculiar satisfaction and complacency1 it is because ,i think them uncommonly interesting1 and also because ,i conceived that they might be of value in this age of refinement and scepticism4 ,if1 among barbarous nations1 the fear of a ,god1 and the practice of religious duties1 tend to soften savage dispositions1 and to prepare the mind for all those sweet enjoyments which result from peace1 order1 industry1 and friendly intercourse2 a belief in the existence of a ,supreme ,intelligence1 who rules and governs the universe with wisdom and goodness1 is not less essential to the happiness of those who1 by cultivating their mental powers1 ,,have ,,learned ,,to ,,know ,,how ,,little ,,can ,,be ,,known4 ,rumford1 in connection with his experiments on the conducting power of liquids1 tried the effect of increasing the viscosity of water by the addition of starch1 and of impeding its movements by the introduction of eider-down1 on the rate of diffusion of heat through it4 ,hence he explained the inequalities of temperature which may obtain in a mass of thick soup--inequalities which had once caused him to burn his mouth--and1 applying the same principles to air1 he at once turned his conclusions to practical account in the matter of warm clothing4 ,after an attempt to determine1 if possible1 the weight of a definite quantity of heat--an attempt in which very great precautions were taken to exclude disturbing causes1 while the balance employed was capable of indicating one-millionth part of the weight of the body weighed--,rumford1 finding no sensible effect on the balance1 concluded that if the weight of gold is neither augmented nor lessened by one-millionth part1 upon being heated from the point of freezing water to that of a bright red heat1 ,i think we may very safely conclude that ,,all ,,attempts ,,to ,,discover ,,any ,,effect ,,of ,,heat ,,upon ,,the ,,apparent ,,weights ,,of ,,bodies ,,will ,,be ,,fruitless4 ,the theoretical investigations of ,principal ,hicks1 based on the vortex theory of matter and the dynamical theory of heat1 have recently led him to the conclusion that the attraction of gravitation may depend to some extent on temperature4 ,a series of very valuable experiments on the radiating powers of different surfaces showed how that power varied with the nature of the surface1 and the effect of a coating of lamp-black in increasing the radiating power of a body4 ,in order to determine the effect of radiation in the cooling of bodies1 ,rumford employed the thermoscope referred to by ,cuvier4 ,the following passage is worthy of attention1 as the truth it expounds in the last thirteen words appears to have been but very imperfectly recognized many years after it was written3-- ,all the heat which a hot body loses when it is exposed in the air to cool is not given off to the air which comes into contact with it1 but 444 a large proportion of it escapes in rays1 which do not heat the transparent air through which they pass1 but1 like light1 generate heat only when and where they are stopped and absorbed4 ,rumford then investigated the absorption of heat by different surfaces1 and established the law that good radiators are good absorbers2 and recommended that vessels in which water is to be heated should be blackened on the outside4 ,in speculating on the use of the colouring matter in the skin of the negro1 he shows his fondness for experiment3-- ,all ,i will venture to say on the subject is that1 were ,i called to inhabit a very hot country1 nothing should prevent me from making the experiment of blackening my skin1 or at least1 of wearing a black shirt1 in the shade1 and especially at night1 in order to find out if1 by those means1 ,i could contrive to make myself more comfortable4 ,in his experiments on the conduction of heat1 ,rumford employed a cylinder with one end immersed in boiling water and the other in melting ice1 and determined the temperature at different points in the length of the cylinder4 ,he found the difficulty which has recently been forcibly pointed out by ,sir ,wm4 ,thomson1 in the article ,heat1 in the ,encyclopaedia ,britannica1 viz4 that the circulation of the water was not sufficiently rapid to keep the temperature of the layer in contact with the metal the same as that of the rest of the water2 and he also called attention to the arbitrary character of thermometer-scales1 and recommended that more attention should be given to the scale of the air thermometer4 ,it was in his visit to ,edinburgh1 in #ahjj1 that1 in company with some of the university professors1 the count conducted some experiments in the university laboratory on the apparent radiation of cold4 ,rumford's views respecting frigorific rays have not been generally accepted1 and ,prevost's theory of exchanges completely explains the apparent radiation of cold without supposing that cold is anything else than the mere absence of heat4 ,we must pass over ,rumford's papers on the use of steam as a vehicle of heat1 on new boilers and stoves for the purpose of economizing fuel1 and all the papers bearing on the nutritive value of different foods4 ,the calorimeter with which he determined the amount of heat generated by the combustion1 and the latent heat of evaporation1 of various bodies has been already alluded to4 ,of the four volumes of ,rumford's works published by the ,american ,academy of ,arts and ,sciences1 the third is taken up entirely with descriptions of fireplaces and of cooking utensils4 ,before deciding on the best way to light the military workhouse at ,munich1 ,rumford made a series of experiments on the relative economy of different methods1 and for this purpose designed his well-known shadow-photometer4 ,in the final form of this instrument the shadows were thrown on a plate of ground glass covered with paper1 forming the back of a small box1 from which all extraneous light was excluded4 ,two rods were placed in front of this screen1 and the lights to be compared were so situated that the shadow of one rod thrown by the first light might be just in contact with that of the other rod thrown by the second light4 ,by introducing coloured glasses in front of the lights1 ,rumford compared the illuminating powers of different sources with respect to light of a particular colour4 ,the complementary tints exhibited by the shadows caused him to devise his theory of the harmony of complementary colours4 ,one result is worthy of mention3 it is a conclusion to which public attention has since been called in connection with duplex burners4 ,rumford found that with wax tapers the amount of light emitted per grain of wax consumed diminished with the diminution of the consumption1 so that a small taper gave out only one-sixteenth as much light as an ordinary candle for the same consumption of wax4 ,he says3-- ,this result can be easily explained if we admit the hypothesis which supposes light to be analogous to sound4444 ,the particles 444 were so rapidly cooled 444 that they had hardly time to shine one instant before they became too cold to be any longer visible4 ,an argand lamp1 when compared with a lamp having a flat wick1 gave more light in the ratio of #ajj to #he for the same consumption of oil4 ,one of the latest investigations of ,rumford was that bearing on the effect of the width of the wheels on the draught of a carriage4 ,to his own carriage1 weighing1 with its passengers1 nearly a ton1 he fitted a spring dynamometer by means of a set of pulleys attached to the under-carriage and the splinter-bar4 ,he used three sets of wheels1 respectively #a-c_/d1 #b-a_/d1 and #d inches wide1 and1 introducing weights into the carriage to make up for the difference in the weights of the wheels1 he found a very sensible diminution in the tractive force required as the width of the wheels was increased1 and in a truly scientific spirit1 despising the ridicule cast upon him1 he persisted in riding about ,paris in a carriage with four-inch tyres4 ,but the piece of work by which ,rumford will be best known to future generations is that described in his paper entitled ,an ,inquiry concerning the ,source of the ,heat which is excited by ,friction4 ,it was while superintending the boring of cannon in the arsenal at ,munich that ,rumford was struck with the enormous amount of heat generated by the friction of the boring-bar against the metal4 ,in order to determine whether the heat had come from the chips of metal themselves1 he took a quantity of the abraded borings and an equal weight of chips cut from the metal with a fine saw1 and1 heating them to the temperature of boiling water1 he immersed them in equal quantities of water at #ei-a_/b deg4 ,fahr4 ,the change of temperature of the water was the same in both cases1 and ,rumford found that there was no change which he could discover in regard to its capacity for heat produced in the metal by the action of the borer4 ,in order to prevent the honeycombing of the castings by the escaping gas1 the cannon were cast in a vertical position with the breech at the bottom of the mould and a short cylinder projecting about two feet beyond the muzzle of the gun1 so that any imperfections in the casting would appear in this projecting cylinder4 ,it was on one of these pieces of waste metal1 while still attached to the gun1 that ,rumford conducted his experiments4 ,having turned the cylinder1 he cut away the metal in front of the muzzle until the projecting piece was connected with the gun by a narrow cylindrical neck1 #b4b inches in diameter and #c4h inches long4 ,the external diameter of the cylinder was #g4ge inches1 and its length #i4h inches1 and it was bored to a depth of #g4b inches1 the diameter of the bore being #c4g inches4 ,the cannon was mounted in the boring-lathe1 and a blunt borer pressed by a screw against the bottom of the bore with a force equal to the weight of #aj1jjj pounds4 ,a small transverse hole was made in the cylinder near its base for the introduction of a thermometer4 ,the cylinder weighed #aac4ac pounds1 and1 with the gun1 was turned at the rate of thirty-two revolutions per minute by horse-power4 ,to prevent loss of heat1 the cylinder was covered with flannel4 ,after thirty minutes' work1 the thermometer1 when introduced into the cylinder1 showed a temperature of #acj deg4 ,fahr4 ,the loss of heat during the experiment was estimated from observations of the rate of cooling of the cylinder4 ,the weight of metal abraded was #hcg grains1 while the amount of heat produced was sufficient to raise nearly five pounds of ice-cold water to the boiling point4 ,to exclude the action of the air1 the cylinder was closed by an air-tight piston1 but no change was produced in the result4 ,as the air had access to the metal where it was rubbed by the piston1 and ,rumford thought this might possibly affect the result1 a deal box was constructed1 with slits at each end closed by sliding shutters1 and so arranged that it could be placed with the boring bar passing through one slit and the narrow neck connecting the cylinder with the gun through the other slit1 the sliding shutters1 with the help of collars of oiled leather1 serving to make the box water-tight4 ,the box was then filled with water and the lid placed on4 ,after turning for an hour the temperature was raised from #fj deg4 to #ajg deg4 ,fahr41 after an hour and a half it was #adb deg4 ,fahr41 at the end of two hours the temperature was #agh deg4 ,fahr41 at two hours and twenty minutes it was #bjj deg4 ,fahr41 and at two hours and thirty minutes it ,,actually ,,boiled6 ,it would be difficult to describe the surprise and astonishment expressed in the countenances of the bystanders on seeing so large a quantity of cold water heated and actually made to boil without any fire4 ,though there was1 in fact1 nothing that could justly be considered as surprising in this event1 yet ,i acknowledge fairly that it afforded me a degree of childish pleasure which1 were ,i ambitious of the reputation of a grave philosopher1 ,i ought most certainly rather to hide than to discover4 ,rumford estimated the total quantity of ice-cold water which1 with the heat actually generated by the friction and accumulated in two hours and thirty minutes1 might have been heated #ahj degrees1 or made to boil at #bf4eh pounds1 and the rate of production he considered exceeded that of nine wax candles1 each consuming ninety-eight grains of wax per hour1 while the work of turning the lathe could easily have been performed by one horse4 ,this was the first rough attempt ever made1 so far as we know1 to determine the mechanical equivalent of heat4 ,in his reflections on these experiments1 ,rumford writes3-- ,it is hardly necessary to add that anything which any insulated body or system of bodies can continue to furnish without limitation cannot possibly be a material substance2 and it appears to me to be extremely difficult1 if not quite impossible1 to form any distinct idea of anything capable of being excited and communicated in the manner the heat was excited and communicated in these experiments1 except it be ,,motion4 ,it has been stated that1 if ,rumford had dissolved in acid the borings and the sawn strips of metal1 the capacity for heat of which he determined1 and had shown that the heat developed in the solution was the same in the two cases1 his chain of argument would have been absolutely complete4 ,considering the amount of heat produced in the experiments1 there are few minds whose conviction would be strengthened by this experiment1 and it is only those who look for faultless logic that will refuse to ,rumford the credit of having established the dynamical nature of heat4 ,davy afterwards showed that two pieces of ice could be melted by being rubbed against one another in a vacuum1 but he does not appear to have made as much as he might of the experiment4 ,mayer calculated the mechanical equivalent of heat from the heat developed in the compression of air1 but he assumed1 what afterwards was shown by ,joule to be nearly true1 that the whole of the work done in the compression was converted into heat4 ,it was ,joule1 however1 who first showed that heat and mechanical energy are mutually convertible1 so that each may be expressed in terms of the other1 a given quantity of heat always corresponding to the same amount of mechanical energy1 whatever may be the intermediate stages through which it passes1 and that we may therefore define the mechanical equivalent of heat as the number of units of energy which1 when entirely converted into heat1 will raise unit mass of water one degree from the freezing point4 ,,thomas ,,young4 ,we here meet with a man altogether beyond the common standard1 one in whom natural endowment and sedulous cultivation rivalled each other in the production of a true philosopher2 nor do we hesitate to state our belief that1 since ,newton1 ,thomas ,young stands unrivalled in the annals of ,british science4 ,such was the verdict of ,principal ,forbes on one who may not only be regarded as one of the founders of the undulatory theory of light1 but who was among the first to apply the theory of elasticity to the strength of structures1 while it is to him that we are indebted in the first instance for all we know of ,egyptian hieroglyphics1 and for the vast field of antiquarian research which the interpretation of these symbols has opened up4 ,thomas ,young was the son of ,thomas and ,sarah ,young1 and the eldest of ten children4 ,his mother was a niece of the well-known physician1 ,dr4 ,richard ,brocklesby1 and both his father and mother were members of the ,society of ,friends1 in whose principles all their children were very carefully trained4 ,it was to the independence of character thus developed that ,dr4 ,young attributed very much of the success which he afterwards attained4 ,he was born at ,milverton1 in ,somersetshire1 on ,june #ac1 #aggc4 ,for the greater part of the first seven years of his life he lived with his maternal grandfather1 ,mr4 ,robert ,davis1 at ,minehead1 in ,somersetshire4 ,according to his own account1 he could read with considerable fluency at the age of two1 and1 under the instructions of his aunt and a village schoolmistress1 he had read the ,bible twice through1 and also ,watts's ,hymns1 before he attained the age of four4 ,it may with reason be thought that both the schoolmistress and the aunt should have been severely reprimanded1 and it is certain that their example is not to be commended2 but ,young's infantile constitution seems to have been proof against over-pressure1 and before he was five years old he could recite the whole of ,goldsmith's ,deserted ,village1 with scarcely a mistake4 ,he commenced learning ,latin before he was six1 under the guidance of a ,nonconformist minister1 who also taught him to write4 ,when not quite seven years of age he went to boarding-school1 where he remained a year and a half2 but he appears to have learned more by independent effort than under the guidance of his master1 for privately he had mastered the last rules of ,walkinghame's ',tutor's ,assistant' before reaching the middle of the book under the master's inspection4 ,after leaving this school1 he lived at home for six months1 but frequently visited a neighbour who was a land surveyor1 and at whose house he amused himself with philosophical instruments and scientific books1 especially a ,dictionary of ,arts and ,sciences4 ,when nearly nine he went to the school of ,mr4 ,thompson1 at ,compton1 in ,dorsetshire1 where he remained nearly four years1 and read several ,greek and ,latin authors1 as well as the elements of natural philosophy--the latter in books lent him by ,mr4 ,jeffrey1 the assistant-master4 ,this ,mr4 ,jeffrey appears to have been something of a mechanical genius1 and he gave ,young lessons in turning1 drawing1 bookbinding1 and the grinding and preparation of colours4 ,before leaving this school1 at the age of thirteen1 ,young had read six chapters of the ,hebrew ,bible4 ,during the school holidays the construction of a microscope occupied considerable time1 and the reading of ,priestley on ,air turned ,young's attention to the subject of chemistry4 ,having learned a little ,french1 he succeeded1 with the help of a schoolfellow1 in gaining an elementary knowledge of ,italian4 ,after leaving school1 he lived at home for some time1 and devoted his energies mainly to ,hebrew and to turning and telescope-making2 but ,eastern languages received a share of attention1 and by the time he was fourteen he had read most of ,sir ,william ,jones's ,persian ,grammar4 ,he then went to ,youngsbury1 in ,hertfordshire1 and resided at the house of ,mr4 ,david ,barclay1 partly as companion and partly as classical tutor to ,mr4 ,barclay's grandson1 ,hudson ,gurney4 ,this was the beginning of a friendship which lasted for life4 ,gurney was about a year and a half junior to ,young1 and for five years the boys studied together1 reading the classical works which ,young had previously studied at school4 ,before the end of these five years ,young had gained more or less acquaintance with fourteen languages2 but his studies were for a time delayed through a serious illness when he was little more than sixteen4 ,to this illness his uncle1 ,dr4 ,brocklesby1 referred in a letter1 of which the following extract is interesting for several reasons3-- ,recollect that the least slip 7as who can be secure against error87 would in you1 who seem in all things to set yourself above ordinary humanity1 seem more monstrous or reprehensible than it might be in the generality of mankind4 ,your prudery about abstaining from the use of sugar on account of the negro trade1 in any one else would be altogether ridiculous1 but as long as the whole of your mind keeps free from spiritual pride or too much presumption in your facility of acquiring language1 which is no more than the dross of knowledge1 you may be indulged in such whims1 till your mind becomes enlightened with more reason4 ,my late excellent friend1 ,mr4 ,day1 the author of ',sandford and ,merton1' abhorred the base traffic in negroes' lives as much as you can do1 and even ,mr4 ,granville ,sharp1 one of the earliest writers on the subject1 has not done half as much service in the business as ,mr4 ,day in the above work4 ,and yet ,mr4 ,day devoured daily as much sugar as ,i do2 for he reasonably concluded that so great a system as the sugar-culture in the ,west ,indies1 where sixty millions of ,british property are employed1 could never be affected either way by one or one hundred in the nation debarring themselves the reasonable use of it4 ,reformation must take its rise elsewhere1 if ever there is a general mass of public virtue sufficient to resist such private interests4 ,read ,locke with care1 for he opens the avenues of knowledge1 though he gives too little himself4 ,with respect to the sugar1 no doubt very much may be said on ,young's side of the question4 ,it appears1 however1 that in his early manhood there was a good deal in his conduct which to-day would be regarded as priggish1 though it was somewhat more in harmony with the spirit of his time4 ,he left ,youngsbury at the age of nineteen1 having read1 besides his classical authors1 the whole of ,newton's ,principia and ,opticks1 and the systems of chemistry by ,lavoisier and ,nicholson1 besides works on botany1 medicine1 mineralogy1 and other scientific subjects4 ,one of ,young's peculiarities was the extraordinary neatness of his handwriting1 and a translation in ,greek iambics of ,wolsey's farewell to ,cromwell1 which he sent1 written very neatly on vellum1 to his uncle1 ,dr4 ,brocklesby1 attracted the attention of ,mr4 ,burke1 ,dr4 ,charles ,burney1 and other classical scholars1 so that when1 a few months later1 ,young went to stay with his uncle in ,london1 and was thrown into contact with some of the chief literary men of the day1 he found that his fame as a scholar had preceded him4 ,this neatness of his handwriting and his power of drawing were of great use in his researches on the ,egyptian hieroglyphics4 ,he had little faith in natural genius1 but believed that anything could be accomplished by persevering application4 ,thou say'st not only skill is gained1 ,but genius too may be obtained1 ,by studious imitation4 ,in the autumn of #agib ,young went to ,london for the purpose of studying medicine4 ,he lived in lodgings in ,westminster1 and attended the ,hunterian ,school of ,anatomy4 ,a year afterwards he entered ,st4 ,bartholomew's ,hospital as a medical student4 ,the notes which he took of the lectures were written sometimes in ,latin1 interspersed with ,greek quotations1 and not unfrequently with mathematical calculations1 which may be assumed to have been made before the lecture commenced4 ,during his school days he had paid some attention to geometrical optics1 and had constructed a microscope and telescope4 ,now his attention was attracted to a far more delicate instrument--the eye itself4 ,young had learned how a telescope can be focussed so as to give clear images of objects more or less distant4 ,some such power of adjustment must be possessed by the eye1 or it could never form distinct images of objects1 whether at a distance of a foot or a mile4 ,the apparently fibrous structure of the crystalline lens of the eye had been noticed and described by ,leuwenhoeck2 and ,pemberton1 a century before ,young took up the subject1 had suggested that the fibres were muscles1 by the action of which the eye was accommodated for near or distant vision4 ,in dissecting the eye of an ox ,young thought he had discovered evidence confirmatory of this view1 and the paper which he wrote on the subject was not only published in the ,philosophical ,transactions1 but secured his election as a ,fellow of the ,royal ,society in ,june1 #agid4 ,this paper was important1 not simply because it led to ,young's election to the ,royal ,society1 but mainly because it was his first published paper on optical subjects4 ,later on he showed incontestably1 by exact measurements1 that it is the crystalline lens which changes its form during adjustment2 but he was wrong in supposing the fibres of the lens to be muscular4 ,by carefully measuring the distance between the images of two candles formed by reflection from the cornea1 he showed that the cornea experienced no change of form4 ,his eyes were very prominent2 and turning them so as to look very obliquely1 he measured the length of the eye from back to front with a pair of compasses whose points were protected1 pressing one point against the cornea1 and the other between the back of the eye and the orbit1 and showed that1 when the eye was focussed for different distances1 there was no change in the length of the axis4 ,the crystalline lens was the only resource left whereby the accommodation could be effected4 ,the accommodation is1 in fact1 brought about by the action of the ciliary muscle4 ,the natural form of the lens is more convex than is consistent with distinct vision1 except for very near objects4 ,the tension of the suspensory ligament1 which is attached to the front of the lens all round its edge1 renders the anterior surface of the lens much less curved than it would naturally be4 ,the ciliary muscle is a ring of muscular fibre attached to the ciliary process close to the circumference of the suspensory ligament4 ,by its contraction it forms a smaller ring1 and1 diminishing the external diameter1 it releases the tension of the suspensory ligament1 thus allowing the crystalline lens to bulge out and adapt itself for the diverging rays coming from near objects4 ,it is the exertion of contracting the ciliary muscle that constitutes the effort of which we are conscious when looking at very near objects4 ,it was not1 however1 till long after the time of ,dr4 ,young that this complicated action was fully made out1 though the change of form of the anterior surface of the crystalline lens was discovered by the change in the image of a bright object formed by reflection4 ,in the spring of #agid ,young took a holiday tour in ,cornwall1 with ,hudson ,gurney1 visiting on his way the ,duke of ,richmond1 who was drinking the waters at ,bath1 under the advice of ,dr4 ,brocklesby4 ,in ,cornwall1 the mining machinery attracted his attention very much more than the natural beauties of the country4 ,towards the end of the summer he visited the ,duke of ,richmond at ,goodwood1 when the duke offered him the appointment of private secretary4 ,he resolved1 however1 to continue his medical course1 one of the reasons which he alleged being his regard for the ,society of ,friends1 whose principles he considered inconsistent with the appointment of ,private ,secretary to the ,master-,general of the ,ordnance4 ,the following winter he spent as a medical student at ,edinburgh4 ,here he gave up the costume of the ,society of ,friends1 and in many ways departed from their rules of conduct4 ,he mingled freely with the university1 attended the theatre1 took lessons in dancing and playing the flute1 and generally cultivated the habits of what is technically known as society4 ,throughout this change in his life he retained his high moral principles as a guide of conduct1 and appears to have acted from a firm conviction of what was right4 ,at the same time1 it must be admitted that the breaking down of barriers1 however conventional they may be1 is an operation attended in most cases by not a little danger4 ,with ,young1 the progress of his scientific education may have been delayed on account of the new demands on his time2 but besides the study of ,german1 ,spanish1 and ,italian1 he appears to have read a considerable amount of general literature during his winter session in ,edinburgh4 ,the following summer he took a tour on horseback through the ,highlands1 taking with him his flute1 drawing materials1 spirits for preserving insects1 boards for drying plants1 paper and twine for packing up minerals1 and a thermometer2 but the geological hammer does not then appear to have been regarded as an essential to the equipment of a philosopher4 ,at ,aberdeen he stayed for three days1 and reported thus on the university3-- ,some of the professors are capable of raising a university to celebrity1 especially ,copeland and ,ogilvie2 but the division and proximity of the two universities 7,king's ,college and ,marischal ,college7 is not favourable to the advancement of learning2 besides1 the lectures are all1 or mostly1 given at the same hour1 and the same professor continues to instruct a class for four years in the different branches4 ,were the colleges united1 and the internal regulations of the system new modelled1 the cheapness of the place1 the number of small bursaries for poor or distinguished students1 and the merit of the instructors1 might make this university a very respectable seminary in some branches of science4 ,the fee to a professor for a five-months' session is only a guinea and a half4 ,i was delighted with the inspection of the rich store of mathematical and philosophical apparatus belonging to ,professor ,copeland of ,marischal ,college1 made in his own house1 and partly with his own hands1 finished with no less care than elegance2 and tending to illustrate every branch of physics in the course of his lectures1 which must be equally entertaining and instructive4 ,before leaving the ,highlands1 ,young visited ,gordon ,castle1 where he stayed two days2 and appears to have distinguished himself by the powers of endurance he exhibited in dancing reels4 ,on leaving he writes3 ,i could almost have wished to break or dislocate a limb by chance1 that ,i might be detained against my will2 ,i do not recollect that ,i have ever passed my time more agreeably1 or with a party that ,i thought more congenial to my own dispositions3 and what would hardly be credited by many grave reasoners on life and manners1 that a person who had spent the whole of his earlier years a recluse from the gay world1 and a total stranger to all that was passing in the higher ranks of