,wireless ,telegraphy and ,telephony ,simply ,explained ,transcriber's ,note ,this book was transcribed from scans of the original found at ,google ,books4 ,i have not transcribed the original book's index4 ,variant spelling are not corrected4 ,some illustrations are rotated4 ,,wireless ,,telegraphy ,,and ,,telephony ,,simply ,,explained1 ,a ,,practical ,,treatise ,embracing ,complete and ,detailed ,explanations of the ,theory and ,practice of ,modern ,radio ,apparatus and its ,present ,day ,applications1 together with a chapter on the ,possibilities of its ,future ,development ,,by ,,alfred ,p4 ,,morgan ,,editor ,,mechanical ,,and ,,electrical ,,department ,,of ,,the ,,boy',s ,,magazine1 ,,author ,,of ,,wireless ,,telegraph ,,construction ,,for ,,amateurs1 ,,etc4 ,,very ,,fully ,,illustrated ,,new ,,york ,,the ,,norman ,w4 ,,henley ,,publishing ,,co4 #acb ,,nassau ,,street #aiaf ,,copyright #aiae ,,and #aiab ,,by ,,the ,,norman ,w4 ,,henley ,,publishing ,,company ,composition1 ,electrotyping and ,printing ,by ,j4 ,j4 ,,little ,ives ,co41 ,new ,york ,,preface ,probably no marvel of modern science so grips the imagination as the mystery of those quivering impulses which go forth invisibly to link a ship sailing over the seas with the shores of the distant land4 ,the author has endeavored to furnish a comprehensive explanation1 in simple language1 of the theory and practice of this wonderful art1 and to explain1 as far as possible1 the importance of the position occupied by wireless telegraphy to-day and the possibilities of to-morrow4 ,the title of this book naturally limits the amount of discussion that can be undertaken1 and so1 in the space at command1 there has not been any real attempt made to enter into any engineering or constructive details further than is necessary to make the text clear4 ,much that might properly be made a part of the preface has been embodied in the book1 in order to avoid repetition1 and to also bring certain matter to the attention of those readers who consider a preface to be merely an opportunity for the author of a book to express opinions very often quite foreign to the title1 and so unconcernedly skip it with hardly more than a passing glance4 ,the author wishes to extend his sincere thanks to ,mr4 ,h4 ,w4 ,young1 ,editor of ,popular ,electricity2 to ,mr4 ,john ,firth1 to ,colonel ,george ,p4 ,scriven1 and to the ,scientific ,american1 for their kindness in supplying photographs for some of the illustrations1 and to his friend1 ,mr4 ,safford ,adams1 who has kindly read the proofs and made many valuable suggestions4 ,,alfred ,p4 ,,morgan4 ,may1 #aiae4 ,,to ,,nikola ,,tesla ,,whose ,,genius ,,has ,,harnessed ,,electricity ,,to ,,the ,,daily ,,work ,,of ,,man ,,and ,,whose ,,inventions ,,are ,,the ,,basis ,,of ,,all ,,modern ,,wireless ,,transmission1 ,,this ,,book ,,is ,,dedicated4 ,,table ,,of ,,contents ,,preface ,,chapter ,i4 ,,introductory3 ,,wireless ,,transmission ,,and ,,reception4 ,,the ,,ether4 ,,electrical ,,oscillations4 ,,electromagnetic ,,waves4 ,,chapter ,,ii4 ,,the ,,means ,,for ,,radiating ,,and ,,intercepting ,,electric ,,waves4 ,,aerial ,,systems4 ,,earth ,,connection4 ,,chapter ,,iii4 ,,the ,,transmitting ,,apparatus4 ,,chapter ,,iv4 ,,the ,,receiving ,,apparatus4 ,,chapter ,v4 ,,tuning ,,and ,,coupling1 ,,directive ,,wave ,,telegraphy4 ,,chapter ,,vi4 ,,the ,,dignity ,,of ,,wireless4 ,,its ,,applications ,,and ,,service4 ,,wireless ,,in ,,the ,,army ,,and ,,navy4 ,,wireless ,,on ,,an ,,aeroplane4 ,,how ,a ,,message ,,is ,,sent ,,and ,,received4 ,,chapter ,,vii4 ,,the ,,ear4 ,,how ,,we ,,hear4 ,,sound ,,and ,,sound ,,waves4 ,,the ,,vocal ,,chords4 ,,the ,,structure ,,of ,,speech4 ,,chapter ,,viii4 ,,the ,,telephone ,,transmitter ,,and ,,receiver4 ,,the ,,photo ,,phone4 ,,the ,,thermophone4 ,,the ,,selenium ,,cell4 ,,the ,,speaking ,,arc4 ,,chapter ,,ix4 ,,the ,,wireless ,,telephone4 ,,chapter ,x4 ,,remarks4 ,,theory4 ,,accomplishments4 ,,maxwell',s ,,hertz',s ,,discovery4 ,,the ,,future4 ,,catalogue ,,of ,,good1 ,,practical ,,books ,,list ,,of ,,illustrations ,fig4 #a4--,throw a stone into a pool of water and little waves will radiate from the spot where the stone struck4 ,fig4 #b4--;,a ,leyden jar is a glass jar lined inside and outside with tinfoil for about two-thirds of its height4 ,fig4 #c4--;,a static machine1 connected to a ,leyden jar4 ,fig4 #d4--;,a ,leyden jar discharging through a coil of wire4 ,fig4 #e4--;,curved line representing an oscillatory discharge of a ,leyden jar4 ,fig4 #f4--,navy type of ,leyden jars4 ,fig4 #g4--,the simplest practical transmitter4 ,fig4 #h4--;,a cross-section of the aerial and atmosphere4 ,fig4 #i4--,under the same conditions1 but viewed from above4 ,fig4 #aj4--;,a simple receiving arrangement4 ,fig4 #aa4--;,an amateur aerial and station4 ,fig4 #ab4--,the ,army wireless station at ,fort ,gibbons4 ,fig4 #ac4--,lightning discharge near ,montclair1 ,n4 ,j4 ,fig4 #ad4-,photo of double lightning discharge passing to earth near the ,first ,orange ,mountain1 ,montclair1 ,n4 ,j4 ,fig4 #ae4--,vertical aerials of the grid1 fan and inverted pyramid types4 ,fig4 #af4--;,a diagram showing pyramid aerial4 ,fig4 #ag4-;,a diagram illustrating the directive action of a flat-top aerial4 ,fig4 #ah4--;,aerials of the ,v and inverted ,l types4 ,fig4 #ai4--;,a diagram showing the arrangement of a ,t aerial4 ,fig4 #bj4--;,flat top aerials of the inverted ,u and ,t types4 ,fig4 #ba4--,umbrella aerial4 ,fig4 #bb4--;,an amateur aerial 7flat top74 ,fig4 #bc4--;,diagram showing the difference between loop and straightaway aerials4 ,fig4 #bd4--,showing how wires are arranged and insulated4 ,fig4 #be4--;,aerial insulator4 ,fig4 #bf4--,leading-in insulator4 ,fig4 #bg4-;,a side view of the aerial shown in ,fig4 #bb4 ,fig4 #bh4--;,diagram showing how batteries may be arranged4 ,fig4 #bi4--,the power plant of a ,marconi transatlantic station4 ,fig4 #cj4--;,if a magnet be suddenly plunged into a hollow coil of wire a momentary current will be induced in the coil4 ,fig4 #ca4--,magnetic phantom formed by a bar magnet4 ,fig4 #cb4--,magnetic phantom formed by a wire carrying current4 ,fig4 #cc4--,magnetic phantom formed by a coil of wire carrying current4 ,fig4 #cd4--;,diagram of induction coil4 ,fig4 #ce4--;,induction coil for wireless telegraph purposes4 ,fig4 #cf4--;,induction coil primary and secondary4 ,fig4 #cg4--;,interrupter for induction coil4 ,fig4 #ch4--;,electrolytic interrupter4 ,fig4 #ci4--,open and closed core transformers4 ,fig4 #dj4--,lines representing direct and intermittent direct currents4 ,fig4 #da4--;,diagram representing alternating current4 ,fig4 #db4--;,high potential humming transformer4 ,fig4 #dc4--;,high potential closed core transformer for wireless work4 ,fig4 #dd4--,leyden jar set for oil immersion4 ,fig4 #de4--,oil immersed condenser4 ,fig4 #df4--;,diagram showing construction of condenser4 ,fig4 #dg4-,tubular condenser4 ,fig4 #dh4--;,helix4 ,fig4 #di4--;,close coupled helix4 ,fig4 #ej4--,spark gap4 ,fig4 #ea4--;,circuit showing tuned transmitting system employing close coupled helix4 ,fig4 #eb4--,photo of spark gap4 ,fig4 #ec4--,quenched spark gap4 ,fig4 #ed4--;,diagram of aerial switch4 ,fig4 #ee4--,photo of aerial switch4 ,fig4 #ef4--;,anchor gap4 ,fig4 #eg4-,wireless key4 ,fig4 #eh4--,photo of wireless key4 ,fig4 #ei4--,key and aerial switch4 ,fig4 #fj4--,portable receiving set and case4 ,fig4 #fa4--;,complete receiving outfit4 ,fig4 #fb4--,portable pack set4 ,fig4 #fc4--;,complete receiving set4 ,fig4 #fd4--,showing the construction of a watch case telephone receiver4 ,fig4 #fe4--,pickard adjustable telephone receivers4 ,fig4 #ff4--;,illustrating the valve action of a rectifying detector4 ,fig4 #fg4--;,a new type of silicon detector4 ,fig4 #fh4--;,diagram drawing analogy between rectifying action of a detector and pump4 ,fig4 #fi4--,pyron detector4 ,fig4 #gj4--,perikon detector4 ,fig4 #ga4--,silicon detector4 ,fig4 #gb4--;,electrolytic detector4 ,fig4 #gc4--;,electrolytic detector in circuit4 ,fig4 #gd4--,potentiometer4 ,fig4 #ge4--;,diagram showing how potentiometer is connected in a circuit4 ,fig4 #gf4--;,analogy between swinging and tuning4 ,fig4 #gg4--,receiving a message in a ,marconi transatlantic station4 ,fig4 #gh4--,tuning coil of the double slide type4 ,fig4 #gi4--;,diagram showing fixed condenser in circuit4 ,fig4 #hj4-;,fixed condenser4 ,fig4 #ha4--,rotary variable condenser4 ,fig4 #hb4--;,interior of rotary variable condenser1 showing construction4 ,fig4 #hc4--;,dr4 ,seibt's rotary variable condenser4 ,fig4 #hd4--,sliding plate variable condenser4 ,fig4 #he4--;,diagram showing arrangement of rotary variable condenser in receiving circuit4 ,fig4 #hf4--;,chain and ball arranged to illustrate the effect of tuning4 ,fig4 #hg4--,loose coupled helix4 ,fig4 #hh4--;,hot-wire ammeter4 ,fig4 #hi4--,the principle of the hot-wire ammeter4 ,fig4 #ij4--;,diagram showing loose coupled helix in circuit4 ,fig4 #ia4--,loose coupled tuning coil4 ,fig4 #ib4--,loose coupled tuner4 ,fig4 #ic4--;,diagram showing position of loose coupler in circuit4 ,fig4 #id4-;,fort ,gibbons1 ,alaska1 wireless station4 ,fig4 #ie4--,transmitting condenser4 ,fig4 #if4--;,braun's method for directing wireless telegraph signals4 ,fig4 #ig4--;,bellini-,tosi radio-goniometer4 ,fig4 #ih4--;,arrangement of ,bellini and ,tosi for directive wireless telegraphy4 ,fig4 #ii4--;,complete receiving and transmitting outfit4 ,fig4 #ajj4--,special lightweight wireless telegraph set for airship service4 ,fig4 #aja4--,telefunken wireless cart1 showing transmitter4 ,fig4 #ajb4--,telefunken wireless cart for military service4 ,fig4 #ajc4--,telefunken wireless wagon set in operation at ,fort ,leavenworth4 ,fig4 #ajd4--,wireless room aboard the ,u4 ,s4 transport ,buford4 ,fig4 #aje4 ,the apparatus set up for operation4 ,fig4 #ajf4--,wireless equipped automobile4 ,fig4 #ajg4--;,co4 ,signal ,corps at ,san ,antonio4 ,fig4 #ajh4--,u4 ,s4 ,signal ,corps pack set shown open and closed4 ,fig4 #aji4--,the receiving apparatus of the airship ,america4 ,fig4 #aaj4--;,interior of the ,n4 ,y4 ,herald ,press station4 ,fig4 #aaa4--,operating the ,u4 ,s4 ,signal ,corps airship wireless apparatus4 ,fig4 #aab4--,the ,n4 ,y4 ,herald station1 showing aerial4 ,fig4 #aac4--,operator ,jack ,irwin overhauling the wireless apparatus for the dirigible balloon ,america4 ,fig4 #aad4--,morse code4 ,fig4 #aae4--;,continental code4 ,fig4 #aaf4--,transmitting equipment of the high-power station at ,nauen4 ,fig4 #aag4--;,duplex receiving apparatus4 ,fig4 #aah4--;,breaking-in system4 ,fig4 #aai4--,the receiving apparatus of the station at ,nauen4 ,fig4 #abj4--;,diagram of the ear4 ,fig4 #aba4--,the ossicles4 ,fig4 #abb4--;,bon jour4 ,fig4 #abc4--;,experiment showing sounding bodies are in vibration4 ,fig4 #abd4--,method of registering vibrations of a tuning fork4 ,fig4 #abe4--,way line made by a bristle attached to a tuning fork prong in vibration when passed over smoked glass4 ,fig4 #abf4--;,illustrating the action of air waves4 ,fig4 #abg4--,the vocal chords in position for making a sound4 ,fig4 #abh4--,the vocal chords when relaxed4 ,fig4 #abi4-,koenig's manometric flame apparatus4 ,fig4 #acj4--;,appearance of manometric flame in revolving mirror4 ,fig4 #aca4--;,diagram of a telephone transmitter4 ,fig4 #acb4--;,diagram showing the principle and construction of the telephone receiver4 ,fig4 #acc4--,the photophone4 ,fig4 #acd4--,photophone receiving apparatus4 ,fig4 #ace4--,photophone transmitting apparatus4 ,fig4 #acf4--,powerful searchlight arranged to transmit speech over a beam of light4 ,fig4 #acg4--,the electric arc4 ,fig4 #ach4--;,circuit showing how a singing arc is arranged4 ,fig4 #aci4--;,a logical form of wireless telephone which is impractical4 ,fig4 #adj4--;,de,forest wireless telephone equipment4 ,fig4 #ada4--,wireless telephone receiving apparatus 7induction method74 ,fig4 #adb4--;,fessenden wireless telephone transmitting phonograph music4 ,fig4 #adc4--;,diagram illustrating why damped oscillations will not carry the voice4 ,fig4 #add4--;,how the sound waves of the voice are impressed upon undamped oscillations4 ,fig4 #ade4--;,arrangement of the speaking arc4 ,fig4 #adf4--;,diagram showing how a wireless telephone transmitting system is arranged4 ,fig4 #adg4--,poulsen wireless telephone equipment4 ,fig4 #adh4--,the ,majorana wireless telephone transmitter4 ,fig4 #adi4--,showing the brush discharge from a ,marconi transatlantic aerial at night4 ,fig4 #aej4--;,an amateur wireless' telegraph station4 ,fig4 #aea4--,the high-power naval wireless telegraph station under construction at ,washington1 ,d4 ,c4 ,fig4 #aeb4--,the curved lines represent the radius of the government high-power wireless stations and show the zones over which direct communication may be had with ships4 ,fig4 #aec4--,the aerial system of a transatlantic station4 ,fig4 #aed4--;,fong ,yee1 a ,chinese amateur wireless operator4 ,fig4 #aee4--,tesla world power plant4 ,fig4 #aef4--,twenty-five-foot sparks from a ,tesla transformer4 ,,chapter ,i4 ,,introductory3 ,,wireless ,,transmission ,,and ,,reception4 ,,the ,,ether4 ,,electrical ,,oscillations4 ,,electromagnetic ,,waves4 ,wireless telegraphy1 that marvelous art which has made possible the instantaneous transmission of intelligence between widely distant parts having no apparent physical connection save that of the earth1 air1 and water1 is one of those wonders of science which appeal to the average mind as either incomprehensible or only explainable through the use of highly technical language4 ,contrary to this general opinion1 however1 the whole theory and practice of the wireless transmission of messages is capable of the simplest explanation4 ,illustration3 ,,fig4 #a4--,throw a stone into a pool of water and little waves will radiate from the spot where the stone struck4 ,throw a stone into a pool of water4 ,a disturbance is immediately created1 and little waves will radiate from the spot where the stone struck the water1 gradually spreading out into enlarging circles until they reach the shores or die away4 ,by throwing several stones in succession with varying intervals between them it would be possible to so arrange a set of signals that they would convey a meaning to one who is initiated1 standing on the opposite side of the pool4 ,the little waves are the vehicle which transmits the intelligence1 and the water the medium in which the waves travel4 ,wireless telegraph instruments are simply a means for creating and detecting waves in a great pool of ether4 ,scientists suppose that all space and matter is pervaded with a hypothetical medium of extreme tenuity and elasticity1 called luminiferous ether1 or simply ether4 ,although ether is invisible1 odorless1 and practically weightless1 it is not merely the fantastic creation of speculative philosophers1 but is as essential to our existence as the air we breathe and the food we eat4 ,by imagining and accepting its reality1 it is possible to explain and understand many scientific puzzles4 ,the universe is a vast pool of ether4 ,it is all-pervading4 ,there is no void4 ,it is diffused even among the molecules of which solid bodies are composed4 ,the study of this substance is1 perhaps1 one of the most fascinating and important duties of the physicist4 ,ninety million miles away from our earth is a huge flaming body of vapors and gases1 called the sun4 ,this seething mass of flame and heat furnishes us more than mere winter and summer and night and day1 for we on this earth are not living on our own resources1 and the real work of the world so necessary for even bare existence is accomplished by the energy of the sun stored up in coal1 in plants and trees and mountain torrents4 ,light is known to be vibrations of an extremely rapid period--99electromagnetic waves991 they are called4 ,heat can be shown to be of the same nature4 ,traveling at the rate of over #ahj1jjj miles per second1 these two great gifts of the sun come streaming continually down to us over the inconceivable distance of almost #ajj1jjj1jjj miles4 ,both require a medium for their propagation4 ,the ether supplies it4 ,it is the substance with which the universe is filled4 ,incidentally it is also the seat of all electrical and magnetic forces4 ,illustration3 ,,fig4 #b4--;,a ,leyden jar is a glass jar lined inside and out with tinfoil for about two-thirds of its height4 ,in throwing the stone into the pool of water1 muscular energy of the arm is transferred to the stone1 and the latter1 upon striking the surface of the pond1 imparts a portion of that stored energy to the little waves which are immediately created in the water4 ,in setting up electromagnetic waves for wireless communication the energy imparted to the ether is electrical energy1 developed by certain interesting instruments explained further on4 ,let us consider briefly how the waves are created in a wireless telegraph station4 ,almost every one has seen and heard the brilliant snapping spark produced by the discharge of a ,leyden jar4 ,a ,leyden jar in its common form is a glass jar lined inside and out with tinfoil for about two thirds of its height4 ,a brass rod1 terminating in a knob1 connects below with the inner coating1 usually by means of a loose chain4 ,it may be described as a device which is capable of storing electricity in the form of energy and discharging this energy again in actual electricity4 ,this discharge has been the subject of many interesting investigations of direct interest4 ,illustration3 ,,fig4 #c4--;,a static machine connected to a ,leyden jar4 ,the inner and outer coatings are connected to the terminals of a static electric machine 7an apparatus for generating electricity71 and the machine set in rotation4 ,after the jar has been charged1 the electric machine is disconnected and one end of a coil of heavy wire connected to the outside coating1 while the other end of the wire is made to approach the knob connected with the inner coating4 ,before the end of the wire reaches the knob a discharge occurs through the coil1 producing a noisy brilliant spark between the wire and the knob4 ,the discharge appears like a single spark1 but in reality it is composed of a great many following each other in rapid succession4 ,the jar discharges its energy1 first by a tremendous rush of current in one direction1 and then another discharge somewhat smaller than the first in the opposite direction4 ,there is a series of these discharges in reverse directions1 but each discharge is less and less1 until the whole amount of energy is expended4 ,the complete series of discharges takes place in an almost immeasurable fraction of time4 ,it is from this phenomenon that the electrical term high frequency oscillations1 so often heard of in wireless parlance1 is derived4 ,illustration3 ,,fig4 #d4--;,a ,leyden jar discharging through a coil of wire produces a brilliant spark and high frequency oscillations are created4 ,illustration3 ,,fig4 #e4--;,curved line representing an oscillatory discharge of a ,leyden jar4 ,illustration3 ,,fig4 #f4--,navy type of ,leyden jars4 ,coated with copper deposited upon the surface of the glass4 ,high frequency oscillations are the pebbles which1 dropped into the vast pool of ether1 everywhere1 set up ripples called electromagnetic waves 7identical with the electromagnetic waves of light1 but longer and so beyond the limits of our spectrum and the vision of the eye74 ,the manner in which this is accomplished may be explained by saying that the charge creates a state of strain in the surrounding ether1 and then abruptly releases it4 ,ether possesses a high degree of elasticity1 so that when the state of strain is thus suddenly released1 it immediately returns to its former state4 ,the sudden motion of the ether results in waves which spread out from their source in enlarging circles4 ,wireless telegraphy1 as it is practiced to-day1 is based upon the fact that a system of wires or circuits1 through which high frequency oscillations are surging1 becomes a source of electromagnetic waves4 ,various methods have been devised for making the system more efficient and capable of giving better results with a given amount of power4 ,illustration3 ,,fig4 #g4--,the simplest practical transmitter that it is possible to devise for the purpose of sending messages4 ,fig4 #g is a diagram showing the simplest practical transmitter that it is possible to devise for the purpose of sending messages a sufficient distance to be of any value4 ,it would be impractical to use a static electric machine for wireless transmission1 and so an induction coil or transformer is employed4 ,these latter instruments are for the purpose of raising electric currents of a comparatively low voltage to the high potential1 where they have the power of generating high frequency oscillations4 ,in the illustration the current from a battery is led into the primary of an induction coil4 ,the primary is simply a coil consisting of a few turns of wire1 which induces a high voltage in a second coil consisting of a larger number of turns1 and called the secondary4 ,the terminals of the secondary are led to a spark gap--an arrangement composed of two polished brass balls1 separated by a small air space4 ,one of the balls1 in turn1 is connected to a metal plate buried in the earth1 and the other to a network of wires suspended high in the air and insulated from all surrounding objects4 ,as noted above1 a ,leyden jar consists of two metallic coatings1 separated by a wall of glass4 ,the purpose of the coatings is to form a conductor and carry an electric charge4 ,a ,leyden jar possesses a characteristic called1 in electricity1 capacity4 ,any two conductors separated by an insulating medium possess capacity and all the properties of a ,leyden jar or condenser4 ,the waves generated by a ,leyden jar would be somewhat weak and confined to its own immediate neighborhood1 so recourse is had to the aerial and ground1 in order to increase the area over which the oscillations exert their influence in setting up the electric waves4 ,the aerial system corresponds to one coating of the ,leyden jar1 and the ground to the other4 ,the insulating medium in between1 corresponding to the glass1 or dielectric1 is the atmosphere4 ,when the key connected to the induction coil is pressed1 the battery current flows through the primary and induces a high voltage current in the secondary1 which charges the aerial and ground exactly as the static machine charges the two coatings of the ,leyden jar4 ,a spark then leaps across the spark gap and the current surges back and forth through the aerial1 generating high frequency oscillations which1 in turn1 set up a state of strain in the surrounding ether1 and cause the waves to travel out from the system4 ,illustration3 ,,fig4 #h4 ,if a cross section of the aerial and atmosphere could be made in the same manner that an apple is sliced with a knife and the waves held stationary1 they would appear as above4 ,these waves follow the contour of the earth1 and so may cross mountains and valleys1 and travel anywhere4 ,they radiate from the aerial like the ripples from a pebble in a pool of water1 in gradually enlarging circles4 ,if a cross section of the aerial and atmosphere could be made in the same manner that an apple can be sliced with a knife1 and the waves held stationary long enough to see them1 they would appear as in ,fig4 #h4 ,the curved lines represent the lines of strain induced by the oscillations4 ,each group of lines represents a wave4 ,it will be noticed as they radiate farther from the aerial that they become larger and spread out4 ,illustration3 ,,fig4 #i4--,under the same conditions1 but when viewed from above1 the appearance would be that of a series of concentric circles4 ,the electromagnetic waves have the power of exciting oscillations in a conductor on which they impinge4 ,this is made use of for the purpose of receiving the messages4 ,when the waves strike the aerial of a distant station they set up high frequency oscillations1 which are usually too weak to make their presence known except with the aid of a sensitive device1 called a detector4 ,illustration3 ,,fig4 #aj4--;,a simple receiving arrangement4 ,the detector rectifies the oscillatory currents passing from the aerial to the ground so that they will flow through the telephone receiver and register as sound4 ,the most prominent type of detector in use to-day is a crystal of silicon1 iron pyrites1 zincite or certain other minerals4 ,the mineral is placed between two contact points1 one or both of which are adjustable so that the most sensitive portion of the mineral may be selected4 ,a telephone receiver is connected across the terminals of the detector4 ,when the electromagnetic waves from the transmitting station strike the aerial of the receiving station1 they set up therein a series of high frequency oscillations1 corresponding to the ,morse signals emitted from the transmitter4 ,the oscillations flow back and forth through the aerial and ground1 striking the mineral detector on their journey4 ,the high frequency oscillations are alternating currents1 because they reverse their direction many thousand times per second4 ,such a current will not pass through the telephone receiver1 because the little magnets contained therein exert a choking action on alternating currents of high frequency and effectually block their passage4 ,the mineral detector acts as a valve1 allowing the current to pass through in one direction1 but not permitting it to return or go in the opposite direction4 ,the result is a series of impulses flowing in one direction only1 and therefore called a direct current4 ,such a current will flow through a telephone receiver and produce a motion of the diaphragm which imparts its motion to the surrounding air1 the result being sound waves audible to the ear4 ,by varying the periods during which the key is pressed and the oscillations are being produced1 according to a prearranged code1 the sounds in the receiver may be made to assume an intelligible meaning4 ,,chapter ,,ii4 ,,the ,,means ,,for ,,radiating ,,and ,,intercepting ,,electric ,,waves4 ,,aerial ,,systems4 ,,earth ,,connection4 ,every radiotelegraphic station may be summed up as comprising these elements3 first of all1 certain appliances collectively forming the transmitter and serving to create the waves2 secondly1 the receiving apparatus1 whose function is to detect the signals of some far-distant sending station1 and lastly1 an external organ called the aerial1 or antenna1 consisting of a huge system of wires elevated high in the air above all surrounding objects1 either vertically or sloping1 or partly horizontal and partly vertical1 which radiates or intercepts the electromagnetic waves1 accordingly as the station is transmitting or receiving4 ,the antenna is at once both the mouth and the ear of the wireless station4 ,its site and arrangement will greatly determine the efficiency and range of the apparatus4 ,the site selected is preferably such that the aerial will not be in the immediate neighborhood of any tall objects1 such as trees1 smokestacks1 telephone wires1 etc41 because such objects not only absorb an appreciable amount of energy when the station is transmitting messages1 but also noticeably shield the aerial from the effects of incoming signals and limit its range4 ,the nature of the ground over which the waves must travel also enters into the question1 and is always considered in locating a station4 ,in gliding over the surface of the earth1 the waves generate weak currents in the earth itself4 ,if the ground is very stony or dry1 these earth currents encounter considerable resistance1 and the possible distance of transmission over soil of this sort is very much less than if it were moist4 ,moist soil and water offer very little resistance1 and the difference in the results obtainable at the receiving station when the waves travel over an area of this sort is very marked4 ,illustration3 ,,fig4 #aa4--;,an amateur aerial and station4 ,a station which can only send #ajj miles over land can send messages three or four hundred miles over the ocean4 ,forests exert a very decided effect upon the electric waves4 ,each individual tree acts as an antenna1 reaching up into the air and absorbing part of the energy4 ,the difference in the range of a station during the summer months and that of the same station in winter is considerable4 ,in summer the trees are full of sap and1 being much better conductors of electricity when in this condition1 act in the capacity of innumerable aerials rising in the air1 and able to absorb appreciable amounts of energy4 ,during these same months the air becomes highly ionized1 in which state the air molecules carry an electric charge1 and are particularly opaque to the waves4 ,this condition also usually exists in the presence of sunlight1 the result being that the most favorable time for the wireless transmission of messages are the hours around midnight4 ,illustration3 ,,fig4 #ab4--,the ,army wireless station at ,fort ,gibbons1 ,alaska1 showing steel lattice work mast and aerial system4 ,locality is another factor which usually receives a fair share of attention in selecting the site4 ,certain sections of the country1 for seemingly no apparent reason1 are very hard to transmit messages1 either to or from4 ,wireless stations located on the ,pacific ,coast1 for instance1 are more efficient than those situated along the ,atlantic seaboard1 while those in the tropical regions are only able to send short distances in comparison to those farther north or south4 ,messages seem to travel better in the direction of the lines of longitude than along the lines of latitude4 ,illustration3 ,,fig4 #ac4--,lightning discharge near ,montclair1 ,n4 ,j4 ,static1 that bugbear of the wireless operator1 is very much more in evidence in the eastern parts of the ,united ,states and in ,south ,america than it is on the western coast of the country4 ,if any one should ask a wireless operator what static is1 he would probably reply1 a nuisance4 ,in reality1 it is caused by atmospheric electricity4 ,when atmospheric electricity jumps1 it is called lightning4 ,a lightning discharge sets up very powerful waves in the ether1 which strike the aerial of the wireless station and produce a peculiar rumbling1 scratching sound in the telephone receivers1 and sometimes seriously interfere with a message4 ,in fact1 it is possible for a wireless operator to predict a thunder shower by many hours from the sounds he is able to hear in his telephone receivers4 ,the cause of lightning is the accumulation of electric charges in the clouds4 ,the electricity resides on the surface of the particles of water in the cloud4 ,these charges grow stronger as the particles of water coalesce to form larger drops1 because1 as they unite1 the surface increases proportionally less than the volume and1 being forced to lodge on a smaller space1 the electricity becomes more concentrated1 so to speak4 ,for this reason the combined charge on the surface of the larger drop is more intense than were the charges on the separate particles1 and the potential is increased4 ,as the countless multitudes of drops grow larger and larger1 in the process of forming rain1 the cloud soon becomes heavily charged4 ,through the effects of a phenomenon called induction1 a charge of the opposite kind is produced on a neighboring cloud or some object of the earth beneath4 ,these charges continually strive to burst across the intervening air and neutralize each other4 ,as soon as the potential becomes sufficient to break down this layer of air1 a lightning stroke from one to ten miles long takes place4 ,the heated air in the path of the lightning expands with great force1 but immediately other air rushes in to fill the partial vacuum1 thus producing atmospheric waves1 which impress the ear as the sound called thunder4 ,wireless stations belonging to the ,united ,states navy and located on land are usually housed in a small building in the immediate neighborhood of the tall wooden mast which supports the aerial4 ,commercial stations are usually situated on the top floor of a high office building1 or a hotel1 and the aerials supported by a steel lattice-work tower4 ,amateurs place a small pole on the roof of the house1 or in a tree1 and locate their station in any convenient room near the top of the house4 ,illustration3 ,,fig4 #ad4--,photo of double lightning discharge passing to earth near the ,first ,orange ,mountain1 ,montclair1 ,n4 ,j4 ,illustration3 ,,fig4 #ae4--,vertical aerials of the grid1 fan and inverted pyramid types4 ,aerials are of numerous classes and forms1 but the most prominent types can be divided into two main groups1 called respectively1 the ,flat-top and vertical antenna4 ,the vertical aerials are the older form1 and are usually employed for long-distance work or ultra-powerful stations4 ,the aerials intended for transmission from ,europe to ,america1 installed by ,marconi1 consisted of huge inverted pyramids1 supported by four heavy lattice-work towers1 over #bjj feet high4 ,vertical aerials also sometimes take the form of an umbrella1 or fan1 where only one supporting pole is available4 ,iron pipe masts may be employed for the purpose1 by setting on an insulating base4 ,the umbrella aerial is used extensively in the army and portable sets4 ,the flat-top aerials are gradually coming into very extended use4 ,they are used to the exclusion of all others on shipboard4 ,they need not be so high as a vertical type aerial in order to be as efficient4 ,flat-top aerials consist of a vertical portion and a nearly horizontal portion4 ,the horizontal portion is practically useless1 as far as its work in radiating waves is concerned1 it being used for the purpose of increasing the capacity of the aerial4 ,an increase in capacity in an aerial means that more energy can be stored and radiated4 ,flat-top aerials have the objection1 however1 of possessing a directive action2 that is1 they receive1 or radiate waves1 better in one direction than in the other4 ,a flat-top aerial always receives or transmits better in the direction that the ends point than in a direction at right angles to the wires4 ,illustration3 ,,fig4 #af4--;,a diagram showing pyramid aerial4 ,the accompanying diagram is an illustration to show the effects of the directive action of a flat-top aerial4 ,the black lines marked ,a ,b1 and appearing very much like a little grating1 represent an aerial of the inverted ,l type1 looking down on it from above4 ,b is the free end of the aerial1 and ,a the closed end1 or end to which the wires leading down to the station are attached4 ,if a snapshot of the lines of strain produced in the ether as the waves move away from the aerial could be taken1 they would appear like the curved lines in the illustration4 ,it can be readily seen that those passing outward from the aerial in a direction opposite to that in which the free end points are the strongest1 and that the radiation in that direction is the best4 ,illustration3 ,,fig4 #ag4-;,a diagram illustrating the directive action of a flat-top aerial4 ,illustration3 ,,fig4 #ah4--;,aerials of the ,v and inverted ,l types4 ,the ,v aerial and also the inverted ,l type both receive waves much better when they come from a direction opposite to that in which the free end points4 ,illustration3 ,,fig4 #ai4--;,a diagram showing the arrangement of a ,t aerial4 ,probably the most interesting feature of the directive action of aerials lies in the fact that a land station is able to determine the approximate bearing of a ship signaling with a horizontal aerial4 ,illustration3 ,,fig4 #bj4--;,flat top aerials of the inverted ,u and ,t types4 ,it is beyond the scope of the book to enter into all of the engineering details pertaining to the installation of a wireless station1 but a few remarks and instructions for the benefit of those who may be interested in this phase of the subject may be appreciated4 ,the flat-top ,t aerial gives the best all around results4 ,the vertical and umbrella forms are close seconds4 ,illustration3 ,,fig4 #ba4--,umbrella aerial4 ,for the very best results1 the top or horizontal portion of a ,t aerial should be slightly shorter than the vertical section4 ,the umbrella type of antenna is very efficient4 ,instead of a wooden mast1 an iron pipe terminating above in a system of wires1 inclining downward and serving both as part of the aerial and as guys to support the pole1 is often used4 ,the bottom of the pole is placed on an insulating base1 protected from the rain by a small shelter4 ,the wires are insulated near the lower ends by strain-insulators4 ,the action of the wires is to serve as a capacity extension to the aerial4 ,illustration3 ,,fig4 #bb4--;,an amateur aerial 7flat-top74 ,vertical aerials are not as efficient as either of those forms just mentioned4 ,they require to be #ej per cent4 higher than a flat-top aerial1 in order to be of the same value4 ,the ,l and ,v types are somewhat directional4 ,they are used where the highest point must be near the station1 with a lower point some distance away4 ,it is possible to secure excellent results with either type4 ,the terms straightaway and loop denote the method of connecting the aerial wires4 ,in the first form the upper or free ends of the wires terminate at the insulators4 ,in the loop form they are all connected together1 and divided into two sections1 each of which is led separately into the operating room4 ,illustration3 ,,fig4 #bc4--;,diagram showing the difference between loop and straightaway aerials4 ,the straightaway aerial is the most efficient in most cases1 but wherever great height cannot be obtained1 or the aerial is necessarily short1 the loop aerial will give the best results4 ,bare copper wire is the best1 and is generally used for aerials4 ,wherever the stretch is #ajj feet or over1 however1 so that the wires are subjected to considerable strain from their own weight1 phosphor bronze is used because of its greater tensile strength4 ,commercial and navy stations employ stranded wire4 ,high frequency currents have the peculiar property of traveling near the surface of wires and conductors4 ,they do not permeate to the center of the wire1 as do normal currents4 ,the surface of a stranded wire is greater in comparison to its cross-section than a solid conductor of the same diameter1 and therefore is often employed because it offers less resistance to currents of this sort4 ,illustration3 ,,fig4 #bd4--,showing how wires are arranged and insulated4 ,aluminum wire is very light1 and causes very little strain on the pole or cross-arms4 ,it offers more resistance than copper1 but some of the larger sizes may be used with equally good results4 ,iron wire must never be used1 even if galvanized or tinned4 ,it possesses a certain reactance tending to choke off the high frequency currents4 ,illustration3 ,,fig4 #be4--;,aerial insulator4 ,the aerial is always very carefully insulated from its supports and surrounding objects by special insulators1 capable of withstanding severe strains1 made of a moulded material having an iron ring imbedded in each end4 ,illustration3 ,,fig4 #bf4--,leading-in insulator4 ,the wires leading from the aerial to the operating room are called the rat-tail1 or lead-in4 ,they must be very carefully insulated by leading through a bushing placed in the wall or window of the operating room4 ,one of the most important factors in a wireless station is the proper earthing arrangement4 ,the usual method is to use large copper plates buried in moist earth1 or thrown in the sea4 ,on shipboard it is merely necessary to connect the earth wire to the metallic plates of which the hull of the vessel is built4 ,amateurs employ the water or gas pipes in the house1 the former being preferred4 ,connections are established by means of a ground clamp4 ,in the country1 where water-pipes are not available1 the best way is to bury a sheet of copper three or four feet deep in moist earth4 ,a very efficient earth can be formed by spreading a large area of chicken wire netting over the ground4 ,this method is the best where the earth is very dry or sandy1 and no other way is readily convenient4 ,illustration3 ,,fig4 #bg4--;,a side view of the aerial shown in ,fig4 #bb4 ,,chapter ,,iii4 ,,the ,,transmitting ,,apparatus4 ,the principal instruments composing the apparatus used for sending the wireless messages comprise an induction coil1 or in its place a transformer1 a key1 a spark gap1 a condenser1 and a helix4 ,the current supply available will determine the type of the instruments1 and whether an induction coil or a transformer is used4 ,unless current mains for light and power are already installed1 it must be generated by an engine and dynamo1 or recourse had to batteries4 ,induction coils may be operated on either direct or alternating current4 ,dry cells are most commonly employed to furnish the current for small induction coils1 but a storage or some form of renewable primary cell1 such as the ,fuller and ,edison1 is necessary if the coil is a large one4 ,when dry cells are used1 they should be connected in series multiple1 as shown in the accompanying diagram4 ,this method of connecting distributes the load1 and considerably lengthens the life of the battery4 ,illustration3 ,,fig4 #bh4--;,diagram showing how batteries may be arranged in series or series multiple4 ,illustration3 ,,fig4 #bi4--,the power plant of a ,marconi transatlantic station1 showing engine and generator4 ,when the source of current supply is alternating1 an induction coil may be operated as a transformer4 ,both induction coils and transformers are instruments for raising the voltage of the ordinary available current from a comparatively low value1 #f-bbj volts1 to a quantity 7#ae1jjj-bj1jjj volts71 where it can properly charge the aerial and create a state of strain1 or1 as it is called in technical parlance1 an electro-static field4 ,illustration3 ,,fig4 #cj4--;,if a magnet is suddenly plunged into a hollow coil of wire a momentary electric current will be induced in the coil4 ,both the induction coil and transformer depend for their operation upon the principles of magnetic induction4 ,in #ahca1 ,michael ,faraday1 a famous ,english chemist and physicist1 discovered that if a magnet be suddenly plunged into a hollow coil of wire1 that a momentary current of electricity is generated in the coil4 ,as long as the magnet remains motionless1 it induces no current in the coil1 but when it is moved back and forth1 it sets up the currents4 ,the source of electrical energy is the mechanical work done in moving the magnet4 ,the medium which changes the mechanical energy into electricity is called the magnetic field4 ,the magnetic field is a peculiar state or condition of the space in the immediate neighborhood of a magnet4 ,its real nature is very hard to explain and not easily understood4 ,suffice it to say1 however1 that the current is induced in the coil of wire only when the magnetic field is changing1 either decreasing or increasing4 ,the change is produced by moving the magnet because its influence on the coil will be great or small accordingly as it is near or far4 ,illustration3 ,,fig4 #ca4--,magnetic phantom formed by bar magnet4 ,it is possible to show the existence of the magnetic field by placing a sheet of glass over a bar magnet and then sprinkling iron filings on the glass4 ,they will settle down in curving lines as in ,fig4 #ca1 forming a magnetic phantom4 ,the curved lines formed by the filings represent the direction of the lines of force which make up the magnetic field4 ,if we should examine the space in the immediate neighborhood of a coil of wire carrying a current of electricity it would be found that a similar state of affairs existed there and that the coil also possessed a magnetic field composed of lines of force flowing around it4 ,this is readily shown by punching a small hole in a piece of cardboard and passing a wire carrying a current of electricity through the hole4 ,if iron filings are sprinkled on the cardboard1 they will arrange themselves in circles around the wires1 forming a magnetic phantom and showing that a coil of wire carrying a current of electricity generates a magnetic field in its vicinity4 ,by forming the wire into a coil the magnetic field generated is much stronger1 for the then combined effect of the wires is secured4 ,illustration3 ,,fig4 #cb4--,magnetic phantom formed by wire carrying current4 ,illustration3 ,,fig4 #cc4--,magnetic phantom formed by coil of wire carrying current4 ,the induction coil and transformer are simply instruments utilizing the principle that a coil of wire carrying a current possesses a magnetic field which will induce a current of electricity in another neighboring coil4 ,illustration3 ,,fig4 #cd4--;,diagram of an induction coil4 ,the induction coil consists essentially of a primary winding of heavy wire wound around a soft iron core and surrounded by a secondary coil consisting of many thousand turns of fine wire1 carefully insulated4 ,the current from a battery is sent through the primary coil and sets up a magnetic field4 ,the magnetic field induces a current in the secondary whose voltage is approximately proportional to the ratio of the turns of the secondary to the primary4 ,thus1 if the secondary contains one hundred times as many turns of wire as the primary the induced voltage will be one hundred times the voltage of the original primary current4 ,the purpose of the iron core is to concentrate the magnetic field and make the coil more efficient4 ,since currents are only induced in the secondary when the magnetic field is changing1 an automatic device called an interrupter or sometimes a vibrator1 is employed to rapidly turn the current flowing through the primary on and off4 ,the interrupter consists of a spring carrying a platinum point against which presses a second piece of platinum on the end of an adjustable thumbscrew4 ,platinum is necessary because the current of electricity would quickly oxidize and burn up any other material4 ,the interrupter spring is placed near the end of the core so that the magnetism of the latter will draw it forward away from the thumbscrew and interrupt the current4 ,as soon as the current ceases to flow the core loses its magnetism and the spring returns to its former position repeating the cycle very rapidly a large number of times per second4 ,the interrupter is fitted with a condenser shunted across its terminals to stop sparking at the platinum points and also to make the currents in the secondary more intense4 ,illustration3 ,,fig4 #ce4--;,induction coil for wireless telegraph purposes4 ,illustration3 ,,fig4 #cf4--;,induction coil1 primary and secondary4 ,the voltage of the currents in the secondary is high enough to leap across an air gap in a torrent of sparks4 ,the spark of an induction coil intended for wireless work should be thick and heavy4 ,it should be sufficiently hot and flaming to ignite a piece of paper4 ,a rapid vibrator giving a high pitched spark is better than a slow one not only because it causes a more intense and powerful spark but because the human ear is the most sensitive to high pitched sounds and such a spark is more easily read at the receiving station4 ,illustration3 ,,fig4 #cg4--;,interrupter for induction coil4 ,illustration3 ,,fig4 #ch4--;,electrolytic interrupter4 ,when the coil is a very large one and operated on the #aaj volt current an electrolytic interrupter is substituted for the mechanical type4 ,one pole of the current is connected to a lead plate placed in a jar containing a mixture of sulphuric acid and water4 ,the other side of the current is connected to a platinum wire placed in a porcelain tube so that only a small part of the lower end is in contact with the solution4 ,when the current passes a bubble forms at the end of the wire shielding it from the liquid1 and thus interrupting the current4 ,the bubble is almost immediately discharged however and the current allowed to flow an instant before a new one forms4 ,this operation is repeated continuously at a frequency sometimes as high as a thousand per second4 ,an electrolytic interrupter is both an expensive and a troublesome device4 ,there are other types of interrupters of value in wireless service but the limitations of space prohibit any account4 ,illustration3 ,,fig4 #ci4--,open and closed core transformers4 ,the transformer is acknowledged to be the best practice as a means of stepping up the voltage of a circuit for wireless telegraph purposes4 ,alternating current is necessary to operate a transformer4 ,there are two distinct types of transformers known as the open and closed core accordingly as the shape of the latter is straight like that of an induction coil or in the form of a hollow rectangle4 ,the closed core transformer consists of two coils of insulated wire1 forming a primary and a secondary1 wound upon a rectangular core like that shown in ,fig4 #ci;,b4 ,the core is built up of sheets of iron called laminations1 to reduce the heating and increase the efficiency of the machine4 ,illustration3 ,,fig4 #dj4--,lines representing direct and intermittent direct currents4 ,as noted above currents are only induced in a coil when the magnetic field is changing4 ,the interrupter is employed to rapidly make and break the circuit4 ,every time that the circuit is made the primary coil creates a field and every time it is broken it is destroyed4 ,a direct current is a current which passes in one direction only4 ,it may be represented by a straight line as ,a in ,fig4 #dj4 ,its voltage is usually very constant and does not vary greatly4 ,in the case of electric lighting circuits the normal voltage is usually #aaj4 ,if an interrupter is included in the circuit the current may be represented by a broken line1 the spaces corresponding to the periods when the current is broken and the lines to the periods it is flowing4 ,the interrupter creates an intermittent direct current4 ,illustration3 ,,fig4 #da4--;,diagram representing alternating current4 ,an alternating current is one which reverses its direction and passes first one way and then the other4 ,it may be represented by the curved line shown in ,fig4 #da4 ,it starts at zero and rises to a maximum1 gradually dying away to zero1 then passes in the opposite direction1 rising to a maximum and dying away again4 ,this is repeated a definite number of times per second2 when the current rises from zero1 reverses and returns to zero it is said to have passed through a cycle4 ,from a to c represents a cycle--from a to b is an alternation4 ,the usual frequency of commercial alternating currents is #fj cycles or #gbjj alternations per minute4 ,illustration3 ,,fig4 #db4--;,high potential ,humming transformer4 ,illustration3 ,,fig4 #dc4--;,high potential closed core transformer for wireless work4 ,illustration3 ,,fig4 #dd4--,leyden jar set for oil immersion to prevent losses from brush discharges4 ,from these facts we may readily see why the troublesome interrupter may be eliminated when alternating current is used4 ,every time that the current rises and falls the magnetic field changes4 ,considerable care must be used in proportioning the windings so that they possess sufficient reactance4 ,reactance is the tendency of a coil to resist the flow of an alternating current4 ,a reactance coil is sometimes placed in circuit with an open core transformer to prevent the spark from arcing4 ,arcing is the tendency of the spark to pass across the gap without charging the condenser and creating any high frequency oscillations4 ,illustration3 ,,fig4 #de4--,oil immersed condenser ,the condenser1 it will be remembered is the means of storing up the energy1 which suddenly rushing across the spark gap1 produces the oscillations necessary to generate the electric waves4 ,a battery of leyden jars may be used as a transmitting condenser in connection with small induction coils4 ,their objection in large stations is that they are very cumbersome and some energy is lost by the brush discharges around the tops of the jars4 ,the usual form of condenser consists of alternate sheets of tinfoil and glass plates arranged in a pile4 ,the alternate sheets of tinfoil are connected together to form the terminals of the instrument4 ,the condenser is usually encased in a wooden box poured full of wax or oil to increase the insulation and efficiency4 ,condensers are arranged in units so that any desired capacity may be readily secured by adding the proper number of units4 ,the capacity of a condenser is its relative ability to receive and retain an electrical charge4 ,illustration3 ,,fig4 #df4--;,diagram showing construction of condenser4 ,the helix is an instrument consisting of copper or brass wire wound around a frame of hard rubber or seasoned wood4 ,a certain amount of inductance is necessary in a wireless telegraph circuit in order to develop high frequency oscillations4 ,inductance is the property of an electric circuit by virtue of which lines of force are developed around it4 ,the helix furnishes the inductance in the circuit or at least the greater part4 ,connections are established to the turns of the helix by means of clips which snap on and off the wires4 ,illustration3 ,,fig4 #dg4--,tubular condenser4 ,illustration3 ,,fig4 #dh4--;,helix4 ,illustration3 ,,fig4 #di4--;,close coupled helix4 ,illustration3 ,,fig4 #ej4--,spark gap4 ,illustration3 ,,fig4 #ea4--;,circuit showing tuned transmitting system employing close coupled helix4 ,the spark gap is the medium for discharging the aerial and condenser and setting up the oscillations4 ,it usually consists of a pair of electrodes supported by suitable standards and so arranged that the distance between the electrodes can be accurately adjusted4 ,the electrodes usually take the form of hollow faced cylindrical rods having flanges to radiate the heat generated and prevent the spark from arcing4 ,various metals are used for spark gaps4 ,silver is probably the best but its expense is prohibitive4 ,a special hard zinc alloy is most generally used4 ,illustration3 ,,fig4 #eb4--,photo of spark gap4 ,illustration3 ,,fig4 #ec4--,quenched spark gap4 ,illustration3 ,,fig4 #ed4--;,diagram of aerial switch4 ,illustration3 ,,fig4 #ee4--,photo of aerial switch4 ,spark gaps take other forms1 two of which are interesting and important enough to describe here4 ,the first is the rotary gap4 ,this consists of a number of small electrodes set around the periphery of a wheel mounted upon the shaft of an electric motor4 ,two other adjustable electrodes are so mounted that the small electrodes on the revolving member pass between4 ,when the motor is set in operation the wheel revolves at a high rate of speed interrupting the spark and causing a peculiar musical pitch to be emitted4 ,a rotary spark gap almost entirely eliminates the arcing of the spark4 ,the quenched gap consists of a number of disks of brass about five inches in diameter having thin mica washers set between and arranged in a pile as in the illustration4 ,the quenched gap radiates considerably more energy than any other form of gap and also has the advantage of being practically noiseless4 ,the crashing discharge of an ordinary gap produces a very disagreeable penetrating noise hard to eliminate4 ,in most commercial stations the spark is muffled to a certain extent by enclosing it in a cylinder of micanite or some other insulating substance4 ,illustration3 ,,fig4 #ef4--;,anchor gap4 ,the aerial switch is necessary for quickly connecting the aerial and ground to either the transmitting or receiving apparatus4 ,amateurs very often employ a small double pole double throw switch4 ,the switch used in commercial stations is built in the manner shown in ,fig4 #ee4 ,illustration3 ,,fig4 #eg4--,wireless key4 ,an anchor gap is a simple little device consisting of a hard rubber ring bearing two or three small electrodes or sparking points4 ,it is a necessary part of the transmitting apparatus wherever a loop aerial is used4 ,one electrode is connected to the transmitting apparatus and the other two to the opposite sides of the aerial so that the currents divide between the two halves and equalize4 ,illustration3 ,,fig4 #eh4--,photo of wireless key4 ,the key is a hand operated switch which controls the electric currents passing through the transformer or coil shutting them on or off at will and so controlling the electric oscillations in the antenna to send out short or long trains of ether waves in accordance with the dot or dash signals of the ,morse alphabet4 ,illustration3 ,,fig4 #ei4--,key and aerial switch4 ,the key used in a wireless station is necessarily much larger and heavier than those employed in ordinary ,morse line work1 in order to carry the heavy currents used by the transmitter4 ,in spite of their size and weight1 however1 such keys when properly designed may be handled with perfect ease4 ,,chapter ,,iv4 ,,the ,,receiving ,,apparatus4 ,the receiving instruments form the most interesting and ingenious part of a wireless station4 ,they are the ears of the wireless station4 ,they are wondrously sensitive but yet simple and incapable of much complication4 ,the receiving station forms an exact counterpart of the transmitter1 and the train of actions taking place are the reverse of those of the latter4 ,the purpose of the transmitter is to change ordinary electric currents into electrical oscillations and thus set up electric waves1 while the receptor converts the waves into oscillations and thence into currents which are capable of manifesting themselves in a telephone receiver4 ,the instruments necessary for receiving comprise a ,detector ,telephone ,receivers ,fixed ,condenser ,tuning ,device ,illustration3 ,,fig4 #fj4--,portable receiving set and case4 ,other instruments such as a potentiometer1 test buzzers1 variometers1 variable condensers1 etc41 complete the outfit and improve its selectivity and sensitiveness4 ,illustration3 ,,fig4 #fa4--;,complete receiving outfit4 ,the detector forms the most vital part of the receptor4 ,in explaining its action it may be well to recall and enlarge upon the description already set forth on page #aa1 where it was explained that electromagnetic or as they are more commonly called when identified with wireless telegraphy1 ,hertzian waves have the power