society1 should feel himself more at home and more at ease in the most magnificent palace in the country than in the humblest dwelling with those whose birth was most similar to his own4 ,without enlarging on the duke's good sense and sincerity1 the duchess's spirit and powers of conversation1 ,lady ,madeline's liveliness and affability1 ,louisa's beauty and sweetness1 ,georgiana's naivete and quickness of parts1 young ,sandy's good nature1 ,i may say that ,i was truly sorry to part with every one of them4 ,young seems not to have known at this time that it is an essential feature of true gentlefolk to dissipate all sense of constraint or uneasiness from those with whom they are brought into contact and that in this they can be readily distinguished from those who have wealth without breeding4 ,the ,duchess of ,gordon gave ,young an introduction to the ,duke of ,argyll1 so1 while travelling through the ,western ,highlands1 he paid a visit to ,inverary ,castle1 and galloped over the country with the duke's daughters4 ,speaking of these ladies1 he says1 ,lady ,charlotte 444 is to ,lady ,augusta what ,venus is to ,minerva2 ,i suppose she wishes for no more4 ,both are goddesses4 ,on his return to the ,west of ,england1 he visited the ,coalbrook ,dale ,iron ,works1 when ,mr4 ,reynolds told him that before the war he had agreed with a man to make a flute a hundred and fifty feet long1 and two and a half in diameter1 to be blown by a steam-engine and played on by barrels4 ,on the #gth of the following ,october ,young left ,london1 and after spending six days on the voyage from ,yarmouth to ,hamburg1 he reached ,goettingen on the #bgth of the same month2 two days afterwards he matriculated1 and on ,november #c he commenced his studies as a member of the university4 ,he continued to take lessons in drawing1 dancing1 riding1 and music1 and commenced learning the clavichord4 ,the ,english students at ,goettingen1 in order to advance their ,german conversation1 arranged to pay a fine whenever they spoke in ,english in one another's company4 ,on ,sundays it was usual for the professors to give entertainments to the students1 though they seldom invited them to dinner or supper4 ,indeed1 they could not well afford1 out of a fee of a louis or two1 to give large entertainments2 but the absence of the hospitality which prevails rather more in ,britain1 is compensated by the light in which the students are regarded2 they are not the less1 but perhaps the more1 respected for being students1 and indeed1 they behave in general like gentlemen1 much more so than in some other ,german universities4 ,at ,goettingen ,young attended1 in addition to his medical lectures1 ,spithler's lectures on the ,history and ,constitution of the ,european ,states1 ,heyne on the ,history of the ,ancient ,arts1 and ,lichtenberg's course on ,physics4 ,speaking of ,blumenbach's lectures on ,natural ,history1 ,young says1 ,he showed us yesterday a laborious treatise1 with elegant plates1 published in the beginning of this century at ,wurzburg1 which is a most singular specimen of credulity in affairs of natural history4 ,dr4 ,behringen used to torment the young men of a large school by obliging them to go out with him collecting petrifactions2 and the young rogues1 in revenge1 spent a whole winter in counterfeiting specimens1 which they buried in a hill which the good man meant to explore1 and imposed them upon him for most wonderful lusus naturae4 ,it is interesting in a metaphysical point of view to observe how the mind attempts to accommodate itself2 in one case1 where the boys had made the figure of a plant thick and clumsy1 the doctor remarks the difference1 and says that ,nature seems to have restored to the plant in thickness that which she had taken away from its other dimensions4 ,on ,april #cj1 #agif1 ,young passed the examination for his medical degree at ,goettingen4 ,the examination appears to have been entirely oral4 ,it lasted between four and five hours4 ,there were four examiners seated round a table provided with cakes1 sweetmeats1 and wine1 which helped to pass the time agreeably4 ,they were not very severe in exacting accurate answers4 ,the subject he selected for his public discussion was the human voice1 and he constructed a universal alphabet consisting of forty-seven letters1 of which1 however1 very little is known4 ,this study of sound laid the foundation1 according to his own account1 of his subsequent researches in the undulatory theory of light4 ,the autumn of #agif ,young spent in travelling in ,germany2 in the following ,february he returned to ,england1 and was admitted a fellow-commoner of ,emmanuel ,college1 ,cambridge4 ,it is said that the ,master1 in introducing ,young to the ,tutors and other ,fellows1 said1 ,i have brought you a pupil qualified to read lectures to his tutors4 ,young's opinion of ,cambridge1 as compared with ,german universities1 was favourable to the former2 but as he had complained of the want of hospitality at ,goettingen1 so in ,cambridge he complained of the want of social intercourse between the senior members of the university and persons in statu pupillari4 ,at that time there was no system of medical education in the university1 and the statutes required that six years should elapse between the admission of a medical student and his taking the degree of ,m4,b4 ,young appears to have attracted comparatively little attention as an undergraduate in college4 ,he did not care to associate with other undergraduates1 and had little opportunity of intercourse with the senior members of the university4 ,he was still keeping terms at ,cambridge when his uncle1 ,dr4 ,brocklesby1 died4 ,to ,young he left the house in ,norfolk ,street1 ,park ,lane1 with the furniture1 books1 pictures1 and prints1 and about ,l#aj1jjj4 ,in the summer of #agih a slight accident at ,cambridge compelled ,young to keep to his rooms1 and being thus forcibly deprived of his usual round of social intercourse1 he returned to his favourite studies in physics4 ,the most important result of this study was the establishment of the principle of interference in sound1 which afforded the explanation of the phenomenon of beats in music1 and which afterwards led up to the discovery of the interference of light--a discovery which ,sir ,john ,herschel characterized as the key to all the more abstruse and puzzling properties of light1 and which would alone have sufficed to place its author in the highest rank of scientific immortality1 even were his other almost innumerable claims to such a distinction disregarded4 ,the principle of interference is briefly this3 ,when two waves meet each other1 it may happen that their crests coincide2 in this case a wave will be formed equal in height 7amplitude7 to the sum of the heights of the two4 ,at another point the crest of one wave may coincide with the hollow of another1 and1 as the waves pass1 the height of the wave at this point will be the difference of the two heights1 and if the waves are equal the point will remain stationary4 ,if a rope be hung from the ceiling of a lofty room1 and the lower end receive a jerk from the hand1 a wave will travel up the rope1 be reflected and reversed at the ceiling1 and then descend4 ,if another wave be then sent up1 the two will meet1 and their passing can be observed4 ,it will then be seen that1 if the waves are exactly equal1 the point at which they meet will remain at rest during the whole time of transit4 ,if a number of waves in succession be sent up the string1 the motions of the hand being properly timed1 the string will appear to be divided into a number of vibrating segments separated by stationary points1 or nodes4 ,these nodes are simply the points which remain at rest on account of the upward series of waves crossing the series which have been reflected at the top and are travelling downwards4 ,the division of a vibrating string into nodes thus affords a simple example of the principle of interference4 ,when a tuning-fork is vibrating there are certain hyperbolic lines along which the disturbance caused by one prong is exactly neutralized by that due to the other prong4 ,if a large tuning-fork be struck and then held near the ear and slowly turned round1 the positions of comparative silence will be readily perceived4 ,if two notes are being sounded side by side1 one consisting of two hundred vibrations per second and the other of two hundred and two1 then1 at any distant point1 it is clear that the two sets of waves will arrive in the same condition1 or phase1 twice in each second1 and twice they will be in opposite conditions1 and1 if of the same intensity1 will exactly destroy one another's effects1 thus producing silence4 ,hence twice in the second there will be silence and twice there will be sound1 the waves of which have double the amplitude due to either source1 and hence the sound will have four times the intensity of either note by itself4 ,thus there will be two beats per second due to interference4 ,later on this principle was applied by ,young to very many optical phenomena of which it afforded a complete explanation4 ,young completed his last term of residence at ,cambridge in ,december1 #agii1 and in the early part of #ahjj he commenced practice as a physician at #dh1 ,welbeck ,street4 ,in the following year he accepted the chair of ,natural ,philosophy in the ,royal ,institution1 which had shortly before been founded1 and soon afterwards1 in conjunction with ,davy1 the ,professor of ,chemistry1 he undertook the editing of the journals of the institution4 ,this circumstance has already been alluded to in connection with ,count ,rumford1 the founder of the institution4 ,he lectured at the ,royal ,institution for two years only1 when he resigned the chair in deference to the popular belief that a physician should give his attention wholly to his professional practice1 whether he has any or not4 ,this fear lest a scientific reputation should interfere with his success as a physician haunted him for many years1 and sometimes prevented his undertaking scientific work1 while at other times it led him to publish anonymously the results he obtained4 ,this anonymous publication of scientific papers caused him great trouble afterwards in order to establish his claim to his own discoveries4 ,many of the articles which he contributed to the supplement to the fourth1 fifth1 and sixth editions of the ,encyclopaedia ,britannica were anonymous1 although the honorarium he received for this work was increased by #be per cent4 when he would allow his name to appear4 ,the practical withdrawal of ,young from the scientific world during sixteen years was a great loss to the progress of natural philosophy1 while the absence of that suavity of manner when dealing with patients which is so essential to the success of a physician1 prevented him from acquiring a valuable private practice4 ,in fact1 ,young was too much of a philosopher in his behaviour to succeed as a physician2 he thought too deeply before giving his opinion on a diagnosis1 instead of appearing to know all about the subject before he commenced his examination1 and this habit1 which is essential to the philosopher1 does not inspire confidence in the practitioner4 ,his fondness for society rendered him unwilling to live within the means which his uncle had left him1 supplemented by what his scientific work might bring1 and it was not until his income had been considerably increased by an appointment under the ,admiralty that he was willing to forego the possible increase of practice which might accrue by appearing to devote his whole attention to the subject of medicine4 ,it was this fear of public opinion which caused him1 in #ahab1 to decline the offer of the appointment of ,secretary to the ,royal ,society1 of which1 in #ahjb1 he accepted the office of ,foreign ,secretary4 ,young's resignation of the chair of ,natural ,philosophy was1 however1 not a great loss to the ,royal ,institution2 for the lecture audience there was essentially of a popular character1 and ,young cannot be considered to have been successful as a popular lecturer4 ,his own early education had been too much derived from private reading for him to have become acquainted with the difficulties experienced by beginners of only average ability1 and his lectures1 while most valuable to those who already possessed a fair knowledge of the subjects1 were ill adapted to the requirements of an unscientific audience4 ,a syllabus of his course of lectures was published by ,young in #ahjb1 but it was not till #ahjg that the complete course of sixty lectures was published in two quarto volumes4 ,they were republished in #ahde in octavo1 with references and notes by ,professor ,kelland4 ,among the subjects treated in these lectures are mechanics1 including strength of materials1 architecture and carpentry1 clocks1 drawing and modelling2 hydrostatics and hydraulics2 sound and musical instruments2 optics1 including vision and the physical nature of light2 astronomy2 geography2 the essential properties of matter2 heat2 electricity and magnetism2 climate1 winds1 and meteorology generally2 vegetation and animal life1 and the history of the preceding sciences4 ,the lectures were followed by a most complete bibliography of the whole subject1 including works in ,english1 ,french1 ,german1 ,italian1 and ,latin4 ,the following is the syllabus of one lecture1 and illustrates the diversity of the subjects dealt with3-- ,,on ,,drawing1 ,,writing1 ,,and ,,measuring4 ,subjects preliminary to the study of practical mechanics2 instrumental geometry2 statics2 passive strength2 friction2 drawing2 outline2 pen2 pencil2 chalks2 crayons2 ,indian ink2 water-colours2 body colours2 miniature2 distemper2 fresco2 oil2 encaustic paintings2 enamel2 mosaic work4 ,writing2 materials for writing2 pens2 inks2 use of coloured inks for denoting numbers2 polygraph2 telegraph2 geometrical instruments2 rulers2 compasses2 flexible rulers2 squares2 triangular compasses2 parallel rulers2 ,marquois's scales2 pantograph2 proportional compasses2 sector4 ,measurement of angles2 theodolites2 quadrants2 dividing-engine2 vernier2 levelling2 sines of angles2 ,gunter's scale2 ,nicholson's circle2 dendrometer2 arithmetical machines2 standard measures2 quotation from ,laplace2 new measures2 decimal divisions2 length of the pendulum and of the meridian of the earth2 measures of time2 objections2 comparison of measures2 instruments for measuring2 micrometrical scales2 log-lines4 ,this represents an extensive area to cover in a lecture of one hour4 ,when ,newton1 by means of a prism1 ,unravelled all the shining robe of day1 he showed that sunlight is made up of light varying in tint from red1 through orange1 yellow1 green1 and blue1 to violet1 and that by recombining all these kinds of light1 or certain of them selected in an indefinite number of ways1 white light could be produced4 ,subsequently ,sir ,wm4 ,herschel showed that rays less refrangible than the red were to be found among the solar radiation2 and other rays more refrangible than the violet1 but1 like the ultra-red rays1 incapable of exciting vision1 were found by ,ritter and ,wollaston4 ,in speaking of ,newton's experiments1 in his thirty-seventh lecture1 ,young says3-- ,it is certain that the perfect sensations of yellow and of blue are produced respectively by mixtures of red and green and of green and violet light1 and there is reason to suspect that those sensations are always compounded of the separate sensations combined2 at least1 this supposition simplifies the theory of colours4 ,it may1 therefore1 be adopted with advantage1 until it be found inconsistent with any of the phenomena2 and we may consider white light as composed of a mixture of red1 green1 and violet only1 444 with respect to the quantity or intensity of the sensations produced4 ,it should be noticed that1 in the above quotation1 ,young speaks only of the sensations produced4 ,objectively considered1 sunlight consists of an infinite number of differently coloured lights comprising nearly all the shades from one end of the spectrum to the other1 though white light may have a much simpler constitution1 and may1 for example1 consist simply of a mixture of homogeneous red1 green1 and violet lights1 or of homogeneous yellow and blue lights1 properly selected4 ,but considered subjectively1 ,young implies that the eye perceives three1 and only three1 distinct colour-sensations1 corresponding to pure red1 green1 and violet2 that when these three sensations are excited in a certain proportion1 the complex sensation is that of white light2 but if the relative intensities of the separate sensations differ from these ratios1 the perception is that of some colour4 ,to exhibit the effects of mixing light of different colours1 ,young painted differently coloured sectors on circles of cardboard1 and then made the discs rotate rapidly about their centres1 when the effect was the same as though the lights emitted by the sectors were mixed in proportion to the breadth of the sectors4 ,this contrivance had been previously employed by ,newton1 and will be again referred to in connection with another memoir4 ,the results of these experiments were embodied by ,young in a diagram of colour1 consisting of an equilateral triangle1 in which the colours red1 green1 and violet1 corresponding to the simple sensations1 were placed at the angles1 while those produced by mixing the primary colours in any proportions1 were to be found within the triangle or along its sides2 the rule being that the colour formed by the admixture of the primary colours in any proportions1 was to be found at the centre of gravity of three heavy particles placed at the angular points of the triangle1 with their masses proportioned to the corresponding amounts of light4 ,thus the colours produced by the admixture of red and green only1 in different proportions1 were placed along one side of the triangle1 these colours corresponding to various tints of scarlet1 orange1 yellow1 and yellowish green2 another side contained the mixtures of green and violet representing the various shades of bluish green and blue2 and the third side comprised the admixtures of red and violet constituting crimsons and purples4 ,the interior of the triangle contained the colours corresponding to the mixture of all three primary sensations1 the centre being neutral grey1 which is a pure white faintly illuminated4 ,if white light of a certain degree of intensity fall on white paper1 the paper appears white1 but if a stronger light fall on another portion of the same sheet1 that which is less strongly illuminated appears grey by contrast4 ,shadows thrown on white paper may possess any degree of intensity1 corresponding to varying shades of neutral grey1 up to absolute blackness1 which corresponds to a total absence of light4 ,thus considered1 chromatically black and white are the same1 differing only in the amount of light they reflect4 ,a piece of white paper in moonlight is darker than black cloth in full sunlight4 ,it must be remembered that ,young's diagram of colours corresponds to the admixture of coloured lights1 not of colouring materials or pigments4 ,the admixture of blue and yellow lights in proper proportions may make white or pink1 but never green4 ,the admixture of blue and yellow pigments makes a green1 because the blue absorbs nearly all the light except green1 blue1 and a little violet1 while the yellow absorbs all except orange1 yellow1 and green4 ,the green light is the only light common to the two1 and therefore the only light which escapes absorption when the pigments are mixed4 ,another point already noticed must also be carefully borne in mind4 ,young was quite aware that1 physically1 there are an infinite number of different kinds of light differing continuously in wave-length from the ultra-red to the ultra-violet1 though colour can hardly be regarded as an attribute of the light considered objectively4 ,the question of colour is essentially one of perception--a physiological1 not a physical1 question--and it is only in this sense that ,young maintained the doctrine of three primary colours4 ,in his paper on the production of colours1 read before the ,royal ,society on ,july #a1 #ahjb1 he speaks of the proportions of the sympathetic fibres of the retina1 corresponding to these primary colour-sensations4 ,according to this doctrine1 white light would always be produced when the three sensations were affected in certain proportions1 whether the exciting cause were simply two kinds of homogeneous light1 corresponding to two pure tones in music1 or an infinite number of different kinds1 as in sunlight2 and a particular yellow sensation might be excited by homogeneous yellow light from one part of the spectrum1 or by an infinite number of rays of different wave-lengths1 corresponding to various shades of red1 orange1 yellow1 and green4 ,subjectively1 the colours would be the same2 objectively1 the light producing them would differ exceedingly4 ,but ,young's greatest service to science was his application of the principle of interference--of which he had already made good use in the theory of sound--to the phenomena of light4 ,the results of these researches were presented to the ,royal ,society1 and two of the papers were selected as ,bakerian lectures in #ahja and #ahjc respectively4 ,unfavourable criticisms of these papers1 which appeared in the ,edinburgh ,review1 and were said to have been written by ,mr4 7afterwards ,lord7 ,brougham1 seem to have caused their contents to be neglected by ,english men of science for many years2 and it was to ,arago and ,fresnel that we are indebted for recalling public attention to them4 ,the undulatory theory of light1 which maintains that light consists of waves transmitted through an ether1 which pervades all space and all matter1 owes its origin to ,hooke and ,huyghens4 ,huyghens showed that this theory explained1 in a very beautiful manner1 the laws of reflection and of refraction1 if it be allowed that light travels more slowly the denser the medium4 ,according to the celebrated principle of ,huyghens1 every point in the front of a wave at any instant becomes a centre of disturbance1 from which a secondary wave is propagated4 ,the fronts of these secondary waves all lie on a surface1 which becomes the new surface of the primary wave4 ,when light enters a denser medium obliquely1 the secondary waves which are propagated within the denser medium extend to a less distance than those propagated in the rarer medium1 and thus the front of the primary wave becomes bent at the point where it meets the common surface4 ,huyghens explained1 not only the laws of ordinary refraction in this manner1 but1 by supposing the secondary waves to form spheroids instead of spheres1 he obtained the laws of refraction of the extraordinary ray in ,iceland-spar4 ,he did not1 however1 succeed in explaining why light should not diverge laterally instead of proceeding in straight lines4 ,newton supported the theory that light consists of particles or corpuscles projected in straight lines from the luminous body1 and sometimes transmitted1 sometimes reflected1 when incident on a transparent medium of different density4 ,to account for the particle being sometimes transmitted and sometimes reflected1 ,newton had recourse to the hypothesis of fits of easy transmission and of easy reflection1 and1 to account for the fits themselves1 he supposed the existence of an ether1 the vibrations of which affected the particles4 ,the laws of reflection were readily explained1 being the same as for a perfectly elastic ball2 the laws of refraction admitted of very simple explanation1 by supposing that the particles of the denser medium exert a greater attraction on the particles of light than those of the rarer medium1 but that this attraction acts only through very short distances1 so that when the light-corpuscle is at a sensible distance from the surface1 it is attracted equally all round1 and moves as though there were no force acting upon it4 ,as a consequence of this hypothesis1 it follows that the velocity of light must be greater the denser the medium1 while the undulatory theory leads to precisely the opposite result4 ,when ,foucault directly measured the velocity of light both in air and water1 and found it less in the denser medium1 the result was fatal to the corpuscular theory4 ,dr4 ,young called attention to another crucial test between the two theories4 ,when a piece of plate-glass is pressed against a slightly convex lens1 or a watch-glass1 a series of coloured rings is formed by reflected light1 with a black spot in the centre4 ,this was accounted for by ,newton by supposing that the light which was reflected in any ring was in a fit of easy transmission 7from glass to air7 when it reached the first surface of the film of air1 and in a fit of easy reflection when it reached the second surface4 ,by measuring the thickness of a film of air corresponding to the first ring of any particular colour1 the length of path corresponding to the interval between two fits for that particular kind of light could be determined4 ,when water instead of air is placed between the glasses1 according to the corpuscular theory the rings should expand2 but according to the undulatory theory they should contract2 for the wave-length corresponds to the distance between successive fits of the same kind on the corpuscular hypothesis4 ,on trying the experiment1 the rings were seen to contract4 ,this result seemed to favour the undulatory theory2 but the objection urged by ,newton that rays of light do not bend round obstacles1 like waves of sound1 still held its ground4 ,this objection ,young completely demolished by his principle of interference4 ,he showed that when light passes through an aperture in a screen1 whatever the shape of the aperture1 provided its width is large in comparison with the length of a wave of light 7one fifty-thousandth of an inch71 no sensible amount of light will reach any point not directly in front of the aperture2 for if any point be taken to the right or left1 the disturbances reaching that point from different points of the aperture will neutralize one another by interference1 and thus no light will be appreciable4 ,when the breadth of the aperture is only a small multiple of a wave-length1 then there will be some points outside the direct beam at which the disturbances from different points of the aperture will not completely destroy one another1 and others at which they will destroy one another2 and these points will be different for light of different wave-lengths4 ,in this way ,young not only explained the rectilinear propagation of light1 but accounted for the coloured bands formed when light diverges from a point through a very narrow aperture4 ,in a similar way he accounted for the hyperbolic bands of colour observed by ,grimaldi within the shadow of a square near its corners4 ,with a strip of card one-thirtieth of an inch in width1 ,young obtained bands of colour within the shadow which completely disappeared when the light was cut off from either side of the strip of card1 showing that they were produced by interference of the two portions of light which had passed1 one to the right1 the other to the left1 of the strip of card4 ,professor ,stokes has succeeded in showing a bright spot at the centre of the shadow of a circular disc of the size of a sovereign4 ,the narrow bands of colour formed near the edge of the shadow of any object1 which ,newton supposed to be due to the inflection of the light by the attraction of the object1 ,young showed to be independent of the material or thickness of the edge1 and completely accounted for them by the principle of interference4 ,newton's rings were explained with equal facility4 ,they were due to the interference of light reflected from the first and second surfaces of the film of air or water between the glasses4 ,the black spot at the centre of the reflected rings was due to the difference between reflection taking place from the surface of a denser or a rarer medium1 half an undulation being lost when the reflection takes place in glass at the surface of air4 ,if a little grease or water be placed between two pieces of glass which are nearly in contact1 but the space between be not filled with the water or grease1 but contain air in some parts1 and water or grease in others1 a series of rings will be seen by transmitted light1 which have been called the colours of mixed plates4 ,young showed that these colours could be accounted for by interference between the light that had passed through the air and that which had passed through the water1 and explained the fact that1 to obtain the same colour1 the distance between the plates must be much greater than in the case of ,newton's rings4 ,the bands of colour produced by the interference of light proceeding from a point and passing on each side of a narrow strip of card1 have already been referred to4 ,the bands are broader the narrower the strip of card4 ,a fine hair gives very broad bands4 ,when a number of hairs cross one another in all directions1 these bands form circular rings of colour4 ,if the width of the hairs be very variable1 the rings formed will be of different sizes and overlapping one another1 no distinct series will be visible2 but when the hairs are of nearly the same diameter1 a series of well-defined circles of colour1 resembling ,newton's rings1 will be seen1 and if the diameter of a particular ring be measured1 the breadth of the hairs can be inferred4 ,young practically employed this method for measuring the diameter of the fibres of different qualities of wool in order to determine their commercial value4 ,the instrument employed he called the eriometer4 ,it consisted of a plate of brass pierced with a round hole about one-thirtieth of an inch in diameter in the centre1 and around this a small circle1 about one-third of an inch in diameter1 