of exciting oscillations in any conductor upon which they impinge4 ,electrical oscillations1 it will be remembered1 are alternating currents of very high frequency4 ,they are generated in the aerial of the receiving station by the action of the waves coming from the distant transmitting station4 ,these currents are exceedingly feeble1 too feeble in fact to operate any form of electrical apparatus except a telephone receiver1 which is one of the most sensitive instruments in existence4 ,illustration3 ,,fig4 #fb4--,portable pack set4 ,the receiving outfit is contained in the left hand case2 also the key and interrupter4 ,the tubular condenser1 spark gap1 and induction coil may be seen in the right hand case4 ,illustration3 ,,fig4 #fc4--;,complete receiving set1 consisting of two ,perikon detectors1 potentiometer1 loose coupler1 variable condenser1 etc4 ,there are probably more different forms of detector than any other piece of radiotelegraph apparatus4 ,those in most common use to-day are the mineral detectors4 ,a small crystal of certain minerals1 iron pyrites1 silicon1 galena1 etc41 is placed between two contact points which are adjustable so that the pressure may be regulated and the most sensitive portion of the mineral selected4 ,a telephone receiver is shunted across the terminals of the detector4 ,illustration3 ,,fig4 #fd4--,showing construction of a watch case telephone receiver4 ,a telephone is shown in diagram in ,fig4 #fd4 ,it consists of a ,u shaped permanent magnet of bar steel1 so mounted as to exert a polarizing influence upon a pair of little electromagnets1 before the poles of which an iron diaphragm is mounted4 ,for convenience these elements are assembled within a small cylindrical casing usually of hard rubber4 ,the permanent magnet exerts a continual pull upon the diaphragm tending to distort it1 concave inwards4 ,when alternating currents are sent through the receiver coils1 that part of the alternation which is flowing in the proper direction to form a magnetic field flowing in the same direction as that of the permanent magnet will strengthen the latter and assist it in attracting the diaphragm and causing it to further approach the magnet4 ,that portion of the current flowing in the opposite direction detracts from the magnetic pull and allows the diaphragm to recede from the magnet4 ,the diaphragm thus takes up a vibrating motion corresponding to the electrical waves supplied to the coil and it imparts motion to the surrounding air1 the result being sound4 ,illustration3 ,,fig4 #fe4--,pickard adjustable telephone receivers for wireless purposes4 ,it might reasonably be asked why a telephone receiver could not be directly connected to the aerial and ground so that it would respond directly to the high frequency currents generated by the incoming waves without the medium of a detector4 ,there are two very good reasons why such a method would not be possible1 the first being that the little magnet coils contained in the telephone receivers exert a choking action upon alternating currents of high frequency which effectually blocks their passage4 ,low frequency alternating currents1 intermittent direct currents and continuous direct currents will readily pass1 producing a sound-each time there is any change in their value4 ,the purpose and action of most types of detectors is to act as a valve allowing the current to pass through in one direction but not permitting it to pass in an opposite one4 ,the high frequency oscillating currents may be represented by a curved line crossing and recrossing a zero line and gradually decreasing in amplitude as shown by ,a in ,fig4 #ff4 ,illustration3 ,,fig4 #ff4--;,illustrating the valve action of a rectifying detector4 ,illustration3 ,,fig4 #fg4--;,a new type of silicon detector in which a crystal of arsenic may be brought to bear against the surface of one of several silicon crystals4 ,the detector1 acting as a valve1 eliminates one half of the alternating current so that the result may be represented by ,b1 in reality a pulsating direct current which rises and falls but is able to flow through the telephone receiver and produce a motion of the diaphragm with consequent sound waves audible to the ear4 ,illustration3 ,,fig4 #fh4--;,diagram drawing analogy between rectifying action of a detector and a pump4 ,the accompanying sketches and the following analogy drawn between the electric currents and the flow of a stream of water may serve to render a better conception of how it is possible for the valve action of a detector to rectify an alternating flow1 continuously reversing its direction to an intermittent current passing in one direction only4 ,the illustration shows two pumps ,a and ,b4 ,each pump is immersed in a pool of water and consists of a cylindrical tube ,t and ,t' having a small opening1 ,o and ,o'1 at the lower end to admit the water and a piston1 ,p and ,p'1 operating up and down inside the tube4 ,every time that the piston ,p is raised in the pump ,a it will draw in water through the small hole ,o4 ,as soon as it descends1 however1 the water will reverse its direction and pass out4 ,the action of the water represents that of an alternating current because it passes in first one direction and then in the other4 ,the pump ,b is fitted with a valve whose action is to permit the water to flow in one direction only4 ,the valve is fitted to the piston ,p'4 ,it is a little flap which opens a hole in the piston when the latter is descending and closes when it is rising4 ,suppose that the piston is raised4 ,water will be drawn in through the little hole ,o'4 ,as soon as the piston reaches the limit of the stroke it commences to descend4 ,in falling it exerts a slight pressure on the valve which opens and allows the water to pass through4 ,the hole in the piston is larger than the hole in the pump and so there is almost none of the water forced back into the pool4 ,the next up stroke of the piston draws more water in1 that which is on top flowing out through the overflow4 ,the nature of the stream passing through the hole ,o' is intermittent1 passing principally in one direction4 ,it may be likened to the intermittent direct current produced by the detector4 ,illustration3 ,,fig4 #fi4--,pyron detector in which a fine wire is brought to bear against a crystal of iron pyrites4 ,some of the many forms of detectors are interesting because of the ingenious manner in which equivalent results are attained4 ,the illustration shows a type of detector known as the ,perikon4 ,two minerals1 zincite 7oxide of zinc7 and chalcopyrites 7copper-iron sulphide71 are mounted in adjustable cups so arranged that the surfaces of the minerals can be brought into variable contact with one another4 ,illustration3 ,,fig4 #gj4--,perikon detector4 ,another very good rectifying detector is that consisting of a flat surface of highly polished silicon mounted in a small cup4 ,a flat brass point mounted on the end of an adjustable thumbscrew is brought to bear on the silicon4 ,illustration3 ,,fig4 #ga4--,silicon detector4 ,other mineral detectors of value are the ,pyron1 molybenite and galena4 ,illustration3 ,,fig4 #gb4--;,electrolytic detector4 ,the carborundum detector is a form of crystal rectifier consisting of a fragment of carborundum held between two carbon blocks4 ,the electrolytic detector consists of a very fine platinum wire 74#jja-4jjjc of an inch in diameter7 dipping into a small cup of dilute nitric acid4 ,a large platinum electrode is sealed in the bottom of the cup so as to make an electrical connection with the liquid4 ,this form of detector is exceedingly sensitive1 probably more so than any other4 ,the electrolytic detector requires a battery4 ,when a slight current passes through the circuit1 very minute bubbles are formed at the wire1 insulating it from the liquid and thus shutting off the battery current from the telephone receivers4 ,however1 upon the arrival of any electric waves and consequent high frequency oscillations the latter destroy the bubbles clustering around the little wire and permit the current to flow4 ,upon the cessation of the high frequency currents the bubbles immediately form again1 only to become broken down by each train of oscillations produced in the aerial4 ,the intermittent currents can be detected by a buzz in the telephone receivers4 ,illustration3 ,,fig4 #gc4--;,electrolytic detector in circuit4 ,the carborundum detector also requires a battery although its action is somewhat different from that just described4 ,illustration3 ,,fig4 #gd4--,potentiometer4 ,when a battery is used in connection with a detector1 an instrument known as a potentiometer becomes necessary4 ,a potentiometer is simply a device for accurately adjusting the voltage of a battery to a value where it will render the detector the most responsive to the incoming signals4 ,illustration3 ,,fig4 #ge4--;,diagram showing how potentiometer is connected in circuit4 ,the ,tuning ,coil is a device for accurately adjusting the oscillation circuits to receive the waves4 ,its action may be illustrated to a certain extent by pressing down the loud pedal of a piano and at the same time whistling a note loudly and clearly4 ,listen carefully and some of the wires in the piano will be heard sounding the note whistled4 ,at each vibration of the note of the whistle a wave of pressure went forth from the lips and reaching the wires gave them all a tiny impulse4 ,the impulses followed each other rapidly at definite intervals giving each of the wires the same push each time4 ,the wires which are tuned to produce the note on the piano corresponding to that of the whistle will vibrate energetically enough to produce a sound themselves4 ,they are the wires to which the impulses are rightly tuned so that each one adds to the motion it has already acquired4 ,we all know how a child sitting in a swing may be made to swing back and forth by giving a succession of little impulses properly timed4 ,the small pushes are superimposed on one another1 the result being a single large motion4 ,illustration3 ,,fig4 #gf4--;,analogy between swinging and tuning4 ,the impulses generated in the receiving aerial are exceedingly weak and in order to produce an effect must be timed so as to follow one another in proper succession4 ,tuning devices are for this purpose and by their means the receiving circuits and instruments may be carefully adjusted to the same wave length or note as the transmitter so that the high frequency currents in the aerial will arrive at the proper time to oscillate or surge back and forth to produce the maximum results4 ,in this way it is possible to convey intelligence over long distances by the repetition of small impulses without it being necessary to send any very energetic ones4 ,by arranging the stations so that each one emits its own definite wave different in period or length from that of the others it is possible to operate several stations at the same time in the same neighborhood without interfering with one another4 ,the apparatus is then said to be selective because the instruments can be adjusted in a few seconds to receive from any desired station and to exclude others4 ,illustration3 ,,fig4 #gg4--,receiving a message in a ,marconi transatlantic station4 ,the tuning coil consists of a cylinder wound with bare copper wire spaced so that the turns do not touch one another4 ,variable contacts called sliders are so arranged that connection can be made almost instantly to any desirable turn of wire4 ,the tuning coil is connected to the aerial and receiving apparatus in the manner illustrated in ,fig4 #gi4 ,by moving the sliders back and forth the wave length of the system may be added to or detracted from and any desired tune quickly reached so that it is possible to listen to any station desirable and exclude the others4 ,the cylinder over which the wire is wound usually consists of a thick cardboard tube treated so as to be moisture proof4 ,bare wire is preferable to all forms of insulated wire4 ,the coil is usually three to four inches in diameter and eight to twelve inches long4 ,illustration3 ,,fig4 #gh4--,tuning coil of the double slide type4 ,illustration3 ,,fig4 #gi4--;,diagram showing fixed condenser in circuit4 ,tuning coils are known as single slide1 double slide and three slide according to the number of contacts they are fitted with4 ,illustration3 ,,fig4 #hj4--;,fixed condenser4 ,the loading coil is a supplementary tuning coil used to furnish extra inductance in case it is desirable to obtain a greater range of resonance or tuning4 ,it is merely a single slide tuning coil connected in series with the regular tuning device4 ,it is not always a necessity but is often part of the equipment when it may be necessary to adjust the apparatus to receive long wave lengths4 ,condensers are devices for collecting and storing electricity4 ,they play a very important part in both the transmitting and receiving operations4 ,condensers and ,leyden jars have already been described in connection with the transmitting apparatus4 ,the condensers used in receiving are very much smaller in size and capacity but are the same in principle4 ,there are two general types of receiving condensers called fixed and variable accordingly as the capacity is alterable or not4 ,fixed condensers consist of a few sheets of tinfoil interposed between sheets of paraffined paper or in some cases mica4 ,the condenser is inclosed in a suitable case1 usually a hollow molded block of insulating composition1 and is provided with suitable terminals to facilitate connection4 ,illustration3 ,,fig4 #ha4--,rotary variable condenser4 ,when a conductor is charged with electricity it has the power of exerting an opposite charge in any adjacent conductors4 ,the two halves of a condenser constitute adjacent conductors1 the separating medium in between being called the dielectric4 ,an alternating current will pass through a condenser because the charge on the plates keeps changing from negative to positive and back from positive to negative again4 ,a direct current will not pass through a condenser4 ,these facts are utilized to considerable advantage in the receptor of a wireless station4 ,as has already been explained1 the high frequency oscillatory currents will not readily pass through the coils of the telephone receivers1 but a path is provided through the condenser4 ,the detector rectifies the alternating current into a direct current which the condenser opposes and forces to pass through the telephone receiver and produce sounds4 ,when a battery is used in connection with a detector a condenser is also necessary to oppose the direct current of the battery and prevent it from flowing around through the tuning coil instead of through the detector4 ,the capacity of the condenser may be smaller if the resistance of the telephone receiver is very great for the reason that as the wire grows smaller it offers greater impedance to the current4 ,the opposite also holds true and condensers of large capacity are better fitted for use with telephone receivers of low resistance4 ,illustration3 ,,fig4 #hb4--;,interior of rotary variable condenser showing construction4 ,variable condensers are divided into two general types1 the rotary and the sliding plate1 accordingly as the plates forming the condenser are adjusted with a rotary or a sliding motion4 ,the rotary type consists of a number of movable semi-circular aluminum plates which swing between a series of fixed semi-circular plates of a slightly larger diameter4 ,the plates must not touch one another and move back and forth with perfect freedom4 ,the dielectric is formed by the air spacing between the plates4 ,illustration3 ,,fig4 #hc4--;,dr4 ,seibt's rotary variable condenser4 ,the plates are turned from a solid casting and the separation between is only 4#ja inch4 ,the advantage of an air dielectric is that no losses of energy take place through hysterisis4 ,hysterisis is the lagging which takes place in the process of charging and discharging4 ,a thumb knob is fitted to the movable plates and provided with a pointer moving over a graduated scale so that the degree of capacity in use is indicated4 ,illustration3 ,,fig4 #hd4--,sliding plate variable condenser4 ,in the sliding plate type of variable condenser the plates are either square or rectangular in shape and move back and forth in grooves cut in a hardwood frame as shown in the illustration4 ,variable condensers are used for tuning and adjusting the receiving circuit in the same way that a tuning coil is employed1 namely to increase or decrease the electrical length of the circuit so that it will respond to different wave lengths4 ,the condensers are capable of finer adjustment than tuning coils because the change is gradual and even and is not in jumps from one step to another as from one turn to the next turn of the coil4 ,if the desired point of resonance should happen to come between two wires of the coil and not in a position to be reached by the slider1 the variable condenser can be adjusted to reach the exact degree of resonance and thus bring the circuit into finer adjustment than would otherwise be possible4 ,the exact way in which this is accomplished and the effect upon the circuit will be left to the next chapter4 ,illustration3 ,,fig4 #he4--;,diagram showing arrangement of rotary variable condenser in receiving circuit4 ,,chapter ,v4 ,,tuning ,,and ,,coupling1 ,,directive ,,wave ,,telegraphy4 ,tuning has been mentioned in several places but not explained in any greater measure than was necessary to render a conception which would enable the reader to follow the text intelligently in order not to depart from the subjects under discussion there and consequently defeat the purpose of clearness4 ,the great importance and value of properly tuning the circuit of radiotelegraphic apparatus cannot be overestimated and for that reason the subject can hardly be passed without some further explanation4 ,its effects are two-fold4 ,in the first place it is always desirable and highly important that wireless messages should be1 so far as is possible1 selective1 inasmuch as there are often several stations in the same immediate neighborhood operating at the same time4 ,this result is reached by tuning and it is possible for them all to transmit different messages at the same time without confusion by the proper arrangement of the wave length4 ,the second effect is the transmission of messages over long distances with the comparative consumption of small amount of power by adjusting the period or electrical length of the circuits until the oscillations flow in harmony with each other and resonance is secured4 ,perhaps the only way that these results may be made clearly intelligible is by resort to a graphical example4 ,suppose that a very heavy weight were suspended from a chain as shown in the illustration and that it is struck at regular intervals1 once every second1 with a hammer4 ,every time that the hammer strikes the ball it will give it an impulse and cause it to swing slightly4 ,if the chain is short1 the ball will swing faster1 while if it is long it will swing more slowly4 ,we will suppose that the ball is struck from such a direction that it starts to swing over toward ,a4 ,the ball is so heavy and the hammer so light in comparison however that the ball does not swing very far and soon commences a return journey4 ,if it should return to the point ,b just as the hammer delivers another blow the force of the blow will be expended in stopping the ball rather than adding to its motion because they are both traveling in opposite directions4 ,however if the chain is lengthened so that it has a period of swing lasting one second1 the succeeding blow will strike the ball after it has reached the point ,c and is on its return journey1 thus imparting fresh energy because both the ball and hammer come together at the right time when they are both swinging together4 ,proper adjustment of the length of the chain will make it possible for the hammer to always descend at the right moment to add its energy and motion to that previously given the ball4 ,the result will be considerable increase in the amplitude of the swing4 ,illustration3 ,,fig4 #hf4--;,chain and ball arranged to illustrate effect of tuning4 ,from this we may easily perceive how it is possible by shortening or lengthening the period of an electrical circuit to so adjust it that resonance is secured and each succeeding oscillation will take place at the proper time to assist the previous one1 not dying away after one or two surges and becoming what is known in technical language as rapidly damped4 ,illustration3 ,,fig4 #hg4--,loose coupled helix4 ,the instruments for accomplishing these things consist as previously explained1 in the case of a transmitter1 of the helix and in the receiving station of various tuning coils and condensers4 ,illustration3 ,,fig4 #hh4--;,hot-wire ammeter4 ,helix and tuning coils are divided into the inductive or loose and the direct or close coupled types4 ,inductive tuning coils are known as loose-couplers and receiving transformers4 ,inductive helixes consist simply of two helixes1 separated from one another as shown in the accompanying illustration4 ,the upper helix1 called the secondary1 can be raised or lowered upon a central support4 ,varying the distance between the primary and secondary is varying the coupling4 ,there are several advantages derived by using loose coupled sending helixes1 the chief of which lie in the fact that it is possible to radiate larger amounts of energy and also decrease the damping4 ,illustration3 ,,fig4 #hi4--,the principle of the hot-wire ammeter4 ,in order to tune a transmitter1 the hot-wire ammeter is necessary4 ,this instrument makes use of the property which electrical conductors possess to become heated and expand when a current is passed through them4 ,the accompanying diagram serves to illustrate the principle of the hot-wire meter4 ,a piece of platinum wire is stretched tightly between two rigidly fixed posts4 ,a thread leads from the center of the hot wire to a small spindle around which it passes once or twice4 ,the spindle is also connected to a spring which exerts a continual tendency to turn the spindle but is prevented from so doing by the thread attaching to the hot wire4 ,any tendency on the part of the string to slacken a little1 however1 will immediately permit the spring to turn the spindle4 ,when a high frequency current is passed through the platinum wire it becomes heated and expands4 ,the expansion of the wire allows the thread to slacken slightly with the immediate result that the spindle turns4 ,the spindle carries a pointer at the upper end which shows the amount of turning4 ,it is therefore easy to tell the comparative strength of current flowing accordingly as the deflection is great or small4 ,illustration3 ,,fig4 #ij4--;,diagram showing loose coupled helix in circuit4 ,the meter is placed in series with the aerial and when the high frequency currents pass through it they heat and expand a fine wire1 causing the needle to move over a graduated scale and indicate the amount of current passing4 ,the apparatus is tuned or in resonance when the length of the spark gap1 the condenser and the helix have been so adjusted that the oscillations flow freely through the system and the maximum amount of current is indicated by the ammeter4 ,illustration3 ,,fig4 #ia4--,loose coupled tuning coil4 ,illustration3 ,,fig4 #ib4--,loose coupled tuner4 ,the loose coupled tuning coil consists of two windings wound over two concentric cylinders1 forming a primary and a secondary4 ,the secondary is the smaller winding and slides in and out of the primary so that the coupling is variable4 ,the primary is adjustable by means of a slider and the secondary by means of a multi-pointed switch4 ,the slider is usually connected to the aerial and one end of the coil to the ground4 ,the detector1 etc41 are connected to the terminals of the secondary4 ,variable condensers may be added with good results to both the primary and secondary circuits4 ,illustration3 ,,fig4 #ic4--;,diagram showing position of loose coupler in circuit4 ,loose couplers also take the form of doughnut tuners in which the secondary revolves instead of slides4 ,the coupling is variable in such an instrument by simply turning the secondary4 ,the wave emitted from a transmitter is in reality made up of two waves of different lengths4 ,the variation in the lengths of these two waves is dependable upon a factor known as the coefficient of coupling4 ,it is almost impossible to clearly explain the phenomenon and in order not to confuse and complicate by a rather lengthy explanation it may be well to simply state that its effect is to make selective tuning difficult unless the coupling of the receiving station can be varied to correspond with that of the transmitter and ask the reader to take it for granted4 ,varying the coupling adjusts the difference in the two wave lengths and when properly accomplished renders the apparatus highly selective4 ,illustration3 ,,fig4 #id4-;,fort ,gibbons1 ,alaska1 wireless station4 ,illustration3 ,,fig4 #ie4--,transmitting condenser 7molded dielectric74 ,directive ,wireless ,telegraphy is an interesting phase of this new art which is receiving considerable attention in the hands of investigators and has resulted in the devisement of several successful systems for confining the propagation of the electric waves to certain directions4 ,illustration3 ,,fig4 #if4--;,braun's method for directing wireless telegraph signals4 ,a general diffusion of waves is often very undesirable for the reasons that the message may be received by an unfriendly neighbor or enemy and also because it is wasteful of energy4 ,by so directing the waves that they may be sent over the earth to any desired point of the compass and only in that direction1 it is possible to communicate without disturbing another station and also for a vessel at sea to secure its bearings and position by tuning its apparatus to respond to electric waves from two different known stations4 ,the manner in which the problem has been solved varies considerably according to the inventor4 ,all are interesting and ingenious4 ,it will be remembered that electric waves possess all the characteristics and properties of light waves1 etc41 and may be reflected1 refracted and polarized4 ,ferdinand ,braun has devised a system consisting of a number of metallic strips arranged to compose a parabolic surface4 ,another similar set of strips below the first set completes the arrangement4 ,the two sets are connected to the terminals of a spark gap and induction coil4 ,this apparatus acts as a huge reflector and sends out waves in one direction only1 but however interesting and ingenious it may be is not entirely practical4 ,illustration3 ,,fig4 #ig4--;,bellini-,tosi radio-goniometer for directive wireless telegraphy4 ,another method devised by ,braun employs two or more aerials at certain distances apart4 ,the alternating currents used to excite the oscillations differ in phase1 i4 e4 are so arranged that they have different comparative values at the same moment4 ,it is possible to send very strong signals in a direction lying in the same plane as the aerials4 ,by the use of three or more antennae suitably differing in their phase of excitation and situated at the vertices of a triangle it is possible to send strong signals in certain directions only4 ,illustration3 ,,fig4 #ih4--;,arrangement of ,bellini and ,tosi for directive wireless telegraphy4 ,messrs4 ,bellini and ,tosi have devised a very ingenious method of directively transmitting and receiving electric waves as shown in the accompanying diagrams4 ,the antenna consists of two closed or nearly closed circuits of triangular shape arranged in two perpendicular planes4 ,the two aerials each contain a circular coil of wire perpendicular to each other with their windings in the planes of the antenna circuits respectively4 ,a third coil is connected to the receiving apparatus when the messages are incoming and to the condenser1 spark gap and coil when the signals are to be transmitted4 ,waves coming in from any particular direction produce oscillations in the two aerial circuits whose intensity varies according to the direction in which the waves ,these currents passing through the coils generate a magnetic field having a direction perpendicular to that from which the waves come4 ,the strength of the currents in the movable coil will depend upon its position in the resultant magnetic field and will be at a maximum when the coil embraces as many as possible of the lines of magnetic force4 ,illustration3 ,,fig4 #ii4--;,complete receiving and transmitting outfit4 ,by providing the movable coil with a pointer it is possible to thereby determine the plane in which the station producing the signals lies4 ,any ambiguity regarding the final position of the station1 whether it is located in the same direction indicated by the pointer or in the opposite one1 is only removed by general knowledge of the location of existing stations4 ,the processes involved in sending messages are the