of very fine holes4 ,the plate was placed in front of a lamp1 and the specimen of wool was held on wires at such a distance in front of the brass plate that the first green ring appeared to coincide with the circle of small holes4 ,the eye was placed behind the lock of wool1 and the distance to which the wool had to be removed in front of the brass plate in order that the first green ring might exactly coincide with the small circle of fine holes1 was proportional to the breadth of the fibres4 ,the same effect is produced if fine particles1 such as lycopodium powder1 or blood-corpuscles1 scattered on a piece of glass1 be substituted for the lock of wool1 and ,young employed the instrument in order to determine the diameter of blood-corpuscles4 ,he determined the constant of his apparatus by comparison with some of ,dr4 ,wollaston's micrometric observations4 ,the coloured halos sometimes seen around the sun ,young referred to the existence of small drops of water of nearly uniform diameter1 and calculated the necessary diameter for halos of different angular magnitudes4 ,the same principle of interference afforded explanation of the colours of striated surfaces1 such as mother-of-pearl1 which vary with the direction in which they are seen4 ,viewed at one angle light of a particular colour reflected from different ridges will be in a condition to interfere1 and this colour will be absent from the reflected light4 ,at a different inclination1 the light reaching the eye from all the ridges 7within a certain angle7 will be in precisely the same phase1 and only then will light of that colour be reflected in its full intensity4 ,with a micrometer scale engraved on glass by ,coventry1 and containing five hundred lines to the inch1 ,young obtained interference spectra4 ,modern gratings1 with several thousand lines to the inch1 afford the purest spectra that can be obtained1 and enable the wave-length of any particular kind of light to be measured with the greatest accuracy4 ,young's dislike of mathematical analysis prevented him from applying exact calculation to the interference phenomena which he observed1 such as subsequently enabled ,fresnel to overcome the prejudice of the ,french ,academy and to establish the principle on an incontrovertible footing4 ,young's papers attracted very little attention1 and ,fresnel made for himself many of ,young's earlier discoveries1 but at once gave ,young the full credit of the work when his priority was pointed out4 ,the phenomena of polarization1 however1 still remained unexplained4 ,both ,young and ,fresnel had regarded the vibrations of light as similar to those of sound1 and taking place in the direction in which the wave is propagated4 ,the fact that light which had passed through a crystal of ,iceland-spar1 was differently affected by a second crystal1 according to the direction of that crystal with respect to the former1 showed that light which had been so transmitted was not like common light1 symmetrical in all azimuths1 but had acquired sides or poles4 ,such want of symmetry could not be accounted for on the hypothesis that the vibrations of light took place at right angles to the wave-front1 that is1 in the direction of propagation of the light4 ,the polarization of light by reflection was discovered by ,malus1 in #ahji4 ,in a letter written to ,arago1 in #ahag1 ,young hinted at the possibility of the existence of a component vibration at right angles to the direction of propagation1 in light which had passed through ,iceland-spar4 ,in the following year ,fresnel arrived independently at the hypothesis of transverse vibrations1 not as constituting a small component of polarized light1 but as representing completely the mode of vibration of all light1 and in the hands of ,fresnel this hypothesis of transverse vibrations led to a theory of polarization and double refraction both in uniaxal and biaxal crystals which1 though it can hardly be regarded as complete from a mechanical point of view1 is nevertheless one of the most beautiful and successful applications of mathematics to physics that has ever been made4 ,to ,young1 however1 belongs the credit of suggesting that the spheroidal form of the waves in ,iceland-spar might be accounted for by supposing the elasticity different in the direction of the optic axis and at right angles to that direction2 and he illustrated his view by reference to certain experiments of ,chladni1 in which it had been shown that the velocity of sound in the wood of the ,scotch fir is different along1 and perpendicular to1 the fibre in the ratio of #e to #d4 ,young was also the first to explain the colours exhibited by thin plates of crystals in polarized light1 discovered by ,arago in #ahaa1 by the interference of the ordinary and extraordinary rays1 and ,fresnel afterwards completed ,young's explanation in #ahbb4 ,it is for his contributions to the undulatory theory of light that ,young will be most honourably remembered4 ,hooke1 in #affd1 referred to light as a quick1 short1 vibrating motion2 ,huyghens's ,traite de la ,lumiere was published in #afij4 ,from that time the undulatory theory lost ground1 until it was revived by ,young and ,fresnel4 ,it soon after received great support from the establishment1 by ,joule and others1 of the mechanical theory of heat4 ,one remark of ,young's respecting the ether opens up a question which has attracted much attention of late years4 ,in a letter addressed to the ,secretary of the ,royal ,society1 and read ,january #af1 #ahjj1 he says3-- ,that a medium1 resembling in many properties that which has been denominated ether1 does really exist1 is undeniably proved by the phenomena of electricity2 and the arguments against the existence of such an ether throughout the universe have been pretty sufficiently answered by ,euler4 ,the rapid transmission of the electrical shock shows that the electric medium is possessed of an elasticity as great as is necessary to be supposed for the propagation of light4 ,whether the electric ether is to be considered as the same with the luminous ether--if such a fluid exists--may perhaps at some future time be discovered by experiment4 ,besides his contributions to optics1 ,young made distinct advances in connection with elasticity1 and with surface-tension1 or capillarity4 ,it is said that ,leonardo da ,vinci was the first to notice the ascent of liquids in fine tubes by so-called capillary attraction4 ,this1 however1 is only one of a series of phenomena now very generally recognized1 and all of which are referable to the same action4 ,the hanging of a drop from the neck of a phial2 the pressure of air required to inflate a soap-bubble2 the flotation of a greasy needle on the surface of water2 the manner in which some insects rest on water1 by depressing the surface1 without wetting their legs2 the possibility of filling a tumbler with water until the surface stands above the edge of the glass2 the nearly spherical form of rain-drops and of small drops of mercury1 even when they are resting on a table1--are all examples of the effect of surface-tension4 ,these phenomena have recently been studied very carefully by ,quincke and ,plateau1 and they have been explained in accordance with the principle of energy by ,gauss4 ,hawksbee1 however1 was the first to notice that the rise of a liquid in a fine tube did not depend on the thickness of the walls of the tube1 and he therefore inferred that1 if the phenomena were due to the attraction of the glass for the liquid1 it could only be the superficial layers which produced any effect4 ,this was in #agji4 ,segner1 in #agea1 introduced the notion of a surface-tension2 and1 according to his view1 the surface of a liquid must be considered as similar to a thin layer of stretched indiarubber1 except that the tension is always the same at the surface bounding the same media4 ,this idea of surface-tension was taken up by ,young1 who showed that it afforded explanation of all the known phenomena of capillarity1 when combined with the fact1 which he was himself the first to observe1 that the angle of contact of the same liquid-surface with the same solid is constant4 ,this angle he called the appropriate angle4 ,but ,young went further1 and attempted to explain the existence of surface-tension itself by supposing that the particles of a liquid not only exert an attractive force on one another1 which is constant1 but also a repulsive force which increases very rapidly when the distance between them is made very small4 ,his views on this subject were embodied in a paper on the cohesion of liquids1 read before the ,royal ,society in #ahjd4 ,he afterwards wrote an article on the same subject for the supplement of the ,encyclopaedia ,britannica4 ,the changes which solids undergo under the action of external force1 and their tendency to recover their natural forms1 were studied by ,hooke and ,gravesande4 ,the experimental fact that1 for small changes of form1 the extension of a rod or string is proportional to the tension to which it is exposed1 is known as ,hooke's law4 ,the compression and extension of the fibres of a bent beam were noticed by ,james ,bernoulli1 in #afcj1 by ,duhamel and others4 ,the bending of beams was also studied by ,coulomb and ,robison1 but ,young appears to have been almost the first to apply the theory of elasticity to the statics of structures4 ,in a letter to the ,secretary of the ,admiralty1 written in #ahaa1 in reply to an invitation to report on ,mr4 ,steppings's improvements in naval architecture1 ,young claimed that he was the only person who had published any attempts to improve the theory of carpentry4 ,it may be here mentioned that ,young accepted the invitation of the ,admiralty1 and sent in a very exhaustive report1 which their ,lordships regarded as too learned to be of great practical value4 ,young's contributions to this subject will be chiefly remembered in connection with his modulus of elasticity4 ,this he originally defined as follows3-- ,the modulus of the elasticity of any substance is a column of the same substance capable of producing a pressure on its base which is to the weight causing a certain degree of compression as the length of the substance is to the diminution of its length4 ,it is not usual now to express ,young's modulus of elasticity in terms of a length of the substance considered4 ,as now usually defined1 ,young's modulus of elasticity is the force which would stretch a rod or string to double its natural length if ,hooke's law were true for so great an extension4 ,so much of ,dr4 ,young's scientific work has been mentioned here because it was during his early years of professional practice that his most original scientific work was accomplished4 ,as already stated1 after two years' tenure of the ,natural ,philosophy chair at the ,royal ,institution1 ,young resigned it because his friends were of opinion that its tenure militated against his prospects as a physician4 ,in the summer of #ahjb he escorted the great-nephews of the ,duke of ,richmond to ,rouen1 and took the opportunity of visiting ,paris4 ,in ,march1 #ahjc1 he took his degree of ,m4,b4 at ,cambridge1 and on ,june #ad1 #ahjd1 he married ,eliza1 second daughter of ,j4 ,p4 ,maxwell1 ,esq41 whose country seat was near ,farnborough4 ,for sixteen years after his marriage1 ,young resided at ,worthing during the summer1 where he made a very respectable practice1 returning to ,london in ,october or ,november4 ,in ,january1 #ahaa1 he was elected one of the physicians of ,st4 ,george's ,hospital1 which appointment he retained for the rest of his life4 ,in this capacity his practice was considerably in advance of the times1 for he regarded medicine as a science rather than an empirical art1 and his careful methods of induction demanded an amount of attention which medical students1 who preferred the more rough-and-ready methods then in vogue1 were slow to give4 ,the apothecary of the hospital stated that more of ,dr4 ,young's patients went away cured than of those who were subjected to the more fashionable treatment2 but his private practice1 notwithstanding the sacrifices he had made1 never became very valuable4 ,in #ahaf ,young was appointed ,secretary to a ,commission for determining the length of the second's pendulum4 ,the reports of this ,commission were drawn up by him1 though the experimental work was carried out by ,captain ,kater4 ,the result of the work was embodied in an ,act of ,parliament1 introduced by ,sir ,george ,clerk1 in #ahbd1 which provided that if the standard yard should be lost it should be restored to the same length1 by making it bear to the length of the second's pendulum at sea-level in ,london1 the ratio of #cf to #ci4acic2 but before the standards were destroyed1 in #ahce1 so many sources of possible error were discovered in the reduction of pendulum observations1 that the ,commission appointed to restore the standards recommended that a material standard yard should be constructed1 together with a number of copies1 so that1 in the event of the standard being again destroyed1 it might be restored by comparison with its copies4 ,in #ahah ,young was appointed ,superintendent of the ,nautical ,almanac and ,secretary of the ,board of ,longitude4 ,when this ,board was dissolved in #ahbh1 its functions were assumed by the ,admiralty1 and ,young1 ,faraday1 and ,colonel ,sabine were appointed a ,scientific ,committee of ,reference to advise the ,admiralty in all matters in which their assistance might be required4 ,the income from these ,government appointments rendered ,young more independent of his practice1 and he became less careful to publish his scientific papers anonymously4 ,in #ahbj he left ,worthing and gave up his practice there4 ,the following year1 in company with ,mrs4 ,young1 he took a tour through ,france1 ,switzerland1 and ,italy1 and at ,paris attended a meeting of the ,institute1 where he met ,arago1 who had called on him in ,worthing1 in #ahaf4 ,at the same time he made the acquaintance of ,laplace1 ,cuvier1 ,humboldt1 and others4 ,in #ahbd he visited ,spa1 and took a tour through ,holland4 ,in the same year ,young was appointed ,inspector of ,calculations and ,medical ,referee to the ,palladium ,insurance ,company4 ,this caused him to turn his attention to the subject of life assurance and bills of mortality4 ,in #ahbe1 as ,foreign ,secretary of the ,royal ,society1 he had the satisfaction of forwarding to ,fresnel the ,rumford ,medal in acknowledgment of his researches on polarized light4 ,fresnel died1 in his fortieth year1 a few days after receiving the medal4 ,dr4 ,young died on ,may #aj1 #ahbi1 in the fifty-sixth year of his age1 his excessive mental exertions in early life having apparently led to a premature old age4 ,he was buried in the parish church of ,farnborough1 and a medallion by ,sir ,francis ,chantrey was erected to his memory in ,westminster ,abbey4 ,but1 though ,young was essentially a scientific man1 his accomplishments were all but universal1 and any memoir of him would be very incomplete without some sketch of his researches in ,egyptian hieroglyphics4 ,his classical training1 his extensive knowledge of ,european and ,eastern languages1 and his neat handwriting and drawing1 have already been referred to4 ,to these attainments must be added his scientific method and power of careful and systematic observation1 and it will be seen that few persons could come to the task of deciphering an unknown language with a better chance of success than ,dr4 ,young4 ,the ,rosetta ,stone was found by the ,french while excavating at ,fort ,st4 ,pierre1 near ,rosetta1 in #agii1 and was brought to ,england in #ahjb4 ,the stone bore an inscription in three different kinds of character--the ,hieroglyphic1 the ,enchorial or ,demotic1 and the ordinary ,greek4 ,young's attention was first called to the ,egyptian characters by a manuscript which was submitted to him in #ahad4 ,he then obtained copies of the inscriptions on the ,rosetta ,stone and subjected them to a careful analysis4 ,the latter part of the ,greek inscription was very much injured1 but was restored by the conjectures of ,porson and ,heyne1 and read as follows3--,what is here decreed shall be inscribed on a block of hard stone1 in sacred1 in enchorial1 and in ,greek characters1 and placed in each temple1 of the first1 second1 and third gods4 ,this indicated that the three inscriptions contained the same decree1 but1 unfortunately1 the beginnings of the first and second inscriptions were lost1 so that there were no very definitely fixed points to start upon4 ,the words ,alexander and ,alexandria1 however1 occurred in the ,greek1 and these words1 being so much alike1 might be recognized in each of the other inscriptions4 ,the word ,ptolemy appeared eleven times in the ,greek inscription1 and there was a word which1 from its length and position1 seemed to correspond to it1 which1 however1 appeared fourteen times in the hieroglyphic inscription4 ,this word1 whenever it appeared in the hieroglyphics1 was surrounded by a ring forming what ,champollion called a cartouche1 which was always employed to denote the names of royal persons4 ,these words were identified by ,baron ,sylvestre de ,sacy and the ,swedish scholar ,akerblad4 ,young appears to have started with the idea1 then generally current1 that hieroglyphic symbols were purely ideographic1 each sign representing a word4 ,his knowledge of ,chinese1 however1 led him to modify this view4 ,in that language native words are represented by single symbols1 but1 when it is necessary to write a foreign word1 a group of word-symbols is employed1 each of which then assumes a phonetic character of the same value as the initial letter of the word which it represents4 ,the phonetic value of these signs is indicated in ,chinese by a line at the side1 or by enclosing them in a square4 ,young supposed that the ring surrounding the royal names in the hieroglyphic inscription had the same value as the phonetic mark in ,chinese1 and from the symbols in the name of ,ptolemy he commenced to construct a hieroglyphic alphabet4 ,he made an error1 however1 in supposing that some of the symbols might be syllabic instead of alphabetic4 ,it is true that in the older inscriptions single signs have sometimes a syllabic value1 and sometimes are used ideographically1 while in other cases a single sign representing the whole word is employed in conjunction with the alphabetic signs1 probably to distinguish the word from others spelt in the same way1 but in inscriptions of so late a date as the ,rosetta ,stone1 the symbols were purely alphabetic4 ,another important step made by ,young was the discovery of the use of homophones1 or different symbols to represent the same letter4 ,young's work was closely followed up by ,champollion1 and afterwards by ,lepsius1 ,birsch1 and others4 ,the greater part of his researches he never published1 though he made careful examinations of several funeral rolls and other documents4 ,it would occupy too much space to give an adequate account of ,young's researches in this subject2 some portion of his work he published in a popular form in the article ,egypt1 in the supplement of the ,encyclopaedia ,britannica1 to which supplement he contributed about seventy articles on widely different subjects4 ,perhaps it is not too much to say that to ,young we owe the foundation of all we now know of hieroglyphics and the ,egyptian history which has been learned from them2 and the obelisk on the ,thames ,embankment should call to mind the memory of no one more prominently than that of ,thomas ,young4 ,,michael ,,faraday4 ,the work of ,michael ,faraday introduced a new era in the history of physical science4 ,unencumbered by pre-existing theories1 and untrammelled by the methods of the mathematician1 he set forth on a line of his own1 and1 while engaged in the highest branches of experimental research1 he sought to explain his results by reference to the most elementary mechanical principles only4 ,hence it was that those conclusions which had been obtained by mathematicians only by the help of advanced analytical methods1 and which were expressed by them only in the language of the integral calculus1 ,faraday achieved without any such artificial aids to thought1 and expressed in simple language1 having reference to the mechanism which he conceived to be the means by which such results were brought about4 ,for a long time ,faraday's methods were regarded by mathematicians with something more than suspicion1 and1 while they could not but admire his experimental skill and were compelled to admit the accuracy of his conclusions1 his mode of thought differed too widely from that to which they were accustomed to command their assent4 ,in ,sir ,william ,thomson1 and in ,clerk ,maxwell1 ,faraday at length found interpreters between him and the mathematical world1 and to the mathematician perhaps the greatest monument of the genius of ,faraday is the ,electricity and ,magnetism of ,clerk ,maxwell4 ,michael ,faraday was born at ,newington1 ,surrey1 on ,september #bb1 #agia1 and was the third of four children4 ,his father1 ,james ,faraday1 was the son of ,robert and ,elizabeth ,faraday1 of ,clapham ,wood ,hall1 in the north-west of ,yorkshire1 and was brought up as a blacksmith4 ,he was the third of ten children1 and1 in #aghf1 married ,margaret ,hastwell1 a farmer's daughter4 ,soon after his marriage he came to ,london1 where ,michael was born4 ,in #agif ,james ,faraday1 with his family1 moved from ,newington1 and took rooms over a coach-house in ,jacob's ,well ,mews1 ,charles ,street1 ,manchester ,square4 ,in looking at this humble abode one can scarcely help thinking that the ,yorkshire blacksmith and his little family would have been far happier in a country smiddy near his native moors than in a crowded ,london court2 but1 had he remained there1 it is difficult to see how the genius of young ,michael could have met with the requisites for its development4 ,james ,faraday was far from enjoying good health1 and his illness often necessitated his absence from work1 and1 as a consequence1 his family were frequently in very straitened circumstances4 ,the early education of ,michael was1 therefore1 not of a very high order1 and consisted of little more than the rudiments of reading1 writing1 and arithmetic4 ,like most boys in a similar position in ,london1 he found his amusement for the most part in the streets1 but1 except that in his games at marbles we may assume that he played with other boys1 we have no evidence whether his time was spent mostly by himself1 or whether he was one of a set of street companions4 ,in #ahjd1 when thirteen years of age1 ,michael ,faraday went as errand-boy to ,mr4 ,geo4 ,riebau1 a bookseller in ,blandford ,street4 ,part of his duty in this capacity was to carry round papers lent on hire by his master1 and in his ,life of ,faraday1 ,dr4 ,bence ,jones tells how anxious the young errand-boy was to collect his papers on ,sunday morning in time to attend the ,sandemanian service with the other members of his family4 ,faraday was apprenticed to ,mr4 ,riebau on ,october #g1 #ahje1 and learned the business of a bookbinder4 ,he occasionally occupied his spare time in reading the scientific books he had to bind1 and was particularly interested in ,mrs4 ,marcet's ,conversations in ,chemistry1 and in the article on ,electricity in the ,encyclopaedia ,britannica4 ,these were days before the existence of the ,london ,society for the ,extension of ,university ,teaching1 and1 though ,professor ,anderson in ,glasgow had shown how the advantages of a university might be extended to those whose fortunes prevented them from becoming regular university students1 ,professor ,stuart had not yet taught the ,english universities that they had responsibilities outside their own borders1 and that the national universities of the future must be the teachers of all classes of the community4 ,but private enterprise supplied in a measure the neglect of public bodies4 ,mr4 ,tatum1 of #dc1 ,dorset ,street1 ,fleet ,street1 advertised a course of lectures on natural philosophy1 to be delivered at his residence at eight o'clock in the evenings4 ,the price of admission was high1 being a shilling for each lecture1 but ,michael's brother ,robert frequently supplied him with the money1 and in attending these lectures ,faraday made many friendships which were valuable to him afterwards4 ,faraday appears to have been aware of the value of skill in drawing--a point to which much attention has recently been called by those interested in technical education--and he spent some portion of his time in studying perspective1 so as to be better able to illustrate his notes of ,mr4 ,tatum's lectures1 as well as of some of ,sir ,humphry ,davy's1 which he was enabled to hear at the ,royal ,institution through the kindness of a customer at ,mr4 ,riebau's shop4 ,in #ahab1 before the end of his apprenticeship1 ,faraday was engaged in experiments with voltaic batteries of his own construction4 ,having cut out seven discs of zinc the size of halfpence1 and covered them with seven halfpence1 he formed a pile by inserting pieces of paper soaked in common salt between each pair1 and found that the pile so constructed was capable of decomposing ,epsom salts4 ,with a somewhat larger pile he decomposed copper sulphate and lead acetate1 and made some experiments on the decomposition of water4 ,on ,july #ba1 #ahab1 in writing to his friend ,abbott1 he mentions the movements of camphor when floating on water1 and adds1 ,science may be illustrated by those minute actions and effects1 almost as much as by more evident and obvious phenomena4444 ,my knife is so bad that ,i cannot mend my pen with it2 it is now covered with copper1 having been employed to precipitate that metal from the muriatic acid4 ,something of ,faraday's disposition1 as well as of the results of his self-education1 may be gathered from the following quotations from letters to ,abbott1 written at this time3-- ,i have again gone over your letter1 but am so blinded that ,i cannot see any subject except chlorine to write on2 but before entering on what ,i intend shall fill up the letter1 ,i will ask your pardon for having maintained an opinion against one who was so ready to give his own up4 ,i suspect from that circumstance ,i am wrong4444 ,in the present case ,i conceive that experiments may be divided into three classes3 first1 those which are for the old theory of oxymuriatic acid1 and consequently oppose the new one2 second1 those which are for the new one1 and oppose the old theory2 and third1 those which can be explained by both theories--apparently so only1 for in reality a false theory can never explain a fact4 ,it is not for me to affirm that ,i am right and you wrong2 speaking impartially1 ,i can as well say that ,i am wrong and you right1 or that we both are wrong and a third right4 ,i am not so self-opinionated as to suppose that my judgment and perception in this or other matters is better or clearer than that of other persons2 nor do ,i mean to affirm that this is the true theory in reality1 but only that my judgment conceives it to be so4 ,judgments sometimes oppose each other1 as in this case2 and as there cannot be two opposing facts in nature1 so there cannot be two opposing truths in the intellectual world4 ,consequently1 when judgments oppose1 one must be wrong--one must be false2 and mine may be so for aught ,i can tell4 ,i am not of a superior nature to estimate exactly the strength and correctness of my own and other men's understanding1 and will assure you1 dear ,a----1 that ,i am far from being convinced that my own is always right4 ,i have given you the theory--not as the true one1 but as the one which appeared true to me--and when ,i perceive errors in it1 ,i will immediately renounce it1 in part or wholly1 as my judgment may direct4 ,from this1 dear friend1 you will see that ,i am very open to conviction2 and from the manner in which ,i shall answer your letter1 you will also perceive that ,i must be convinced before ,i renounce4 ,on ,october #g1 #ahab1 ,faraday's apprenticeship terminated1 and immediately afterwards he started life as a journeyman bookbinder4 ,he now found that he had less time at his disposal for scientific work than he had enjoyed when an apprentice1 and his desire to give up his trade and enter fully upon scientific pursuits became stronger than ever4 ,during his apprenticeship he had written to ,sir ,joseph ,banks1 then ,president of the ,royal ,society1 in the hope of obtaining some scientific employment2 he now applied to ,sir ,humphry ,davy4 ,in a letter written to ,dr4 ,paris1 in #ahbi1 ,faraday gave an account of this application4 ,my desire to escape from trade1 which ,i thought vicious and selfish1 and to enter into the service of science1 which ,i imagined made its pursuers amiable and liberal1 induced me at last to take the bold and simple step of writing to ,sir ,h4 ,davy1 expressing my wishes1 and a hope that1 if an opportunity came in his way1 he would favour my views2 at the same time1 ,i sent the notes ,i had taken of his lectures4 ,the answer1 which makes all the point of my communication1 ,i send you in the original1 requesting you to take great care of it1 and to let me have it back1 for you may imagine how much ,i value it4 ,you will observe that this took place at the end of the year #ahab2 and early in #ahac he requested to see me1 and told me of the situation of assistant in the laboratory of the ,royal ,institution1 then just vacant4 ,at the same time that he thus gratified my desires as to scientific employment1 he still advised me not to give up the prospects ,i had before me1 telling me that ,science was a harsh mistress1 and1 in a pecuniary point of view1 but poorly rewarding those who devoted themselves to her service4 ,he smiled at my notion of the superior moral feelings of philosophic men1 and said he would leave me to the experience of a few years to set me right on that matter4 ,finally1 through his good efforts1 ,i went to the ,royal ,institution1 early in ,march of #ahac1 as assistant in the laboratory2 and in ,october of the same year went with him abroad1 as his assistant in experiments and in writing4 ,i returned with him in ,april1 #ahae1 resumed my station in the ,royal ,institution1 and have1 as you know1 ever since remained there4 ,sir ,h4 ,davy's letter was as follows3-- ,,sir1 ,i am far from displeased with the proof you have given me of your confidence1 and which displays great zeal1 power of memory1 and attention4 ,i am obliged to go out of town1 and shall not be settled in town till the end of ,january2 ,i will then see you at any time you wish4 ,it would gratify me to be of any service to you2 ,i wish it may be in my power4 ,i am1 sir1 ,your obedient humble servant1 ,h4 ,,davy4 ,the minutes of the meeting of managers of the ,royal ,institution1 on ,march #a1 #ahac1 contain the following entry3--,sir ,humphry ,davy has the honour to inform the managers that he has found a person who is desirous to occupy the situation in the institution lately filled by ,william ,payne4 ,his name is ,michael ,faraday4 ,he is a youth of twenty-two years of age4 ,his habits seem good1 his disposition active and cheerful1 and his manner intelligent4 ,he is willing to engage himself on the same terms as those given to ,mr4 ,payne at the time of quitting the institution4 ,resolved1 that ,michael ,faraday be engaged to fill the situation lately occupied by ,mr4 ,payne1 on the same terms4 ,about this time ,faraday joined the ,city ,philosophical ,society1 which had been started at ,mr4 ,tatum's house in #ahjh4 ,the members met every ,wednesday evening1 either for a lecture or discussion2 and perhaps the society did not widely differ from some of the students' associations which have more recently been started in connection with other educational enterprises4 ,magrath was secretary of this society1 and from it there sprang a smaller band of students1 who1 meeting once a week1 either at ,magrath's warehouse in ,wood ,street1 or at ,faraday's private rooms in the attics of the ,royal ,institution1 for mutual improvement1 read together1 and freely criticized each other's pronunciation and composition4 ,in a letter to ,abbott six weeks after commencing work at the ,royal ,institution1 ,faraday says3-- ,a stranger would certainly think you and ,i were a couple of very simple beings1 since we find it necessary to write to each other1 though we so often personally meet2 but the stranger would1 in so judging1 only fall into that error which envelops all those who decide from the outward appearances of things4444 ,when writing to you ,i seek that opportunity of striving to describe a circumstance or an experiment clearly2 so that you will see ,i am urged on by selfish motives partly to our mutual correspondence1 but1 though selfish1 yet not censurable4 ,during the summer of #ahac ,faraday1 in his letters to ,abbott1 gave his friend the benefit of his experience on the subject of lectures and lecturers in general1 in a manner that speaks very highly of his power of observation of men as well as things4 ,he was of opinion that a lecture should not last more than an hour1 and that the subject should fit the audience4 ,a lecturer may consider his audience as being polite or vulgar 7terms ,i wish you to understand according to ,shuffleton's new dictionary71 learned or unlearned 7with respect to the subject71 listeners or gazers4 ,polite company expect to be entertained1 not only by the subject of the lecture1 but by the manner of the lecturer2 they look for respect1 for language consonant to their dignity1 and ideas on a level with their own4 ,the vulgar--that is to say1 in general1 those who will take the trouble of thinking1 and the bees of business--wish for something that they can comprehend4 ,this may be deep and elaborate for the learned1 but for those who are as yet tyros and unacquainted with the subject1 must be simple and plain4 ,lastly1 listeners expect reason and sense1 whilst gazers only require a succession of words4 ,in favour of experimental illustration he says3-- ,i need not point out 444 the difference in the perceptive powers of the eye and the ear1 and the facility and clearness with which the first of these organs conveys ideas to the mind--ideas which1 being thus gained1 are held far more retentively and firmly in the memory than when introduced by the ear4444 ,apparatus1 therefore1 is an essential part of every lecture in which it can be introduced4444 ,when 444 apparatus is to be exhibited1 some kind of order should be observed in the arrangement of them on the lecture-table4 ,every particular part illustrative of the lecture should be in view1 no one thing should hide another from the audience1 nor should anything stand in the way of or obstruct the lecturer4 ,they should be so placed1 too1 as to produce a kind of uniformity in appearance4 ,no one part should appear naked and another crowded1 unless some particular reason exists and makes it necessary to be so4 ,on ,october #ac1 #ahac1 ,faraday left the ,royal ,institution1 in order to accompany ,sir ,humphry ,davy in a tour on the ,continent4 ,his journal gives some interesting details1 showing the inconveniences of foreign travel at that time4 ,sir ,humphry ,davy took his carriage with him in pieces1 and these had to be put together after escaping the dangers of the ,french custom-house on the quay at ,morlaix1 two years before the battle of ,waterloo4 ,one apparently trivial incident somewhat marred ,faraday's pleasure throughout this journey4 ,it was originally intended that the party should comprise ,sir ,humphry and ,lady ,davy1 ,faraday1 and ,sir ,humphry's valet1 but at the last moment that most important functionary declined to leave his native shores4 ,davy then requested ,faraday to undertake such of the duties of valet as were essential to the well-being of the party1 promising to secure the services of a suitable person in ,paris4 ,but no eligible candidate appeared for the appointment1 and thus ,faraday had throughout to take charge of domestic affairs as well as to assist in experiments4 ,had there been only ,sir ,humphry and himself1 this would have been no hardship4 ,sir ,humphry had been accustomed to humble life in his early days2 but the case was different with his lady1 and1 apparently1 ,faraday was more than once on the point of leaving his patron and returning home alone4 ,a circumstance which occurred at ,geneva illustrates the position of affairs4 ,professor ,e4 de la ,rive invited ,sir ,humphry and ,lady ,davy and ,faraday to dinner4 ,sir ,humphry could not go into society with one who1 in some respects1 acted as his valet4 ,when this point was represented to the professor1 he replied that he was sorry1 as it would necessitate his giving another dinner-party4 ,faraday subsequently kept up a correspondence with ,de la ,rive1 and continued it with his son4 ,in writing to the latter he says1 in speaking of ,professor ,e4 de la ,rive1 that he was the first who personally at ,geneva1 and afterwards by correspondence1 encouraged and by that sustained me4 ,at ,paris ,faraday met many of the most distinguished men of science of the time4 ,one morning ,ampere1 ,clement1 and ,desormes called on ,davy1 to show him some iodine1 a substance which had been discovered only about two years before1 and ,davy1 while in ,paris1 and afterwards at ,montpellier1 executed a series of experiments upon it4 ,after three months' stay1 the party left ,paris for ,italy1 via ,montpellier1 ,aix1 and ,nice1 whence they crossed the ,col de ,tende to ,turin4 ,the transfer of the carriage and baggage across the ,alps was effected by a party of sixty-five men1 with sledges and a number of mules4 ,the description of the journey1 as recorded in ,faraday's diary1 makes us respect the courage of an ,englishman who1 in the early part of this century1 would attempt the conveyance of a carriage across the ,alps in the winter4 ,from ,turin we proceeded to ,genoa1 which place we left afterwards in an open boat1 and proceeded by sea towards ,lerici4 ,this place we reached after a very disagreeable passage1 and not without apprehensions of being overset by the way4 ,as there was nothing there very enticing1 we continued our route to ,florence2 and1 after a stay of three weeks or a month1 left that fine city1 and in four days arrived here at ,rome4 ,the foregoing is from ,faraday's letter to his mother4 ,at ,florence a good deal of time was spent in the ,academia del ,cimento4 ,here ,faraday saw the telescope with which ,galileo discovered ,jupiter's satellites1 with its tube of wood and paper about three feet and a half long1 and simple object-glass and eye-glass4 ,a red velvet electric machine with a rubber of gold paper1 ,leyden jars pierced by the discharge between their armatures1 the first lens constructed by ,galileo1 and a number of other objects1 were full of interest to the recently enfranchised bookbinder's apprentice2 but it was the great burning-glass of the grand-duke which was the most serviceable of all the treasures of the museum4 ,with this glass--which consisted of two convex lenses about three feet six inches apart1 the first lens having a diameter of about fourteen or fifteen inches1 and the second a diameter of three inches--,davy succeeded in burning several diamonds in oxygen gas1 and in proving that the diamond consists of little else than carbon4 ,in #ahah ,faraday published a paper on this subject in the ,quarterly ,journal of ,science4 ,at ,genoa some experiments were made with the torpedo1 but the specimens caught were very small and weak1 and their shocks so feeble that no definite results were obtained4 ,at ,rome ,davy attempted to repeat an experiment of ,signor ,morrichini1 whereby a steel needle was magnetized by causing the concentrated violet and blue rays from the sun to traverse the needle from the middle to the north end several times4 ,the experiment did not succeed in the hands of ,davy and ,faraday1 and it was left to the latter to discover a relation between magnetism and light4 ,from ,rome they visited ,naples and ascended ,vesuvius1 and shortly afterwards left ,italy for ,geneva4 ,in the autumn of #ahad they returned from ,switzerland through ,germany1 visiting ,berne1 ,zurich1 the ,tyrol1 ,padua1 ,venice1 and ,bologne1 to ,florence1 where ,davy again carried out some chemical investigations in the laboratory of the academy4 ,thence they returned to ,rome1 and in the spring went on to ,naples1 and again visited ,vesuvius1 returning to ,england in ,april1 via ,rome1 the ,tyrol1 ,stuttgart1 ,brussels1 and ,ostend4 ,a fortnight after his return from the ,continent ,faraday was again assistant at the ,royal ,institution1 but with a salary of thirty shillings a week4 ,his character will be sufficiently evident from the quotations which have been given from his diary and letters4 ,henceforth we must be mainly occupied with the consideration of his scientific work4 ,in ,january1 #ahaf1 he gave his first lecture to the ,city ,philosophical ,society4 ,in a lecture delivered shortly afterwards before the same society1 the following passage1 which gives an idea of one of the current beliefs of the time1 occurs3-- ,the conclusion that is now generally received appears to be that light consists of minute atoms of matter of an octahedral form1 possessing polarity1 and varying in size or in velocity4444 ,if now we conceive a change as far beyond vaporization as that is above fluidity1 and then take into account also the proportional increased extent of alteration as the changes rise1 we shall1 perhaps1 if we can form any conception at all1 not fall far short of radiant matter2#f and as in the last conversion many qualities were lost1 so here also many more would disappear4 ,footnote #f3 ,not ,crookes's4 ,it was the opinion of ,newton1 and of many other distinguished philosophers1 that this conversion was possible1 and continually going on in the processes of nature1 and they found that the idea would bear without injury the application of mathematical reasoning--as regards heat1 for instance4 ,if assumed1 we must also assume the simplicity of matter2 for it would follow that all the variety of substances with which we are acquainted could be converted into one of three kinds of radiant matter1 which again may differ from one another only in the size of their particles or their form4 ,the properties of known bodies would then be supposed to arise from the varied arrangements of their ultimate atoms1 and belong to substances only as long as their compound nature existed2 and thus variety of matter and variety of properties would be found co-essential4 ,the simplicity of such a system is singularly beautiful1 the idea grand and worthy of ,newton's approbation4 ,it was what the ancients believed1 and it may be what a future race will realize4 ,in the closing words of his fifth lecture to the ,city ,philosophical ,society1 ,faraday said3-- ,the philosopher should be a man willing to listen to every suggestion1 but determined to judge for himself4 ,he should not be biassed by any appearances2 have no favourite hypothesis2 be of no school2 and in doctrine have no master4 ,he should not be a respecter of persons1 but of things4 ,truth should be his primary object4 ,if to these qualities be added industry1 he may indeed hope to walk within the veil of the temple of nature4 ,many years afterwards he stated that1 of all the suggestions to which he had patiently listened after his lectures at the ,royal ,institution1 only one proved on investigation to be of any value1 and that led to the discovery of the extra current and the whole subject of self-induction4 ,faraday always kept a note-book1 in which he jotted down any thoughts which occurred to him in reference to his work1 as well as extracts from books or other publications which attracted his attention4 ,he called it his commonplace-book4 ,many of the queries which he here took note of he subsequently answered by experiment4 ,for example3-- ,query3 the nature of sounds produced by flame in tubes4 ,convert magnetism into electricity4 ,general effects of compression1 either in condensing gases or producing solutions1 or even giving combinations at low temperature4 ,do the pith-balls diverge by the disturbance of electricity through mutual induction or not8 ,speaking of this book1 he says1 ,i already owe much to these notes1 and think such a collection worth the making by every scientific man4 ,i am sure none would think the trouble lost after a year's experience4 ,in a letter dated ,may #c1 #ahah1 he writes3-- ,i have this evening been busy with an atmospherical electrical apparatus4 ,it was a very temporary thing1 but answered the purpose completely4 ,a wire1 with some small brush-wire rolled round the top of it1 was elevated into the atmosphere by a thin wood rod having a glass tube at the end1 and tied to a chimney-pot on the housetop2 and this wire was continued down 7taking care that it touched nothing in its way7 into the lecture-room2 and we succeeded1 at intervals1 in getting sparks from it nearly a quarter of an inch in length1 and in charging a ,leyden jar1 so as to give a strong shock4 ,the electricity was positive4 ,now1 ,i think you could easily make an apparatus of this kind1 and it would be a constant source of interesting matter2 only take care you do not kill yourself or knock down the house4 ,on ,june #ab1 #ahbj1 he married ,miss ,sarah ,barnard1 third daughter of ,mr4 ,barnard1 of ,paternoster ,row--an event which1 to use his own words1 more than any other contributed to his earthly happiness and healthful state of mind4 ,it was his wish that the day should be just like any other day--that there should be no bustle1 no noise1 no hurry occasioned even in one day's proceeding1 though in carrying out this plan he offended some of his relations by not inviting them to his wedding4 ,up to this time ,faraday's experimental researches had been for the most part in the domain of chemistry1 and for two years a great part of his energy had been expended in investigating1 in company with ,mr4 ,stodart1 a surgical instrument-maker1 the properties of certain alloys of steel1 with a view to improve its manufacture for special purposes4 ,it was in #ahba that he commenced his great discoveries in electricity4 ,in the autumn of that year he wrote an historical sketch of electro-magnetism for the ,annals of ,philosophy1 and he repeated for himself most of the experiments which he described4 ,in the course of these experiments1 in ,september1 #ahba1 he discovered the rotation of a wire conveying an electric current around the pole of a magnet4 ,,oersted had discovered1 in #ahbj1 the tendency of a magnetic needle to set itself at right angles to a wire conveying a current4 ,this action is due to a tendency on the part of the north pole to revolve in a right-handed direction around the current1 while the south pole tends to revolve in the opposite direction4 ,the principle that action and reaction are equal and opposite indicates that1 if a magnetic pole tend to rotate around a conductor conveying a current1 there must be an equal tendency for the conductor to rotate around the pole4 ,it was this rotation that constituted ,faraday's first great discovery in electro-dynamics4 ,on ,december #ba1 in the same year1 ,faraday showed that the earth's magnetism was capable of exerting a directive action on a wire conveying a current4 ,writing to ,de la ,rive on the subject1 he says3-- ,i find all the usual attractions and repulsions of the magnetic needle by the conjunctive wire are deceptions1 the motions being1 not attractions or repulsions1 nor the result of any attractive or repulsive forces1 but the result of a force in the wire1 which1 instead of bringing the pole of the needle nearer to or further from the wire1 endeavours to make it move round it in a never-ending circle and motion whilst the battery remains in action4 ,i have succeeded1 not only in showing the existence of this motion theoretically1 but experimentally1 and have been able to make the wire revolve round a magnetic pole1 or a magnetic pole round the wire1 at pleasure4 ,the law of revolution1 and to which all the other motions of the needle are reducible1 is simple and beautiful4 ,conceive a portion of connecting wire north and south1 the north end being attached to the positive pole of a battery1 the south to the negative4 ,a north magnetic pole would then pass round it continually in the apparent direction of the sun1 from east to west above1 and from west to east below4 ,reverse the connections with the battery1 and the motion of the pole is reversed2 or1 if the south pole be made to revolve1 the motions will be in the opposite direction1 as with the north pole4 ,if the wire be made to revolve round the pole1 the motions are according to those mentioned4444 ,now1 ,i have been able1 experimentally1 to trace this motion into its various forms1 as exhibited by ,ampere's helices1 etc41 and in all cases to show that the attractions and repulsions are only appearances due to this circulation of the pole2 to show that dissimilar poles repel as well as attract1 and that similar poles attract as well as repel2 and to make1 ,i think1 the analogy between the helix and common bar magnet far stronger than before4 ,but yet ,i am by no means decided that there are currents of electricity in the common magnet4 ,i have no doubt that electricity puts the circles of the helix into the same state as those circles are in that may be conceived in the bar magnet2 but ,i am not certain that this state is directly dependent on the electricity1 or that it cannot be produced by other agencies2 and therefore1 until the presence of electric currents be proved in the magnet by other than magnetical effects1 ,i shall remain in doubt about ,ampere's theory4 ,the most convenient rule by which to remember the direction of these electro-magnetic rotations is probably that given by ,clerk ,maxwell1 which will be stated in its place4#g ,if a circular plate of copper and another of zinc be connected by a piece 7or better1 by three pieces7 of insulated wire1 so that the zinc is about an inch above the copper1 and the combined plates be suspended by a silk fibre in a small beaker of dilute sulphuric acid1 which is placed on the pole of a large magnet1 the liquid will be seen to rotate about a vertical axis in one direction1 and the two plates with their connecting wires in the opposite direction4 ,on reversing the polarity of the magnet1 both rotations will be reversed4 ,this is a very simple mode of exhibiting ,faraday's discovery4 ,a little powdered resin renders the motion of the liquid readily visible4 ,footnote #g3 ,see p4 #cjb4 ,in #ahbc ,faraday published his work on the liquefaction of gases1 from which he concluded that there was no difference in kind between gases and vapours4 ,in the course of this work he met with more than one serious explosion4 ,on ,january #h1 #ahbd1 he was elected a ,fellow of the ,royal ,society1 and in #ahbe1 on the recommendation of ,sir ,humphry ,davy1 he was appointed ,director of the ,laboratory of the ,royal ,institution1 and in this capacity he instituted the laboratory conferences1 which developed into the ,friday evening lectures4 ,for five years after this1 the greater part of ,faraday's spare time was occupied in some investigations in connection with optical glass1 made at the request of the ,royal ,society1 and at the expense of the ,government4 ,mr4 ,dollond and ,sir ,john ,herschel were associated with him on this committee1 but the results obtained were not of much value to opticians4 ,the silico-borate of lead which ,faraday prepared in the course of these experiments was1 however1 the substance with which he first demonstrated the effect of a magnetic field on the plane of polarization of light1 and with which he discovered diamagnetic action4 ,faraday's experimental researches were generally guided by theoretical considerations4 ,frequently these theories were based on very slender premises1 and sometimes were little else than flights of a scientific imagination1 but they served to guide him into fruitful fields of discovery1 and he seldom placed much confidence in his conclusions till he had succeeded in verifying them experimentally4 ,for many years he had held the opinion that electric currents should exhibit phenomena analogous to those of electro-static induction4 ,again and again he returned to the investigation1 and attempted to obtain an induced current in one wire through the passage of a powerful current through a neighbouring conductor2 but he looked for a permanent induced current to be maintained during the whole time that the primary current was flowing4 ,at length1 employing two wires wound together as a helix on a wooden rod1 the first capable of transmitting a powerful current from a battery1 while the second was connected with a galvanometer1 he observed that1 when the current started in the primary1 there was a movement of the galvanometer1 and when it ceased there was a movement in the opposite direction1 though the galvanometer remained at zero while the current continued steady4 ,hence it was apparent that it is by changes in the primary current that induced currents may be generated1 and not by their steady continuance2 and it was demonstrated that1 when a current is started in a conductor1 a temporary current is induced in a neighbouring conductor in the opposite direction1 while a current is induced in the same direction as the primary when the latter ceases to flow4 ,before obtaining this result with the wires on a wooden bobbin1 he had experimented with a wrought-iron ring about six inches in diameter1 and made of #g_/h-;inch round iron4 ,he wound two sets of coils round it1 one occupying nearly half the ring1 and the other filling most of the other half4 ,one of these he connected with a galvanometer1 the other could be connected at will with a battery4 ,on sending the battery current through the latter coil1 the galvanometer needle swung completely round four or five times1 and a similar action took place1 but in the opposite direction1 on stopping the current4 ,here it was clearly the magnetism induced in the iron ring which produced so powerful a current in the galvanometer circuit4 ,next he wound a quantity of covered copper wire on a small iron bar1 and connecting the ends to a galvanometer1 he placed the little bobbin between the opposite poles of a pair of bar magnets1 whose other ends were in contact4 ,as soon as the iron core touched the magnets1 a current appeared in the galvanometer4 ,on breaking contact1 the current was in the opposite direction4 ,then came the experiment above mentioned1 in which no iron was employed4 ,after this1 one end of a cylindrical bar magnet was introduced into a helix of copper wire1 and then suddenly thrust completely in4 ,the galvanometer connected with the coil showed a transient current4 ,on withdrawing the magnet1 the current appeared in the opposite direction2 so that currents were induced merely by the relative motion of a magnet and a conductor4 ,a copper disc was mounted so that it could be made to rotate rapidly4 ,a wire was placed in connection with the centre of the disc1 and the circuit completed by a rubbing contact on the circumference4 ,a galvanometer was inserted in the circuit1 and the large horseshoe magnet of the ,royal ,institution so placed that the portion of the disc between the centre and the rubbing contact passed between the poles of the magnet4 ,a current flowed through the galvanometer as long as the disc was kept spinning4 ,then he found that the mere passage of a copper wire between the poles of the magnet was sufficient to induce a current in it1 and concluded that the production of the current was connected with the cutting of the magnetic curves1 or lines of magnetic force which would be depicted by iron filings4 ,thus in the course of ten days' experimental work1 in the autumn of #ahca1 ,faraday so completely investigated the phenomena of electro-magnetic induction as to leave little1 except practical applications1 to his successors4 ,a few weeks later he obtained induction currents by means of the earth's magnetism only1 first with a coil of wire wound upon an iron bar in which a strong current was produced when it was being quickly placed in the direction of the magnetic dip or being removed from that position1 and afterwards with a coil of wire without an iron core4 ,on ,february #h1 #ahcb1 he succeeded in obtaining a spark from the induced current4 ,unless the electro-motive force is very great1 it is not possible to obtain a spark between two metallic surfaces which are separated by a sensible thickness of air4 ,if1 however1 the circuit of a wire is broken while the current is passing1 a little bridge of metallic vapour is formed1 across which for an instant the spark leaps4 ,the induced current being of such short duration1 the difficulty was to break the circuit while it was flowing4 ,faraday wound a considerable length of fine wire around a short bar of iron2 the ends of the wire were crossed so as just to be in contact with one another1 but free to separate if exposed to a slight shock4 ,the ends of the iron bar projected beyond the coil1 and were held just over the poles of the magnet4 ,on releasing the bar it fell so as to strike the magnetic poles and close the circuit of the magnet4 ,an induced current was generated in the wire1 but1 while this was passing1 the shock caused by the bar striking the magnet separated the ends of the wire1 thus breaking the circuit of the conductor1 and a spark appeared at the gap4 ,in this little spark was the germ of the electric light of to-day4 ,subsequently ,faraday improved the apparatus1 by attaching a little disc of amalgamated copper to one end of the wire1 and bending over the other end so as just to press lightly against the surface of the disc4 ,with this apparatus he showed the magnetic spark at the meeting of the ,british ,association at ,oxford4 ,faraday supposed that when a coil of wire was in the neighbourhood of a magnet1 or near to a conductor conveying a current1 the coil was thrown into a peculiar condition1 which he called the electro-tonic state1 and that the induced currents appeared whenever this state was assumed or lost by the coil4 ,he frequently reverted to his conception of the electro-tonic state1 though he saw clearly that1 when the currents were induced by the relative motion of a wire and a magnet1 the current induced depended on the rate at which the lines of magnetic force had been cut by the wire4 ,of his conception of lines of force filling the whole of space1 we shall have more to say presently4 ,it is sufficient to remark here that1 in the electro-tonic state of ,faraday1 ,clerk ,maxwell recognized the number of lines of magnetic force enclosed by the circuit1 and showed that the electro-motive force induced is proportional to the rate of change of the number of lines of force thus enclosed4 ,it is seldom that a great discovery is made which has not been gradually led up to by several observed phenomena which awaited that discovery for their explanation4 ,in the case of electro-magnetic induction1 however1 there appears to have been but one experiment which had baffled philosophers1 and the key to which was found in ,faraday's discovery1 while the complete explanation was given by ,faraday himself4 ,arago had found that1 if a copper plate were made rapidly to rotate beneath a freely suspended magnetic needle1 the needle followed 7slowly7 the plate in its revolution1 though a sheet of glass were inserted between the two to prevent any air-currents acting on the magnet4 ,the experiment had been repeated by ,sir ,john ,herschel and ,mr4 ,babbage1 but no explanation was forthcoming4 ,faraday saw that the revolution of the disc beneath the poles