reverse of those entering into the receiving apparatus4 ,the movable coil being connected with the condenser1 gap and transformer or induction coil creates a magnetic field which induces oscillating currents in the other two coils and consequent waves in the aerial whose strongest exertions will lie in a plane determined by the third coil4 ,changing the position of the latter will send the messages in any direction desired4 ,,chapter ,,vi4 ,,the ,,dignity ,,of ,,wireless4 ,,its ,,applications ,,and ,,service4 ,,wireless ,,in ,,the ,,army ,,and ,,navy4 ,,wireless ,,on ,,an ,,aeroplane4 ,,how ,a ,,message ,,is ,,sent ,,and ,,received4 ,wireless telegraphy and that precocious infant1 wireless telephony1 have outlived all the speculative and tentative achievements of their early days and have established themselves in an important and settled position among our methods of conveying intelligence4 ,the field has been so greatly enlarged in recent years and the apparatus and methods so improved that the broadest possible view of its future development and importance is justified4 ,and there must inevitably come the time when our merchant marine and wireless service will come under such reasonable regulation that it will be removed from any dependence upon stock jobbing wireless telegraph and telephone companies4 ,illustration3 ,,fig4 #ajj4--,special light weight wireless telegraph set for airship service4 ,official sources show that the equipping of sea-going vessels with wireless apparatus is progressing at a rapid rate and it is not difficult in the face of certain facts to appreciate the enormous volume of business that sooner or later will be handled by wireless4 ,three hundred and sixty-three ,united ,states naval vessels and about eight hundred merchant vessels are equipped at this writing4 ,the large number of commercial shore stations1 army forts and posts1 and those used by corporations1 isolated stations1 etc41 for various private purposes comprise a list which reaches an enormous total4 ,illustration3 ,,fig4 #aja4--,telefunken wireless cart1 showing transmitter4 ,whatever may have been the status of wireless previous to the ,titanic disaster1 it now occupies a position far more important than that taken merely from any commercial standpoint1 for it is no longer merely a convenience to business or a means of furnishing the latest news for the entertainment of passengers1 but is a life-saving proposition taking its place with the elaborate and costly systems of railroad signals4 ,illustration3 ,,fig4 #ajb4--,telefunken wireless cart for military service1 showing receiving apparatus4 ,illustration3 ,,fig4 #ajc4--,telefunken wireless wagon set in operation at ,fort ,leavenworth1 ,kansas4 ,the aerial is of the umbrella type supported by a steel pole resting on a porcelain base4 ,it is a curious fact that many of the most startling and newest inventions find ready and peculiar application as an aid in modern warfare4 ,the nerves of every war vessel and fort are the wires of the telephones1 telegraphs1 telautographs1 dynamos1 storage batteries etc41 that transmit orders by speech or in writing1 find the range1 fire the guns1 explode the mines and seek out the enemy with a powerful searchlight4 ,every battle-ship1 cruiser1 etc41 of the ,united ,states ,navy is now equipped and with the completion of the new ultrapowerful station at ,washington the ,war ,department will be enabled to issue instructions to a ship no matter where it may be on the ocean or in what harbor it may lie4 ,the government maintains an elaborate equipment at the ,brooklyn ,navy ,yard where the future wireless operators of the ,navy are given a course extending from seven to ten weeks4 ,the first few days are spent in mastering the theory4 ,the second week usually commences alternate study and practice of the ,continental ,code which lasts throughout the entire course or until thoroughly mastered4 ,each week some special branch of study is given out such as repairing and overhauling certain instruments4 ,at the end of seven weeks the student can usually send and receive #ae words a minute4 ,he is then given two weeks to prepare for an examination which if passed rates him as an electrician1 third class1 and qualifies him for active work4 ,illustration3 ,,fig4 #ajd4--,wireless room aboard the ,u4 ,s4 transport ,buford4 ,it is certain that wireless telegraphy and telephony will be important factors in military campaigns of the future4 ,for coast defense1 wireless is as valuable as on the ocean4 ,illustration3 ,,fig4 #aje4--,the apparatus set up for operation4 ,this method of transmitting army orders is quite dependable4 ,with the most recent developments and improvements it is now possible to direct the movements of a great army and navy simultaneously from a centrally located point4 ,illustration3 ,,fig4 #ajf4--,wireless equipped automobile4 ,one of the most interesting and spectacular applications of wireless telegraphy in military service is the wireless telegraph automobile4 ,the automobile is a stock pattern touring car of #cj ,h4 ,p4 provided with a special body arranged to carry six passengers4 ,the seats are elevated so as to afford storage space below for the entire wireless equipment and a truly astonishing amount of miscellaneous supplies4 ,illustration3 ,,fig4 #ajg4--;,company ,d ,signal ,corps at ,san ,antonio ,texas1 #aiaa1 showing pack sets and telescoping pole carried by pack mules4 ,the mast used to elevate the aerial is of light steel construction divided into eight sections which nest into one another with admirable economy of space4 ,the socket for the foot of the mast is located in the center of the tonneau4 ,only a few minutes are required to raise the mast and aerial4 ,the same gasoline motor employed to drive the automobile also drives a small dynamo which supplies the electric current for the transmitting apparatus4 ,two of these cars have been experimentally operated over a number of the old battle-fields of the ,civil ,war4 ,illustration3 ,,fig4 #ajh4--,u4 ,s4 ,signal ,corps pack sets shown open and closed4 ,receiving apparatus on the left4 ,the tests were made under all sorts of road and weather conditions but no great difficulty was experienced in establishing communication over distances varying from #ce to #ej miles4 ,there is probably no application of wireless telegraphy1 however1 quite as picturesque as the combination of wireless and an aeroplane and the idea of a double seated aeroplane carrying an aviator and a wireless operator hovering over a hostile country to keep the commanding officer informed of all conditions and movements of the enemy4 ,illustration3 ,,fig4 #aji4--,the receiving apparatus of the airship ,america 7,wellman expedition74 ,the huge dirigible balloon ,akron in which ,melville ,vanniman proposed to cross the ,atlantic ,ocean was fitted with wireless equipment in order to transmit news of the expedition en route to various of the daily newspapers of ,new ,york and ,london and also in case of an accident or emergency to summon aid4 ,illustration3 ,,fig4 #aaj4--;,interior of the ,n4 ,y4 ,herald 7,o4 ,h4 ,x47 press station4 ,the equipment is interesting because of the peculiar conditions imposed upon instruments to be used under such circumstances4 ,a three kilowatt transformer1 the latest type of musical rotary gap and a valve detector were included in the outfit4 ,it was proposed to obtain the necessary ground connection by trailing a #abjj foot phosphor bronze ground lead in the ocean4 ,the frame of the balloon was to be used as the aerial4 ,should it have become necessary to take the lifeboat which the balloon carried1 a kite would have been raised and by substituting a copper wire in lieu of a string an aerial provided1 and once more a ,,cq ,d and its appeal for aid would have gone vibrating forth through the ether4 ,illustration3 ,,fig4 #aaa4--,operating the ,u4 ,s4 ,signal ,corps airship wireless apparatus4 ,several enterprising newspapers have recognized the value of wireless telegraphy in collecting shipping news and have installed outfits for the assistance of their reporting bureau4 ,this innovation in modern journalism has quickly developed into a useful feature of those publications which have seen fit to adopt it4 ,when the baseball season is under way every steamship within calling distance wants the latest baseball scores or sporting results4 ,illustration3 ,,fig4 #aab4--,the ,n4 ,y4 ,herald station1 showing aerial4 ,illustration3 ,,fig4 #aac4--,operator ,jack ,irwin overhauling the wireless apparatus for the dirigible balloon ,america4 ,railroads have found an auxiliary wireless service to be of the utmost value in relieving the heavily loaded wire lines between important centers4 ,during some of the winter storms and blizzards1 when miles of wires were down in all directions1 wireless has been the sole means of communication in certain instances4 ,the process of sending a wireless message is very simple4 ,the aerial switch is usually kept in such a position that the receiving instruments are connected to the ground and aerial so that the operator is always able to hear any one calling him4 ,we will suppose for illustration that the land station at #db ,broadway1 ,new ,york ,city1 wishes to transmit a message to the steamer ,horatio ,hall4 ,illustration3 ,,fig4 #aad4--,morse code4 ,every wireless station on land or sea has assigned to it two or more call letters1 which distinguish it from all other stations1 and serve as the key to messages intended for it to receive and when signed to a message as an indication of its origin4 ,the call of the land station in this case is ,n4 ,y41 and that of the steamer1 ,j4 ,h4 ,illustration3 ,,fig4 #aae4--;,continental code4 ,in order to send the message to the ship1 ,n4 ,y4 throws the aerial into position for sending4 ,this act also starts the motor generator set supplying current to the transformer4 ,pressing the key1 the operator then signals in the telegraph code ,j4 ,h41 ,j4 ,h41 ,j4 ,h4--,m4 ,s4 ,g4-,n4 ,y4--and gives the finish signal4 ,m4 ,s4 ,g4 is the abbreviation for message4 ,the ,n4 ,y4 operator then throws his switch back into the receiving position and waits for a reply4 ,if one is not forthcoming shortly the calling process is repeated4 ,illustration3 ,,fig4 #aaf4--,transmitting equipment of the high power station at ,nauen1 twenty-five miles northwest of ,berlin1 ,germany1 showing six induction coils 7in the foreground7 arranged to charge the ,leyden jars 7composed of #cfj units74 ,illustration3 ,,fig4 #aag4--;,duplex receiving apparatus4 ,the set to the left may be adjusted to receive short wave lengths and that to the right to receive long waves4 ,when the handle of the listening key1 shown in the center of the illustration1 is in the center1 the left hand phone of the head set is connected to the instruments on the left and the right hand phone to those on the right1 so that the operator is always ready to receive either short or long waves if received4 ,swinging the key connects both phones to either set at will4 ,as soon as the operator on board the steamer hears the call1 he waits until the finish signal is received1 and then responds in the following manner3 ,n4 ,y41 ,n4 ,y41 ,n4 ,y4--,j4 ,h4--,o4 ,k41 ,o4 ,k4--,g4 ,a4--,g4 ,a4--,n4 ,y41 ,j4 ,h4--and gives the finish signal4 ,o4 ,k4 is the abbreviation for all right1 and ,g4 ,a4 means go ahead4 ,upon receipt of this1 the land station transmits the body of the message1 and signs its call and finish signal4 ,if the steamer understands the message1 she replies ,o4 ,k41 and signs4 ,illustration3 ,,fig4 #aah4--;,breaking-in system4 ,there are two ,codes in general use for wireless telegraph purposes1 the ,morse and ,continental4 ,it takes about five per cent4 longer space of time to send a message in ,continental than it does in ,morse1 but the former has the advantage of not containing any letters requiring proper spacing in order to be recognizable4 ,american coastwise steamers use the ,morse code2 transatlantic ships use the ,continental code4 ,one of the greatest disadvantages of most systems of wireless telegraphy lies in the fact that no arrangement is provided for simultaneously transmitting and receiving wireless signals4 ,it is usually necessary for one operator listening to another to have to wait until the finish signal is given before he can reply or interrupt in case he cannot understand part of the message1 because the receiving apparatus of the transmitting station is necessarily disconnected from the aerial and the ground during the period a message is being sent4 ,if it were to be connected at this time the powerful currents of the transmitter would rush through the receiving apparatus into the ground without setting up any very powerful waves in the aerial and seriously injure the delicate receiving instruments4 ,the ,breaking-in-,system is a method of simultaneously transmitting and receiving wireless signals4 ,this is accomplished by providing the transmitting key with a second set of contacts1 so arranged that when the key is released between the dots and dashes of the code the aerial and ground are automatically connected to the receiving apparatus4 ,when the key is pressed the receptor is automatically cut off4 ,the advantages of such a system are more or less obvious4 ,when interference or a misunderstanding occurs the fact can be immediately signaled to the sending operator1 and the message commenced over again4 ,illustration3 ,,fig4 #aai4--,the receiving apparatus of the station at ,nauen4 ,the message is being printed on tape by a recording device4 ,,chapter ,,vii4 ,,the ,,ear4 ,,how ,,we ,,hear4 ,,sound ,,and ,,sound ,,waves4 ,,the ,,vocal ,,chords4 ,,the ,,structure ,,of ,,speech4 ,on either side of the head1 lodged in a cavity which they do not completely fill1 and situated in the midst of a dense and solid mass of bone1 entering into the base of the skull and forming the temporal bone1 are two membraneous bags called the membraneous labyrinth and the scala media of the cochlea4 ,each bag is filled with a liquid1 and is also surrounded and supported by a fluid which fills the cavity in which they are lodged4 ,certain small1 hard bodies1 free to move around1 lie in the fluid of the bag4 ,the ends of the auditory nerve of hearing are distributed around the wall of the sac1 so that they are subjected to the blows of the little particles of calcareous sand1 or otoconia1 as they are called1 whenever the fluid in the bags is disturbed4 ,illustration3 ,,fig4 #abj4--;,diagram of the ear4 ,the membraneous lining on which the ultimate ends of the nerves are spread is virtually a sensitive beach1 and the little otoconia1 showers of pebbles and sand1 which are raised and let fall by each succeeding wavelet of sound4 ,this wonderful mechanism constitutes the inner ear4 ,the ear1 as a whole1 consists of three parts3 the outer ear1 which is a trumpet-shaped passageway called the pinna serving to collect the sound waves and pass them on through the auditory canal to a small membrane called the eardrum2 the ossicles1 a series of three little bones1 the hammer1 the anvil1 and the stirrup1 they are called2 and the inner ear just described4 ,illustration3 ,,fig4 #aba4--,the ossicles4 ,the foot of the stirrup is connected with an oval membrane1 which closes a hole in the inner ear4 ,sounds passing through the auditory canal cause the drum to vibrate and send tremors through the bones to the liquid in the little sacs4 ,the tumbling of the pebbles against the filaments of the auditory nerve sends the intelligence to the brain4 ,the impression which the mind receives through the organ of hearing is called sound4 ,all bodies which produce sounds are in a state of vibration1 and they communicate their vibrations to the surrounding air and thus set it into waves1 just as a stick waved back and forth in a pool of water creates ripples4 ,sound implies vibration1 and whenever a sound is heard some substance1 a solid1 a liquid1 or a gas is in vibration and the surrounding air is in unison with it4 ,illustration3 ,,fig4 #abb4--;,bon jour 7good day in ,french7 as represented by a wave picture4 ,the picture was made by a mirror arranged to move under the influence of the voice and to cast a beam of light upon a strip of sensitized paper4 ,sound has been likened to a picture painted not in the space and color of substance but in time and motion4 ,what really passes out from the source is merely a rhythmical motion of the air particles1 manifesting themselves as changes in pressure1 spreading out in ever-widening spheres through the atmosphere4 ,the order of these compressions is different for every sound4 ,the musical sounds of an orchestra embody a different set of vibrations for each note of each particular instrument4 ,if the fluctuations in pressure of a sound wave are irregular and non-periodic1 the sound is called a noise2 if they are cyclic1 and follow a regular and sufficiently rapid periodic lag1 the sound is musical4 ,we may easily satisfy ourselves that in every instance in which the sensation of sound is produced the body from whence the sound comes must have been thrown into a state of rapid tremor1 implying the existence of a motion to and fro of the particles of which it consists4 ,illustration3 ,,fig4 #abc4--;,experiment showing sounding bodies are in vibration4 ,if the face of a tuning fork prong be touched with a small ball of cork suspended from a fine silk fiber1 after the fork has been struck and caused to emit its note1 the cork will be violently repelled from the latter4 ,why8 ,because the prong of the fork is in vibration4 ,if a small wire or bristle is fastened to the prong of the fork and a piece of smoked glass drawn across it while the fork is giving forth a sound1 the trace of the point will appear as a wavy line1 showing that while the glass was drawn along the prong went to and fro many times4 ,the vibrations or disturbances set up in the air by a sound emitting body are known as sound waves4 ,these waves consist of a series of condensations and rarefactions succeeding each other at regular intervals1 each air particle swinging to and fro in a very short path4 ,illustration3 ,,fig4 #abd4--,method of registering vibrations of a tuning fork4 ,air waves cannot be seen by the naked eye1 but their nature may be easily represented or illustrated4 ,fig4 #abf gives a pictorial representation of the crowding together of the air particles during the passage of a wave4 ,the loudness of the sound depends upon the amount and suddenness of the change in pressure1 and the note or pitch on the number of complete to and fro motions of the particles per second4 ,illustration3 ,,fig4 #abe4--,wavy line made by a bristle attached to a tuning fork prong in vibration when passed over smoked glass4 ,the timbre of a sound or the quality that distinguishes the note of a violin from that of a piano depends upon the smoothness or abruptness of the changes in pressure4 ,therein lies the difficulty of the production of sound by means of a phonograph or telephone1 for the sound waves must resemble each other in every detail in order that the result may be like the original4 ,illustration3 ,,fig4 #abf4--;,illustrating the action of air waves4 ,the mechanism with which we speak or sing is composed of two flexible membranes1 stretched side by side across a small cylindrical box located at the top of the windpipe4 ,the membranes are called the vocal chords1 and the box the larynx4 ,the chords are so arranged and controlled by muscles that their tension may be changed at will4 ,in breathing1 the air to and from the lungs passes freely between the chords4 ,when the controlling muscles are tightened1 so as to stretch the chords1 the edges are also brought parallel and quite close to each other4 ,if the breath from the lungs is then forced through the narrow slit between them1 they vibrate like the reed of a musical instrument1 and produce the sounds of the voice4 ,the multitude of sounds which it is possible for a human being to produce are the result of various degrees of stretching of the vocal chords1 together with the movements of the mouth1 lips and tongue4 ,illustration3 ,,fig4 #abg4--,the vocal cords in position for making a sound4 ,illustration3 ,,fig4 #abh4--,the vocal when relaxed4 ,speech is the sound produced by the vocal chords of a human being1 modified by the movements of the lips1 tongue1 and cavity of the mouth4 ,the consonants are made by movements of the tongue and lips obstructing the sounds at their beginning or end1 while the vowels are formed by a steady voice modified by the resonance of the different shapes or sizes given the parts of the mouth4 ,the waves produced in this manner are transmitted to the ear1 and the sensation of sound is caused by the impact of the otoconia against the auditory nerve1 giving a series of impressions1 musical or unmusical1 pleasing or displeasing1 as the case may be4 ,many interesting experiments showing the nature of the sounds of the human voice may be performed by means of a simple apparatus invented by ,koenig of ,paris4 ,a box is separated into two compartments by a rubber membrane4 ,gas is led into one of these compartments by a rubber tube1 and then allowed to issue to a burner4 ,the other compartment is connected to a megaphone4 ,illustration3 ,,fig4 #abi4--,koenig's manometric flame apparatus4 ,illustration3 ,,fig4 #acj4--;,appearance of manometric flames in a revolving mirror4 ,two pieces of mirror are arranged so as to revolve in front of the lighted jet or burner4 ,when the human voice is produced in front of the megaphone1 the air waves strike the membrane and cause changes of pressure in the gas4 ,the height of the flames varies with each change in the pressure1 and when viewed in the mirror resemble a band of light having an edge like a saw4 ,the teeth are faithful representations of the changes in the voice1 and immediately take on a new appearance when a new sound is emitted4 ,the shape of the teeth changes with the tone1 and the number of teeth with the pitch4 ,fig4 #acj shows the flames produced by singing the sound oo1 as in tool4 ,the same sound an octave lower in pitch will show as in ,b1 where there are just one-half as many teeth or vibrations4 ,the sound of oo is a simple sound4 ,if o on the note is sung into the megaphone1 the image in the mirror will appear like that shown by ,c1 being made up of alternating large and small teeth1 the former corresponding to every alternate vibration of the octave of the higher sound coinciding with a vibration of the octave below4 ,illustration3 ,,fig4 #acj a4 ,the sound causing the flame to appear1 as in ,d1 is made up of two simple vibrations combined4 ,,chapter ,,viii4 ,,the ,,telephone ,,transmitter ,,and ,,receiver4 ,,the ,,photo ,,phone4 ,,the ,,thermophone4 ,,the ,,selenium ,,cell4 ,,the ,,speaking ,,arc4 ,the telephone is an instrument for the transmission of sounds to a distance by the agency of electricity1 wherein the speaker talks to an elastic plate of thin sheet-iron1 which vibrates and transmits its every movement1 electrically1 causing it to vibrate in an identical manner and emit the same sounds4 ,the transmission of the vibrations depends upon well known principles of electricity1 and consists1 not of an actual transmission of the sounds1 but the passage of electric waves1 or impulses1 which keep perfect accord and agree in phase and period with the atmospheric waves produced by the voice4 ,these in turn1 through the medium of an electromagnet1 cause vibrations of a plate or membrane1 which agitates the air in a manner similar to the original disturbance1 and thus emits sounds4 ,the parts of the apparatus which take up the sound waves and change them into electric currents compose the transmitter4 ,in the form of transmitter most commonly used1 the motions of the diaphragm cause variations in the strength of a current flowing from a battery by varying the resistance in the path of the electric current4 ,the sounds are directed to the mouthpiece1 which causes the vibrations of the air to strike the diaphragm1 on the back and center of which is fastened a small cup shaped piece of carbon4 ,a second cup is mounted in a rigid position directly in back of the first4 ,the space between is filled with small polished granules of carbon4 ,illustration3 ,,fig4 #aca4--;,diagram of a telephone transmitter4 ,when these are in a perfectly free and loose state their resistance to an electric current is very great1 and they allow almost none to flow4 ,when slightly compressed their resistance is greatly lowered1 and they permit the current to pass4 ,the vibrations of the diaphragm exert a varying pressure upon the granules1 with a corresponding variation in their resistance and the amount of current flowing4 ,illustration3 ,,fig4 #acb4--;,diagram showing the principle and construction of the telephone receiver4 ,the receiver1 as has already been explained1 consists of a thin iron disk1 placed very near but not quite touching the end of a small bar of steel1 permanently magnetized1 about which is wound a coil of fine insulated wire4 ,the ends of this coil are connected to the wires leading from the transmitter and battery4 ,the varying currents of electricity1 produced by the transmitter1 generate corresponding changes in the magnetism of the receiving instrument1 and thus1 by alternately attracting and repelling the diaphragm1 cause it to vibrate and emit sounds4 ,illustration3 ,,fig4 #acc4--,the photophone4 ,alexander ,graham ,bell1 the ingenious inventor of the telephone1 with the aid of ,sumner ,tainter was the first who achieved success in the attempts to transmit speech without the aid of connecting wires between the source of intelligence and the receptor4 ,in #ahgc ,willoughby ,smith announced that the element selenium possesses the abnormal property of changing its electrical resistance under the influence of light4 ,bell and ,tainter took advantage of this discovery1 and devised selenium cells1 in which selenium is formed into narrow strips between the edges of broad conducting plates of brass4 ,the resistance of the cell in the darkness is approximately twice the resistance when illuminated4 ,illustration3 ,,fig4 #acd4--,photophone receiving apparatus4 ,illustration3 ,,fig4 #ace4--,photophone transmitting apparatus1 using acetylene flame to furnish light4 ,this property of the cell was immediately applied to the construction of the photophone1 an instrument which transmits sounds to a distance by means of a beam of light reflected to a distant spot from a thin mirror thrown into vibration by the voice4 ,over fifty different forms were devised but the most successful consisted of a transmitter composed of a glass disk1 silvered to reflect a pencil of light focused from the sun1 or an arc lamp4 ,this glass disk was used as a diaphragm similar to that of an ordinary telephone transmitter1 except that the rear side of it was made free to reflect the beam of light4 ,bell used for this purpose disks about two inches in diameter and the thickness of ordinary paper4 ,the receiver consisted of a parabolic reflector1 with a selenium cell placed at its focus4 ,in series with the cell was placed a battery and telephone receiver4 ,when the membrane was set into vibration by the sound waves1 it became alternately concave and convex1 the normally parallel rays of light correspondingly converging and diverging4 ,the receiving station was thus under the influence of light rays of rapidly varying intensity in perfect phase with the vibrations of the voice4 ,the reflector concentrated the rays on the selenium cell1 and their varying strength changed its resistance and caused a pulsating current to flow through the receiver and reproduce the speech produced at the transmitter4 ,in another arrangement employed by ,bell and ,tainter1 they used the rays of a powerful electric arc lamp1 and by varying the electric current supplying the arc caused the light to fluctuate and produce the same results at the receiver4 ,these ingenious inventors also devised a method of transmitting speech called the thermophone4 ,the transmitter remained the same as in the photophone-a thin silvered membrane1 or glass diaphragm1 stretched across the back of a mouthpiece1 and arranged to reflect the rays of the sun1 or the light of an arc lamp4 ,the receiver was a small glass bulb containing a plate of mica covered with lampblack1 or little charred pieces of cork4 ,the glass bulb was placed in the focus of a reflector1 which collected the rays and concentrated them4 ,the variations in the intensity of the heat radiations caused the air in the bulb to expand or contract with each vibration4 ,rubber tubes extended from the bulb to the ears of the observer1 and the pulsations of air1 traveling through the tube as sound waves1 would strike the ear-drum and reproduce the speech4 ,illustration3 ,,fig4 #acf4--,powerful searchlight arranged to transmit speech over a beam of light4 ,both of these methods were later very much improved by the employment of ,koenig's manometric flame in place of the silvered mirror as a transmitter4 ,as explained in the last chapter1 speech