of the magnet must generate induced currents in the disc1 as the different portions of the metal would be constantly cutting the lines of force of the magnet4 ,these currents would react upon the magnet1 causing a mechanical stress to act between the two1 which1 as stated by ,lenz1 would be in the direction tending to oppose the relative motion1 and therefore to drag the magnet after the disc in its revolution4 ,in the above figure the unfledged arrows show the general distribution of the currents in the disc1 while the winged arrows indicate the direction of the disc's rotation4 ,the currents in the semicircle ,a will repel the north pole and attract the south pole4 ,those in the semicircle ,b will produce the opposite effect1 and hence there will be a tendency for the magnet to revolve in the direction of the disc1 while the motion of the disc will be resisted4 ,this resistance to the motion of a conductor in a magnetic field was noticed by ,faraday1 and1 independently1 by ,tyndall1 and it is sufficiently obvious in the power absorbed by dynamos when they are generating large currents4 ,faraday's next series of researches was devoted to the experimental proof of the identity of frictional and voltaic electricity4 ,he showed that a magnet could be deflected and iodide of potassium decomposed by the current from his electrical machine1 and came to the conclusion that the amount of electricity required to decompose a grain of water was equal to #hjj1jjj charges of his large ,leyden battery4 ,the current from the frictional machine also served to deflect the needle of his galvanometer4 ,these investigations led on to a complete series of researches on the laws of electrolysis1 wherein ,faraday demonstrated the principle that1 however the strength of the current may be varied1 the amount of any compound decomposed is proportional to the whole quantity of electricity which has passed through the electrolyte4 ,when the same current is sent through different compounds1 there is a constant relation between the amounts of the several compounds decomposed4 ,in modern language1 ,faraday's laws may be thus expressed3-- ,if the same current be made to pass through several different electrolytes1 the quantity of each ion produced will be proportional to its combining weight divided by its valency1 and if the current vary1 the quantity of each ion liberated per second will be proportional to the current4 ,this is the great law of electro-chemical equivalents4 ,the amount of hydrogen liberated per second by a current of one ampere is about 4#jjjjajch gramme1 or nearly one six-thousandth of a grain4 ,this is the electro-chemical equivalent of hydrogen4 ,that of any other substance may be found by ,faraday's law4 ,from ,faraday's results it appears that the passage of the same amount of electricity is required in order to decompose one molecule of any compound of the same chemical type1 but it does not follow that the same amount of energy is employed in the decomposition4 ,for example1 the combining weights of copper and zinc are nearly equal4 ,hence it will require the passage of about the same amount of electricity to liberate a pound of copper from1 say1 the copper sulphate as to liberate a pound of zinc from zinc sulphate2 but the work to be done is much less in the case of the copper4 ,this is made manifest in the following way3--,a battery1 which will just decompose the copper salt slowly1 liberating copper1 oxygen1 and sulphuric acid1 will not decompose the zinc salt at all so as to liberate metallic zinc1 but immediately on sending the current through the electrolyte1 polarization will set in1 and the opposing electro-motive force thus introduced will become equal to that of the battery1 and stop the current before metallic zinc makes its appearance4 ,in the case of the copper1 polarization also sets in1 but never attains to equality with the electro-motive force of the primary battery4 ,in fact1 in all cases of electrolysis1 polarization produces an opposing electro-motive force strictly proportional to the work done in the cell by the passage of each unit of electricity4 ,if the strength of the battery be increased1 so that it is able to decompose the zinc sulphate1 and if this battery be applied to the copper sulphate solution1 the latter will be rapidly decomposed1 and the excess of energy developed by the battery will be converted into heat in the circuit4 ,one important point in connection with electrolysis which ,faraday demonstrated is that the decomposition is the result of the passage of the current1 and is not simply due to the attraction of the electrodes4 ,thus he showed that potassium iodide could be decomposed by a stream of electricity coming from a metallic point on the prime conductor of his electric machine1 though the point did not touch the test-paper on which the iodide was placed4 ,it was in #ahcd that ,mr4 ,wm4 ,jenkin1 after one of the ,friday evening lectures at the ,royal ,institution1 called the attention of ,faraday to a shock which he had experienced in breaking the circuit of an electro-magnet1 though the battery employed consisted of only one pair of plates4 ,faraday repeated the experiment1 and found that1 with a large magnet in circuit1 a strong spark could thus be obtained4 ,on ,november #ad1 #ahcd1 he writes1 ,the phenomenon of increased spark is merely a case of the induction of electric currents4 ,if a current be established in a wire1 and another wire forming a complete circuit be placed parallel to it1 at the moment the current in the first is stopped it induces a current in the same direction in the second1 itself then showing but a feeble spark4 ,but if the second be away1 it induces a current in its own wire in the same direction1 producing a strong spark4 ,the strong spark in the current when alone is therefore the equivalent of the current it can produce in a neighbouring wire when in company4 ,the strong spark does1 in fact1 represent the energy of the current due to the self-induction of its circuit1 which energy would1 in part at least1 be expended in inducing a current in a neighbouring wire if such existed4 ,his time from #ahce till #ahch was largely taken up with his work on electro-static induction4 ,faraday could never be content with any explanation based on direct action at a distance2 he always sought for the machinery through which the action was communicated4 ,in this search the lines of magnetic force1 which he had so often delineated in iron filings1 came to his aid4 ,faraday made many pictures in iron filings of magnetic fields due to various combinations of magnets4 ,he employed gummed paper1 and when the filings were arranged on the hard gummed surface1 he projected a feeble jet of steam on the paper1 which melted the gum and fixed the filings4 ,several of his diagrams were exhibited at the ,loan ,collection at ,south ,kensington4 ,he conceived electrical action to be transmitted along such lines as these1 and to him the whole electric field was filled with lines passing always from positive to negative electrification1 and in some respects resembling elastic strings4 ,the action at any place could then be expressed in terms of the lines of force that existed there1 the electrifications by which these lines were produced being left out of consideration4 ,the acting bodies were thus replaced by the field of force they produced4 ,he showed that it was impossible to call into existence a charge of positive electricity without at the same time producing an equal negative charge4 ,from every unit of positive electricity he conceived a line of force to start1 and thus1 with the origin of the line1 there was created simultaneously a charge of negative electricity on which the line might terminate4 ,by the famous ice-pail experiment he showed that1 when a charged body is inserted in a closed or nearly closed hollow conductor1 an equal amount of the same kind of electricity appeared on the outside of the hollow conductor1 while an equal amount of the opposite kind appeared on the interior surface of the conductor4 ,with the ice-pail and the butterfly-net he showed that there could be no free electricity on the interior of a conductor4 ,lines of force cannot pass through the material of a conductor without producing electric displacement4 ,every element of electricity must be joined to an equal amount of the opposite kind by a line of force4 ,such lines cannot pass through the conductor itself2 hence the charge must be entirely on the outside of the conductor1 so that every element of the charge may be associated with an equal amount of the opposite electricity upon the surfaces of surrounding objects4 ,thus to ,faraday every electrical action was an exhibition of electric induction4 ,all this work had been done before by ,henry ,cavendish1 but neither ,faraday nor any one else knew about it at the time4 ,from the fact that there could be no electricity in the interior of a hollow conductor1 ,cavendish deduced1 in the best way possible1 the truth of the law of inverse squares as applied to electrical attraction and repulsion1 and thus laid the foundation of the mathematical theory of electricity4 ,to ,cavendish every electrical action was a displacement of an incompressible fluid which filled the whole of space1 producing no effect in conductors on account of the freedom of its motion1 but producing strains in insulators by displacing the material of the body4 ,faraday1 in his lines of force1 saw1 as it were1 the lines along which the displacements of ,cavendish's fluid took place4 ,faraday thought that1 if he could show that electric induction could take place along curved lines1 it would prove that the action took place through a medium1 and not directly at a distance4 ,he succeeded in experimentally demonstrating the curvature of these lines2 but his conclusions were not warranted1 for if we conceive of two or more centres of force acting directly at a distance according to the law of inverse squares1 the resultant lines of force will generally be curved4 ,of course1 this does not prove the possibility of direct action at a distance1 but only shows that the curvature of the lines is as much a consequence of the one hypothesis as of the other4 ,it soon appeared to ,faraday that the nature of the dielectric had very much to do with electric induction4 ,the capacity of a condenser1 for instance1 depends on the nature of the dielectric as well as on the configuration of the conductors4 ,to express this property1 ,faraday employed the term specific inductive capacity4 ,he compared the electric capacity of condensers1 equal in all other respects1 but one possessing air for its dielectric1 and the other having other media1 and thus roughly determined the specific inductive capacities of several insulators4 ,these results turned out afterwards to be of great value in connection with the insulation of submarine cables4 ,even now the student of electricity is sometimes puzzled by the manner in which specific inductive capacity is introduced to his notice as modifying the capacity of condensers1 after learning that the capacity of any system of conductors can be calculated from its geometrical configuration2 but the fact is that the intensity of all electrical actions depends on the nature of the medium through which they take place1 and it will require more electricity to exert upon an equal charge a unit force at unit distance when the intervening medium has a high than when it possesses a low specific inductive capacity4 ,in #ahce ,faraday received a pension from the civil list2 in #ahcf he was appointed scientific adviser to the ,elder ,brethren of the ,trinity ,house4 ,in the same year he was made a member of the ,senate of the ,university of ,london1 and in that capacity he has exerted no small influence on the scientific education of the country1 for he was one of those who drew up the schedules of the various examinations4 ,in his early years1 ,faraday thought that all kinds of matter might ultimately consist of three materials only1 and that as gases and vapours appeared more nearly to resemble one another than the liquids or solids to which they corresponded1 so each might be subject to a still higher change in the same direction1 and the gas or vapour become radiant matter--either heat1 light1 or electricity4 ,later on1 ,faraday clearly recognized the dynamical nature of heat and light2 but his work was always guided by his theoretical conceptions of the correlation of the physical forces4 ,for a long time he had tried to discover relations between electricity and light2 at length1 on ,september #ac1 #ahde1 after experimenting on a number of other substances1 he placed a piece of silico-borate of lead1 or heavy-glass1 in the field of the magnet1 and found that1 when a beam of polarized light was transmitted through the glass in the direction of the lines of magnetic force1 there was a rotation of the plane of polarization4 ,afterwards it appeared that all the transparent solids and liquids experimented on were capable of producing this rotation in a greater or less degree1 and in the case of all non-magnetic substances the rotation was in the direction of the electric current1 which1 passing round the substance1 would produce the magnetic field employed4 ,abandoning the magnet1 and using only a coil of wire with the transparent substance within it1 similar effects were obtained4 ,thus at length a relation was found between light and electricity4 ,on ,november #d1 employing a piece of heavy-glass and a new horseshoe magnet1 ,faraday noticed that the magnet appeared to have a directive action upon the glass4 ,further examination showed that the glass was repelled by the magnetic poles4 ,three days afterwards he found that all sorts of substances1 including most metals1 were acted upon like the heavy-glass4 ,small portions of them were repelled1 while elongated cylinders tended to set with their lengths perpendicular to the lines of magnetic force4 ,such actions could be imitated by suspending a feebly magnetic body in a medium more magnetic than itself4 ,faraday1 therefore1 sought for some medium which would be absolutely neutral to magnetic action4 ,filling a glass tube with compressed oxygen1 and suspending it in an atmosphere of oxygen at ordinary pressure1 the compressed gas behaved like iron or other magnetic substances4 ,faraday compared the intensity of its action with that of ferrous sulphate1 and this led to an explanation of the diurnal variations of the compass-needle based on the sun's heat diminishing the magnetic permeability of the oxygen of the air4 ,repeating the experiment with nitrogen1 he found that the compressed gas behaved in a perfectly neutral manner when surrounded by the gas at ordinary pressure4 ,hence he inferred that in nitrogen he had found the neutral medium required4 ,repeating his experiments in an atmosphere of nitrogen1 it still appeared that most bodies were repelled by the magnetic poles1 and set equatorially1 or at right angles to the lines of force when elongated portions were tested4 ,to this action ,faraday gave the name of diamagnetism4 ,about a month after his marriage1 ,faraday joined the ,sandemanian ,church1 to which his family had for several generations belonged1 by confession of sin and profession of faith4 ,not unfrequently he used to speak at the meetings of his ,church1 but in #ahdj he was elected an elder1 and then he took his turn regularly in conducting the services4 ,the notes of his addresses he generally made on small pieces of card4 ,he had a curious habit of separating his religious belief from his scientific work1 although the spirit of his religion perpetually pervaded his life4 ,a lecture on mental education1 given in #ahed1 at the ,royal ,institution1 in the presence of the late ,prince ,consort1 he commenced as follows3-- ,before entering on this subject1 ,i must make one distinction1 which1 however it may appear to others1 is to me of the utmost importance4 ,high as man is placed above the creatures around him1 there is a higher and far more exalted position within his view2 and the ways are infinite in which he occupies his thoughts about the fears1 or hopes1 or expectations of a future life4 ,i believe that the truth of that future cannot be brought to his knowledge by any exertion of his mental powers1 however exalted they may be2 that it is made known to him by other teaching than his own1 and is received through simple belief of the testimony given4 ,let no one suppose for a moment that the self-education ,i am about to commend1 in respect of the things of this life1 extends to any considerations of the hope set before us1 as if man by reasoning could find out ,god4 ,it would be improper here to enter upon this subject further than to claim an absolute distinction between religious and ordinary belief4 ,i shall be reproached with the weakness of refusing to apply those mental operations which ,i think good in respect of high things to the very highest4 ,i am content to bear the reproach4 ,yet even in earthly matters ,i believe that 'the invisible things of ,him from the creation of the world are clearly seen1 being understood by the things that are made1 even ,his eternal power and ,godhead2' and ,i have never seen anything incompatible between those things of man which can be known by the spirit of man which is within him1 and those higher things concerning his future which he cannot know by that spirit4 ,on more than one occasion the late ,prince ,consort had discussed physical questions with ,faraday1 and in #aheh the ,queen offered him a house on ,hampton ,court ,green4 ,this was his home until ,august #be1 #ahfg4 ,he saw not only the magnetic spark1 which he had first produced1 employed in the lighthouses at the ,south ,foreland and ,dungeness1 but he saw also his views respecting lines of electric induction examined and confirmed by the investigations of ,thomson and ,clerk ,maxwell4 ,of the ninety-five distinctions conferred upon him1 we need only mention that of ,commandant of the ,legion of ,honour1 which he received in ,january1 #ahef4 ,,james ,,clerk ,,maxwell4 ,the story of the life of ,james ,clerk ,maxwell has been told so recently by the able pen of his lifelong friend1 ,professor ,lewis ,campbell1 that it is unnecessary1 in the few pages which now remain to us1 to attempt to give a repetition of the tale which would not only fail to do justice to its subject1 but must of necessity fall far short of the merits of the 7confessedly imperfect7 sketch which has recently been placed within the reach of all4 ,looking back on the life of ,clerk ,maxwell1 he seems to have come amongst us as a light from another world--to have but partly revealed his message to minds too often incapable of grasping its full meaning1 and all too soon to have returned to the source from whence he came4 ,there was scarcely any branch of natural philosophy that he did not grapple with1 and upon which his vivid imagination and far-seeing intelligence did not throw light4 ,he was born a philosopher1 and at every step ,nature partly drew aside the veil and revealed that which was hidden from a gaze less prophetic4 ,a very brief sketch of the principal incidents in his life may1 however1 not be out of place4 ,james ,clerk ,maxwell was born in ,edinburgh1 on ,june #ac1 #ahca4 ,his father1 ,john ,clerk ,maxwell1 was the second son of ,james ,clerk1 of ,penicuik1 and took the name of ,maxwell on inheriting the estate at ,middlesbie4 ,his mother was the daughter of ,r4 ,h4 ,cay1 ,esq41 of ,north ,charlton1 ,northumberland4 ,james was the only child who survived infancy4 ,some years before his birth his parents had built a house at ,glenlair1 which had been added to their ,middlesbie estate1 and resided there during the greater part of the year1 though they retained their house in ,edinburgh4 ,hence it was that ,james's boyish days were spent almost entirely in the country1 until he entered the ,edinburgh ,academy in #ahda4 ,as a child1 he was never content until he had completely investigated everything which attracted his attention1 such as the hidden courses of bell-wires1 water-streams1 and the like4 ,his constant question was ,what's the go o' that8 and1 if answered in terms too general for his satisfaction1 he would continue1 ,but what's the particular go of it8 ,this desire for the thorough investigation of every phenomenon was a characteristic of his mind through life4 ,from a child his knowledge of ,scripture was extensive and accurate1 and when eight years old he could repeat the whole of the hundred and nineteenth psalm4 ,about this time his mother died1 and thenceforward he and his father became constant companions4 ,together they would devise all sorts of ingenious mechanical contrivances4 ,young ,james was essentially a child of nature1 and free from all conventionality4 ,he loved every living thing1 and took delight in petting young frogs1 and putting them into his mouth to see them jump out4 ,one of his attainments was to paddle on the duck-pond in a wash-tub1 and to make the vessel go without spinning--a recreation which had to be relinquished on washing-days4 ,he was never without the companionship of one or two terriers1 to whom he taught many tricks1 and with whom he seemed to have complete sympathy4 ,as a boy1 ,maxwell was not one to profit much by the ordinary teaching of the schools1 and experience with a private tutor at home did not lead to very satisfactory results4 ,at the age of ten1 therefore1 he was sent to the ,edinburgh ,academy1 under the care of ,archdeacon ,williams1 who was then rector4 ,on his first appearance in this fashionable school1 he was naturally a source of amusement to his companions2 but he held his ground1 and soon gained more respect than he had previously provoked ridicule4 ,while at school in ,edinburgh1 he resided with his father's sister1 ,mrs4 ,wedderburn1 and devoted a very considerable share of his time and attention to relieving the solitude of the old man at ,glenlair1 by letters written in quaint styles1 sometimes backwards1 sometimes in cypher1 sometimes in different colours1 so arranged that the characters written in a particular colour1 when placed consecutively1 formed another sentence4 ,all the details of his school and home life1 and the special peculiarities of the masters at the academy1 were thus faithfully transmitted to his father1 by whom the letters were religiously preserved4 ,at thirteen he had evidently made progress in solid geometry1 though he had not commenced ,euclid1 for he writes to his father1 ,i have made a tetrahedron1 a dodecahedron1 and two other hedrons whose names ,i don't know4 ,in these letters to ,glenlair he generally signed himself1 ,your most obedient servant4 ,sometimes his fun found vent even upon the envelope2 for example3-- ,mr4 ,john ,clerk ,maxwell1 ,postyknowswere1 ,kirkpatrick ,durham1 ,dumfries4 ,sometimes he would seal his letters with electrotypes of natural objects 7beetles1 etc471 of his own making4 ,in ,july1 #ahde1 he writes3-- ,i have got the eleventh prize for scholarship1 the first for ,english1 the prize for ,english verses1 and the mathematical medal4 ,when only fifteen a paper on oval curves was contributed by him to the ,proceedings of the ,royal ,society of ,edinburgh4 ,in the spring of #ahdg he accompanied his uncle on a visit to ,mr4 ,nicol1 the inventor of the ,nicol prism1 and on his return he made a polariscope with glass and a lucifer-match box1 and sketched in water-colours the chromatic appearances presented by pieces of unannealed glass which he himself prepared4 ,these sketches he sent to ,mr4 ,nicol1 who presented him in return with a pair of prisms of his own construction4 ,the prisms are now in the ,cavendish ,laboratory at ,cambridge4 ,maxwell found that1 for unannealed glass1 pieces of window-glass placed in bundles of eight or nine1 one on the other1 answered the purpose very well4 ,he cut the figures1 triangles1 squares1 etc41 with a diamond1 heated the pieces of glass on an iron plate to redness in the kitchen fire1 and then dropped them into a plate of iron sparks 7scales from the smithy7 to cool4 ,in #ahdg ,maxwell entered the ,university of ,edinburgh1 and during his course of study there he contributed to the ,royal ,society of ,edinburgh papers upon rolling curves and on the equilibrium of elastic solids4 ,his attention was mostly devoted to mathematics1 physics1 chemistry1 and mental and moral philosophy4 ,in #ahej he went to ,cambridge1 entering ,peterhouse1 but at the end of a year he migrated to ,trinity2 here he was soon surrounded with a circle of friends who helped to render his ,cambridge life a very happy one4 ,his love of experiment sometimes extended to his own mode of life1 and once he tried sleeping in the evening and working after midnight1 but this was soon given up at the request of his father4 ,one of his friends writes1 ,from #b to #b4cj a4m4 he took exercise by running along the upper corridor1 down the stairs1 along the lower corridor1 then up the stairs1 and so on until the inhabitants of the rooms along his track got up and laid perdus behind their sporting-doors1 to have shots at him with boots1 hair-brushes1 etc41 as he passed4 ,his love of fun1 his sharp wit1 his extensive knowledge1 and above all1 his complete unselfishness1 rendered him a universal favourite in spite of the temporary inconveniences which his experiments may have occasionally caused to his fellow-students4 ,an undergraduate friend writes1 ,every one who knew him at ,trinity can recall some kindness or some act of his which has left an ineffaceable impression of his goodness on the memory--for 'good' ,maxwell was in the best sense of the word4 ,the same friend wrote in his diary in #ahed1 after meeting ,maxwell at a social gathering1 ,maxwell1 as usual1 showing himself acquainted with every subject on which the conversation turned4 ,i never met a man like him4 ,i do believe there is not a single subject on which he cannot talk1 and talk well too1 displaying always the most curious and out-of-the-way information4 ,his private tutor1 the late well-known ,mr4 ,hopkins1 said of him1 ,it is not possible for that man to think incorrectly on physical subjects4 ,in #ahed ,maxwell took his degree at ,cambridge as second wrangler1 and was bracketed with the senior wrangler 7,mr4 ,e4 ,j4 ,routh7 for the ,smith's prize4 ,during his undergraduate course1 he appears to have done much of the work which formed the basis of his subsequent papers on electricity1 particularly that on ,faraday's lines of force4 ,the colour-top and colour-box appear also to have been gradually developing during this time1 while the principle of the stereoscope and the art of squinting received their due share of attention4 ,shortly after his degree1 he devoted a considerable amount of time to the preparation of a manuscript on geometrical optics1 which was intended to form a university text-book1 but was never completed4 ,in the autumn of #ahee he was elected ,fellow of ,trinity4 ,about this time the colour-top was in full swing1 and he also constructed an ophthalmoscope4 ,in ,may1 #ahee1 he writes3-- ,the colour trick came off on ,monday1 #gth4 ,i had the proof-sheets of my paper1 and was going to read2 but ,i changed my mind and talked instead1 which was more to the purpose4 ,there were sundry men who thought that blue and yellow make green1 so ,i had to undeceive them4 ,i have got ,hay's book of colours out of the ,university ,library1 and am working through the specimens1 matching them with the top4 ,the colour trick came off before the ,cambridge ,philosophical ,society4 ,while a ,bachelor ,fellow1 ,maxwell gave lectures to working men in ,barnwell1 besides lecturing in college4 ,his father died in ,april1 #ahef1 and shortly afterwards he was appointed ,professor of ,natural ,philosophy in ,marischal ,college1 ,aberdeen4 ,this appointment he held until the fusion of the college with ,king's ,college in #ahfj4 ,these four years were very productive of valuable work4 ,during them the dynamical top was constructed1 which illustrates the motion of a rigid body about its axis of greatest1 least1 or mean moment of inertia2 for1 by the movement of certain screws1 the axis of the top may be made to coincide with any one at will4 ,the ,adams ,prize ,essay on the stability of ,saturn's rings belongs also to this period4 ,in this essay ,maxwell showed that the phenomena presented by ,saturn's rings can only be explained on the supposition that they consist of innumerable small bodies--a flight of brickbats--each independent of all the others1 and revolving round ,saturn as a satellite4 ,he compared them to a siege of ,sebastopol from a battery of guns measuring thirty thousand miles in one direction1 and a hundred miles in the other1 the shots never stopping1 but revolving round a circle of a hundred and seventy thousand miles radius4 ,a solid ring of such dimensions would be completely crushed by its own weight1 though made of the strongest material of which we have any knowledge4 ,if revolving at such a rate as to balance the attraction of the planet at one part1 the stress in other parts would be more than sufficient to crush or tear the ring4 ,laplace had shown that a narrow ring might revolve about the planet and be stable if so loaded that its centre of gravity was at a considerable distance from its centre1 and thought that ,saturn's rings might consist of a number of such unsymmetrical rings--a theory to which some support was given by the many small divisions observable in the bright rings4 ,maxwell showed that1 for stability1 the mass required to load each of ,laplace's rings must be four and a half times that of the rest of the ring2 and the system would then be far too artificially balanced to be proof against the action of one ring on another4 ,he further showed that1 in liquid rings1 waves would be produced by the mutual action of the rings1 and that before long some of