delivered into the mouthpiece causes the gas to become compressed or rarefied in direct accordance with the sound waves1 and the flame rises and falls with a rapidity too great to be detected by the naked eye4 ,these rapid alterations in the intensity of the illumination of the flame act on the selenium cell1 and reproduce the original voice perfectly in the telephone receiver4 ,illustration3 ,,fig4 #acg4--,the ,electric arc4 ,it is obvious1 however1 that such methods as these are only capable of transmitting speech over very limited distances1 and if greater ranges are to be traversed much more powerful transmitters must be employed for the purpose4 ,ernest ,ruhmer1 after long and laborious researches1 finally succeeded in transmitting speech many miles by taking advantage of the speaking arc1 discovered by ,simon1 who observed that an arc lamp gave out a loud rattling noise if its current supply was interfered with4 ,an electric arc consists of two carbon rods1 connected to a generator4 ,when the carbons are brought into contact for a moment and then drawn apart to a short distance1 a kind of electric flame or arc is produced between the points of carbon1 and a brilliant white light is emitted by the white hot points of the carbon electrodes4 ,ruhmer immediately made the arc serve as a telephone receiver and speak by utilizing the pulsating current of a telephone transmitter to vary the current supplying the arc4 ,illustration3 ,,fig4 #ach4--;,circuit showing how a singing arc is arranged4 ,the arc could thus be made to sing1 whistle or reproduce music and the human voice perfectly1 if the sounds were clearly conveyed into the transmitter4 ,further investigations showed that every alteration of current caused by the action of the transmitter also caused an alteration in the intensity of the light and radiation of the lamp4 ,the speaking arc could therefore be used as a perfect photophone transmitter by directing the rays toward the receiving station with the aid of a parabolic reflector4 ,in #aijb ,ruhmer performed a series of experiments in ,germany on the ,wannsee1 near ,berlin4 ,a large motorboat1 the ,germania1 was fitted with an electric searchlight connected with a microphone1 so as to form a speaking arc4 ,the receiving station was located on the shore1 so that the distance between the stations could be easily enlarged by moving the boat4 ,the receptor was an ordinary selenium cell1 placed at the focus of a large reflector and connected with a telephone receiver and battery4 ,no difficulty was encountered in reproducing the speech over varying distances up to about three miles4 ,,chapter ,,ix4 ,,the ,,wireless ,,telephone4 ,the applications of any of the wireless telephone systems thus far described are very limited1 for at the best they only operate under the most favorable conditions1 and then over rather limited distances4 ,in the case of any system whereby the speech must be transmitted over a beam of light1 the great resulting limitations are that the transmission can only take place in a straight line over water or clear country1 and that stormy weather or a fog will interrupt communication4 ,none of these objections are present1 however1 when recourse is had to ,hertzian1 or electromagnetic waves4 ,wireless transmission of speech has therefore followed in the wake of wireless telegraphy1 and the methods and apparatus employed are very similar4 ,some who have followed the text closely might reasonably ask why it would not be possible to establish wireless telephony by simply connecting a telephone transmitter in some manner to an ordinary wireless telegraph1 and by directing speech into the latter1 vary the strength of the oscillations emitted4 ,such a system1 at first thought1 seems very plausible1 and many experimenters have devised countless methods trying to attain this result1 only to meet with ultimate failure4 ,the reason is very simple4 ,suppose that an induction coil1 having a high-speed interruptor1 and therefore able to produce a very rapid stream of sparks at the gap1 is connected to the aerial and ground in the usual manner and a telephone transmitter placed in series with the ground wire4 ,when the coil is set in operation the sparks jump across the gap1 each spark setting up a train of oscillations4 ,if speech is conveyed into the transmitter1 the resistance in the path of the oscillations will be varied and correspondingly also the strength of the waves emitted4 ,the sounds will be reproduced to a certain extent by the receptor4 ,whistling1 certain musical tones1 and words containing many vowels are sometimes heard in the receptor1 with sufficient distinctness to be recognizable4 ,the voice cannot1 however1 be heard at all times1 and the system is of no real value other than an interesting experiment4 ,illustration3 ,,fig4 #aci4--;,a logical form of wireless telephone which is impracticable4 ,illustration3 ,,fig4 #adj4--;,de ,forest wireless telephone equipment4 ,the reason is very simple and readily explained4 ,for the sake of clearness we will suppose that the speed of the interruptor attached to the coil is #ajj per second4 ,it will therefore produce #ajj sparks per second at the spark gap if the electrodes are close together4 ,the passage of the sparks is not continuous1 each one only occupying a very small space of time4 ,the pause between each is very distinct1 although it could not be detected with the naked eye4 ,the ten straight lines in ,fig4 #ada represent ten sparks which cover a period of one-tenth of a second1 since they pass at the rate of #ajj per second4 ,each spark produces a train of oscillations1 which surge back and forth in the aerial1 rapidly dying out1 however1 or becoming damped in the manner already explained4 ,illustration3 ,,fig4 #ada4-,wireless telephone receiving apparatus 7induction method74 ,illustration3 ,,fig4 #adb4--;,fessenden wireless telephone transmitting phonograph music4 ,it may now readily be realized that there are long pauses between the sparks when there are no oscillations in the aerial1 and1 consequently1 no electromagnetic waves passing between the transmitter and receptor during those periods4 ,the wavy line1 ,c1 represents the vibrations of the human voice when producing speech4 ,part of it has been represented by a continuous line1 and part by a dotted line4 ,the portions represented by the dotted line occur when there are no oscillations in the aerial1 and consequently these portions are not transmitted4 ,the continuous portions are the only ones reaching the receptor4 ,literally1 there are holes in the voice1 and the result is a jumble of sounds1 sometimes bearing a resemblance to speech1 but usually untranslatable4 ,illustration3 ,,fig4 #adc4--;,diagram illustrating the reason why damped oscillations will not carry the voice4 ,the fault lies in the method of producing the oscillations which are damped and therefore do not exist continuously4 ,if they could be made to keep on swinging and at a sufficiently high speed so that their tone would be inaudible and not confuse the speech1 the problem would be solved4 ,in other words1 three things are necessary for the successful operation of a wireless telephone4 #a4 ,a means of producing and radiating a stream of undampened electrical waves sufficiently continuous to transmit the upper harmonics of the voice1 on which the quality and recognition of the speech depends4 #b4 ,means for varying or modulating the stream of electrical waves in accordance with the sound waves4 #c4 ,a receiver1 continuously responsive and capable of corresponding with sufficient rapidity to the speech harmonics4 ,in order to obtain the desired result1 recourse is had to an arc lamp as a generator of undamped high frequency oscillations4 ,when an arc is properly connected with a condenser and an impedance coil it will emit a musical note4 ,the note is due to rapid changes in the arc1 a very important factor which led to its recognition as a a value in wireless telephony4 ,illustration3 ,,fig4 #add4--;,how the sound waves of the voice are impressed upon undamped oscillations4 ,when the condenser and inductance are shunted across an arc supplied with direct current1 the condenser immediately becomes charged1 and the current through the arc is diminished4 ,the potential difference across the latter is therefore instantly increased1 tending to further charge the condenser4 ,this increase of charge reacts on the arc1 increasing its current4 ,the condenser discharges1 through the inductance coil1 and becomes charged in the opposite direction1 just like a spring1 which released1 goes beyond its normal position and then returns4 ,the operation is repeated many times per second 7usually over #a1jjj1jjj71 setting up persistent undamped oscillations4 ,illustration3 ,,fig4 #ade4--;,arrangement of the speaking arc4 ,perhaps a better conception of how it is possible for a continuous current1 such as that which supplies the arc1 to change into alternating current1 vibrating backward and forward1 may be gained by comparison with the steady forward motion of a violin bow1 which produces a to and fro motion of the strings4 ,illustration3 ,,fig4 #adf4--;,diagram showing how a wireless telephone transmitting system is arranged4 ,it was later discovered by ,poulsen that if one of the arc electrodes was kept cool by making it of copper and passing water through it that the efficiency was greatly increased4 ,a further improvement was obtained by burning the arc in an atmosphere of coal gas or hydrogen4 ,by surrounding the arc with a powerful magnetic field1 its resistance is greatly increased and the voltage raised4 ,illustration3 ,,fig4 #adg4--,poulsen wireless telephone equipment4 ,the condenser shunted around the are usually consists of a number of metal plates1 placed above one another in a tank of insulating oil4 ,the inductance is simply a single helix or bare wire4 ,by connecting a telephone transmitter to the arc in the same manner that it is connected to the speaking arc1 the oscillations can be varied in accordance with the vibrations of the voice4 ,the apparatus is connected to the aerial and the earth through the medium of a loose-coupled helix1 formed by providing the helix in series with the arc and condenser1 with a secondary winding4 ,illustration3 ,,fig4 #adh4--,the ,majorana wireless telephone transmitter4 ,the ordinary carbon transmitter1 in its common form1 is unsuited for wireless telephonic work1 on account of its inability to handle large amounts of power4 ,many modifications have been designed1 the usual procedure being to make it on a larger scale4 ,one of the most interesting forms1 and also probably the best1 is that devised by an ,italian inventor1 ,majorana4 ,its action will be clear from the illustration4 ,t is a tube in which water or some other liquid is allowed to flow in the direction of the arrow4 ,the bottom of the tube is contracted so that the stream will issue in a fine jet4 ,the tube is made of strong1 rigid material1 except at one point1 ,d1 where an opening is covered with a thin elastic diaphragm4 ,this diaphragm is connected by means of a short rod to a second diaphragm1 which is provided with a mouthpiece4 ,the water normally flows out of the jet in a smooth1 unbroken column1 breaking into drops at about the point ,a4 ,as soon as it is disturbed in any way1 however1 the distance from the outlet of the tube and the point where the drops commence becomes shortened4 ,the vibrations of the voice1 thrown into the mouthpiece and striking the diaphragm1 are transmitted to the membrane through the medium of the little rod1 and so cause corresponding changes in the pressure of the fluid in the tube4 ,each variation or disturbance in the pressure increases or decreases the length of the stream before it breaks into drops4 ,a pair of fine wires are inserted in the stream where the contractions are the strongest4 ,connection is established between the wires by the liquid4 ,if the stream is narrow its resistance will be greater than if it were expanded at that point4 ,the contracted portion of the liquid will jump up and down with the vibrations of the voice1 and thus alter the amount of current flowing4 ,the receiving apparatus consists of some form of detector and a telephone receiver and battery4 ,the usual form of detector employed is the electrolytic4 ,the currents generated in the receiving aerial by the incoming waves vary in amplitude with those of the transmitting aerial1 and1 being in perfect accordance with the vibrations conveyed into the transmitter1 cause the detector and telephone transmitter to reproduce the speech perfectly4 ,experiments in wireless telephony have developed an interesting type of detector1 known as the ,audion4 ,this consists of a six-volt1 low-candlepower1 incandescent lamp1 having a small1 nickel plate fastened a short distance from the filament1 and a grid bent from wire placed midway between the two4 ,when the filament is lighted from a battery1 it throws off a stream of extremely small particles charged with electricity and called ions4 ,these ions pass through the grid and discharge against the plate4 ,when the aerial is connected to the grid1 and the plate to the ground1 the stream of ions carries that part of the alternating current in the aerial which flows in the same direction1 across1 but does not allow the current tending to pass in the opposite direction4 ,in reality it is a valve1 or rectifier1 opening one way and closing the other2 thus changing the current into an intermittent1 direct current1 capable of manifesting itself in a telephone receiver4 ,illustration3 ,,fig4 #adi4--,showing the brush discharge from a ,marconi transatlantic aerial at night4 ,the ,audion is a very sensitive device1 and is much employed for wireless telephone purposes4 ,with such a system it has been found possible to transmit speech and music to a distance of two hundred miles4 ,in fact1 even greater distances have been covered1 and there does not seem to be any good reason why it is limited to any range4 ,transmission by wireless telephone is considerably more distinct than by wire line1 and the fine inflections of the voice are brought out much better4 ,unlike the ordinary line telephone1 no rumbling or roaring noises are heard which confuse the speech1 and there is absolute silence in the wireless telephone receiver1 except when talking is going on4 ,any noises or sounds produced in the transmitting station1 such as walking about the room1 or the breathing of the person speaking into the transmitter1 are reproduced faithfully at the receiving station many miles away4 ,,chapter ,x4 ,,remarks4 ,,theory4 ,,accomplishments4 ,,maxwell',s ,,hertz',s ,,discovery4 ,,the ,,future4 ,the history of wireless telegraphy and telephony is a striking example of how it is possible for scientists laboring in the field of pure research and stimulated by accumulated knowledge and imagination to arrive at discoveries of the most vital importance4 ,heinrich ,hertz and ,clerk ,maxwell in experimental effort to attain other results unwittingly laid the foundation of this art4 ,in #ahfg ,maxwell proposed the theory that light is not mere mechanical motion of the ether1 but consists of electrical undulations4 ,these undulations are partly magnetic and partly electrical4 ,moreover1 according to the theory1 the phenomena of electromagnetism and also that of light are due to certain modes of motion in the ether1 electric currents1 and magnetism1 being due to whirls1 or body displacements in the substance of the ether1 while light is due to vibrations to and fro4 ,twenty years later ,hertz discovered the most convincing experimental proofs of ,maxwell's wonderful theory1 and succeeded in producing electromagnetic waves in such a manner that their propagation through space could be examined1 and it readily showed that while they were much longer than the ordinary waves of light1 they possessed the same properties1 were capable of being reflected1 polarized1 refracted1 etc41 and traveled at the same speed4 ,the waves that ,hertz produced are the electromagnetic or ,hertzian waves of radiotelegraphy4 ,many thousand commercial wireless stations dot the face of the earth4 ,daily time signals1 weather reports and storm warnings flash to ships far out in the ocean from government observatories4 ,late at night1 in the midnight hours1 when the world is asleep1 powerful land stations commence to whisper press dispatches1 and the next morning the ocean daily1 containing the same news as our morning paper1 is laid on the breakfast table of the ocean greyhound4 ,a distress signal sends revenue cutters scurrying along the coast1 and brings rescue to hundreds of imperiled lives4 ,the ,navy ,department issues an order1 and a few minutes later it is in the hands of the commanding officer of a fleet1 a thousand miles away4 ,wireless links two continents across a table1 and yet this wonderful apparatus is so simple that a sixteen-year-old boy can build instruments with a little guidance and listen to a far-distant station1 #a1ejj miles away1 spell out its news4 ,illustration3 ,,fig4 #aej4--;,an amateur wireless telegraph station4 ,illustration3 ,,fig4 #aea4--,the high-power ,naval wireless telegraph station under construction at ,washington1 ,d4 ,c4 ,wireless telegraphy is part of the established order of things4 ,the wireless telephone is practical for limited distance1 but is not a commercial rival of the telegraph4 ,great distances are claimed1 but they are matters for proof and speculation4 ,there is no immediate possibility that wireless telephony will take the place of local exchanges4 ,if the time ever does come that it in any way tends to supplant the line telephone for some uses1 it is more than probable that each subscriber must have his own generating station and call up direct4 ,there is a very decided field of opportunity for wireless telephony for long-distance work4 ,the present systems of long-distance wires are very expensive to construct and maintain1 and are subject to the whims of storms and the elements4 ,wireless telephones will not only transmit the speech more clearly and distinctly1 but have the further advantages that the initial cost is very much lower than that of wire lines1 the maintenance is almost nil in comparison1 the depreciation is smaller1 the number of employees required is less1 and a break-down is limited to the inside of the station1 where it could be quickly remedied by the substitution of a duplicate spare piece of apparatus4 ,furthermore1 no franchises or rights of way would need to be purchased4 ,no serious difficulty would be encountered because of interference4 ,wireless telephony1 like wireless telegraphy1 but to an even greater extent1 is peculiarly suited for the conveyance of marine intelligence4 ,wireless telephony occupies a unique position in this regard-no operator is required4 ,the additional expense of an operator is an objection to the wireless telegraph in many cases1 and forbids its installation4 ,anybody can operate the wireless telephone4 ,it is also much quicker-words can be spoken more rapidly than they can be put into ,morse signals and translated4 ,illustration3 ,,fig4 #aeb4----,the curved lines represent the radius of the government high power wireless stations and show the zones over which direct communication may be had with ships4 ,illustration3 ,,fig4 #aec4--,the aerial system of a transatlantic station4 ,the wireless telephone enables a passenger on board ship to communicate direct with his home by relaying the message over the line wires4 ,by the same means the captain of a ship can call his home office and communicate with the owner of the vessel4 ,telegraphs and telephones are the nerves of the world1 carrying swift messages from its brain centers to its hands1 annihilating distance in thought4 ,all differences between men as individuals and people as nations can be traced to the lack of close contact4 ,reduce or annihilate all distance in thought and action1 and mankind would possess unbounded opportunities for peaceful economic and healthful development4 ,no force more vital than the possibilities of wireless has ever presented itself or could be demanded to attain such an end4 ,such a statement1 in the light of actual developments1 might even be considered conservative1 and is neither absurd nor the dream of a vivid imagination4 ,the greatest obstacle to all efforts in radically new directions is the resistance of the human race4 ,the antagonism of prejudice and skepticism can only disappear when the world as a whole grasps a new proof and learns to appreciate it4 ,inertia must be overcome1 and the great masses set to thinking and striving toward an end before the aweing genie finally bursts forth and amazes the ,aladdins of science4 ,within the memory of older men and women are primers of science1 which speculate about the developments of electrical force1 and guardedly discuss its possibilities4 ,and now1 electricity--this mysterious agent-has multiplied the muscular strength of man a billion times4 ,the tasks of ,hercules are now but chores to be accomplished by the closing of a switch4 ,mighty rivers roar through intake and turbine to drive the wheels of industry in a distant city and turn the night into day4 ,any attempt to chronicle all the applications of this wondrous power would be absurd4 ,such is electricity to-day4 ,only a few years ago ,langley launched his famous aerodrome over the waters of the ,potomac1 while the world stood by and sneered1 ridiculed a man whose work is now one of the classics of aeronautical literature1 and scoffed at a machine whose principles embodied the conclusions of years of careful thought and scientific effort4 ,a decade later and aeroplanes have become a living reality4 ,a man and a little frame of sticks and canvas can throw off the fetters of gravity and go soaring dizzily two miles up into the blue sky1 and daring more1 come skimming and diving back to earth with motor dead4 ,such wonders only came to pass1 however1 when numbers of men accepted the problem as one to be solved by trying1 and bent their energies toward its solution4 ,science has not reached the limits of its resources4 ,it never will4 ,the art of wireless may always be embarrassed by novelty in many directions4 ,illustration3 ,,fig4 #aed4-;,fong ,yee1 a ,chinese amateur wireless operator at ,oakland1 ,cal41 who is also an aviator and has been summoned home by the republican ,chinese government to demonstrate apparatus of his own invention to the ,chinese army4 ,one of the greatest steps forward toward the day when methods and appliances regarded as permanent as the mountains will pass and be considered only as the curious remnants of a cruder age is the interest of #bjj1jjj wireless amateurs in the ,united ,states4 ,some of these will develop into men who will bring some of the wonders of the future to their full fruition4 ,illustration3 ,,fig4 #aee4--,tesla world power plant 7experimental station74 ,what is this great change that can be coolly and precisely forecast8 ,along what lines will these wonderful developments come8 ,the answer is wireless-not the wireless of a ,marconi or a ,de ,forest1 but the wireless of a ,tesla--of high potential magnifying transmitters-of nodes and loops--of oscillatory currents that leave their conductors behind-the wireless of the day when a system is introduced enabling any person to reach any other on the globe1 not simply through a spoken word or thought conveyed1 but visually a perfect transmission of images which will enable one person to see another1 as though that other were by his side-wireless of a time when the great operations of commerce and industry will be vitalized by huge wireless power stations1 turning the machinery of factories1 lighting cities1 or sending swift aeroplanes and ships darting to the farthest points of the earth4 ,of course1 there may be something of the dramatic in such assertions1 but they are founded upon scientific facts1 and1 if imaginary1 are scientifically imaginary4 ,the wonderful mysteries of oscillatory currents1 whose natural medium is the ether1 currents which object to being confined to wires and cables1 and defy all ordinary laws2 currents that will melt masses of metal with the violence of an explosion1 but yet pass through the human body without producing any sensation2 currents that will instantly manifest themselves #b1jjj miles away from their source1 with no visible means of propagation1 are the open sesame to the treasures of a wonderful future4 ,there are many places in the world where water power is available capable of generating almost unlimited electrical energy4 ,the present difficulty lying in the way of its utilization is the limitation of electrical transmission by wire1 for not only is the cost of long lines of copper tremendous1 but power can only be carried in this manner for limited distances4 ,central distributing wireless power stations could send the power of ,niagara1 which alone might be made to supply a fifth of all the power in the ,united ,states1 and the energy of ,victoria to the ends of the earth with little loss4 ,the ,great ,falls of ,zambesi1 in the heart of ,africa1 could be made to run the subway trains1 the factories1 lights1 railroads1 ferries1 trucks1 heaters1 etc41 in that vast1 most complex1 most bewildering and inspiring city of the ,western ,world1 the ,city of ,new ,york4 ,ocean vessels would no longer carry thousands of tons of coal1 locomotives would not wheeze and cough a trail of soot and smoke through the country1 chimneys would cease to belch1 and aeroplanes would travel silently and swiftly overhead4 ,illustration3 ,,fig4 #aef4--,twenty-five foot sparks from a ,tesla transformer4 ,it is easy1 in the face of certain facts1 to conjure up situations which would be pleasant and make for the betterment of the world4 ,any one whose imagination is vivid enough can make a prediction1 but when the great truth is accidentally revealed1 or experimentally confirmed1 as the case may be1 and rendered absolutely sure of accomplishment1 will its incalculable consequences continue to baffle the imagination and carry us further into the land of wonderment8 ,only the future knows4 ,,the ,,end4 ,,books ,,for ,,home ,,study ,,opportunity ,,practical ,,scientific ,,technical ,,each ,,book ,,in ,,this ,,catalogue ,,is ,,written ,,by ,,an ,,expert ,,and ,,is ,,written ,,so ,,you ,,can ,,understand ,,it ,,the ,,norman ,w4 ,,henley ,,publishing ,,company ,publishers of ,scientific and ,practical ,books #acb ,nassau ,street ,new ,york1 ,u4 ,s4 ,a4 ,any book in this ,catalogue sent prepaid on receipt of price4 ,,catalogue ,,of ,,good1 ,,practical ,,books ,,automobile ,,the ,,modern ,,gasoline ,,automobile-,,its ,,design1 ,,construction1 ,,maintenance ,,and ,,repair4 ,by ,,victor ,w4 ,,page1 ,m4 ,e4 ,the latest and most complete treatise on the ,gasoline ,automobile ever issued4 ,written in simple language by a recognized authority1 familiar with every branch of the automobile industry4 ,free from technical terms4 ,everything is explained so simply that anyone of average intelligence may gain a comprehensive knowledge of the gasoline automobile1 ,the information is up-to-date and includes1 in addition to an exposition of principles o construction and description of all types of automobiles and their components1 valuable money-saving hints on the care and operation of motor cars propelled by internal combustion engines4 ,among some of the subjects treated might be mentioned3 ,torpedo and other symmetrical body forms designed to reduce air resistance2 sleeve valve1 rotary valve and other types of silent motors2 increasing tendency to favor worm-gear power-transmission2 universal application of magneto ignition2 development of automobile electric-lighting systems2 block motors2 underslung chassis2 application of practical self-starters2 long stroke and offset cylinder motors2 latest automatic lubrication systems2 silent chains for valve operation and change-speed gearing2 the use of front wheel brakes and many other detail refinements4 ,by a careful study of the pages of this book one can gain practical knowledge of automobile construction that will save time1 money and worry4 ,the book tells you just what to do1 how and when to do it4 ,nothing has been omitted1 no detail has been slighted4 ,every part of the automobile1 its equipment1 accessories1 tools1 supplies1 spare parts necessary1 etc41 have been discussed comprehensively4 ,if you are or intend to become a motorist1 or are in any way interested in the modern ,gasoline ,automobile1 this is a book you cannot afford to be without ,nearly #fjj #f x #i pages--and more than #ejj new and specially made detail illustrations as well as many full page and double page plates1 showing all parts of the automobile4 ,including nine large folding plates4 ,price #b4ej ,,balloons ,,and ,,flying ,,machines ,,model ,,balloons ,,and ,,flying ,,machines4 ,,with ,a ,,short ,,account ,,of ,,the ,,progress ,,of ,,aviation4 ,by ,j4 ,h4 ,,alexander4 ,this book has been written with a view to assist those who desire to construct a model airship or flying machine4 ,it