these waves would be sure to acquire such an amplitude as would cause the rings to break up into small portions4 ,finally1 he concluded that the only admissible theory is that of the independent satellites1 and that the average density of the rings so found cannot be much greater than that of air at ordinary pressure and temperature4 ,while he remained at ,aberdeen1 ,maxwell lectured to working men in the evenings1 on the principles of mechanics4 ,on the whole1 it is doubtful whether ,aberdeen society was as congenial to him as that of ,cambridge or ,edinburgh4 ,he seems not to have been understood even by his colleagues4 ,on one occasion he wrote3-- ,gaiety is just beginning here again4444 ,no jokes of any kind are understood here4 ,i have not made one for two months1 and if ,i feel one coming ,i shall bite my tongue4 ,but every cloud has its bright side1 and1 however ,maxwell may have been regarded by his colleagues1 he was not long without congenial companionships4 ,an honoured guest at the home of the ,principal1 in ,february1 #aheh1 he announced his betrothal to ,katherine ,mary ,dewar1 and they were married early in the following ,june4 ,professor ,campbell speaks of his married life as one of unexampled devotion1 and those who enjoyed the great privilege of seeing him at home could more than endorse the description4 ,in #ahfj ,maxwell accepted the chair of ,natural ,philosophy at ,king's ,college1 ,london4 ,here he continued his lectures to working men1 and even kept them up for one session after resigning the chair in #ahfe4 ,on ,may #ag1 #ahfa1 he gave his first lecture at the ,royal ,institution1 on ,the ,theory of the ,three ,primary ,colours4 ,this lecture embodies many of the results of his work with the colour-top and colour-box1 to be again referred to presently4 ,while at ,king's ,college1 he was placed on the ,electrical ,standards ,committee of the ,british ,association1 and most of the work of the committee was carried out in his laboratory4 ,here1 too1 he compared the electro-static repulsion between two discs of brass with the electro-magnetic attraction of two coils of wire surrounding them1 through which a current of electricity was allowed to flow1 and obtained a result which he afterwards applied to the electro-magnetic theory of light4 ,the colour-box was perfected1 and his experiments on the viscosity of gases were concluded during his residence in ,london4 ,these last were described by him in the ,bakerian ,lecture for #ahff4 ,after resigning the professorship at ,king's ,college1 ,maxwell spent most of his time at ,glenlair1 having enlarged the house1 in accordance with his father's original plans4 ,here he completed his great work on ,electricity and ,magnetism1 as well as his ,theory of ,heat1 an elementary text-book which may be said to be without a parallel4 ,on ,march #h1 #ahga1 he accepted the chair of ,experimental ,physics in the ,university of ,cambridge4 ,this chair was founded in consequence of an offer made by the ,duke of ,devonshire1 the ,chancellor of the ,university1 to build and equip a physical laboratory for the use of the university4 ,in this capacity ,maxwell's first duty was to prepare plans for the laboratory4 ,with this view1 he inspected the laboratories of ,sir ,william ,thomson at ,glasgow1 and of ,professor ,clifton at ,oxford1 and endeavoured to embody the best points of both in the new building4 ,the result was that1 in conjunction with ,mr4 ,w4 ,m4 ,fawcett1 the architect1 he secured for the university a laboratory noble in its exterior1 and admirably adapted to the purposes for which it is required4 ,the ground-floor comprises a large battery-room1 which is also used as a storeroom for chemicals2 a workshop2 a room for receiving goods1 communicating by a lift with the apparatus-room2 a room for experiments on heat2 balance-rooms2 a room for pendulum experiments1 and other investigations requiring great stability2 and a magnetic observatory4 ,the last two rooms are furnished with stone supports for instruments1 erected on foundations independent of those of the building1 and preserved from contact with the floor4 ,on the first floor is a handsome lecture-theatre1 capable of accommodating nearly two hundred students4 ,the lecture-table is carried on a wall1 which passes up through the floor without touching it1 the joists being borne by separate brick piers4 ,the lecture-theatre occupies the height of the first and second floors2 its ceiling is of wood1 the panels of which can be removed1 thus affording access to the roof-principals1 from which a load of half a ton or more may be safely suspended over the lecture-table4 ,the panels of the ceiling1 adjoining the wall which is behind the lecturer1 can also be readily removed1 and a window in this wall communicates with the large electrical-room on the second floor4 ,access to the space above the ceiling of the lecture-theatre is readily obtained from the tower4 ,adjoining the lecture-room is the preparation-room1 and communicating with the latter is the apparatus-room4 ,this room is fitted with mahogany and plate-glass wall and central cases1 and at present contains1 besides the more valuable portions of the apparatus belonging to the laboratory1 the marble bust of ,james ,clerk ,maxwell1 and many of the home-made pieces of apparatus and other relics of his early work4 ,the rest of the first floor is occupied by the professor's private room and the general students' laboratory4 ,throughout the building the brick walls have been left bare for convenience in attaching slats or shelves for the support of instruments4 ,the second floor contains a large room for electrical experiments1 a dark room for photography1 and a number of private rooms for original work4 ,water is laid on to every room1 including a small room in the top of the tower1 and all the windows are provided with broad stone ledges without and within the window1 the two portions being in the same horizontal plane1 for the support of heliostats or other instruments4 ,the building is heated with hot water1 but in the magnetic observatory the pipes are all of copper and the fittings of gun-metal4 ,open fireplaces for basket fires are also provided4 ,over the principal entrance of the laboratory is placed a stone statue of the present ,duke of ,devonshire1 together with the arms of the university and of the ,cavendish family1 and the ,cavendish motto1 ,cavendo ,tutus4 ,maxwell presented to the laboratory1 in #ahgd1 all the apparatus in his possession4 ,he usually gave a course of lectures on heat and the constitution of bodies in the ,michaelmas term2 on electricity in the ,lent term2 and on electro-magnetism in the ,easter term4 ,the following extract from his inaugural lecture1 delivered in ,october1 #ahga1 is worthy of the attention of all students of science3-- ,science appears to us with a very different aspect after we have found out that it is not in lecture-rooms only1 and by means of the electric light projected on a screen1 that we may witness physical phenomena1 but that we may find illustrations of the highest doctrines of science in games and gymnastics1 in travelling by land and by water1 in storms of the air and of the sea1 and wherever there is matter in motion4 ,the habit of recognizing principles amid the endless variety of their action can never degrade our sense of the sublimity of nature1 or mar our enjoyment of its beauty4 ,on the contrary1 it tends to rescue our scientific ideas from that vague condition in which we too often leave them1 buried among the other products of a lazy credulity1 and to raise them into their proper position among the doctrines in which our faith is so assured that we are ready at all times to act on them4 ,experiments of illustration may be of very different kinds4 ,some may be adaptations of the commonest operations of ordinary life2 others may be carefully arranged exhibitions of some phenomenon which occurs only under peculiar conditions4 ,they all1 however1 agree in this1 that their aim is to present some phenomenon to the senses of the student in such a way that he may associate with it some appropriate scientific idea4 ,when he has grasped this idea1 the experiment which illustrates it has served its purpose4 ,in an experiment of research1 on the other hand1 this is not the principal aim4444 ,experiments of this class--those in which measurement of some kind is involved--are the proper work of a physical laboratory4 ,in every experiment we have first to make our senses familiar with the phenomenon2 but we must not stop here--we must find out which of its features are capable of measurement1 and what measurements are required in order to make a complete specification of the phenomenon4 ,we must then make these measurements1 and deduce from them the result which we require to find4 ,this characteristic of modern experiments--that they consist principally of measurements--is so prominent that the opinion seems to have got abroad that1 in a few years1 all the great physical constants will have been approximately estimated1 and that the only occupation which will then be left to men of science will be to carry these measurements to another place of decimals4 ,if this is really the state of things to which we are approaching1 our laboratory may1 perhaps1 become celebrated as a place of conscientious labour and consummate skill2 but it will be out of place in the university1 and ought rather to be classed with the other great workshops of our country1 where equal ability is directed to more useful ends4 ,but we have no right to think thus of the unsearchable riches of creation1 or of the untried fertility of those fresh minds into which these riches will continually be poured4444 ,the history of ,science shows that1 even during that phase of her progress in which she devotes herself to improving the accuracy of the numerical measurement of quantities with which she has long been familiar1 she is preparing the materials for the subjugation of new regions1 which would have remained unknown if she had been contented with the rough methods of her early pioneers4 ,maxwell's ,electricity and ,magnetism was published in #ahgc4 ,shortly afterwards there were placed in his hands1 by the ,duke of ,devonshire1 the ,cavendish ,manuscripts on ,electricity1 already alluded to4 ,to these he devoted much of his spare time for several years1 and many of ,cavendish's experiments were repeated in the laboratory by ,maxwell himself1 or under his direction by his students4 ,the introductory matter and notes embodied in ,the ,electrical ,researches of the ,honourable ,henry ,cavendish1 ,f4,r4,s41 afford sufficient evidence of the amount of labour he expended over this work4 ,the volume was published only a few weeks before his death4 ,another of ,maxwell's publications1 which1 as a text-book1 is unique and beyond praise1 is the little book on ,matter and ,motion1 published by the ,s4,p4,c4,k4 ,in #ahgh ,maxwell1 at the request of the ,vice-,chancellor1 delivered the ,rede ,lecture in the ,senate-,house4 ,his subject was the telephone1 which was just then absorbing a considerable amount of public attention4 ,this was the last lecture which he ever gave to a large public audience4 ,it was during his tenure of the ,cambridge chair that one of the cottages on the ,glenlair estate was struck by lightning4 ,the discharge passed down the damp soot and blew out several stones from the base of the chimney1 apparently making its way to some water in a ditch a few yards distant4 ,the cottage was built on a granite rock1 and this event set ,maxwell thinking about the best way to protect1 from lightning1 buildings which are erected on granite or other non-conducting foundations4 ,he decided that the proper course was to place a strip of metal upon the ground all round the building1 to carry another strip along the ridge-stay1 from which one or more pointed rods should project upwards1 and to unite this strip with that upon the ground by copper strips passing down each corner of the building1 which is thus1 as it were1 enclosed in a metal cage4 ,after a brief illness1 ,maxwell passed away on ,november #e1 #ahgi4 ,his intellect and memory remained perfect to the last1 and his love of fun scarcely diminished4 ,during his illness he would frequently repeat hymns1 especially some of ,george ,herbert's1 and ,richard ,baxter's hymn beginning ,lord1 it belongs not to my care4 ,no man ever met his death more consciously or more calmly4 ,it has been stated that ,thomas ,young propounded a theory of colour-vision which assumes that there exist three separate colour-sensations1 corresponding to red1 green1 and violet1 each having its own special organs1 the excitement of which causes the perception of the corresponding colour1 other colours being due to the excitement of two or more of these simple sensations in different proportions4 ,maxwell adopted blue instead of violet for the third sensation1 and showed that if a particular red1 green1 and blue were selected and placed at the angular points of an equilateral triangle1 the colours formed by mixing them being arranged as in ,young's diagram1 all the shades of the spectrum would be ranged along the sides of this triangle1 the centre being neutral grey4 ,for the mixing of coloured lights1 he at first employed the colour-top1 but1 instead of painting circles with coloured sectors1 the angles of which could not be changed1 he used circular discs of coloured paper slit along one radius4 ,any number of such discs can be combined so that each shows a sector at the top1 and the angle of each sector can be varied at will by sliding the corresponding disc between the others4 ,maxwell used discs of two different sizes1 the small discs being placed above the larger on the same pivot1 so that one set formed a central circle1 and the other set a ring surrounding it4 ,he found that1 with discs of five different colours1 of which one might be white and another black1 it was always possible to combine them so that the inner circle and the outer ring exactly matched4 ,from this he showed that there could be only three conditions to be satisfied in the eye1 for two conditions were necessitated by the nature of the top1 since the smaller sectors must exactly fill the circle and so must the larger4 ,maxwell's experiments1 therefore1 confirmed1 in general1 ,young's theory4 ,they showed1 however1 that the relative delicacy of the several colour-sensations is different in different eyes1 for the arrangement which produced an exact match in the case of one observer1 had to be modified for another2 but this difference of delicacy proved to be very conspicuous in colour-blind persons1 for in most of the cases of colour-blindness examined by ,maxwell the red sensation was completely absent1 so that only two conditions were required by colour-blind eyes1 and a match could therefore always be made in such cases with four discs only4 ,holmgren has since discovered cases of colour-blindness in which the violet sensation is absent4 ,he agrees with ,young in making the third sensation correspond to violet rather than blue4 ,maxwell explained the fact that persons colour-blind to the red divide colours into blues and yellows by the consideration that1 although yellow is a complex sensation corresponding to a mixture of red and green1 yet in nature yellow tints are so much brighter than greens that they excite the green sensation more than green objects themselves can do1 and hence greens and yellows are called yellow by such colour-blind persons1 though their perception of yellow is really the same as perception of green by normal eyes4 ,later on1 by a combination of adjustable slits1 prisms1 and lenses arranged in a colour-box1 ,maxwell succeeded in mixing1 in any desired proportions1 the light from any three portions of the spectrum1 so that he could deal with pure spectral colours instead of the complex combinations of differently coloured lights afforded by coloured papers4 ,from these experiments it appears that no ray of the solar spectrum can affect one colour-sensation alone1 so that there are no colours in nature so pure as to correspond to the pure simple sensations1 and the colours occupying the angular points of ,maxwell's diagram affect all three colour-sensations1 though they influence two of them to a much smaller extent than the third4 ,a particular colour in the spectrum corresponds to light which1 according to the undulatory theory1 physically consists of waves all of the same period1 but it may affect all three of the colour-sensations of a normal eye1 though in different proportions4 ,thus1 yellow light of a given wave-length affects the red and green sensations considerably and the blue 7or violet7 slightly1 and the same effect may be produced by various mixtures of red or orange and green4 ,for his researches on the perception of colour1 the ,royal ,society awarded to ,clerk ,maxwell the ,rumford ,medal in #ahfj4 ,another optical contrivance of ,maxwell's was a wheel of life1 in which the usual slits were replaced by concave lenses of such focal length that the picture on the opposite side of the cylinder appeared1 when seen through a lens1 at the centre1 and thus remained apparently fixed in position while the cylinder revolved4 ,the same result has since been secured by a different contrivance in the praxinoscope4 ,another ingenious optical apparatus was a real-image stereoscope1 in which two lenses were placed side by side at a distance apart equal to half the distance between the pictures on the stereoscopic slide4 ,these lenses were placed in front of the pictures at a distance equal to twice their focal length4 ,the real images of the two pictures were then superposed in front of the lenses at the same distance from them as the pictures1 and these combined images were looked at through a large convex lens4 ,the great difference in the sensibility to different colours of the eyes of dark and fair persons when the light fell upon the fovea centralis1 led ,maxwell to the discovery of the extreme want of sensibility of this portion of the retina to blue light4 ,this he made manifest by looking through a bottle containing solution of chrome alum1 when the central portion of the field of view appears of a light red colour for the first second or two4 ,a more important discovery was that of double refraction temporarily produced in viscous liquids4 ,maxwell found that a quantity of ,canada balsam1 if stirred1 acquired double-refracting powers1 which it retained for a short period1 until the stress temporarily induced had disappeared4 ,but ,maxwell's investigations in optics must be regarded as his play2 his real work lay in the domains of electricity and of molecular physics4 ,in #agch ,daniel ,bernouilli published an explanation of atmospheric pressure on the hypothesis that air consists of a number of minute particles moving in all directions1 and impinging on any surface exposed to their action4 ,in #ahdg ,herapath explained the diffusion of gases on the hypothesis that they consisted of perfectly hard molecules impinging on one another and on surfaces exposed to them1 and pointed out the relation between their motion and the temperature and pressure of a gas4 ,the present condition of the molecular theory of gases1 and of molecular science generally1 is due almost entirely to the work of ,joule1 ,clausius1 ,boltzmann1 and ,maxwell4 ,to ,maxwell is due the general method of solving all problems connected with vast numbers of individuals--a method which he called the statistical method1 and which consists1 in the first place1 in separating the individuals into groups1 each fulfilling a particular condition1 but paying no attention to the history of any individual1 which may pass from one group to another in any way and as often as it pleases without attracting attention4 ,maxwell was the first to estimate the average distance through which a particle of gas passes without coming into collision with another particle4 ,he found that1 in the case of hydrogen1 at standard pressure and temperature1 it is about #a_/bejjjj of an inch2 for air1 about #a_/chijjj of an inch4 ,these results he deduced from his experiments on viscosity1 and he gave a complete explanation of the viscosity of gases1 showing it to be due to the diffusion of momentum accompanying the diffusion of material particles between the passing streams of gas4 ,one portion of the theory of electricity had been considerably developed by ,cavendish2 the application of mathematics to the theory of attractions1 and hence to that of electricity1 had been carried to a great degree of perfection by ,laplace1 ,lagrange1 ,poisson1 ,green1 and others4 ,faraday1 however1 could not satisfy himself with a mathematical theory based upon direct action at a distance1 and he filled space1 as we have seen1 with tubes of force passing from one body to another whenever there existed any electrical action between them4 ,these conceptions of ,faraday were regarded with suspicion by mathematicians4 ,sir ,william ,thomson was the first to look upon them with favour2 and in #ahdf he showed that electro-static force might be treated mathematically in the same way as the flow of heat2 so that there are1 at any rate1 two methods by which the fundamental formulae of electro-statics can be deduced4 ,but it is to ,maxwell that mathematicians are indebted for a complete exposition of ,faraday's views in their own language1 and this was given in a paper wherein the phenomena of electro-statics were deduced as results of a stress in a medium which1 as suggested by ,newton and believed by ,faraday1 might well be that same medium which serves for the propagation of light2 and the lines of force were shown to correspond to an actual condition of the medium when under electrical stress4 ,maxwell1 in fact1 showed1 not only that ,faraday's lines formed a consistent system which would bear the most stringent mathematical analysis1 but were more than a conventional system1 and might correspond to a state of stress actually existing in the medium through which they passed1 and that a tension along these lines1 accompanied by an equal pressure in every direction at right angles to them1 would be consistent with the equilibrium of the medium1 and explain1 on mechanical principles1 the observed phenomena4 ,the greater part of this work he accomplished while an undergraduate at ,cambridge4 ,he showed1 too1 that ,faraday's conceptions were equally applicable to the case of electro-magnetism1 and that all the laws of the induction of currents might be concisely expressed in ,faraday's language4 ,defining the positive direction through a circuit in which a current flows as the direction in which a right-handed screw would advance if rotating with the current1 and the positive direction around a wire conveying a current as the direction in which a right-handed screw would rotate if advancing with the current1 ,maxwell pointed out that the lines of magnetic force due to an electric current always pass round it1 or through its circuit1 in the positive direction1 and that1 whenever the number of lines of magnetic force passing through a closed circuit is changed1 there is an electro-motive force round the circuit represented by the rate of diminution of the number of lines of force which pass through the circuit in the positive direction4 ,the words in italics form a complete statement of the laws regulating the production of currents by the motion of magnets or of other currents1 or by the variation of other currents in the neighbourhood4 ,maxwell showed1 too1 that ,faraday's electro-tonic state1 on the variation of which induced currents depend1 corresponds completely with the number of lines of magnetic force passing through the circuit4 ,he also showed that1 when a conductor conveying a current is free to move in a magnetic field1 or magnets are free to move in the neighbourhood of such a conductor1 the system will assume that condition in which the greatest possible number of lines of magnetic force pass through the circuit in the positive direction4 ,but ,maxwell was not content with showing that ,faraday's conceptions were consistent1 and had their mathematical equivalents1--he proceeded to point out how a medium could be imagined so constituted as to be able to perform all the various duties which were thus thrown upon it4 ,assuming a medium to be made up of spherical1 or nearly spherical1 cells1 and that1 when magnetic force is transmitted1 these cells are made to rotate about diameters coinciding in direction with the lines of force1 the tension along those lines1 and the pressure at right angles to them1 are accounted for by the tendency of a rotating elastic sphere to contract along its polar axis and expand equatorially so as to form an oblate spheroid4 ,by supposing minute spherical particles to exist between the rotating cells1 the motion of one may be transmitted in the same direction to the next1 and these particles may be supposed to constitute electricity1 and roll as perfectly rough bodies on the cells in contact with them4 ,maxwell further imagined the rotating cells1 and therefore1 a fortiori1 the electrical particles1 to be extremely small compared with molecules of matter2 and that1 in conductors1 the electrical particles could pass from molecule to molecule1 though opposed by friction1 but that in insulators no such transference was possible4 ,the machinery was then complete4 ,if the electric particles were made to flow in a conductor in one direction1 passing between the cells1 or molecular vortices1 they compelled them to rotate1 and the rotation was communicated from cell to cell in expanding circles by the electric particles1 acting as idle wheels1 between them4 ,thus rings of magnetic force were made to surround the current1 and to continue as long as the current lasted4 ,if an attempt were made to displace the electric particles in a dielectric1 they would move only within the substance of each molecule1 and not from molecule to molecule1 and thus the cells would be deformed1 though no continuous motion would result4 ,the deformation of the cells would involve elastic stress in the medium4 ,again1 if a stream of electric particles were started into motion1 and if there were another stream of particles in the neighbourhood free to flow1 though resisted by friction1 these particles1 instead of at once transmitting the rotary motion of the cells on one side of them to the cells on the other side1 would at first1 on account of the inertia of the cells1 begin to move themselves with a motion of translation opposite to that of the primary current1 and the motion would only gradually be destroyed by the frictional resistance and the molecular vortices on the other side made to revolve with their full velocity4 ,a similar effect1 but in the opposite direction1 would take place if the primary current ceased1 the vortices not stopping all at once if there were any possibility of their continuing in motion4 ,the imaginary medium thus serves for the production of induced currents4 ,the mechanical forces between currents and magnets and between currents and currents1 as well as between magnets and currents1 were accounted for by the tension and pressure produced by the molecular vortices4 ,when currents are flowing in the same direction in neighbouring conductors1 the vortices in the space between them are urged in opposite directions by the two currents1 and remain almost at rest2 the lateral pressure exerted by those on the outside of the conductors is thus unbalanced1 and the conductors are pushed together as though they attracted each other4 ,when the currents flow in opposite directions in parallel conductors1 they conspire to give a greater velocity to the vortices in the space between them1 than to those outside them1 and are thus pushed apart by the pressure due to the rotation of the vortices1 as though they repelled each other4 ,in a similar way1 the actions of magnets on conductors conveying currents may be explained4 ,the motion of a conductor across a series of lines of magnetic force may squeeze together and lengthen the threads of vortices in front1 and thus increase their speed of rotation1 while the vortices behind will move more slowly because allowed to contract axially and expand transversely4 ,the velocity of the vortices thus being greater on one side of the wire than the other1 a current must be induced in the wire4 ,thus the current induced by the motion of a conductor in a magnetic field may be accounted for4 ,this conception of a medium was given by ,maxwell1 not as a theory1 but to show that it was possible to devise a mechanism capable1 in imagination at least1 of producing all the phenomena of electricity and magnetism4 ,according to our theory1 the particles which form the partitions between the cells constitute the matter of electricity4 ,the motion of these particles constitutes an electric current2 the tangential force with which the particles are pressed by the matter of the cells is electro-motive force2 and the pressure of the particles on each other corresponds to the tension or potential of the electricity4 ,when a current is maintained in a wire1 the molecular vortices in the surrounding space are kept in uniform motion2 but if an attempt be made to stop the current1 since this would necessitate the stoppage of the vortices1 it is clear that it cannot take place suddenly1 but the energy of the vortices must be in some way used up4 ,for the same reason it is impossible for a current to be suddenly started by a finite force4 ,thus the phenomena of self-induction are accounted for by the supposed medium4 ,the magnetic permeability of a medium ,maxwell identified with the density of the substance composing the rotating cells1 and the specific inductive capacity he showed to be inversely proportional to its elasticity4 ,he then proved that the ratio of the electro-magnetic unit to the electro-static unit must be equal to the velocity of transmission of a transverse vibration in the medium1 and consequently proportional to the square root of the elasticity1 and inversely proportional to the square root of the density4 ,if the medium is the same as that engaged in the propagation of light1 then this ratio ought to be equal to the velocity of light1 and1 moreover1 in non-magnetic media1 the refractive index should be proportional to the square root of the specific inductive capacity4 ,the different measurements which had been made of the ratio of the electrical units gave a mean very nearly coinciding with the best determinations of the velocity of light1 and thus the truth underlying ,maxwell's speculation was strikingly confirmed1 for the velocity of light was determined by purely electrical measurements4 ,in the case also of bodies whose chemical structure was not very complicated1 the refractive index was found to agree fairly well with the square root of the specific inductive capacity2 but the phenomenon of residual charge rendered the accurate measurement of the latter quantity a matter of great difficulty4 ,it therefore appeared highly probable that light is an electro-magnetic disturbance due to a motion of the electric particles in an insulating medium producing a strain in the medium1 which becomes propagated from particle to particle to an indefinite distance4 ,in the case of a conductor1 the electric particles so displaced would pass from molecule to molecule against a frictional resistance1 and thus dissipate the energy of the disturbance1 so that true 7i4e4 metallic7 conductors must be nearly impervious to light2 and this also agrees with experience4 ,maxwell thus furnished a complete theory of electrical and electro-magnetic action in which all the effects are due to actions propagated in a medium1 and direct action at a distance is dispensed with1 and exposed his theory successfully to most severe tests4 ,in his great work on electricity and magnetism1 he gives the mathematical theory of all the above actions1 without1 however1 committing himself to any particular form of mechanism to represent the constitution of the medium4 ,this part of that book1 ,professor ,tait says1 is one of the most splendid monuments ever raised by the genius of a single individual4444 ,there seems to be no longer any possibility of doubt that ,maxwell has taken the first grand step towards the discovery of the true nature of electrical phenomena4 ,had he done nothing but this1 his fame would have been secured for all time4 ,but1 striking as it is1 this forms only one small part of the contents of this marvellous work4 ,,conclusion4 ,,some ,,of ,,the ,,results ,,of ,,faraday',s ,,discoveries1 ,,and ,,the ,,principle ,,of ,,energy4 ,in early days1 the spirit of the amber1 when aroused by rubbing1 came forth and took to itself such light objects as it could easily lift4 ,later on1 and the spirit gave place to the electric effluvium1 which proceeded from the excited1 or charged1 body into the surrounding space4 ,still later1 and a fluid1 or two fluids1 acting directly upon itself1 or upon matter1 or on one another1 through intervening space without the aid of intermediate mechanism1 took the place of the electric effluvium--a step which in itself was1 perhaps1 hardly an advance4 ,then came the time for accurate measurement4 ,the simple observation of phenomena and of the results of experiment must be the first step in science1 and its importance cannot be over-estimated2 but before any quantity can be said to be known1 we must have learned how to measure it and to reproduce it in definite amounts4 ,the great law of electrical action1 the same as that of gravitation--the law of the inverse square--soon followed1 as well as the associated fact that the electrification of a conductor resides wholly on its surface1 and there only in a layer whose thickness is too small to be discovered4 ,the fundamental laws of electricity having thus been established1 there was no limit to the application of mathematical methods to the problems of the science1 and1 in the hands of the ,french mathematicians1 the theory made rapid advances4 ,george ,green1 of ,sneinton1 ,nottingham1 introduced the term potential in an essay published by subscription1 in ,nottingham1 in #ahbh1 and to him we are indebted for some of our most powerful analytical methods of dealing with the subject2 but his work remained unappreciated and almost unknown until many of his theorems had been rediscovered4 ,but the idea of a body acting where it is not1 and without any conceivable mechanism to connect it with that upon which it operates1 is repulsive to the minds of most2 and1 however well such a theory may lend itself to mathematical treatment and its consequences be borne out by experiment1 we still feel that we have not solved the problem until we have traced out the hidden mechanism4 ,the pull of the bell-rope is followed by the tinkling of the distant bell1 but the young philosopher is not satisfied with such knowledge1 but must learn what is the particular go of that4 ,this universal desire found its exponent in ,faraday1 whose imagination beheld lines or tubes of force connecting every body with every other body on which it acted4 ,to his mind these lines or tubes had just as real an existence as the bell-wire1 and were far better adapted to their special purposes4 ,maxwell1 as we have seen1 not only showed that ,faraday's system admitted of the same rigorous mathematical treatment as the older theory1 and stood the test as well1 but he gave reality to ,faraday's views by picturing a mechanism capable of doing all that ,faraday required of it1 and of transmitting light as well4 ,thus the problem of electric1 magnetic1 and electro-magnetic actions was reduced to that of strains and stresses in a medium the constitution of which was pictured to the imagination4 ,were this theory verified1 we might say that we know at least as much about these actions as we know about the transmission of pressure or tension through a solid4 ,with regard to the nature of electricity1 it must be admitted that our knowledge is chiefly negative2 but1 before deploring this1 it is worth while to inquire what we mean by saying that we know what a thing is4 ,a definition describes a thing in terms of other things simpler1 or more familiar to us1 than itself4 ,if1 for instance1 we say that heat is a form of energy1 we know at once its relationship to matter and to motion1 and are content2 we have described the constitution of heat in terms of simpler things1 which are more familiar to us1 and of which we think we know the nature4 ,but if we ask what matter is1 we are unable to define it in terms of anything simpler than itself1 and can only trust to daily experience to teach us more and more of its properties2 unless1 indeed1 we accept the theory of the vortex atoms of ,thomson and ,helmholtz4 ,this theory1 which has recently been considerably extended by ,professor ,j4 ,j4 ,thomson1 the present occupier of ,clerk ,maxwell's chair in the ,university of ,cambridge1 supposes the existence of a perfect fluid1 filling all space1 in which minute whirlpools1 or vortices1 which in a perfect fluid can be created or destroyed only by superhuman agency1 form material atoms4 ,these are atoms1 that is to say1 they defy any attempts to sever them1 not because they are infinitely hard1 but because they have an infinite capacity for wriggling1 and thus avoid direct contact with any other atoms that come in their way4 ,perhaps a theory of electricity consistent with this theory of matter may be developed in the future2 but1 setting aside these theories1 we may possibly say that we know as much about electricity as we know about matter2 for while we are conversant with many of the properties of each1 we know nothing of the ultimate nature of either4 ,but while the theory of electricity has scarcely advanced beyond the point at which it was left by ,clerk ,maxwell1 the practical applications of the science have experienced great developments of late years4 ,less than a century ago the lightning-rod was the only practical outcome of electrical investigations which could be said to have any real value4 ,,oersted's discovery1 in #ahbj1 of the action of a current on a magnet1 led1 in the hands of ,wheatstone1 ,cooke1 and others1 to the development of the electric telegraph4 ,sir ,william ,thomson's employment of a beam of light reflected from a tiny mirror attached to the magnet of the galvanometer enabled signals to be read when only extremely feeble currents were available1 and thus rendered submarine telegraphy possible through very great distances4 ,the discovery by ,arago and ,davy1 that a current of electricity flowing in a coil surrounding an iron bar would convert the bar into a magnet1 at once rendered possible a variety of contrivances whereby a current of electricity could be employed to produce small reciprocating movements1 or even continuous rotation1 where not much power was required1 at a distance from the battery4 ,an illustration of the former is found in the common electric bell2 it is only necessary that the vibrating armature should form part of the circuit of the electro-magnet1 and be so arranged that1 while it is held away from the magnet by a spring1 it completes the battery circuit1 but breaks the connection as soon as it moves towards the magnet under the magnetic attraction4 ,to produce continuous rotation1 a number of iron bars may be attached to a fly-wheel1 and pass very close to the poles of the magnet without touching them2 when a bar is near the magnet1 and approaching it1 contact should be made in the circuit1 but should be broken1 so that the magnet may lose its power1 as soon as the bar has passed the poles2 or the continuous rotation may be produced from an oscillating armature by any of the mechanical contrivances usually adopted for the conversion of reciprocating into continuous circular motion4 ,but all such motors are extremely wasteful in their employment of energy4 ,faraday's discovery of the rotation of a wire around a magnetic pole laid the foundation for a great variety of electro-motors1 in some of which the efficiency has attained a very high standard4 ,about ten years ago1 ,clerk ,maxwell said that the greatest discovery of recent times was the reversibility of the ,gramme machine1 that is1 the possibility of causing the armature to rotate between the field-magnets by sending a current through the coils4 ,the electro-motors of to-day differ but little from dynamos in the principles of their construction4 ,the copper disc spinning between the poles of a magnet while an electric current was sent from the centre to the circumference1 or vice versa1 formed the simplest electro-motor4 ,all the later motors are simply modifications of this1 designed to increase the efficiency or power of the machine4 ,similarly1 the earliest machine for the production of an electric current at the expense of mechanical power only1 but through the intervention of a permanent magnet1 was the rotating disc of ,faraday1 described on page #bfb4 ,this contrivance1 however1 caused a waste of nearly all the energy employed1 for while there was an electro-motive force from the centre to the circumference1 or in the reverse direction1 in that part of the disc which was passing between the poles of the magnet1 the current so generated found its readiest return path through the other portions of the disc1 and very little traversed the galvanometer or other external circuit4 ,this source of waste could be1 for the most part1 got rid of by cutting the disc into a number of separate rays1 or spokes1 and filling up the spaces between them with insulating material4 ,the current then generated in the disc would be obliged to complete its circuit through the external conductor4 ,if we can so arrange matters as to employ at once several turns of a continuous wire in place of one arm1 or ray1 of the copper disc1 we may multiply in a corresponding manner the electro-motive force induced by a given speed of rotation4 ,all magneto-electric generators are simply contrivances with this object4 ,the iron cores frequently employed within the coils of the armature tend to concentrate the lines of force of the magnet1 causing a greater number to pass through the coils in certain positions than would pass through them were no iron present4 ,the electro-motive force of such a generator depends on the strength of the magnetic field1 the length of wire employed in cutting the lines of force1 and the speed with which the wire moves across these lines4 ,the point to aim at in constructing an armature is to make the resistance as small as possible consistent with the electro-motive force required4 ,as there is a limit to the strength of the magnetic field1 it follows that for strong currents1 where thick wire must be employed1 the generator must be made of large dimensions1 or the armature must be driven at very high speed to enable a shorter length of wire to be used4 ,the so-called compound-interest principle1 by which a very small charge of electricity might be employed to develop a very large one by the help of mechanical power1 was first applied about a century ago in the revolving doubler4 ,long afterwards1 ,sir ,william ,thomson availed himself of the same principle in the construction of the mouse-mill1 or replenisher4 ,the ,holtz machine1 the ,voss and ,wimshurst machines1 and the other induction-machines of the same class1 all work on this principle4 ,it may be illustrated as follows3 ,take two canisters1 call them ,a and ,b1 and place them on glass supports4 ,let a very small positive charge be given to ,a1 ,b remaining uncharged4 ,now take a brass ball1 supported by a silk string4 ,place it inside ,a1 and let it touch its interior surface4 ,the ball will1 as shown by ,franklin1 ,cavendish1 and ,faraday1 remain uncharged4 ,now raise it near the top of the canister1 and1 while there1 touch it4 ,the ball will become negatively electrified1 because the small positive charge in ,a will attract negative electricity from the earth into the ball4 ,take the ball1 with its negative charge1 still hanging by the silk thread1 and lower it into ,b till it touches the bottom4 ,it will give all its charge to ,b1 which will thus acquire a slight negative charge4 ,raise the ball till it is near the top of ,b1 and then touch it with the finger or a metal rod4 ,it will receive a positive charge from the earth because of the attraction of the negative charge on ,b4 ,now remove the ball and let it again touch the interior of ,a4 ,it will give up all its charge to ,a2 and then1 repeating the whole cycle of operations1 the charge carried on the ball will be greater than before1 and increase in each successive operation1 the electrification increasing in geometrical progression like compound interest4 ,a ,leyden jar having one coating connected to ,a and the other to ,b1 may thus be highly charged in course of time4 ,a pair of carrier balls or plates1 or a number of pairs1 may be used instead of one4 ,the carriers1 just before leaving ,a and ,b1 may be put in contact with one another instead of being put to earth2 they may be mounted on a revolving shaft1 and the forms of ,a and ,b modified to admit of the revolution of the carriers1 and all the necessary contacts may be made automatically4 ,we thus get various forms of the continuous electrophorus1 and if the carriers are mounted on glass plates1 and rows of points placed alongside the springs or brushes used for making the contacts1 when the charges on the carriers become very strong1 electricity will be radiated from the points on to the revolving glass plates1 which will thus themselves take the place of the metal carriers4 ,such is the action in the ,voss and other similar machines4 ,but after ,faraday had shown how to construct a magneto-electric machine1 the idea of applying the compound-interest principle1 and thus converting the magneto-electric machine into the dynamo1 occurred apparently simultaneously and independently to ,siemens1 ,varley1 and ,wheatstone4 ,the first dynamo constructed by ,wheatstone is still in the museum of ,king's ,college1 ,london4 ,wilde employed a magneto-electric machine to generate a current which was used to excite the electro-magnet of a similar but larger machine1 having an electro-magnet instead of a permanent steel magnet4 ,the electro-magnet could be made much larger and stronger than the steel magnet1 and from its armature1 when made to revolve by steam power1 a correspondingly stronger current could be maintained4 ,the idea which occurred to ,siemens1 ,varley1 and ,wheatstone was to use the whole1 or a part1 of the current produced by the armature to excite its own electro-magnet1 and thus to dispense with the magneto-electric machine which served as the separate exciter4 ,when a part only of the current is thus employed1 and is set apart entirely for this duty1 the machine is a shunt dynamo2 when the whole of the current traverses the field-magnet coils as well as the external circuit1 it is a series dynamo4 ,the apparent difficulty lies in starting the current1 but a mass of iron once magnetized always retains a certain amount of residual magnetism1 unless special means are taken to get rid of it1 and even then the earth's magnetism would generally induce sufficient in the iron to start the action4 ,commencing1 then1 with a slight trace of residual magnetism1 the revolution of the armature generates a feeble current1 which passing round the magnet coils1 strengthens the magnetism1 whereupon a stronger current is generated1 which in turn makes the magnet still stronger1 and so on until the magnet becomes saturated or the limit of power of the engine is reached1 and the speed begins to diminish1 or a condition of affairs is reached at which an increased current in the armature injures the magnetic field as much as the corresponding increase in the field-magnet coils strengthens it1 and then no further increase of current will take place without increasing the speed of rotation4 ,in a true dynamo the whole of the energy1 both of the current and of the electro-magnets1 is obtained from the source of power employed in driving the machine4 ,but ,faraday's discovery of electro-magnetic induction led to practical developments in other directions4 ,graham ,bell placed a thin iron disc in front of the pole of a bar magnet1 and wound a coil of fine wire round the bar very near the pole4 ,the ends of the coils of two such instruments he connected together4 ,when the iron disc of one instrument approached the pole of the magnet1 the lines of force were disturbed1 fewer escaped radially from the bar1 and more left it at the end1 so as to go straight to the iron disc2 thus the number of lines of force passing through the coil was altered1 and a current was induced which1 passing round the coil of the other instrument1 strengthened or weakened its magnet1 and caused the iron disc to approach it or recede from it1 according to the way in which the coils were coupled4 ,thus the movements of the first disc were faithfully repeated by the second1 and the minute vibrations set up in the disc by sound-waves were all faithfully repeated by the second instrument4 ,this was ,graham ,bell's telephone1 in which the transmitter and receiver were convertible4 ,but another and an earlier application of ,faraday's discoveries is found in the induction coil4 ,a short length of thick wire and a very great length of thin wire are wound upon an iron bar4 ,the ends of the long thin wire1 or secondary coil1 form the terminals of the machine2 the short thick wire1 or primary coil1 is connected with a battery1 but in the circuit is placed an interrupter4 ,this is generally a small piece of iron1 or hammer1 mounted on a steel spring opposite one end of the iron core1 the spring pressing the hammer back against a screw the end of which1 like the back of the hammer1 is tipped with platinum2 and this contact completes the battery circuit4 ,when the current starts1 the iron core becomes a magnet1 attracts the hammer1 breaks the contact1 stops the current1 the magnetism dies away1 the hammer is forced back by the spring1 and then the cycle of events is repeated4 ,but the starting of the current in the primary causes a great many lines of magnetic force to pass through each of the many thousand turns of wire in the secondary1 especially as the iron core conducts most of the lines of force of each turn of the primary almost from end to end of the coil1 and thus through nearly all the turns of the secondary4 ,this action might be further increased by connecting the ends of the iron core with an iron tube or series of longitudinal bars placed outside the whole coil4 ,when the primary current ceases1 all these lines of force vanish4 ,thus during the starting of the primary current1 which1 on account of self-induction1 occupies a considerable time1 there will be an inverse current in the secondary proportional to the rate of increase of the primary2 and while the primary is dying away1 there will be a direct current in the secondary proportional to its rate of decrease4 ,the primary current cannot be increased at a faster rate than corresponds to the power of the battery1 but by making a very sharp break it may be stopped very rapidly4 ,still1 however rapidly the circuit is broken1 self-induction causes a spark to fly across the gap until the energy of the current is used up4 ,the introduction of the condenser1 consisting of a number of sheets of tinfoil insulated by paper steeped in paraffin wax1 and connected alternately with one end or the other of the primary coil1 serves to increase the rapidity with which the primary current died away1 by rapidly using up its energy in charging the condenser1 and produces a corresponding diminution in the spark at the contact-breaker4 ,this rapid destruction of the primary current causes a correspondingly great electro-motive force in the secondary coil1 and thus very long sparks are produced between the terminals of the secondary coil when the primary current is broken1 though no such sparks are produced when the primary current starts4 ,if the secondary coil be connected up with a galvanometer1 so that there is a metallic circuit throughout1 it will be found that just as much electricity flows in one direction through the circuit at the break of the primary as flows in the other direction at the make1 the difference being that the first is a very strong current of great electro-motive force but lasting a very short time1 the second a feebler current lasting a correspondingly longer time4 99 99 99 99 99 ,but though the recent advances in electrical science have been very great1 the grandest triumph of this century is the establishment of the principle of the conservation of energy1 which has settled for ever the problem of the perpetual motion1 by showing that it has no solution4 ,this problem was not simply to find a mechanism which should for ever move1 but one from which energy might be continuously derived for the performance of external work--in fact1 an engine which should require no fuel4 ,but in spite of all that has been proved1 numbers of patents are annually taken out for contrivances to effect this object4 ,we have seen how ,rumford showed that heat was motion1 and how he approximately determined its mechanical equivalent4 ,seguin1 a nephew of ,montgolfier1 endeavoured to show that1 when a steam-engine was working1 less heat entered the condenser than when the same amount of steam was blown idly through the engine4 ,this ,hirn succeeded in showing1 thus proving that heat was actually used up in doing work4 ,mayer1 of ,heilbronn1 measured the work done in compressing air1 and the heat generated by the compression1 and assumed that the whole of the work done in the compression1 and no more1 was converted into the heat developed1 which was the same thing as assuming that no work was done in altering the positions of the particles of gas4 ,from these measurements he deduced a value of the mechanical equivalent of heat4 ,the assumption which ,mayer made was shown experimentally by ,joule to be nearly correct4 ,joule proved that1 when air expands from a high pressure into a vacuum1 no heat is generated or absorbed on the whole4 ,this he did by compressing air in an iron bottle1 which was connected with another bottle from which the air had been exhausted1 the connecting tube being closed by a stop-cock4 ,the whole apparatus was immersed in a bath of water1 and on allowing the air to rush from one vessel into the other1 and then stirring the water1 the temperature was found to be the same as before4 ,when the iron bottles were in separate baths of water1 that from which the air rushed was cooled1 and that into which it rushed was heated to the same extent4 ,joule and ,thomson afterwards showed that a very small amount of heat is absorbed in this experiment4 ,joule also showed that the heat generated in a battery circuit is proportional to the product of the electro-motive force and the current1 or to the product of the resistance and the square of the current1 which1 in virtue of ,ohm's law1 is the same thing4 ,this relation is often known as ,joule's law4 ,he also proved that1 for the same amount of chemical action in the battery1 the heat generated was the same1 whether it were all generated within the battery or part in the battery and part in an external wire2 and that in the latter case1 if the wire became so hot as to emit light1 the heat measured was less than before1 on account of the energy radiated as light4 ,with a magneto-electric machine he employed mechanical power to produce a current1 and the energy of the current he converted into heat4 ,in all cases he found that1 whatever transformations the energy might undergo in its course1 a definite amount of mechanical energy1 if entirely converted into heat1 always produced the same amount of heat2 and he thereby proved1 not only that heat is essentially motion1 but that it corresponds precisely with that particular dynamical quantity which is called energy2 and thus justified the attempt to find a relation between heat and energy1 or to express the mechanical equivalent of heat as so many foot-pounds4 ,joule then set to work to determine1 in the most accurate manner possible1 the number of foot-pounds of work which1 if entirely converted into heat1 would raise one pound of water through #a deg4 ,fahr4 ,the best known of his experiments is that in which he caused a paddle to revolve by means of a falling weight1 and thereby to churn a quantity of water contained in a cylindrical vessel1 the rotation of the water being prevented by fixed vanes4 ,in these experiments he allowed for the work done outside the vessel of water or calorimeter1 for the buoyancy of the air on the descending weight1 and for the energy still retained by the weight when it struck the floor4 ,from the results obtained he deduced #ggb foot-pounds as the mechanical equivalent of heat4 ,expressed in terms of the ,centigrade scale1 ,joule's equivalent1 that is1 the number of foot-pounds of work in the latitude of ,manchester1 which1 if entirely converted into heat1 will raise one pound of water #a deg4 ,c41 is #acij4 ,joule's experiments show that the same amount of energy always corresponds to1 and can be converted into1 the same amount of heat1 and that no transformations1 electrical or other1 can ever increase or diminish this quantity4 ,maxwell expressed this principle as follows3-- ,the energy of a system is a quantity which can neither be increased nor diminished by any actions taking place between the parts of the system1 though it may be transformed into any of the forms of which energy is susceptible4 ,this is the great principle of the conservation of energy which is applicable equally to all branches of science4 ,another principle1 almost equally general in its applicability1 is that of the dissipation of energy1 for which we are indebted in the first instance to ,sir ,william ,thomson4 ,all forms of energy may be converted into heat1 and heat tends so to diffuse itself throughout all bodies as to bring them to one uniform temperature4 ,this is its ultimate state of degradation1 and from that state no methods with which we are acquainted can transform any portion of it4 ,when energy is possessed by a system in consequence of the relative positions or motions of bodies which we can handle1 and whose movements we may control1 the whole of the energy may be employed in doing any work we please2 in fact1 it is all available for our purpose1 or its availability may be said to be perfect4 ,energy in any other form is limited in its availability by the conditions under which we can place it4 ,for example1 the energy of chemical action in a battery may be used to produce a current1 and this to drive a motor by which mechanical work is effected1 but some of the energy must inevitably be degraded into the form of heat by the resistance of the battery and of the conductor1 and this portion will be greater as the rate of doing work is increased4 ,the ratio of the quantity of energy which can be employed for mechanical purposes with the means at our disposal1 to the whole amount present1 is called the availability of the energy4 ,all forms of energy may be wholly converted into heat1 but only a fraction of any quantity of heat can be transformed into higher forms of energy1 and this depends on the temperature of the source of heat and of the coldest body which can be employed as a condenser1 being greater the greater the difference between the temperatures of the source and condenser1 and the lower the temperature of the latter4 ,in every operation which takes place in nature there is a degradation of energy1 and though some portion of the energy may be raised in availability1 another portion is lowered1 so that on the whole the availability is diminished4 ,thus1 