contains five folding plates of working drawings1 each sheet containing a different sized machine4 ,much instruction and amusement can be obtained from the making and flying of these models4 ,a short account of the progress of aviation is included1 which will render the book of greater interest4 ,several illustrations of full sized airship and flying machines of the latest types are scattered throughout the text4 ,this practical work gives data1 working drawings1 and details which will assist materially those interested in the problems of flight4 #abg pages1 #de illustrations1 #e folding plates4 ,price #a4ej ,,brazing ,,and ,,soldering ,,brazing ,,and ,,soldering4 ,by ,,james ,f4 ,,hobart4 ,the only book that shows you just how to handle any job of brazing or soldering that comes along2 tells you what mixture to use1 how to make a furnace if you need one4 ,full of valuable kinks4 ,the fifth edition of this book has just been published1 and to it much new matter and a large number of tested formulas for all kinds of solders and fluxes have been added4 ,illustrated4 #be cents4 ,,charts ,,modern ,,submarine ,,chart ,,with #bjj ,,parts ,,numbered ,,and ,,named4 ,a cross-section view1 showing clearly and distinctly all the interior of a ,submarine of the latest type4 ,you get more information from this chart1 about the construction and operation of a ,submarine1 than in any other way4 ,no details omitted-everything is accurate and to scale4 ,it is absolutely correct in every detail1 having been approved by ,naval ,engineers4 ,all the machinery and devices fitted in a modern ,submarine ,boat are shown1 and to make the engraving more readily understood all the features are shown in operative form1 with ,officers and ,men in the act of performing the duties assigned to them in service conditions4 ,this ,,chart ,,is ,,really ,,an ,,encyclopedia ,,of ,a ,,submarine4 ,it is educational and worth many times its cost4 ,mailed in a ,tube for #be cents4 ,,box ,,car ,,chart4 ,a chart showing the anatomy of a box car1 having every part of the car numbered and its proper name given in a reference list4 #bj cents4 ,,gondola ,,car ,,chart4 ,a chart showing the anatomy of a gondola car1 having every part of the car numbered and its proper reference name given in a reference list4 #bj cents4 ,,passenger ,,car ,,chart4 ,a chart showing the anatomy of a passenger car1 having every part of the car numbered and its proper name given in a reference list4 #bj cents4 ,,westinghouse ,,air-,,brake ,,charts4 ,chart ,i4--,shows 7in colors7 the most modern ,westinghouse ,high ,speed and ,signal ,equipment used on ,passenger ,engines1 ,passenger ,engine ,tenders1 and ,passenger ,cars4 ,chart ,,ii4--,shows 7in colors7 the ,standard ,westinghouse ,equipment for ,freight and ,switch ,engines1 ,freight and ,switch ,engine ,tenders1 and ,freight ,cars4 ,price for the set #ej cents4 ,,tractive ,,power ,,chart4 ,a chart whereby you can find the tractive power or drawbar pull of any locomotive1 without making a figure4 ,shows what cylinders are equal1 how driving wheels and steam pressure affect the power4 ,what sized engine you need to exert a given drawbar pull or anything you desire in this line4 #ej cents4 ,,horse ,,power ,,chart4 ,shows the horse power of any stationary engine without calculation4 ,no matter what the cylinder diameter of stroke2 the steam pressure or cut-off2 the revolutions1 or whether condensing or non-condensing1 it's all there4 ,easy to use1 accurate1 and saves time and calculations4 ,especially useful to engineers and designers4 #ej cents4 ,,boiler ,,room ,,chart4 ,by ,,geo4 ,l4 ,,fowler4 ,a ,chart-size #ad x #bh inches-showing in isometric perspective the mechanisms belonging in a modern boiler room4 ,water tube boilers1 ordinary grates and mechanical stokers1 feed water heaters and pumps comprise the equipment4 ,the various parts are shown broken or removed1 so that the internal construction is fully illustrated4 ,each part is given a reference number1 and these1 with the corresponding name1 are given in a glossary printed at the sides4 ,this chart is really a dictionary of the boiler room--the names of more than #bjj parts being given4 ,it is educational-worth many times its cost4 #be cents4 ,,civil ,,engineering ,,henley',s ,,encyclopedia ,,of ,,practical ,,engineering ,,and ,,allied ,,trades4 ,edited by ,,joseph ,g4 ,,horner1 ,a4 ,m4 ,i4 ,e4 ,m4 ,this set of five volumes contains about #b1ejj pages with thousands of illustrations1 including diagrammatic and sectional drawings with full explanatory details44 ,this work covers the entire practice of ,civil and ,mechanical ,engineering4 ,the best known experts in all branches of engineering have contributed to these volumes4 ,the ,cyclopedia is admirably well adapted to the needs of the beginner and the self-taught practical man1 as well as the mechanical engineer1 designer1 draftsman1 shop superintendent1 foreman1 and machinist4 ,the work will be found a means of advancement to any progressive man4 ,it is encyclopedic in scope1 thorough and practical in its treatment of technical subjects1 simple and clear in its descriptive matter1 and without unnecessary technicalities or formulae4 ,the articles are as brief as may be and yet give a reasonably clear and explicit statement of the subject1 and are written by men who have had ample practical experience in the matters of which they write4 ,it tells you all you want to know about engineering and tells it so simply1 so clearly1 so concisely1 that one cannot help but understand4 ,as a work of reference it is without a peer4 #f4jj per single volume4 ,for complete set of five volumes1 #be4jj ,,coke ,,coke-,,modern ,,coking ,,practice2 ,,including ,,the ,,analysis ,,of ,,materials ,,and ,,products4 ,by ,t4 ,h4 ,,byrom and ,j4 ,e4 ,,christopher4 ,a handbook for those engaged in ,coke manufacture and the recovery of ,by-products4 ,fully illustrated with folding plates1 ,it has been the aim of the authors1 in preparing this book1 to produce ore which shall be of use and benefit to those who are associated with1 or interested in1 the modern developments of the industry4 ,contents3 ,i4 ,introductory4 ,,ii4 ,general ,classification of ,fuels4 ,,iii4 ,coal ,washing4 ,,iv4 ,the ,sampling and ,valuation of ,coal1 ,coke1 etc4 ,v4 ,the ,calorific ,power of ,coal and ,coke4 ,,vi4 ,coke ,ovens4 ,,vii3 ,coke ,ovens1 continued4 ,,viii4 ,coke ,ovens1 continued4 ,,ix4 ,charging and ,discharging of ,coke ,ovens1 ,x4 ,cooling and ,condensing ,plant4 ,,xi4 ,gas ,exhausters4 ,,xii4 ,composition and ,analysis of ,ammoniacal ,liquor4 ,,xiii4 ,working-up of ,ammoniacal ,liquor4 ,,xiv4 ,treatment of ,waste ,gases from ,sulphate ,plants4 ,,xv4 ,valuation of ,ammonium ,sulphate4 ,,xvi4 ,direct ,recovery of ,ammonia from ,coke ,oven ,gases4 ,,xvii4 ,surplus ,gas from ,coke ,oven4 ,useful ,tables4 ,very fully illustrated4 ,price #c4ej net4 ,,compressed ,,air ,,compressed ,,air ,,in ,,all ,,its ,,applications4 ,by ,,gardner ,d4 ,,hiscox4 ,this is the most complete book on the subject of ,air that has ever been issued1 and its thirty-five chapters include about every phase of the subject one can think of4 ,it may be called an encyclopedia of compressed air4 ,it is written by an expert1 who1 in its #ffe pages1 has dealt with the subject in a comprehensive manner1 no phase of it being omitted4 ,includes the physical properties of air from a vacuum to its highest pressure1 its thermodynamics1 compression1 transmission and uses as a motive power2 in the ,operation of ,stationary and ,portable ,machinery1 in ,mining1 ,air ,tools1 ,air ,lifts1 ,pumping of ,water1 ,acids1 and ,oils2 the ,air ,blast for ,cleaning and ,painting1 the ,sand ,blast and its ,work1 and the ,numerous ,appliances in which ,compressed ,air is a ,most ,convenient and ,economical ,transmitter of ,power for ,mechanical ,work1 ,railway ,propulsion1 ,refrigeration1 and the ,various ,uses to which ,compressed ,air has been applied4 ,includes forty-four tables of the physical properties of air1 its compression1 expansion1 and volumes required for various kinds of work1 and a list of patents on compressed air from #ahge to date4 ,over #ejj illustrations1 #eth ,edition1 revised and enlarged4 ,cloth bound1 #e4jj4 ,half ,morocco1 price4 #f4ej ,,concrete ,,ornamental ,,concrete ,,without ,,molds4 ,by ,a4 ,a4 ,,houghton4 ,the process for making ornamental concrete without molds has long been held as a secret1 and now1 for the first time1 this process is given to the public4 ,the book reveals the secret and is the only book published which explains a simple1 practical method whereby the concrete worker is enabled1 by employing wood and metal templates of different designs1 to mold or model in concrete any ,cornice1 ,archivolt1 ,column1 ,pedestal1 ,base ,cap1 ,urn or ,pier in a monolithic form-right upon the job4 ,these may be molded in units or blocks1 and then built up to suit the specifications demanded4 ,this work is fully illustrated1 with detailed engravings4 ,price #b4jj ,,concrete ,,from ,,sand ,,molds4 ,by ,a4 ,a4 ,,houghton4 ,a ,practical ,work treating on a process which has heretofore been held as a trade-secret by the few who possessed it1 and which will successfully mold every and any class of ornamental concrete work4 ,the process of molding concrete with sand molds is of the utmost practical value1 possessing the manifold advantages of a low cost of molds1 the ease and rapidity of operation1 perfect details to all ornamental designs1 density1 and increased strength of the concrete1 perfect curing of the work without attention and the easy removal of the molds regardless of any undercutting the design may have4 #aib pages4 ,fully illustrated4 ,price #b4jj ,,concrete ,,wall ,,forms4 ,by ,a4 ,a4 ,,houghton4 ,a new automatic wall clamp is illustrated with working drawings4 ,other types of wall forms1 clamps1 separators1 etc41 are also illustrated and explained4 #ej cents4 ,,concrete ,,floors ,,and ,,sidewalks4 ,by ,a4 ,a4 ,,houghton4 ,the molds for molding squares1 hexagonal and many other styles of mosaic floor and sidewalk blocks are fully illustrated and explained4 #ej cents4 ,,practical ,,concrete ,,silo ,,construction4 ,by ,a4 ,a4 ,,houghton4 ,complete working drawings and specifications are given for several styles of concrete silos1 with illustrations of molds for monolithic and block silos4 ,the tables1 data and information presented in this book are of the utmost value in planning and constructing all forms of concrete silos4 #ej cents4 ,,molding ,,concrete ,,chimneys1 ,,slate ,,and ,,roof ,,tiles4 ,by ,a4 ,a4 ,,houghton4 ,the manufacture of all types of concrete slate and roof tile is fully treated4 ,valuable data on all forms of reinforced concrete roofs are contained within its pages4 ,the construction of concrete chimneys by block and monolithic systems is fully illustrated and described4 number of ornamental designs of chimney construction with molds are shown in this valuable treatise4 #ej cents4 ,,molding ,,and ,,curing ,,ornamental ,,concrete4 ,by ,a4 ,a4 ,,houghton4 ,the proper proportions of cement and aggregates for various finishes1 also the methods of thoroughly mixing and placing in the molds1 are fully treated4 ,an exhaustive treatise on this subject that every concrete worker will find of daily use and value4 #ej cents4 ,,concrete ,,monuments1 ,,mausoleums ,,and ,,burial ,,vaults4 ,by ,a4 ,a4 ,,houghton4 ,the molding of concrete monuments to imitate the most expensive cut stone is explained in this treatise1 with working drawings of easily built molds4 ,cutting inscriptions and designs is also fully treated4 #ej cents4 ,,molding ,,concrete ,,bath ,,tubs1 ,,aquariums ,,and ,,natatoriums4 ,by ,a4 ,a4 ,,houghton4 ,simple molds and instruction are given for molding many styles of concrete bath tubs1 swimming pools1 etc4 ,these molds are easily built and permit rapid and successful work4 #ej cents4 ,,concrete ,,bridges1 ,,culverts ,,and ,,sewers4 ,by ,a4 ,a4 ,,houghton4 ,a number of ornamental concrete bridges with illustrations of molds are given4 ,a collapsible center or core for bridges1 culverts and sewers is fully illustrated with detailed instructions for building #ej cents4 ,,constructing ,,concrete ,,porches4 ,by ,a4 ,a4 ,,houghton4 ,a number of designs with working drawings of molds are fully explained so any one can easily construct different styles of ornamental concrete porches without the purchase of expensive molds4 #ej cents4 ,,molding ,,concrete ,,flower ,,pots1 ,,boxes1 ,,jardinieres1 ,,etc4 ,by ,a4 ,a4 ,,houghton4 ,the molds for producing many original designs of flower pots1 urns1 flower boxes1 jardinires1 etc41 are fully illustrated and explained1 so the worker can easily construct and operate same4 #ej cents4 ,,molding ,,concrete ,,fountains ,,and ,,lawn ,,ornaments4 ,by ,a4 ,a4 ,,houghton4 ,the molding of a number of designs of lawn seats1 curbing1 hitching posts1 pergolas1 sun dials and other forms of ornamental concrete for the ornamentation of lawns and gardens1 is fully illustrated and described4 #ej cents4 ,,concrete ,,for ,,the ,,farm ,,and ,,shop4 ,by ,a4 ,a4 ,,houghton4 ,the molding of drain tile1 tanks1 cisterns1 fence posts1 stable floors1 hog and poultry houses and all the purposes for which concrete is an invaluable aid to the farmer are numbered among the contents of this handy volume4 #ej cents4 ,,popular ,,handbook ,,for ,,cement ,,and ,,concrete ,,users4 ,by ,,myron ,h4 ,,lewis1 ,this is a concise treatise of the principles and methods employed in the manufacture and use of cement in all classes of modern works4 ,the author has brought together in this work all the salient matter of interest to the user of concrete and its many diversified products4 ,the matter is presented in logical and systematic order1 clearly written1 fully illustrated and free from involved mathematics4 ,everything of value to the concrete user is given including kinds of cement employed in construction1 concrete architecture1 inspection and testing1 waterproofing1 coloring and painting1 rules1 tables1 working1 and cost data4 ,the book comprises thirty-three chapters1 as follows3 ,introductory4 ,kinds of ,cements and ,how ,they are ,made4 ,properties1 ,testing and ,requirements of ,hydraulic ,cement4 ,concrete and its ,properties4 ,sand1 ,broken ,stone and ,gravel for ,concrete4 ,how to ,proportion the ,materials4 ,how to ,mix and ,place ,concrete4 ,forms for ,concrete ,construction4 ,the ,architectural and ,artistic ,possibilities of ,concrete4 ,concrete ,residences4 ,mortars1 ,plasters and ,stucco and ,how to ,use ,them4 ,the ,artistic ,treatment of ,concrete ,surfaces4 ,concrete ,building ,blocks4 ,the ,making of ,ornamental ,concrete4 ,concrete ,pipes1 ,fences1 ,posts1 ,etc4 ,essential ,features and ,advantages of ,reenforced ,concrete4 ,how to ,design ,reenforced ,concrete ,beams1 ,slabs and ,columns4 ,explanations of the ,methods and ,principles in ,designing ,reenforced ,concrete ,beams and ,slabs4 ,systems of ,reenforcement ,employed4 ,reenforced ,concrete in ,factory and ,general ,building ,construction4 ,concrete in ,foundation ,work4 ,concrete ,retaining ,walls1 ,abutments1 and ,bulkheads4 ,concrete ,arches and ,arch ,bridges4 ,concrete ,beam and ,girder ,bridges4 ,concrete in ,sewerage and ,drainage ,works4 ,concrete ,tanks1 ,dams and ,reservoirs4 ,concrete ,sidewalks1 ,curbs and ,pavements4 ,concrete in ,railroad ,constructions4 ,the ,utility of ,concrete on the ,farm4 ,the ,waterproofing of ,concrete ,structure4 ,grout or ,liquid ,concrete and ,its ,use4 ,inspection of ,concrete ,work4 ,cost of ,concrete ,work4 ,some of the special features of the book are3 #a4 ,the ,attention ,paid to the ,artistic and ,architectural ,side of ,concrete ,work4 #b4 ,the ,authoritative ,treatment of the ,problem of ,waterproofing ,concrete4 #c4 ,an ,excellent ,summary of the ,rules to be ,followed in ,concrete ,construction4 #d4 ,the ,valuable ,cost ,data and ,useful ,tables given4 ,a valuable ,addition to the ,library of ,every ,cement and ,concrete ,user4 ,price #b4ej ,,waterproofing ,,concrete4 ,by ,,myron ,h4 ,,lewis4 ,modern ,methods of ,waterproofing ,concrete and ,other ,structures4 ,a condensed statement of the ,principles1 ,rules1 and ,precautions to be ,observed in ,waterproofing and ,damp-proofing ,structures and ,structural ,materials4 ,paper binding4 ,illustrated4 ,price #ej cents4 ,,dictionaries ,,standard ,,electrical ,,dictionary4 ,by ,t4 ,o',,conor ,,sloane4 ,an indispensable work to all interested in electrical science4 ,suitable alike for the student and professional4 ,a practical hand-book of reference containing definitions of about #e1jjj distinct words1 terms and phrases4 ,the definitions are terse and concise and include every term used in electrical science4 ,recently issued4 ,an entirely new edition4 ,should be in the possession of all who desire to keep abreast with the progress of this branch of science4 ,complete1 concise and convenient4 #fhb pages4 #cic illustrations4 ,price #c4jj ,,dies-,,metal ,,work ,,dies3 ,,their ,,construction ,,and ,,use ,,for ,,the ,,modern ,,working ,,of ,,sheet ,,metals4 ,by ,j4 ,v4 ,,woodworth4 ,a most useful book1 and one which should be in the hands of all engaged in the press working of metals2 treating on the ,designing1 ,constructing1 and ,use of ,tools1 ,fixtures and ,devices1 together with the manner in which they should be used in the ,power ,press1 for the cheap and rapid production of the great variety sheet metal articles now in use4 ,it is designed as a guide to the production of sheet metal parts at the minimum of cost with the maximum of output4 ,the hardening and tempering of ,press tools and the classes of work which may be produced to the best advantage by the use of dies in the power press are fully treated4 ,its #eje illustrations show dies1 press fixtures and sheet metal working devices1 the descriptions of which are so clear and practical that all metal-working mechanics will be able to understand how to design1 construct and use them4 ,many of the dies and press fixtures treated were either constructed by the author or under his supervision4 ,others were built by skilful mechanics and are in use in large sheet metal establishments and machine shops4 ,price #c4jj ,,punches1 ,,dies ,,and ,,tools ,,for ,,manufacturing ,,in ,,presses4 ,by ,j4 ,v4 ,,woodworth4 ,this work is a companion volume to the author's elementary work entitled ,dies1 ,their ,construction and ,use4 ,it does not go into the details of die making to the extent of the author's previous book1 but gives a comprehensive review of the field of operations carried on by presses4 ,a large part of the information given has been drawn from the author's personal experience4 ,it might well be termed an ,encyclopedia of ,die ,making4 ,punch ,making1 ,die ,sinking1 ,sheet ,metal ,working1 and ,making of ,special ,tools1 ,sub-presses1 ,devices and ,mechanical ,combinations for ,punching1 ,cutting1 ,bending1 ,forming1 ,piercing1 ,drawing1 ,compressing and ,assembling ,sheet ,metal ,parts1 and also ,articles of other ,materials in ,machine ,tools4 #bnd ,edition4 ,price4 #d4jj ,,drop ,,forging1 ,,die ,,sinking ,,and ,,machine ,,forming ,,of ,,steel4 ,by ,j4 ,v4 ,,woodworth4 ,this is a practical treatise on ,modern ,shop ,practice1 ,processes1 ,methods1 ,machines1 ,tools1 and ,details1 treating on the ,hot and ,cold ,machine-,forming of ,steel and ,iron into ,finished shapes2 ,together with ,tools1 ,dies1 and ,machinery involved in the manufacture of ,duplicate ,forgings and ,interchangeable ,hot and ,cold ,pressed ,parts from ,bar and ,sheet ,metal4 ,this book fills a demand of long standing for information regarding drop forging1 die-sinking and machine forming of steel and the shop practice involved1 as it actually exists in the modern drop forging shop4 ,the processes of die-sinking and force-making1 which are thoroughly described and illustrated in this admirable work1 are rarely to be found explained in such a clear and concise manner as is here set forth4 ,the process of die-sinking relates to the engraving or sinking of the female or lower dies1 such as are used for drop forgings1 hot and cold machine forging1 swedging and the press working of metals4 ,the process of force-making relates to the engraving or raising of the male or upper dies used in producing the lower dies for the press-forming and machine-forging of duplicate parts of metal4 ,in addition to the arts above mentioned the book contains explicit information regarding the drop forging and hardening plants1 designs1 conditions1 equipment1 drop hammers1 forging machines1 etc41 machine forging1 hydraulic forging1 autogenous welding and shop practice4 ,the book contains eleven chapters1 and the information contained in these chapters is just what will prove most valuable to the forged metal worker4 ,all operations described in the work are thoroughly illustrated by means of perspective half-tones and outline sketches of the machinery employed4 #cjj detailed illustrations4 ,price #b4ej ,,drawing-,,sketching ,,paper ,,linear ,,perspective ,,self-,,taught4 ,by ,,herman ,t4 ,c4 ,,kraus4 ,this work gives the theory and practice of linear perspective1 as used in architectural1 engineering1 and mechanical drawings4 ,persons taking up the study of the subject by themselves will be able by the use of the instruction given to readily grasp the subject1 and by reasonable practice become good perspective draftsmen4 ,the arrangement of the book is good2 the plate is on the left-hand1 while the descriptive text follows on the opposite page1 so as to be readily referred to4 ,the drawings are on sufficiently large scale to show the work clearly and are plainly figured4 ,the whole work makes a very complete course on perspective drawing1 and will be found of great value to architects1 civil and mechanical engineers1 patent attorneys1 art designers1 engravers1 and draftsmen4 #b4ej ,,practical ,,perspective4 ,by ,,richards and ,,colvin4 ,shows just how to make all kinds of mechanical drawings in the only practical perspective isometric4 ,makes everything plain so that any mechanic can understand a sketch or drawing in this way4 ,saves time in the drawing room1 and mistakes in the shops4 ,contains practical examples of various classes of work4 #crd ,edition4 #ej cents4 ,,self-,,taught ,,mechanical ,,drawing ,,and ,,elementary ,,machine ,,design4 ,by ,f4 ,l4 ,,sylvester1 ,m4,e41 ,draftsman1 with additions by ,,erik ,,oberg1 associate editor of ,machinery4 ,this is a practical treatise on ,mechanical ,drawing and ,machine ,design1 comprising the first principles of geometric and mechanical drawing1 workshop mathematics1 mechanics1 strength of materials and the calculations and design of machine details4 ,the author's aim has been to adapt this treatise to the requirements of the practical mechanic and young draftsman and to present the matter in as clear and concise a manner as possible4 ,to meet the demands of this class of students1 practically all the important elements of machine design have been dealt with1 and in addition algebraic formulas have been explained1 and the elements of trigonometry treated in the manner best suited to the needs of the practical man4 ,the book is divided into #bj chapters1 and in arranging the material1 mechanical drawing1 pure and simple1 has been taken up first1 as a thorough understanding of the principles of representing objects facilitates the further study of mechanical subjects4 ,this is followed by the mathematics necessary for the solution of the problems in machine design which are presented later1 and a practical introduction to theoretical mechanics and the strength of materials4 ,the various elements entering into machine design1 such as cams1 gears1 sprocket wheels1 cone pulleys1 bolts1 screws1 couplings1 clutches1 shafting and flywheels have been treated in such a way as to make possible the use of the work as a textbook for a continuous course of study4 ,it is easily comprehended and assimilated even by students of limited previous training4 #ccj pages1 #bae engravings4 ,price4 #b4jj ,a ,,new ,,sketching ,,paper4 ,a new specially ruled paper to enable you to make sketches or drawings in isometric perspective without any figuring or fussing4 ,it is being used for shop details as well as for assembly drawings1 as it makes one sketch do the work of three1 and no workman can help seeing just what is wanted4 ,pads of #dj sheets1 #f x #i inches1 #be cents4 ,pads of #dj sheets1 #i x #ab inches4 #ej cents2 #dj sheets1 #ab x #ah1 ,price #a4jj4 ,,electricity ,,arithmetic ,,of ,,electricity4 ,by ,prof4 ,t4 ,o',,conor ,,sloane4 ,a practical treatise on electrical calculations of all kinds reduced to a series of rules1 all of the simplest forms1 and involving only ordinary arithmetic2 each rule illustrated by one or more practical problems1 with detailed solution of each one4 ,this book is classed among the most useful works published on the science of electricity covering as it does the mathematics of electricity in a manner that will attract the attention of those who are not familiar with algebraical formulas4 #bjth ,edition4 #afj pages4 ,price #a4jj ,,commutator ,,construction4 ,by ,,wm4 ,,baxter1 ,,jr4 ,the business end of any dynamo or motor of the direct current type is the commutator4 ,this book goes into the designing1 building1 and maintenance of commutators1 shows how to locate troubles and how to remedy them2 everyone who fusses with dynamos needs this4 #be cents4 ,,dynamo ,,building ,,for ,,amateurs1 ,,or ,,how ,,to ,,construct ,a ,,fifty-,,watt ,,dynamo4 ,by ,,arthur ,j4 ,,weed1 ,member of ,n4 ,y4 ,electrical ,society4 ,a practical treatise showing in detail the construction of a small dynamo or motor1 the entire machine work of which can be done on a small foot lathe4 ,dimensioned working drawings are given for each piece of machine work and each operation is clearly described4 ,this machine1 when used as a dynamo1 has an output of fifty watts2 when used as a motor it will drive a small drill press or lathe4 ,it can be used to drive a sewing machine on any and all ordinary work4 ,the book is illustrated with more than sixty original engravings showing the actual construction of the different parts4 ,among the contents are chapters on #a4 ,fifty ,watt ,dynamo4 #b4 ,side ,bearing ,rods4 #c4 ,field ,punchings4 #d4 ,bearings4 #e4 ,commutator4 #f4 ,pulley4 #g4 ,brush ,holders4 #h4 ,connection ,board4 #i4 ,armature ,shaft4 #aj4 ,armature4 #aa4 ,armature ,winding4 #ab4 ,field ,winding4 #ac4 ,connecting and ,starting4 ,price1 paper1 #ej cents4 ,cloth4 #a4jj4 ,,electric ,,furnaces ,,and ,,their ,,industrial ,,applications4 ,by ,j4 ,,wright ,this is a book which will prove of interest to many classes of people2 the manufacturer who desires to know what product can be manufactured successfully in the electric furnace1 the chemist who wishes to post himself on the electro-chemistry1 and the student of science who merely looks into the subject from curiosity4 ,the book is not so scientific as to be of use only to the technologist1 nor so unscientific as to suit only the tyro in electro-chemistry2 it is a practical treatise of what has been done1 and of what is being done1 both experimentally and commercially with the electric furnace4 ,in important processes not only are the chemical equations given1 but complete thermal data are set forth and both the efficiency of the furnace and the cost of the product are worked out1 thus giving the work a solid commercial value aside from its efficacy as a work of reference4 ,the practical features of furnace building are given the space that the subject deserves4 ,the forms and refractory materials used in the linings1 the arrangement of the connections to the electrodes1 and other important details are explained4 #bhh pages4 ,new ,revised ,edition4 ,fully illustrated4 ,price #c4jj ,,electric ,,lighting ,,and ,,heating ,,pocket ,,book4 ,by ,,sydney ,f4 ,,walker4 ,this book puts in convenient form useful information regarding the apparatus which is likely to be attached to the mains of an electrical company4 ,tables of units and equivalents are included and useful electrical laws and formulas are stated4 ,one section is devoted to dynamos1 motors1 transformers and accessory apparatus2 another to accumulators1 another to switchboards and related equipment1 a fourth to a description of various systems of distribution1 a fifth section to a discussion of instruments1 both for portable use and switchboards2 another section deals with electric lamps of various types and accessory appliances1 and the concluding section is given up to electric heating apparatus4 ,in each section a large number of commercial types are described1 frequent tables of dimensions being included4 ,a great deal of detail information of each' line of apparatus is given and the illustrations shown give a good idea of the general appearance of the apparatus under discussion4 ,the book also contains much valuable information for the central station engineer4 #dch pages4 #cjj engravings4 ,bound in leather pocket book form4 ,price #c4jj ,,electric ,,wiring1 ,,diagrams ,,and ,,switchboards4 ,by ,,newton ,,harrison4 ,a thoroughly practical treatise covering the subject of ,electric ,wiring in all its branches1 including explanations and diagrams which are thoroughly explicit and greatly simplify the subject4 ,practical every-day problems in wiring are presented and the method of obtaining intelligent results clearly shown4 ,only arithmetic is used4 ,ohm's law is given a simple explanation with reference to wiring for direct and alternating currents4 ,the fundamental principle of drop of potential in circuits is shown with its various applications4 ,the simple circuit is developed with the position of mains1 feeders and branches2 their treatment as a part of a wiring plan and their employment in house-wiring clearly illustrated4 ,some simple facts about testing are included in connection with the wiring4 ,molding and conduit work are given careful consideration2 and switchboards are systematically treated1 built up and illustrated1 showing the purpose they serve1 for connection with the circuits1 and to shunt and compound wound machines4 ,the simple principles of switchboard construction1 the development of the switchboard1 the connections of the various instruments including the lightning arrester1 are also plainly set forth4 ,alternating current wiring is treated1 with explanations of the power factor1 conditions calling for various sizes of wire and a simple way of obtaining the sizes for single-phase1 two-phase and three-phase circuits4 ,this is the only complete work issued showing and telling you what you should know about direct and alternating current wiring4 ,it is a ready reference4 ,the work is free from advanced technicalities and mathematics1 arithmetic being used throughout4 ,it is in every respect a handy1 well-written1 instructive1 comprehensive volume on wiring for the wireman1 foreman1 contractor1 or electrician4 #bgb pages2 #aje illustrations4 ,price #a4ej ,,electric ,,toy ,,making1 ,,dynamo ,,building1 ,,and ,,electric ,,motor ,,construction4 ,by ,,prof4 ,t4 ,o',,conor ,,sloane4 ,this work treats of the making at home of electrical toys1 electrical apparatus1 motors1 dynamos and instruments in general1 and is designed to bring within the reach of young and old the manufacture of genuine and useful electrical appliances4 ,the work is especially designed for amateurs and young folks4 ,thousands of our young people are daily experimenting1 and busily engaged in making electrical toys and apparatus of various kinds4 ,the present work is just what is wanted to give the much needed information in a plain1 practical manner1 with illustrations to make easy the carrying out of the work4 #aith ,edition4 ,price #a4jj ,,electrician',s ,,handy ,,book4 ,by ,,prof4 ,t4 ,o',,conor ,,sloane4 ,this work of #gfh pages is intended for the practical electrician who has to make things go4 ,the entire field of electricity is covered within its pages4 ,among some of the subjects treated are3 ,the ,theory of the ,electric ,current and ,circuit1 ,electro-,chemistry1 ,primary ,batteries1 ,storage ,batteries1 ,generation and ,utilization of ,electric ,powers1 ,alternating ,current1 ,armature ,winding1 ,dynamos and ,motors1 ,motor ,generators1 ,operation of the ,central ,station ,switchboards1 ,safety ,appliances1 ,distribution of ,electric ,light and ,power1 ,street ,mains1 ,transformers1 ,arc and ,incandescent ,lighting1 ,electric ,measurements1 ,photometry1 ,electric ,railways1 ,telephony1 ,bell-,wiring1 ,electro-,plating1 ,electric ,heating1 ,wireless ,telegraphy1 etc4 ,it contains no useless theory2 everything is to the point4 ,it teaches you just what you want to know about electricity4 ,it is the standard work published on the subject4 ,forty-one chapters1 #faj engravings1 handsomely bound in red leather with title and edges in gold4 ,price3 #c4ej ,,electricity ,,in ,,factories ,,and ,,workshops1 ,,its ,,cost ,,and ,,convenience4 ,by ,,arthur ,p4 ,,haslam4 ,a practical book for power producers and power users showing what a convenience the electric motor1 in its various forms1 has become to the modern manufacturer4 ,it also deals with the conditions which determine the cost of electric driving1 and compares this with other methods of producing and utilizing power4 ,among the chapters contained in the book are3 ,the ,direct ,current ,motor2 ,the ,alternating ,current ,motor2 ,the ,starting and ,speed ,regulation of ,electric ,motors2 ,the ,rating and ,efficiency of ,electric ,motors2 ,the ,cost of ,energy as ,affected by ,conditions of ,working1 ,the ,question for the ,small ,power ,user2 ,independent ,generating ,plants2 ,oil and ,gas ,engine ,plants2 ,steam ,plants2 ,power ,station ,tariffs2 ,the ,use of ,electric ,power in ,textile ,factories2 ,electric ,power in ,printing ,works2 ,the ,use of ,electric ,power in ,engineering ,workshops ,miscellaneous ,application of ,electric ,power2 ,the ,installation of ,electric ,motors2 ,the ,lighting of ,industrial ,establishments #cab pages4 ,very fully illustrated4 ,price #b4ej ,,electricity ,,simplified4 ,by ,,prof4 ,t4 ,o',,conor ,,sloane4 ,the object of ,electricity ,simplified is to make the subject as plain as possible and to show what the modern conception of electricity is2 to show how two plates of different metals immersed in acid can send a message around the globe2 to explain how a bundle of copper wire rotated by a steam engine can be the agent in lighting our streets1 to tell what the volt1 ohm and ampere are1 and what high and low tension mean2 and to answer the questions that perpetually arise in the mind in this age of electricity4 #agb pages4 ,illustrated4 ,price #a4jj ,,house ,,wiring4 ,by ,,thomas ,w4 ,,poppe4 ,this work describes and illustrates the actual installation of ,electric ,light ,wiring1 the manner in which the work should be done1 and the method of doing it4 ,the book can be conveniently carried in the pocket4 ,it is intended for the ,electrician1 ,helper and ,apprentice4 ,it solves all ,wiring ,problems1 and contains nothing that conflicts with the rulings of the ,national ,board of ,fire ,underwriters4 ,it gives just the information essential to the ,successful ,wiring of a ,building4 ,among the subjects treated are3 ,locating the ,meter4 ,panel ,boards4 ,switches4 ,plug ,receptacles4 ,brackets4 ,ceiling ,fixtures4 ,the ,meter ,connections4 ,the ,feed ,wires4 ,the ,steel ,armored ,cable ,system4 ,the ,flexible ,steel ,conduit ,system4 ,the ,ridig ,conduit ,system4 ,a digest of the ,national ,board of ,fire ,underwriters' rules relating to metallic wiring systems4 ,various switching arrangements explained and diagrammed4 ,the easiest method of testing the ,three and ,four-way circuits explained4 ,the grounding of all metallic wiring systems and the reason for doing so shown and explained4 ,the insulation of the metal parts of lamp fixtures and the reason for the same described and illustrated4 #abe pages4 ,fully illustrated4 ,flexible cloth4 ,price #ej cents4 ,,how ,,to ,,become ,a ,,successful ,,electrician4 ,by ,,prof4 ,t4 ,o',,conor ,,sloane4 ,every young man who wishes to become a successful electrician should read this book4 ,it tells in simple language the surest and easiest way to become a successful electrician4 ,the studies to be followed1 methods of work1 field of operation and the requirements of the successful electrician are pointed out and fully explained4 ,every young engineer will find this an excellent stepping-stone to more advanced works on electricity which he must master before success can be attained4 ,many young men become discouraged at the very out-start by attempting to read and study books that are far beyond their comprehension4 ,this book serves as the connecting link between the rudiments taught in the public schools and the real study of electricity4 ,it is interesting from cover to cover4 ,fifteenth edition4 #bjb pages4 ,illustrated4 ,price #a4jj ,,management ,,of ,,dynamos4 ,by ,,lummis-,,paterson4 ,a handbook of theory and practice4 ,this work is arranged in three parts4 ,the first part covers the elementary theory of the dynamo4 ,the second part1 the construction and action of the different classes of dynamos in common use are described2 while the third part relates to such matters as affect the practical management and working of dynamos and motors4 ,the following chapters are contained in the book3 ,electrical ,units2 ,magnetic ,principles2 ,theory of the ,dynamo2 ,armature2 ,armature in ,practice2 ,field ,magnets2 ,field ,magnets in ,practice2 ,regulating ,dynamos2 ,coupling ,dynamos2 ,installation1 ,running1 and ,maintenance of ,dynamos2 ,faults in ,dynamos2 ,faults in ,armatures2 ,motors4 #bib pages4 #aag illustrations4 ,price #a4ej ,,standard ,,electrical ,,dictionary4 ,by ,t4 ,o',,conor ,,sloane4 ,an indispensable work to all interested in electrical science4 ,suitable alike for the student and professional4 ,a practical hand-book of reference containing definitions of about #e1jjj distinct words1 terms and phrases4 ,the definitions are terse and concise and include every term used in electrical science4 ,recently issued4 ,an entirely new edition4 ,should be in the possession of all who desire to keep abreast with the progress of this branch of science4 ,in its arrangement and typography the book is very convenient4 ,the word or term defined is printed in black-faced type which readily catches the eye1 while the body of the page is in smaller but distinct type4 ,the definitions are well worded1 and so as to be understood by the non-technical reader4 ,the general plan seems to be to give an exact1 concise definition1 and then amplify and explain in a more popular way4 ,synonyms are also given1 and references to other words and phrases are made4 ,a very complete and accurate index of fifty pages is at the end of the volume2 and as this index contains all synonyms1 and as all phrases are indexed in every reasonable combination of words1 reference to the proper place in the body of the book is readily made4 ,it is difficult to decide how far a book of this character is to keep the dictionary form1 and to what extent it may assume the encyclopedia form4 ,for some purposes1 concise1 exactly worded definitions are needed2 for other purposes1 more extended descriptions are required4 ,this book seeks to satisfy both demands1 and does it with considerable success4 ,complete1 concise1 and convenient4 #fhb pages4 #cic illustrations4 ,twelfth edition4 ,price #c4jj ,,switchboards4 ,by ,,william ,,baxter1 ,,jr4 ,this book appeals to every engineer and electrician who wants to know the practical side of things4 ,it takes up all sorts and conditions of dynamos1 connections and circuits and shows by diagram and illustration just how the switchboard should be connected4 ,includes direct and alternating current boards1 also those for arc lighting1 incandescent1 and power circuits4 ,special treatment on high voltage boards for power transmission4 #bnd ,edition4 #aij pages4 ,illustrated4 ,price #a4fj ,,telephone ,,construction1 ,,installation1 ,,wiring1 ,,operation ,,and ,,maintenance4 ,by ,w4 ,h4 ,,radcliffe and ,h4 ,c4 ,cushing4 ,this book gives the principles of construction and operation of both the ,bell and ,independent instruments2 approved methods of installing and wiring them2 the means of protecting them from lightning and abnormal currents2 their connection together for operation as series or bridging stations2 and rules for their inspection and maintenance4 ,line wiring and the wiring and operation of special telephone systems are also treated4 ,intricate mathematics are avoided1 and all apparatus1 circuits and systems are thoroughly described4 ,the appendix contains definitions of units and terms used in the text4 ,selected wiring tables1 which are very helpful1 are also included4 ,among the subjects treated are ,construction1 ,operation1 and installation of ,telephone ,instruments1 ,inspection and ,maintenance of ,telephone ,instruments2 ,telephone ,line ,wiring2 ,testing ,telephone ,line ,wires and ,cables2 ,wiring and ,operation of ,special ,telephone ,systems2 etc4 #ajj pages1 #abe illustrations4 #a4jj ,,wireless ,,telegraphy ,,and ,,telephony ,,simply ,,explained4 ,by ,,alfred ,p4 ,,morgan4 ,this is undoubtedly one of the most complete and comprehensible treatises on the subject ever published1 and a close study of its pages will enable one to master all the details of the wireless transmission of messages4 ,the author has filled a long felt want and has succeeded in furnishing1 a lucid1 comprehensible explanation in simple language of the theory and practice of wireless telegraphy and telephony4 ,among the contents are3 ,introductory2 ,wireless ,transmission and ,reception--,the ,aerial ,system1 ,earth ,connections--,the ,transmitting ,apparatus1 ,spark ,coils and ,transformers1 ,condensers1 ,helixes1 ,spark ,gaps1 ,anchor ,gaps1 ,aerial ,switches--,the ,receiving ,apparatus1 ,detectors1 etc4--,tuning and ,coupling1 ,tuning ,coils1 ,loose ,couplers1 ,variable ,condensers1 ,directive ,wave ,systems-,miscellaneous ,apparatus3 ,telephone ,receivers1 ,range of ,stations1 ,static1 ,interference ,wireless ,telephones1 ,sound and ,sound ,waves1 ,the ,vocal ,cords and ,ear--,wireless ,telephones1 ,how ,sounds are changed into ,electric ,waves ,wireless ,telephones1 ,the ,apparatus-,summary4 #bjj pages4 #aej engravings4 ,price #a4jj ,,wireless ,,telephones ,,and ,,how ,,they ,,work4 ,by ,,james ,,erskine-,,murray4 ,this work is free from elaborate details and aims at giving a clear survey of the way in which ,wireless ,telephones work4 ,it is intended for amateur workers and for those whose knowledge of electricity is slight4 ,chapters contained3 ,how ,we ,hear2 ,historical2 ,the ,conversion of ,sound into ,electric ,waves2 ,wireless ,transmission2 ,the ,production of ,alternating ,currents of ,high ,frequency2 ,how the ,electric ,waves are ,radiated and ,received2 ,the ,receiving ,instruments2 ,detectors2 ,achievements and ,expectations2 ,glossary of ,technical ,words1 ,cloth4 ,price #a4jj ,,wiring ,a ,,house4 ,by ,,herbert ,,pratt4 ,shows a house already built2 tells just how to start about wiring it2 where to begin2 what wire to use2 how to run it according to ,insurance ,rules2 in fact just the information you need4 ,directions apply equally to a shop4 ,fourth edition4 #be cents4 ,,factory ,,management1 ,,etc4 ,,modern ,,machine ,,shop ,,construction1 ,,equipment ,,and ,,management4 ,by ,o4 ,e4 ,,perrigo1 ,m4,e4 ,the only work published that describes the modern machine shop or manufacturing plant from the time the grass is growing on the site intended for it until the finished product is shipped4 ,by a careful study of its thirty-two chapters the practical man may economically build1 efficiently equip1 and successfully manage the modern machine shop or manufacturing establishment4 ,just the book needed by those contemplating the erection of modern shop buildings1 the re-building and re-organization of old ones1 or the introduction of modern shop methods1 time and cost system4 ,it is a book written and illustrated by a practical shop man for practical shop men who are too busy to read theories and want facts4 ,it is the most complete all around book of its kind ever published4 ,it is a practical book for practical men1 from the apprentice in the shop to the president in the office4 ,it minutely describes and illustrates the most simple and yet the most efficient time and cost system yet devised4 ,price #f4jj ,,fuel ,,combustion ,,of ,,coal ,,and ,,the ,,prevention ,,of ,,smoke4 ,by ,,wm4 ,m4 ,,barr4 ,this book has been prepared with special reference to the generation of heat by the combustion of the common fuels found in the ,united ,states1 and deals particularly with the conditions necessary to the economic and smokeless combustion of bituminous coals in ,stationary and ,locomotive ,steam ,boilers4 ,the presentation of this important subject is systematic and progressive4 ,the arrangement of the book is in a series of practical questions to which are appended accurate answers1 which describe in language1 free from technicalities1 the several processes involved in the furnace combustion of ,american fuels2 it clearly states the essential requisites for perfect combustion1 and points out the best methods for furnace construction for obtaining the greatest quantity of heat from any given quality of coal4 ,nearly #cej pages1 fully illustrated4 ,price #a4jj ,,smoke ,,prevention ,,and ,,fuel ,,economy4 ,by ,,booth and ,,kershaw4 ,a complete treatise for all interested in smoke prevention and combustion1 being based on the ,german work of ,ernst ,schmatolla1 but it is more than a mere translation of the ,german treatise1 much being added4 ,the authors show as briefly as possible the principles of fuel combustion1 the methods which have been and are at present in use1 as well as the proper scientific methods for obtaining all the energy in the coal and burning it without smoke4 ,considerable space is also given to the examination of the waste gases1 and several of the representative ,english and ,american mechanical stoker and similar appliances are described4 ,the losses carried away in the waste gases are thoroughly analyzed and discussed in the ,appendix1 and abstracts are also here given of various patents on combustion apparatus4 ,the book is complete and contains much of value to all who have charge of large plants4 #aid pages4 ,illustrated4 ,price #b4hj ,,gas ,,engines ,,and ,,gas ,,gasoline ,,engines3 ,,their ,,operation1 ,,use ,,and ,,care4 ,by ,a4 ,,hyatt ,,verrill4 ,the ,simplest1 ,latest and ,most ,comprehensive popular work published on ,gasoline ,engines describing what the ,gasoline engine is2 its construction and operation2 how to install it2 how to select it2 how to use it and how to remedy troubles encountered4 ,intended for owners1 ,operators and ,users of ,gasoline ,motors of all kinds4 ,this work fully describes and illustrates the various types of ,gasoline engines used in ,motor ,boats1 ,motor ,vehicles and ,stationary ,work4 ,the parts1 accessories and ,appliances are described1 with chapters on ignition1 fuel1 lubrication1 operation and engine troubles4 ,special attention is given to the care1 operation and repair of motors with useful hints and suggestions on emergency repairs and make-shifts4 ,a complete glossary of technical terms and an alphabetically arranged table of troubles and their symptoms form most valuable and unique features of this manual4 ,nearly every illustration in the book is original1 having been made by the author4 ,every page is full of interest and value4 ,a book which you cannot afford to be without4 #cbj pages4 ,nearly #aej specially made engravings4 ,price #a4ej ,,gas1 ,,gasoline1 ,,and ,,oil ,,engines4 ,by ,,gardner ,d4 ,,hiscox4 ,just issued1 #bjth revised and enlarged edition4 ,every user of a gas engine needs this book4 ,simple1 instructive1 and right up-to-date4 ,the only complete work on the subject4 ,tells all about the running and management of gas1 gasoline and oil engines1 as designed and manufactured in the ,united ,states4 ,explosive motors for stationary1 marine and vehicle power are fully treated1 together with illustrations of their parts and tabulated sizes1 also their care and running are included4 ,electric ignition by induction coil and jump spark' are fully explained and illustrated1 including valuable information on the testing for economy and power and the erection of power plants4 ,the rules and regulations of the ,board of ,fire ,underwriters in regard to the installation and management of gasoline motors is given in full1 suggesting the safe installation of explosive motor power4 ,a list of ,united ,states ,patents issued on gas1 gasoline1 and oil engines and their adjuncts from #ahge to date is included4 #dhd pages4 #daj engravings ,price #b4ej ,,modern ,,gas ,,engines ,,and ,,producer ,,gas ,,plants4 ,by ,r4 ,e4 ,,mathor1 ,m4,e4 ,a guide for the gas engine designer1 user1 and engineer in the construction1 selection1 purchase installation1 operation1 and maintenance of gas engines4 ,more than one book on gas engines has been written1 but not one has thus far even encroached on the field covered by this book4 ,above all ,mr4 ,mathor's work is a practical guide4 ,recognizing the need of a volume that would assist the gas engine user in understanding thoroughly the motor upon which he depends for power1 the author has discussed his subject without the help of any mathematics and without elaborate theoretical explanations4 ,every part of the gas engine is described in detail1 tersely1 clearly1 with a thorough understanding of the requirements of the mechanic4 ,helpful suggestions as to the purchase of an engine1 its installation1 care1 and operation form a most valuable feature of the work4 #cbj pages4 #age detailed illustrations4 ,price #b4ej ,,gas ,,engine ,,construction1 ,,or ,,how ,,to ,,build ,a ,,half-,,horse-,,power ,,gas ,,engine4 ,by ,,parsell and ,,weed4 ,a practical treatise of #cjj pages describing the theory and principles of the action of ,gas ,engines of various types and the design and construction of a half-horse power ,gas ,engine1 with illustrations of the work in actual progress1 together with the dimensioned working drawings giving clearly the sizes of the various details2 for the student1 the scientific investigator and the amateur mechanic4 ,this book treats of the subject more from the standpoint of practice than that of theory4 ,the principles of operation of ,gas ,engines are clearly and simply described and then the actual construction of a half-horse power engine is taken up1 step by step1 showing in detail the making of the ,gas ,engine4 #c;d ,edition4 #cjj pages4 ,price #b4ej ,,the ,,gasoline ,,engine ,,on ,,the ,,farm3 ,,its ,,operation1 ,,repair ,,and ,,uses4 ,by ,,xeno ,w4 ,,putnam4 ,this is a practical treatise on the ,gasoline and ,kerosene engine intended for the man who wants to know just how to manage his engine and how to apply it to all kinds of farm work to the best advantage4 ,the book includes selecting the most suitable engine for farm work1 its most convenient and efficient installation1 with chapters on troubles1 their remedies and how to avoid them4 ,the care and management of the farm tractor in plowing1 harrowing1 harvesting and road grading are fully covered2 also plain directions are given for handling the tractor on the road4 ,special attention is given to relieving farm life of its drudgery by applying power to the disagreeable small tasks which must otherwise be done by hand4 ,many homemade contrivances for cutting wood1 supplying kitchen1 garden and barn with water1 loading1 hauling and unloading hay1 delivering grain to the bins or the feed trough are included2 also full directions for making the engine milk the cows1 churn1 wash1 sweep the house and clean the windows1 etc4 ,very fully illustrated with drawings of working parts and cuts showing ,stationary1 ,portable and ,tractor ,engines doing all kinds of farm work4 #cjj pages4 ,nearly #aej engravings4 #abmo4 ,price #a4ej ,,chemistry ,,of ,,gas ,,manufacture4 ,by ,h4 ,m4 ,,royles4 ,this book covers points likely to arise in the ordinary course of the duties of the engineer or manager of a gas works not large enough to necessitate the employment of a separate chemical staff4 ,it treats of the testing of the raw materials employed in the manufacture of illuminating coal gas1 and of the gas produced4 ,the preparation of standard solutions is given as well as the chemical and physical examination of gas coal including among its contents-,preparations of ,standard ,solutions1 ,coal1 ,furnaces1 ,testing and ,regulation4 ,products of ,carbonization4 ,analysis of ,crude ,coal ,gas4 ,analysis of ,lime4 ,ammonia4 ,analysis of ,oxide of ,iron4 ,naphthalene4 ,analysis of ,fire-,bricks and ,fire-,clay4 ,weldom and ,spent ,oxide4 ,photometry and ,gas ,testing4 ,carburetted ,water ,gas4 ,metropolis ,gas4 ,miscellaneous ,extracts4 ,useful ,tables4 #d4ej ,,gearing ,,and ,,cams ,,bevel ,,gear ,,tables4 ,by ,d4 ,,ag4 ,,engstrom4 ,a book that will at once commend itself to mechanics and draftsmen4 ,does a way with all the trigonometry and fancy figuring on bevel gears and makes it easy for anyone to lay them out or make them just right4 ,there are #cf full-page tables that show every necessary dimension for all sizes or combinations you're apt to need4 ,no puzzling figuring or guessing4 ,gives placing distance1 all the angles 7including cutting angles71 and the correct cutter to use4 ,a copy of this prepares you for anything in the bevel gear line4 #a4jj ,,change ,,gear ,,devices4 ,by ,,oscar ,e4 ,,perrigo4 ,a practical book for every designer1 draftsman1 and mechanic interested in the invention and development of the devices for feed changes on the different machines requiring such mechanism4 ,all the necessary information on this subject is taken up1 analyzed1 classified1 sifted1 and concentrated for the use of busy men who have not the time to go through the masses of irrelevant matter with which such a subject is usually encumbered and select such information as will be useful to them4 ,it shows just what has been done1 how it has been done1 when it was done1 and who did it4 ,it saves time in hunting up patent records and re-inventing old ideas4 #hh pages4 #a4jj ,,drafting ,,of ,,cams4 ,by ,louis ,,rouillion4 ,the laying out of cams is a serious problem unless you know how to go at it right4 ,this puts you on the right road for practically any kind of cam you are likely to run up against4 #be cents4 ,,hydraulics ,,hydraulic ,,engineering4 ,by ,,gardner ,d4 ,,hiscox4 ,a treatise on the properties1 power1 and resources of water for all purposes4 ,including the measurement of streams1 the flow of water in pipes or conduits2 the horse-power of falling water2 turbine and impact water-wheels1 wave motors1 centrifugal1 reciprocating1 and airlist pumps4 ,with #cjj figures and diagrams and #cf practical tables4 ,all who are interested in water-works development will find this book a useful one1 because it is an entirely practical treatise upon a subject of present importance1 and cannot fail in having a far-reaching influence1 and for this reason should have a place in the working library of every engineer4 ,among the subjects treated are3 ,historical-,hydraulics1 ,properties of ,water2 ,measurement of the flow of ,streams2 ,flow from ,subsurface orifices and nozzles2 ,flow of water in ,pipes2 ,siphons of various kinds2 ,dams and ,great ,storage ,reservoirs2 ,city and ,town ,water ,supply2 ,wells and their reenforcement2 ,air lift methods of raising water2 artesian wells2 ,irrigation of ,arid districts2 ,water ,power1 ,water ,wheels2 ,pumps and ,pumping ,machinery2 ,reciprocating ,pumps2 ,hydraulic ,power ,transmission2 ,hydraulic ,mining2 ,canals2 ,ditches2 ,conduits and ,pipe ,lines2 ,marine ,hydraulics2 ,tidal and ,sea ,wave power1 etc4 #cbj pages4 ,price #d4jj ,,ice ,,and ,,refrigeration ,,pocket ,,book ,,of ,,refrigeration ,,and ,,ice ,,making4 ,by ,a4 ,j4 ,,wallis-,,taylor ,this is one of the latest and most comprehensive reference books published on the subject of refrigeration and cold storage4 ,it explains the properties and refrigerating effect of the different fluids in use1 the management of refrigerating machinery and the construction and insulation of cold rooms with their required pipe surface for different degrees of cold2 freezing mixtures and non-freezing brines1 temperatures of cold rooms for all kinds of provisions1 cold storage charges for all classes of goods1 ice making and storage of ice1 data and memoranda for constant reference by refrigerating engineers1 with nearly one hundred tables containing valuable references to every fact and condition required in the installment and operation of a refrigerating plant4 ,illustrated4 7#eth ,edition1 revised47 ,price #a4ej ,,inventions ,,patents ,,inventor',s ,,manual1 ,,how ,,to ,,make ,a ,,patent ,,pay4 ,this is a book designed as a guide to inventors in perfecting their inventions1 taking out their patents and disposing of them4 ,it is not in any sense a ,patent ,solicitor's ,circular1 nor a ,patent ,broker's ,advertisement4 ,no advertisements of any description appear in the work4 ,it is a book containing a quarter of a century's experience of a successful inventor1 together with notes based upon the experience of many other inventors4 ,among the subjects treated in this work are3 ,how to ,invent4 ,how to ,secure a ,good ,patent4 ,value of ,good ,invention4 ,how to exhibit an ,invention4 ,how to ,interest ,capital4 ,how to ,estimate the value of a ,patent4 ,value of ,design ,patents4 ,value of ,foreign ,patents4 ,value of ,small ,inventions4 ,advice on ,selling ,patents4 ,advice on the formation of ,stock ,companies4 ,advice on the ,formation of ,limited ,liability ,companies4 ,advice on ,disposing of ,old ,patents4 ,advice as to ,patent ,attorneys4 ,advice as to ,selling ,agents4 ,forms of ,assignments4 ,license and ,contracts4 ,state ,laws ,concerning ,patent ,rights4 #aijj ,census of the ,united ,states by counties of over #aj1jjj population4 ,revised edition4 #abj pages4 ,price #a4jj ,,knots ,,knots1 ,,splices ,,and ,,rope ,,work4 ,by ,a4 ,,hyatt ,,verrill4 ,this is a