in the case of the heat-engine1 work can be obtained from heat only by allowing another portion of the heat to fall in temperature2 and1 as originally stated by ,sir ,william ,thomson1 it is impossible1 by means of inanimate material agency1 to obtain mechanical effect from any portion of matter by cooling it below the temperature of the coldest of the surrounding objects1 and to leave the working substance in the same condition in which it was at the commencement of the operations4 ,accepting this principle1 ,professor ,james ,thomson showed that increase of pressure must lower the freezing point of water1 for otherwise it would be possible to construct an engine which1 working by the expansion of water in freezing1 would continue to do work by cooling a body below the temperature of any other body available1 and he calculated the amount of pressure necessary to lower the freezing point through one degree4 ,the conclusion was afterwards experimentally verified by ,sir ,william ,thomson1 and served to explain all the phenomena of regelation4 ,thus1 like the principle of the conservation of energy1 the principle of the dissipation of energy serves as a guide in the search after truth4 ,but there is this difference between the two principles--no one can conceive of any method by which to circumvent the conservation of energy2 but ,clerk ,maxwell showed that the principle of dissipation of energy might be overridden by the exercise of intelligence on the part of any creature whose faculties were sufficiently delicate to deal with individual molecules4 ,in the case of gases1 the temperature depends on the average energy of motion of the individual particles1 and heat consists simply of this motion2 but in any mass of gas1 whatever the average energy may be1 some of the particles will be moving with very great1 and some with very small1 velocities4 ,by imagining two portions of gas1 originally at the same temperature1 separated by a partition containing trap-doors which could be opened or closed without expenditure of energy1 and supposing a demon placed in charge of each door1 who would open the door whenever a particle was approaching very rapidly from one side1 or very slowly from the other1 but keep it shut under other circumstances1 he showed that it would be possible to sort the particles1 so that those in the one compartment should have a great velocity1 and those in the other a small one4 ,hence1 out of a mass of gas at uniform temperature1 two portions might be obtained1 one at a high temperature and the other at a low1 and1 by means of a heat-engine1 work could be obtained until the two portions were again at equal temperatures1 when the services of the demons might be again taken advantage of1 and the operations repeated until all the heat was used up4 ,any theory which is brought forward to explain a phenomenon1 or any process which is proposed to effect any operation1 must in the first instance submit to the test of the application of these two principles of conservation and dissipation of energy2 and any proposal which fails to bear these tests may be at once rejected4 ,the essential feature of the science of to-day is its quantitative character4 ,we must1 for instance1 not only know that radiant energy comes to us from the sun1 but we must learn how much energy is annually received by the earth in this way2 and1 in the next place1 how much energy is radiated by the sun in all directions in the same time4 ,when we have learned this1 we want to know what is the source of this energy2 and no theory of the sun which does not enable us to explain how this constant expenditure of energy is maintained can be accepted4 ,last century it was possible to believe1 with ,sir ,william ,herschel1 that the greater part of the sun's mass is comparatively cool1 and that it is surrounded by only a thin sheet of flame4 ,to-day such a theory would be rejected at once1 simply because the thin shell of flame could not provide energy for the solar radiation for any considerable time4 ,the contact theory of the galvanic cell1 as originally enunciated1 fell to the ground for a similar reason4 ,the simple contact of dissimilar metals could afford no continuous supply of energy to sustain the current4 ,applied to the steam-engine1 the doctrine of energy teaches us1 not only that1 corresponding to the combustion of a pound of coal1 there is a definite quantity of work which is the mechanical equivalent of the heat generated1 and is such that no engine of which we can conceive is capable of deriving from the combustion of the pound of coal a greater amount of work1 but it teaches us that there is a further limitation fixed to the amount of work obtainable4 ,this limitation depends upon the range of temperature at our command2 and1 when the range is known1 we can express the amount of energy realizable by a perfect engine working through that range as a definite fraction of the whole energy corresponding to the heat of combustion of the fuel4 ,thus1 if we find that a particular engine realizes only #ae per cent4 of the energy of its fuel in work done1 we must not suppose that mechanical improvements in the engine would enable us to realize any considerable portion of the other #he per cent42 for it may be that a theoretically perfect engine1 working with its boiler and condenser at the same temperatures as those of the engine considered1 could only realize #be per cent4 of the energy of the fuel1 reducing the margin for improvement from #he to #aj per cent41 as long as the range of temperature is unaltered4 ,to improve the efficiency beyond this limit1 the range of temperature must be increased1 that is1 generally1 hotter steam must be used4 ,the principles of energy are thus guides1 not only to the scientific theorist1 but to the practical engineer1 and they have been established only through careful measurement4 ,the simple observation of phenomena1 and of the conditions under which they occur1 could never have led to the establishment of such principles2 and1 though the carrying out of experiments which do not involve measurements is of great value1 it is the careful measurement1 however simple1 which affords the highest training to the mind and hand1 and without which any course of instruction in experimental physics is of little value4 ,the ,hindoos used to regard the earth as a vast dome carried on the backs of elephants4 ,the elephants themselves1 however1 required support1 and were represented as standing on the back of a gigantic tortoise4 ,it does not1 however1 appear that any support was provided for the tortoise4 ,in some respects this figure represents the apparently perpetual condition of scientific knowledge4 ,phenomena are investigated1 and are shown to depend upon other actions which appear simpler or more fundamental than the phenomena at first observed4 ,these1 again1 are found to obey laws which are of much wider application1 or appear to be still more fundamental2 but it may be that we are as far off as ever from discovering the great secret of the universe1 the ultimate nature of all things4 ,,index4 ,a4 ,abbott1 ,faraday's letters to1 #bda1 #bdf4 ,aberdeen ,university1 ,maxwell appointed professor in1 #bhd2 ,young's report on1 #bjc4 ,absorption1 ,rumford's experiments on1 #ahe2 of sun's rays by cloth of different colours1 #ii4 ,academy of ,sciences1 ,franklin nominated ,foreign ,associate of1 #aaa4 ,adjustment of the eye1 ,young's paper on the1 #bjj4 ,a,epinus's completion of ,franklin's theory1 #gg4 ,air1 ,boyle's conception of the constitution of1 #ai4 ,air-pump1 ,boyle's experiments with1 #ai2 constructed by ,boyle1 #bg4 ,american ,independence1 ,declaration of1 #aac4 ,american ,philosophical ,society1 foundation of1 #fa4 ,ampere's theory1 ,faraday's views on1 #beg4 ,anchor-ring experiment1 ,faraday's1 #bfj4 ,arago's experiment1 #bfd4 ,argand lamp1 efficiency of1 #ahh4 ,armstrong gun1 principle of the1 #ahj4 ,atmospheric electricity1 ,faraday's experiments on1 #bed2 obtained by a pointed rod1 #hd4 ,autobiography of ,franklin1 #ci4 ,availability of energy1 #cbf4 ,b4 ,baily1 ,francis1 repetition of the ,cavendish experiment by1 #adf4 ,beats in music1 explanation of1 #bji4 ,beggary in ,bavaria banished by ,rumford1 #afd4 ,bernoulli's1 ,daniel1 molecular theory of gases1 #bii4 ,boston1 blockade of1 #aaj4 ,boyle1 ,hon4 ,robert1 birth1 #h2 conversion1 #aa2 first air-pump1 #ag2 conception of the constitution of the air1 #ai2 experiments with the air-pump1 #ai1 et seq42 argument on the cause of a vacuum1 #bc2 experiments establishing his law1 #be2 statement of his law1 #bi2 observations on cold1 #cb1 and on the expansion of water in freezing1 #cc2 experiments on induced magnetism1 #cd2 the province of experimental science1 #cg4 ,boyle's law1 #bi4 ,brocklesby1 ,dr41 death of1 #bjh4 ,brougham's criticisms of ,thomas ,young1 #bah4 ,bumper1 electrical1 #hj4 ,c4 ,camera obscura1 invention of1 #b4 ,canada balsam1 stresses in1 #bih4 ,candle-flame1 effect of1 in discharging electricity1 #ge4 ,capacity1 electrical1 #acg2 ,franklin's experiments on1 #ha1 #hi2 ,cavendish's unit of1 #ach2 ,cavendish's measures of1 #acd1 #ach2 of disc1 measured by ,cavendish1 #acd4 ,capillarity1 #bbh4 ,cascade method of charging ,leyden jars1 #gg4 ,cavendish1 ,hon4 ,henry1 ,f4,r4,s41 birth and parentage1 #abf2 social habits1 #abg2 appointed member of the ,r4,s4 ,committee on ,lightning-,conductors1 #aca2 elected ,foreign ,associate of the ,french ,institute1 #acb2 death1 #acc2 proof of the law of inverse squares1 #ace2 experiment with the spheres repeated by ,mac,alister1 #acg2 experiments on the torpedo1 #adj2 experiments on the resistance of conductors1 #adb2 discovery of ,ohm's law1 #adc2 view of latent heat1 #add2 apparatus for determining the melting point of mercury1 #ade2 the ,cavendish experiment1 #adf4 ,cavendish experiment1 #adf2 ,laboratory1 #bhh2 ,manuscripts1 #acd2 ,maxwell's work on the ,manuscripts1 #bic4 ,city ,philosophical ,society1 joined by ,faraday1 #bde2 ,faraday's lectures to1 #bea4 ,cold1 ,boyle's observations on1 #cb4 ,collinson1 ,peter1 present of1 to the ,library ,company1 #gb4 ,colour-blindness1 ,maxwell's experiments on1 #bif4 ,colour-box1 ,maxwell's1 #big4 ,colours1 effect of1 on absorption of sun's rays1 #ii1 #ahf4 ,colours of the spectrum mixed by ,boyle1 #ca4 ,colour-top1 ,maxwell's1 #bhd1 #bie2 ,young's1 #bae4 ,colour-vision1 ,maxwell's theory of1 #bid2 ,young's theory of1 #bad4 ,commonplace-book1 ,faraday's1 #bec4 ,compound-interest principle1 #caf4 ,condenser1 use of1 in induction coils1 #cba4 ,conduction of heat1 ,rumford's experiments on1 #ahf4 ,conductors1 multiple1 flow of electricity through1 #ada4 ,conductors necessarily opaque1 #cjg4 ,conservation of energy1 ,maxwell's statement of the principle of1 #cbe4 ,copley ,medal awarded to ,franklin1 #ff1 #gd4 ,cork1 ,earl of1 autobiography of1 #e4 ,creeping of electricity on glass1 #aci4 ,crystalline lens1 fibrous structure of1 #bjj2 mode of adjustment of1 #bja4 ,cuneus's discovery of the ,leyden jar1 #d4 ,d4 ,davy1 ,sir ,humphry1 appointed professor at the ,royal ,institution1 #agd2 letter of1 to ,faraday1 #bdd4 ,declaration of ,american ,independence signed1 #aac4 ,defence of the ,american ,colonies against ,france and ,spain1 #fb4 ,degree of electrification1 #acg4 ,de la ,rive's invitation to ,faraday1 #bdi4 ,density of the earth1 determinations of the mean1 #adf4 ,desaguliers on electrics and non-electrics1 #d4 ,diagram of colour1 ,young's1 #bae2 ,maxwell's1 #bie4 ,diamagnetism discovered by ,faraday1 #bgd4 ,diamonds burned by ,davy1 #bej4 ,dichroism of ,lignum nephriticum1 #cj4 ,discharge1 electrical1 difference between positive and negative1 #hg4 ,dissipation of energy1 principle of1 #cbf4 ,distilled water1 resistance of1 #adb4 ,double refraction explained by ,huyghens1 #bai4 ,dufay showed that all bodies could be electrified1 #d4 ,dynamical nature of heat1 suggested by ,bacon1 #b1 #cb2 maintained by ,boyle1 #cb2 investigated by ,rumford1 #ahi2 established by ,joule1 #aic1 #cbd4 ,dynamical top1 ,maxwell's1 #bhe4 ,dynamo1 constructed by ,wheatstone1 #cah2 action of1 #cai2 essential feature of1 #cai4 ,e4 ,effect of points in discharging electricity1 #gd4 ,electrical picnic1 #hj4 ,electrical ,standards ,committee1 #bhg4 ,electric intensity1 #acg2 potential1 #acg4 ,electricity1 first obtained from clouds1 #gd2 velocity of1 #ic4 ,electrics and non-electrics1 #c4 ,electrolysis1 ,faraday's laws of1 #bff4 ,electro-magnetic induction1 discovered by ,faraday1 #bei2 ,maxwell's statement of the laws of1 #cja4 ,electro-magnetic theory of light1 #cjf4 ,electro-motors1 #cac4 ,electro-tonic state1 conceived by ,faraday1 #bfd2 explained by ,maxwell1 #cjb4 ,energy of ,leyden jar resident in the glass1 #gi4 ,eriometer1 ,young's1 #bbc4 ,ether1 ,maxwell's illustration of the possible constitution of1 #cjb4 ,expansion of water on freezing1 #cc4 ,extra current1 #bfh4 ,f4 ,faraday1 ,michael1 birth1 #bch2 life in ,jacob's ,well ,mews1 #bch2 becomes an errand-boy1 #bci2 apprenticeship1 #bci2 attends lectures at ,tatum's1 #bdj2 constructs a voltaic pile1 #bda2 letters to ,abbott1 #bda1 #bdf2 starts as a journeyman1 #bdc2 application to ,davy1 #bdc2 appointed assistant at the ,royal ,institution1 #bde2 joins the ,city ,philosophical ,society1 #bde2 opinions respecting lectures1 #bdf1 #bdg2 journey with ,davy1 #bdh2 acquaintance with ,de la ,rive1 #bdi2 crosses the ,alps1 #bdi2 at the ,academia del ,cimento1 #bej2 returns from the ,continent1 #bea2 lectures to the ,city ,philosophical ,society1 #bea2 commonplace-book1 #bec2 atmospheric electricity apparatus1 #bed2 marriage1 #bee2 discovery of electro-magnetic rotation1 #bee2 of the earth's action on a current1 #bef2 letter to ,e4 de la ,rive1 #bef2 views on ,ampere's theory1 #beg2 elected ,f4,r4,s41 #beh2 appointed director of the laboratory at the ,royal ,institution1 #beh2 work on optical glass1 #bei2 discovery of induced currents1 #bei2 institutes ,friday evening lectures1 #bei2 anchor-ring experiment1 #bfj2 magneto-electric machine1 #bfb2 obtains induced current by action of the earth1 #bfb2 obtains magnetic spark1 #bfb2 explanation of ,arago's experiment1 #bfd2 laws of electrolysis1 #bff2 proves the identity of frictional and voltaic electricity1 #bff2 experiments on self-induction1 #bfh2 diagrams of lines of magnetic force1 #bfi2 conception of lines of electric force1 #bgj2 ice-pail experiment1 #bgj2 butterfly-net1 #bgj2 experiments on specific inductive capacity1 #bgb2 appointed scientific adviser to ,trinity ,house1 #bgc2 appointed member of the ,senate of the ,university of ,london1 #bgc2 discovery of the electro-magnetic rotation of the plane of polarization1 #bgc2 investigations in diamagnetism1 #bgd2 joins the ,sandemanian ,church1 #bge2 lectures before the ,prince ,consort1 #bge2 retirement to ,hampton ,court1 #bgg2 death1 #bgg2 lines of force investigated by ,thomson and ,maxwell1 #cjj4 ,forbes's1 ,principal1 opinion of ,young1 #aid4 ,foucault's measurement of the velocity of light1 #bbj4 ,fovea centralis1 insensibility of1 to blue light1 #bih4 ,franciscus ,linus1 funicular hypothesis of1 #be4 ,franklin1 ,benjamin1 autobiography of1 #ci2 birth1 #dj2 on the disputatious temper1 #db2 method of learning prose composition1 #dc2 tries vegetarianism1 #dd2 adopts the ,socratic method1 #dd2 first voyage to ,england1 #dh2 experience as a journeyman in ,london1 #di2 views on beer as a food1 #di2 marriage1 #ed2 endeavours to attain moral perfection1 #ef2 method of reconciling an enemy1 #fj2 elected ,f4,r4,s41 #ff2 second voyage to ,england1 #gj2 begins electrical experiments1 #gb2 electrical papers ridiculed by the ,royal ,society1 #gc2 discovers the effect of points1 #gd2 one-fluid theory of electricity1 #gf2 theory of the ,leyden jar1 #gh2 invention of the lightning-rod1 #hc2 golden fish1 #he2 view of the nature of light1 #hf2 kite1 #hh2 experiments on capacity1 #ha1 #hi2 experiments on electrical induction1 #ij2 proof of the absence of electricity in a hollow conductor1 #ia2 third voyage to ,england1 #ajb2 examination before the ,parliamentary ,committee1 #aje2 nominated ,foreign ,associate of the ,academy of ,sciences1 #aaj2 signs the ,declaration of ,independence1 #aac2 sent to ,paris1 #aac2 made ,minister ,plenipotentiary to the ,court of ,france1 #aaf2 signs the ,treaty of ,peace1 #aai2 elected ,president of ,pennsylvania1 #abj2 death1 #abb4 ,fresnel1 awarded the ,rumford ,medal1 #bcc4 ,fresnel's repetition of ,young's experiments1 #bbe4 ,friction as a source of heat1 ,rumford's experiments on1 #ahi4 ,friday evening lectures instituted by ,faraday1 #bei4 ,g4 ,galileo and ,torricelli on the pressure of the air1 #af4 ,garnett1 ,dr4 ,thomas1 professor at the ,royal ,institution1 #agc4 ,gilbert1 ,dr41 founder of electrical science1 #c4 ,goettingen1 ,young's university course at1 #bjf4 ,graham ,bell's telephone1 #cai4 ,gray1 ,stephen1 discovers electric conduction1 #c4 ,grimaldi's fringes explained by ,young1 #bbb4 ,gunpowder1 ,rumford's experiments on1 #agi4 ,h4 ,halos1 coloured1 ,young's explanation of1 #bbd4 ,hawksbee's observations on capillary attraction1 #bbh4 ,heat1 a form of energy1 #cb2 generated by friction in vacuum1 #cb2 generated by friction1 ,rumford's experiments on1 #ahi4 ,herapath's explanation of gaseous diffusion1 #bii4 ,herschel's1 ,sir ,john1 comments on ,young's principle of interference1 #bjh4 ,hicks's1 ,principal1 investigations on the influence of temperature on gravitation1 #ahd4 ,hieroglyphics1 ,young's work on1 #bcd4 ,hobbes1 opposition of1 to ,boyle1 #be4 ,hollow conductor1 ,franklin's experiments on1 #ia2 ,cavendish's experiments on1 #ace2 ,faraday's experiments on1 #bgj4 ,honorary degrees conferred on ,franklin1 #ff1 #aja4 ,hooke's law1 #bbi4 ,hooke1 ,theodore1 founds the ,royal ,society1 #ad4 ,huyghens's explanation of double refraction1 #bai2 principle1 #bah4 ,hydrogen1 electro-chemical equivalent of1 #bfg4 ,i4 ,ice-pail experiment of ,faraday1 #bgj4 ,identity of frictional and voltaic electricity1 #bff4 ,induced currents1 discovered by ,faraday1 #bei2 explained by structure of ether1 #cjd2 from earth's action1 #bfb4 ,induction coil1 #cbj4 ,induction1 ,franklin's experiments on1 #ij2 self1 #adb1 #cjf4 ,induction machines1 principle of1 #caf4 ,insulators for lightning-rods1 #if4 ,interference1 principle of1 discovered by ,young1 #bjh2 spectra of1 obtained by ,young1 #bbe4 ,invisible college1 #ac4 ,j4 ,jenkin1 ,william1 discovery of the extra current by1 #bfh4 ,joule and ,thomson's determination of the heat absorbed by air in expanding1 #cbd4 ,joule1 ,dr41 establishment of mechanical theory of heat by1 #aic1 #cbd4 ,joule's law1 #cbd2 proof that heat and energy are equivalent1 #cbd2 determination of the mechanical equivalent of heat1 #cbe4 ,junto ,club1 formation of the1 #ea4 ,k4 ,kelland's1 ,professor1 edition of ,young's lectures1 #bab4 ,kinnersley commences lecturing1 #gc4 ,kite1 ,franklin's1 #hh4 ,knobs versus points1 #ie4 ,l4 ,laboulaye's comments on ,franklin1 #ch4 ,laplace's theory of ,saturn's rings1 #bhe4 ,latent heat1 ,black's theory of1 #add2 ,cavendish's views on1 #add4 ,leonardo da ,vinci's observation of capillary attraction1 #bbh4 ,leyden jar1 discovery of1 #d2 energy of1 resident in the glass1 #gi4 ,leyden jars charged by cascade1 #gg4 ,light1 ,franklin's view of nature of1 #hf2 ,maxwell's electro-magnetic theory of1 #cjf2 rotation of the plane of polarization of1 #bgc4 ,lightning1 effects of1 on ,newbury steeple1 #ib4 ,lightning-protectors1 ,maxwell's1 #bid4 ,lightning-rod1 illustrations of the1 #hc4 ,lignum nephriticum1 dichroism of1 #cj4 ,lines of force mathematically investigated by ,thomson and ,maxwell1 #cjj4 ,lines of magnetic force fixed by ,faraday1 #bfi4 ,luminiferous ether1 the vehicle of electrical action1 #bbg2 illustration of the possible constitution of1 #cjb4 ,m4 ,magdeburg hemispheres1 experiments with1 by ,otto von ,guericke1 #ag4 ,magic squares1 ,franklin's proficiency in1 #ff4 ,magnetic spark obtained by ,faraday1 #bfb4 ,magnetization by induction1 ,boyle's experiments on1 #cd4 ,magneto-electric machine1 ,faraday's1 #bfb1 #cad4 ,magneto-electric machines1 ,wilde's1 #cah2 objects to be aimed at in the construction of1 #cae4 ,maxwell1 ,james ,clerk1 birth and parentage1 #bgi2 enters ,edinburgh ,academy1 #bhj2 letters to his father1 #bhj2 early papers before the ,royal ,society of ,edinburgh1 #bha2 visit to ,mr4 ,nicol1 #bha2 experiments with unannealed glass1 #bhb2 enters the ,university of ,edinburgh1 #bhb2 enters ,peterhouse1 #bhb2 migrates to ,trinity1 #bhb2 degree in ,cambridge1 #bhc2 elected ,fellow of ,trinity1 #bhd2 appointed ,professor at ,marischal ,college1 #bhd2 marriage1 #bhg2 essay on ,saturn's rings1 #bhe2 dynamical top1 #bhe2 appointed professor at ,king's ,college1 #bhg2 lecture on colour at the ,royal ,institution1 #bhg2 work on the ,electrical ,standards ,committee1 #bhg2 appointed ,professor of ,experimental ,physics at ,cambridge1 #bhh2 plans the ,cavendish ,laboratory1 #bhh2 lectures at ,cambridge1 #bij2 work on the ,cavendish ,manuscripts1 #acd1 #bic2 delivers the ,rede ,lecture1 #bic2 method of protecting buildings from lightning1 #bid2 death1 #bid2 colour-top1 #bie2 experiments on colour-blindness1 #bif2 colour-box1 #big2 awarded the ,rumford ,medal1 #big2 wheel of life1 #big2 real-image spectroscope1 #bih2 discovery of stresses in ,canada balsam1 #bih2 of the insensibility of the fovea centralis to blue light1 #bih2 statistical method1 #bii2 explanation of the viscosity of gases1 #bii2 investigations of ,faraday's lines of force1 #cjj2 statement of the laws of electro-magnetic induction1 #cja2 mechanical illustration of the ether1 #cjb2 explanation of induced currents1 #cjd2 of the mechanical action between currents and currents1 and between magnets and currents1 #cjd2 of self-induction1 #cjf2 electro-magnetic theory of light1 #cjf2 contrivance for overcoming the principle of the dissipation of energy1 #cbh4 ,maxwell's experiment for showing electro-magnetic rotation1 #beh4 ,mayer's determination of the mechanical equivalent of heat1 #cbc4 ,mechanical equivalent of heat1 definition of1 #aic2 ,rumford's determination of1 #aib4 ,mercury1 melting point of1 #ade4 ,mirabeau's declamation on ,franklin1 #abc4 ,mixed plates1 colours of1 #bbc4 ,moral perfection1 ,franklin's endeavour to attain1 #ef4 ,mother-of-pearl1 ,young's explanation of the colours of1 #bbd4 ,n4 ,nautical ,almanack1 ,young appointed superintendent of the1 #bcb4 ,newton's analysis and synthesis of white light1 #bac2 rings1 ,young's explanation of1 #bbb2 theory of light1 #bai4 ,nicol prisms given to ,clerk ,maxwell1 #bhb4 ,o4 ,,oersted's discovery1 #bee4 ,ohm's law1 discovered by ,cavendish1 #adc2 meaning of1 #adc4 ,optical glass1 ,faraday's work on1 #bei4 ,otto von ,guericke1 contributions of1 to electricity1 #c2 experiments of1 with the ,magdeburg hemispheres1 #ag4 ,p4 ,paris1 ,dr41 ,faraday's letter to1 #bdc4 ,pascal takes a barometer up the ,puy de ,dome1 #ag4 ,pennsylvania fireplace invented by ,franklin1 #fc2 ,gazette published by ,franklin1 #ec4 ,perpetual motion1 ,rumford's contrivances for1 #aej2 impossibility of1 #cbb4 ,philadelphia1 ,franklin's first arrival in1 #df2 ,library1 foundation of the1 #ee4 ,photometer1 ,rumford's1 #ahg4 ,pigments1 effects of mixing1 #bag4 ,points versus knobs1 #ie1 #aca4 ,polarization1 explained by transverse vibrations1 #bbf2 of light discovered by ,malus1 #bbf4 ,poor ,richard's ,almanack1 #fj4 ,pressure of the air the cause of suction1 #bi4 ,r4 ,radiation1 ,rumford's experiments on1 #ahd2 of cold1 ,rumford's experiments on1 #ahf4 ,rede ,lecture1 delivered by ,clerk ,maxwell1 #bic4 ,refraction of light1 laws of1 #a2 mentioned by ,pliny1 #a4 ,relative economy of different sources of light1 #ahh4 ,resistance of conductors1 ,cavendish's experiments on1 #adb4 ,roemer1 measurement of the velocity of light by1 #b4 ,rosetta ,stone1 discovery of the1 #bcd2 inscription on1 #bcd4 ,royal ,institution1 foundation of the1 #afi2 ,young's lectures at the1 #bab2 ,faraday's appointment at the1 #bde2 ,maxwell's lecture on colour at the1 #bhg4 ,royal ,society1 origin of the1 #ac-ae4 ,rumford1 ,count1 birth and parentage1 #adh2 life as a medical student1 #aec2 becomes a schoolmaster at ,concord1 #aed2 marriage1 #aed2 summoned before the ,committee of ,safety1 #aef2 imprisoned at ,woburn1 #aef2 first journey to ,london1 #aeh2 receives an appointment in the ,colonial ,office1 #aeh2 experiments on the explosion of gunpowder1 #aeh1 #agi2 elected ,f4,r4,s41 #aeh2 made lieutenant-colonel in the ,british army1 #aei2 promoted to colonel1 #afj2 visits ,elector of ,bavaria1 #afj2 cured of martial ambition1 #afj2 enters the service of the ,elector of ,bavaria1 #afa2 knighted by ,george ,,iii41 #afa2 reforms in the ,bavarian army1 #afb2 attack on the beggars1 #afc2 made ,count of the ,holy ,roman ,empire1 #afe2 robbed of his manuscripts1 #aff2 visited by his daughter1 #aff2 his roaster1 #aff2 experiments on fire-places1 #aff2 founds the ,rumford ,medal1 #afg2 appointed ,minister ,plenipotentiary to the ,court of ,great ,britain1 #afi2 founds the ,royal institution1 #afi2 plans for the ,institution1 #afi2 residence in ,paris1 #age2 marriage with ,madame ,lavoisier1 #age2 death2 #agf2 ,cuvier's eloge on1 #agf2 statue at ,munich1 #agh2 experiments on the conduction of heat in fluids1 #aha2 on the convection of heat in viscous liquids1 #ahd2 on the weight of heat1 #ahe2 on radiation1 #ahe2 on the conduction of heat1 #ahf2 on the apparent radiation of cold1 #ahg2 shadow-photometer1 #ahh2 experiments on the relative economy of candles and tapers1 #ahh2 on the traction of carriages1 #ahi2 on friction as a source of heat1 #ahi2 determination of the mechanical equivalent of heat1 #aib4 ,rumford ,medal1 foundation of the1 #afg2 recipients of the1 #afg2 awarded to ,fresnel1 #bcc2 awarded to ,clerk ,maxwell1 #big4 ,rumford roaster1 #aff4 ,s4 ,sandford and ,merton1 influence of1 on the negro traffic1 #aig4 ,saturn's rings1 ,maxwell's essay on1 #bhe4 ,sea-water1 resistance of1 #adb4 ,seguin's attempt to measure loss of heat in the steam-engine1 #cbc4 ,self-induction1 effect of1 on sudden discharge1 #adb2 of electro-magnet1 #bfh2 effect of1 in induction coil1 #cba4 ,sensation of heat1 cause of1 #cc4 ,seraphic love1 ,boyle's essay on1 #ae4 ,shaw's1 ,dr41 comments on ,boyle1 #cg4 ,snellius's laws of refraction1 #a4 ,socratic method adopted by ,franklin1 #dd4 ,specific inductive capacity1 discovered by ,cavendish1 #aci2 rediscovered by ,faraday1 #bgb4 ,spectral colours1 mixed by ,boyle1 #ca2 mixed by ,maxwell1 #big4 ,s4,p4,g41 foundation of the1 #cj4 ,spheroidal waves in ,iceland-spar explained by ,young1 #bbf4 ,stamp ,act1 #aab4 ,standards ,commission1 report of1 #bcb4 ,statistical method1 ,maxwell's1 #bii4 ,steeple struck by lightning at ,newbury1 #ib4 ,stereoscope1 ,maxwell's real-image1 #bih4 ,stokes's1 ,professor ,g4 ,g41 exhibition of the bright centre in the shadow of a disc1 #bbb4 ,suction caused by atmospheric pressure1 #bi4 ,surface-tension1 #bbh2 suggested by ,segner1 #bbi2 ,young's investigations on1 #bbi4 ,t4 ,table of results of experiments on ,boyle's law1 #bg4 ,tatum's lectures on natural philosophy1 #bdj4 ,telephone1 ,graham ,bell's1 #cai4 ,temperature1 its nature1 #cc4 ,thermometers first hermetically sealed1 #b4 ,thomson's1 ,professor ,james1 application of the principle of dissipation of energy to the freezing of water under pressure1 #cbg4 ,thomson's1 ,sir ,william1 statement of the principle of dissipation of energy1 #cbg2 vortex theory of matter1 #cab2 mirror galvanometer1 #cac2 replenisher1 #caf4 ,thunder-storms1 ,franklin's theory of1 #ha4 ,torpedo1 ,cavendish's experiments on the1 #adj2 ,davy's experiments on the1 #bea4 ,traction of carriages1 ,rumford's experiments on1 #ahi4 ,trial plate used by ,cavendish1 #aci4 ,tyres1 relative advantages of broad and narrow1 #ahi4 ,u4 ,undulatory theory founded by ,hooke and ,huyghens1 #bah4 ,union of the ,american ,states1 ,franklin's plan for1 #fh4 ,university of ,philadelphia1 foundation of the1 #fd4 ,v4 ,vacuum1 ,boyle's argument on the cause of a1 #bc4 ,velocity of electricity1 #ic2 of light measured by ,roemer1 #b2 of light deduced from electro-magnetic theory1 #cjf4 ,viscosity of gases explained by ,maxwell1 #bii4 ,voltaic pile constructed by ,faraday1 #bda4 ,vortex theory of matter1 #cab4 ,voss machine1 #caf4 ,w4 ,wallis1 ,dr41 account of the ,royal ,society by1 #ad4 ,wealth1 ways to acquire1 #ajj4 ,wheel of life1 ,clerk ,maxwell's1 #big4 ,wilson1 ,dr41 account of ,cavendish by1 #acb1 #adg4 ,y4 ,young1 ,thomas1 ,principal ,forbes's opinion of1 #aid2 birth and parentage1 #aid2 early education1 #aie2 becomes a ,london medical student1 #aii2 paper on the power of adjustment of the eye1 #aii2 elected ,f4,r4,s41 #bjj2 visit to ,cornwall1 #bja2 first visit to the ,duke of ,richmond1 #bja2 enters the ,medical ,school at ,edinburgh1 #bjb2 declines secretaryship to the ,duke of ,richmond1 #bjb2 visits ,gordon ,castle1 #bjd2 visits ,inverary ,castle1 #bje2 enters the ,university of ,goettingen1 #bjf2 examination in medicine at ,goettingen1 #bjg2 enters ,emmanuel ,college1 #bjg2 discovers the principle of interference1 #bjh2 appointed ,professor of ,natural ,philosophy at the ,royal ,institution1 #agd1 #baj2 lectures at the ,royal ,institution1 #bab2 theory of colour-vision1 #bad2 his colour-top1 #bae2 colour-diagram1 #bae2 his ,bakerian lectures1 #bah2 explanation of the rectilinear propagation of light1 #bba2 of ,newton's rings1 #bbb2 eriometer1 #bbc2 explanation of coloured halos1 #bbd2 of the colours exhibited by mother-of-pearl1 #bbd2 interference spectra1 #bbe2 explanation of spheroidal waves in ,iceland-spar1 #bbf2 of the colours of thin plates1 #bbg2 hypothesis of an electric ether1 #bbg2 investigations on surface-tension1 #bbi2 modulus of elasticity1 #bcj2 his marriage1 #bca2 appointed physician in ,st4 ,george's ,hospital1 #bca2 superintendent of the ,nautical ,almanack1 #bcb2 death1 #bcc4 ,,printed ,,by ,,william ,,clowes ,,and ,,sons1 ,,limited1 ,,london ,,and ,,beccles4