practical book giving complete and simple directions for making all the most useful and ornamental knots in common use1 with chapters on ,splicing1 ,pointing1 ,seizing1 ,serving1 etc4 ,this book is fully illustrated with one hundred and fifty original engravings which show how each knot1 tie or splice is formed and its appearance when finished4 ,the book will be found of the greatest value to ,campers1 ,yachtsmen1 ,travelers1 ,boy ,scouts in fact to anyone having occasion to use or handle rope or knots for any purpose4 ,the book is thoroughly reliable and practical and is not only a guide but a teacher4 ,it is the standard work on the subject4 ,among the contents are3 #a4 ,cordage1 ,kinds of ,rope1 ,construction of ,rope1 ,parts of ,rope ,cable and ,bolt ,rope1 ,strength of ,rope1 ,weight of ,rope4 #b4 ,simple knots and ,bends4 ,terms used in ,handling ,rope4 ,seizing ,rope4 #c4 ,ties and ,hitches4 #d4 ,noose1 ,loops and ,mooring ,knots4 #e4 ,shortenings1 ,grommets and ,selvages4 #f4 ,lashings4 ,seizings and ,splices4 #g4 ,fancy ,knots and ,rope ,work4 #abh pages4 #aej original engravings4 ,price #fj cents4 ,,lathe ,,work ,,modern ,,american ,,lathe ,,practice4 ,by ,,oscar ,e4 ,,perrigo4 ,this is a new book from cover to cover1 and the only complete ,american work on the subject written by a man who knows not only how work ought to be done1 but who also knows how to do it1 and how to convey this knowledge to others4 ,it is strictly up-to-date in its descriptions and illustrations1 which represent the very latest practice in lathe and boring mill operations as well as the construction of and latest developments in the manufacture of these important classes of machine tools4 ,lathe history and the relations of the ,lathe to manufacturing are given2 also a description of the various devices for ,feeds and ,thread ,cutting mechanisms from early efforts in this direction to the present time4 ,lathe design is thoroughly discussed1 including ,back ,gearing1 ,driving ,cones1 ,thread ,cutting ,gears1 and all the essential elements of the modern ,lathe4 ,the classification of ,lathes is taken up1 giving the essential differences of the several types of ,lathes1 including1 as is usually understood1 ,engine ,lathes1 ,bench ,lathes1 ,speed ,lathes1 ,forge ,lathes1 ,gap ,lathes1 ,pulley ,lathes1 ,forming ,lathes1 ,multiple ,spindle ,lathes1 ,rapid ,reduction ,lathes1 ,precision ,lathes1 ,turret ,lathes1 ,special ,lathes1 ,electrically ,driven ,lathes1 etc4 #dbd pages4 #cad illustrations4 ,price #b4ej ,,practical ,,metal ,,turning4 ,by ,,joseph ,g4 ,,horner4 ,this important and practical subject is treated in a full and exhaustive manner and nothing of importance is omitted4 ,the principles and practice and all the different branches of ,turning are considered and well illustrated4 ,all the different kinds of ,chucks of usual forms1 as well as some unusual kinds1 are shown4 ,a feature of the book is the important section devoted to modern ,turret practice2 ,boring is another subject which is treated fully2 and the chapter on ,tool ,holders illustrates a large number of representative types4 ,thread ,cutting is treated at reasonable length2 and the last chapter contains a good deal of information relating to the ,high-,speed ,steels and their work4 ,the numerous tools used by machinists are illustrated1 and also the adjuncts of the lathe4 ,in fact1 the entire subject is treated in such a thorough manner as to make this book the standard one on the subject4 ,it is indispensable to the manager1 engineer1 and machinist as well as to the student1 amateur1 and experimental1 man who desires to keep up-to-date4 #djj pages1 fully illustrated4 ,price #c4ej ,,turning ,,and ,,boring ,,tapers4 ,by ,,fred ,h4 ,,colvin4 ,there are two ways to turn tapers2 the right way and one other4 ,this treatise has to do with the right way2 it tells you how to start the work properly1 how to set the lathe1 what tools to use and how to use them1 and forty and one other little things that you should know4 ,fourth edition4 #be cents4 ,,liquid ,,air ,,liquid ,,air ,,and ,,the ,,liquefaction ,,of ,,gases4 ,by ,t4 ,o',,conor ,,sloane4 ,this book gives the history of the theory1 discovery1 and manufacture of ,liquid ,air1 and contains an illustrated description of all the experiments that have excited the wonder of audiences all over the country4 ,it shows how liquid air1 like water1 is carried hundreds of miles and is handled in open buckets4 ,it tells what may be expected from it in the near future4 ,a book that renders simple one of the most perplexing chemical problems of the century4 ,startling developments illustrated by actual experiments4 ,it is not only a work of scientific interest and authority1 but is intended for the general reader1 being written in a popular style-easily understood by every one4 ,second edition4 #cfe pages4 ,price #b4jj ,,locomotive ,,engineering ,,air-,,brake ,,catechism4 ,by ,,robert ,h4 ,,blackall4 ,this book is a standard text book4 ,it covers the ,westinghouse ,air-,brake ,equipment1 including the ,no4 #e and the ,no4 #f ,e4 ,t ,locomotive ,brake ,equipment2 the ,k 7,quick-,service7 ,triple ,valve for ,freight ,service2 and the ,cross-,compound ,pump4 ,the operation of all parts of the apparatus is explained in detail1 and a practical way of finding their peculiarities and defects1 with a proper remedy1 is given4 ,it contains #b1jjj questions with their answers1 which will enable any railroad man to pass any examination on the subject of ,air ,brakes4 ,endorsed and used by air-brake instructors and examiners on nearly every railroad in the ,united ,states4 #beth ,edition4 #cej pages1 fully illustrated with folding plates and diagrams4 #b4jj ,,american ,,compound ,,locomotives4 ,by ,,fred4 ,h4 ,,colvin4 ,the only book on compounds for the engineman or shopman that shows in a plain1 practical way the various features of compound locomotives in use4 ,shows how they are made1 what to do when they break down or balk4 ,contains sections as follows3-,a ,bit of ,history4 ,theory of ,compounding ,steam ,cylinders4 ,baldwin ,two-,cylinder ,compound4 ,pittsburg ,two-,cylinder ,compound4 ,rhode ,island ,compound4 ,richmond ,compound4 ,rogers ,compound4 ,schenectady ,two-,cylinder ,compound4 ,vauclain ,compound4 ,tandem ,compounds4 ,baldwin ,tandem4 ,the ,colvin-,wightman ,tandem4 ,schenectady ,tandem4 ,balanced ,locomotives4 ,baldwin ,balanced ,compound4 ,plans for ,balancing4 ,locating ,blows4 ,breakdowns4 ,reducing ,valves4 ,drifting4 ,valve ,motion4 ,disconnecting4 ,power of ,compound ,locomotives4 ,practical ,notes4 ,fully illustrated and containing ten special ,duotone inserts on heavy ,plate ,paper1 showing different types of ,compounds4 #adb pages4 ,price #a4jj ,,application ,,of ,,highly ,,superheated ,,steam ,,to ,,locomotives4 ,by ,,robert ,,garbe4 ,a practical book4 ,contains special chapters on ,generation of ,highly ,superheated ,steam2 ,superheated ,steam and the ,two-,cylinder ,simple ,engine2 ,compounding and ,superheating2 ,designs of ,locomotive ,superheaters2 ,constructive ,details of ,locomotives using ,highly ,superheated ,steam2 ,experimental and ,working ,results4 ,illustrated with folding places and tables4 ,price #b4ej ,,combustion ,,of ,,coal ,,and ,,the ,,prevention ,,of ,,smoke4 ,by ,,wm4 ,m4 ,,barr4 ,this book has been prepared with special reference to the generation of heat by the combustion of the common fuels found in the ,united ,states1 and deals particularly with the conditions necessary to the economic and smokeless combustion of bituminous coal in ,stationary and ,locomotive ,steam ,boilers4 ,the presentation of this important subject is systematic and progressive4 ,the arrangement of the book is in a series of practical questions to which are appended accurate answers1 which describe in language1 free from technicalities1 the several processes involved in the furnace combustion of ,american fuels2 it clearly states the essential requisites for perfect combustion1 and points out the best methods of furnace construction for obtaining the greatest quantity of heat from any given quality of coal4 ,nearly #cej pages1 fully illustrated4 ,price #a4jj ,,diary ,,of ,a ,,round ,,house ,,foreman4 ,by ,t4 ,s4 ,,reilly4 ,this is the greatest book of railroad experiences ever published4 ,containing a fund of information and suggestions along the line of handling men1 organizing1 etc41 that one cannot afford to miss4 #agf pages4 ,price #a4jj ,,link ,,motions1 ,,valves ,,and ,,valve ,,setting4 ,by ,,fred ,h4 ,,colvin1 ,associate ,editor of ,american ,machinist4 ,a handy book for the engineer or machinist that clears up the mysteries of valve setting4 ,shows the different valve gears in use1 how they work1 and why4 ,piston and slide valves of different types are illustrated and explained4 ,a book that every railroad man in the motive power department ought to have4 ,contains chapters on ,locomotive ,link ,motion1 ,valve ,movements1 ,setting ,slide ,valves1 ,analysis by ,diagrams1 ,modern ,practice1 ,slip of ,block1 ,slide ,valves1 ,piston ,valves1 ,setting ,piston ,valves1 ,joy-,allen ,valve ,gear1 ,walschaert ,valve ,gear1 ,gooch ,valve ,gear1 ,alfree-,hubbell ,valve ,gear1 etc41 etc4 ,fully illustrated4 ,price #ej cents4 ,,locomotive ,,boiler ,,construction4 ,by ,,frank ,a4 ,,kleinhans4 ,the construction of boilers in general is treated1 and following this1 the locomotive boiler is taken up in the order in which its various parts go through the shop4 ,shows all types of boilers used2 gives details of construction2 practical facts1 such as life of riveting1 punches and dies2 work done per day1 allowance for bending and flanging sheets1 and other data4 ,locomotive boilers present more difficulty in laying out and building than any other type1 and for this reason the author uses them as examples4 ,anyone who can handle them can tackle anything4 ,contains chapters on ,laying ,out ,work2 ,flanging and ,forging2 ,punching2 ,shearing3 ,plate ,planing2 ,general ,tables2 ,finishing ,parts2 ,bending2 ,machinery ,parts2 ,riveting2 ,boiler ,details2 ,smoke ,box ,details2 ,assembling and ,caulking2 ,boiler ,shop ,machinery1 etc41 etc4 ,there isn't a man who has anything to do with boiler work1 either new or repair work1 who doesn't need this book4 ,the manufacturer1 superintendent1 foreman1 and boiler worker all need it4 ,no matter what the type of boiler1 you'll find a mint of information that you wouldn't be without4 ,over #djj pages1 five large folding plates4 ,price3 #c4jj ,,locomotive ,,breakdowns ,,and ,,their ,,remedies4 ,by ,,geo4 ,l4 ,,fowler4 ,revised by ,,wm4 ,w4 ,wood1 ,air-,brake ,instructor4 ,just issued4 ,revised pocket edition4 ,it is out of the question to try and tell you about every subject that is covered in this pocket edition of ,locomotive ,breakdowns4 ,just imagine all the common troubles that an engineer may expect to happen some time1 and then add all of the unexpected ones1 troubles that could occur1 but that you had never thought about1 and you will find that they are all treated with the very best methods of repair4 ,walschaert ,locomotive ,valve ,gear ,troubles1 ,electric ,headlight ,troubles1 as well as ,questions and ,answers on the ,air ,brake are all included4 #bid pages4 #gth ,revised ,edition4 ,fully illustrated4 #a4jj ,,locomotive ,,catechism4 ,by ,,robert ,,grimshaw4 ,the revised edition of ,locomotive ,catechism1 by ,robert ,grimshaw1 is a ,new ,book from ,cover to ,cover4 ,it contains twice as many pages and double the number of illustrations of previous editions4 ,includes the greatest amount of practical information ever published on the construction and management of modern locomotives4 ,specially ,prepared ,chapters on the ,walschaert ,locomotive ,valve ,gear1 the ,air ,brake ,equipment and the ,electric ,head ,light are given4 ,it commends itself at once to every ,engineer and ,fireman1 and to all who are going in tor examination or promotion4 ,in plain language1 with full complete answers1 not only all the questions asked by the examining engineer are given1 but those which the young and less experienced would ask the veteran1 and which old hands ask as stickers4 ,it is a veritable ,encyclopedia of the ,locomotive1 is entirely free from mathematics1 easily1 understood and thoroughly up-to-date4 ,contains over #d1jjj ,examination ,questions with their ,answers4 #hbe pages1 #dcg illustrations and three folding plates4 #bhth ,revised ,edition4 #b4ej ,,practical ,,instructor ,,and ,,reference ,,book ,,for ,,locomotive ,,firemen ,,and ,,engineers4 ,by ,,chas4 ,f4 ,,lockhart4 ,an entirely new book on the ,locomotive4 ,it appeals to every railroad man1 as it tells him how things are done and the right way to do them4 ,written by a man who has had years of practical experience in locomotive shops and on the road firing and running4 ,the information given in this book cannot be found in any other similar treatise4 ,eight hundred and fifty-one questions with their answers are included1 which will prove specially helpful to those preparing for examination4 ,practical information on3 ,the ,construction and ,operation of ,locomotives4 ,breakdowns and their ,remedies2 ,air4 ,brakes and ,valve ,gears4 ,rules and ,signals are handled in a thorough manner4 ,as a book of reference it cannot be excelled4 ,the book is divided into six parts1 as follows3 #a4 ,the ,fireman's ,duties4 #b4 ,general description of the ,locomotive4 #c4 ,breakdowns and their ,remedies4 #d4 ,air ,brakes4 #e4 ,extracts from ,standard ,rules4 #f4 ,questions for examination4 ,the #hea questions have been carefully selected and arranged4 ,these cover the examinations required by the different railroads4 #cfh pages4 #hh illustrations4 ,price #a4ej ,,prevention ,,of ,,railroad ,,accidents1 ,,or ,,safety ,,in ,,railroading4 ,by ,,george ,,bradshaw4 ,this book is a heart-to-heart talk with ,railroad ,employees1 dealing with facts1 not theories1 and showing the men in the ranks1 from every-day experience1 how accidents occur and how they may be avoided4 ,the book is illustrated with seventy original photographs and drawings showing the safe and unsafe methods of work4 ,no visionary schemes1 no ideal pictures4 ,just plain facts and ,practical ,suggestions are given4 ,every railroad employee who reads the book is a better and safer man to have in railroad service4 ,it gives just the information which will be the means of preventing many injuries and deaths4 ,all railroad employees should procure a copy1 read it1 and do your part in preventing accidents4 #afi pages4 ,pocket ,size4 ,fully illustrated4 ,price #ej cents4 ,,train ,,rule ,,examinations ,,made ,,easy4 ,by ,g4 ,e4 ,,collingwood4 ,this is the only practical work on train-rules in print4 ,every detail is covered1 and puzzling points are explained in simple1 comprehensive language1 making it a practical treatise for the ,train ,dispatcher1 ,engineman1 ,trainman1 and all others who have to do with the movements of trains4 ,contains complete and reliable information of the ,standard ,code of ,train4 ,rules for single track4 ,shows ,signals in ,colors1 as used on the different roads4 ,explains fully the practical application of train orders1 giving a clear and definite understanding of all orders which may be used4 ,the meaning and necessity for certain rules are explained in such a manner that the student may know beyond a doubt the rights conferred under any orders he may receive or the action required by certain rules4 ,as nearly all roads require trainmen to pass regular examinations1 a complete set of examination questions1 with their answers1 are included4 ,these will enable the student to pass the required examinations with credit to himself and the road for which he works4 #bef pages4 ,fully illustrated with ,train ,signals in colors4 ,price #a4bf ,,train ,,rules ,,and ,,despatching4 ,by ,h4 ,a4 ,,dalby4 ,every railroad man1 no matter what department he's in1 needs a copy of this book4 ,it gives the standard rules for both single and double track1 shows all the signals1 with colors wherever necessary1 and has a list of towns where time changes1 with a map showing the whole country4 ,the rules are explained wherever there is any doubt about their meaning or where they are modified by different railroads4 ,it's the only practical book on train rules in print4 ,over #bbj pages4 ,leather cover4 ,price #a4ej ,,the ,,walschaert ,,and ,,other ,,modern ,,radial ,,valve ,,gears ,,for ,,locomotives4 ,by ,,wm4 ,w4 ,wood4 ,if you would thoroughly understand the ,walschaert ,valve ,gear you should possess a copy of this book1 as the author takes the plainest form of a steam engine-a stationary engine in the rough1 that will only turn its crank in one direction and from it builds up--with the reader's help--a modern locomotive equipped with the ,walschaert ,valve ,gear1 complete4 ,the points discussed are clearly illustrated2 two large folding plates that show the positions of the valves of both inside or outside admission type1 as well as the links and other parts of the gear when the crank is at nine different points in its revolution1 are especially valuable in making the movement clear4 ,these employ sliding cardboard models which are contained in a pocket in the cover4 ,the book is divided into five general divisions1 as follows3 ,i4 ,analysis of the gear4 ,,ii4 ,designing and erecting the gear4 ,,iii4 ,advantages of the gear4 ,,iv4 ,questions and answers relating to the ,walschaert ,valve ,gear4 ,v4 ,setting valves with the ,walschaert ,valve ,gear2 the three primary types of locomotive valve motion2 modern radial valve gears other than the ,walschaert2 the ,hobart ,all-free valve and valve gear1 with questions and answers on breakdowns2 the ,baker-,pilliod valve gear2 the ,improved ,baker-,pilliod ,valve ,gear1 with questions and answers on breakdowns4 ,the questions with full answers given will be especially valuable to firemen and engineers in preparing for an examination for promotion4 #bde pages4 ,third ,revised ,edition4 ,price #a4ej ,,westinghouse ,e-,t ,,air-,,brake ,,instruction ,,pocket ,,book4 ,by ,,wm4 ,w4 ,wood1 ,air-,brake ,instructor4 ,here is a book for the railroad man1 and the man who aims to be one4 ,it is without doubt the only complete work published on the ,westinghouse ,e-,t ,locomotive ,brake ,equipment4 ,written by an ,air ,brake ,instructor who knows just what is needed4 ,it covers the subject thoroughly4 ,everything about the ,new ,westinghouse ,engine and ,tender ,brake ,equipment1 including the ,standard ,no4 #e and the ,perfected ,no4 #f ,style of brake1 is treated in detail4 ,written in plain ,english and profusely illustrated with ,colored ,plates1 which enable one to trace the flow of pressures throughout the entire equipment4 ,the best book ever published on the ,air ,brake4 ,equally good for the beginner and the advanced engineer4 ,will pass any one through any examination4 ,it informs and enlightens you on every point4 ,indispensable to every engineman and trainman4 ,contains examination questions and answers on the ,e-,t equipment4 ,covering what the ,e-,t ,brake is4 ,how it should be operated4 ,what to do when defective4 ,not a question can be asked of the engineman up for promotion on either the ,no4 #e or the ,no4 #f ,e-,t equipment that is not asked and answered in the book4 ,if you want to thoroughly understand the ,e-,t equipment get a copy of this book4 ,it covers every detail4 ,makes ,air ,brake troubles and examinations easy4 ,price #a4ej ,,machine ,,shop ,,practice ,,american ,,tool ,,making ,,and ,,interchangeable ,,manufacturing4 ,by ,j4 ,v4 ,,woodworth4 ,a shoppy book1 containing no theorizing1 no problematical or experimental devices1 there are no badly proportioned and impossible diagrams1 no catalogue cuts1 but a valuable collection of drawings and descriptions of devices1 the rich fruits of the author's own experience4 ,in its #ejj-odd pages the one subject only1 ,tool ,making1 and whatever relates thereto1 is dealt with4 ,the work stands without a rival4 ,it is a complete practical treatise on the art of ,american ,tool ,making and system of interchangeable manufacturing as carried on to-day in the ,united ,states4 ,in it are described and illustrated all of the different types and classes of small tools1 fixtures1 devices1 and special appliances which are in general use in all machine manufacturing and metal working establishments where economy1 capacity1 and interchangeability in the production of machined metal parts are imperative4 ,the science of jig making is exhaustively discussed1 and particular attention is paid to drill jigs1 boring1 profiling and milling fixtures and other devices in which the parts to be machined are located and fastened within the contrivances4 ,all of the tools1 fixtures1 and devices illustrated and described have been or are used for the actual production of work1 such as parts of drill presses1 lathes1 patented machinery1 typewriters1 electrical apparatus1 mechanical appliances1 brass goods1 composition parts1 mould products1 sheet metal articles1 drop forgings1 jewelry1 watches1 medals1 coins1 etc4 #eca pages4 ,price #d4jj ,,henley',s ,,encyclopedia ,,of ,,practical ,,engineering ,,and ,,allied ,,trades4 ,edited by ,,joseph ,g4 ,,horner1 ,a4,m4,i41 ,m4,e4 ,this set of five volumes contains about #b1ejj pages with thousands of illustrations1 including diagrammatic and sectional drawings with full explanatory details4 ,this work covers the entire practice of ,civil and ,mechanical ,engineering4 ,the best known expert in all branches of engineering have contributed to these volumes4 ,the ,cyclopedia is admirably well adapted to the needs of the beginner and the self-taught practical man1 as well as the mechanical engineer1 designer1 draftsman1 shop superintendent1 foreman1 and machinist4 ,the work will be found a means of advancement to any progressive man4 ,it is encyclopedic in scope1 thorough and practical in its treatment of technical subjects1 simple and clear in its descriptive matter1 and without unnecessary technicalities or formulae4 ,the articles are as brief as may be and yet give a reasonably clear and explicit statement of the subject1 and are written by men who have had ample practical experience in the matters of which they write4 ,it tells you all you want to know about engineering and tells it so simply1 so clearly1 so concisely1 that one cannot help but understand4 ,as a work of reference it is without a peer4 #f4jj per volume4 ,for complete set of five volumes1 price #be4jj ,,machine ,,shop ,,arithmetic4 ,by ,,colvin-,,cheney4 ,this is an arithmetic of the things you have to do with daily4 ,it tells you plainly about3 how to find areas of figures2 how to find surface or volume of balls or spheres2 handy ways for calculating2 about compound gearing2 cutting screw threads on any lathe2 drilling for taps2 speeds of drills1 taps1 emery wheels1 grindstones1 milling cutters1 etc42 all about the ,metric system with conversion tables2 properties of metals2 strength of bolts and nuts2 decimal equivalent of an inch4 ,all sorts of machine shop figuring and #a1jja other things1 any one of which ought to be worth more than the price of this book to you1 and it saves you the trouble of bothering the boss4 #fth ,edition4 #aca pages4 ,price #ej cents4 ,,modern ,,machine ,,shop ,,construction1 ,,equipment ,,and ,,management4 ,by ,,oscar ,e4 ,,perrigo4 ,the only work published that describes the ,modern ,machine ,shop or ,manufacturing ,plant from the time the grass is growing on the site intended for it until the finished product is shipped4 ,just the book needed by those contemplating the erection of modern shop buildings1 the rebuilding and reorganization of old ones1 or the introduction of ,modern ,shop ,methods1 time and cost systems4 ,it is a book written and illustrated by a practical shop man for practical shop men who are too busy to read theories and want facts4 ,it is the most complete all-around book of its kind ever published4 #djj large quarto pages4 #bbe original and specially-made illustrations4 ,price #e4jj ,,mechanical ,,appliances1 ,,mechanical ,,movements ,,and ,,novelties ,,of ,,construction4 ,by ,,gardner ,d4 ,,hiscox4 ,this is a supplementary volume to the one upon mechanical movements4 ,unlike the first volume1 which is more elementary in character1 this volume contains illustrations and descriptions of many combinations of motions and of mechanical devices and appliances found in different lines of machinery4 ,each device being shown by a line drawing with a description showing its working parts and the method of operation4 ,from the multitude of devices described1 and illustrated1 might be mentioned1 in passing1 such items as conveyors and elevators1 ,prony brakes1 thermometers1 various types of boilers1 solar engines1 oil-fuel burners1 condensers1 evaporators1 ,corliss and other valve gears1 governors1 gas engines1 water motors of various descriptions1 air ships1 motors and dynamos1 automobile and motor bicycles1 railway block signals1 car couplers1 link and gear motions1 ball bearings1 breech block mechanism for heavy guns1 and a large accumulation of others of equal importance4 #a1jjj specially made engravings4 #cif octavo pages4 ,price #b4ej ,,mechanical ,,movements1 ,,powers1 ,,and ,,devices4 ,by ,,gardner ,d4 ,,hiscox4 ,this is a collection of #a1hij engravings of different mechanical motions and appliances1 accompanied by appropriate text1 making it a book of great value to the inventor1 the draftsman1 and to all readers with mechanical tastes4 ,the book is divided into eighteen sections or chapters in which the subject matter is classified under the following heads3 ,mechanical ,powers2 ,transmission of ,power2 ,measurement of ,power1 ,steam ,power2 ,air ,power ,appliances2 ,electric ,power and ,construction1 ,navigation and ,roads2 ,gearing2 ,motion and ,devices2 ,controlling ,motion2 ,horological2 ,mining2 ,mill and ,factory ,appliances2 ,construction and ,devices2 ,drafting ,devices3 ,miscellaneous ,devices1 etc4 #abth edition4 #djj octavo pages4 ,price #b4ej ,,machine ,,shop ,,tools ,,and ,,shop ,,practice4 ,by ,w4 ,h4 ,,vandervoort4 ,a work of #eee pages and #fgc illustrations1 describing in every detail the construction1 operation1 and manipulation of both hand and machine tools4 ,includes chapters on filing1 fitting1 and scraping surfaces2 on drills1 reamers1 taps1 and dies2 the lathe and its tools2 planers1 shapers1 and their tools2 milling machines and cutters2 gear cutters and gear cutting2 drilling machines and drill work2 grinding machines and their work2 hardening and tempering2 gearing1 belting and transmission machinery3 useful data and tables4 #fth edition1 ,price #c4jj ,,the ,,modern ,,machinist4 ,by ,,john ,t4 ,,usher4 ,this is a book showing1 by plain description and by profuse engravings1 made expressly for the work1 all that is best1 most advanced1 and of the highest efficiency in modern machine shop practice1 tools1 and implements1 showing the way by which and through which1 as ,mr4 ,maxim says1 ,american machinists have become and are the finest mechanics in the world4 ,indicating as it does1 in every line1 the familiarity of the author with every detail of daily experience in the shop1 it cannot fail to be of service to any man practically connected with the shaping or finishing of metals4 ,there is nothing experimental or visionary about the book1 all devices being in actual use and giving good results4 ,it might be called a compendium of shop methods1 showing a variety of special tools and appliances which will give new ideas to many mechanics1 from the superintendent down to the man at the bench4 ,it will be found a valuable addition to any machinist's library1 and should be consulted whenever a new or difficult job is to be done1 whether it is boring1 milling1 turning1 or planing1 as they are all treated in a practical manner4 ,fifth ,edition4 #cbj pages4 #bej illustrations4 ,price #b4ej ,,modern ,,milling ,,machines3 ,,their ,,design1 ,,construction ,,and ,,operation4 ,by ,,joseph ,g4 ,,horner4 ,this book describes and illustrates the ,milling ,machine and its work in such a plain1 clear1 and forceful manner1 and illustrates the subject so clearly and completely1 that the up-to-date machinist1 student1 or mechanical engineer cannot afford to do without the valuable information which it contains4 ,it describes not only the early machines of this class1 but notes their gradual development into the splendid machines of the present day1 giving the design and construction of the various types1 forms1 and special features produced by prominent manufacturers1 ,american and foreign4 ,milling cutters in all their development and modernized forms are illustrated and described1 and the operations they are capable of producing upon different classes of work are carefully described in detail1 and the speeds and feeds necessary are discussed1 and valuable and useful data given for determining these usually perplexing problems4 ,the book is the most comprehensive work published on the subject4 #cjd pages4 #cjj illustrations4 ,price #d4jj ,,shop ,,kinks4 ,by ,,robert ,,grimshaw4 ,a book of #djj pages and #bbb illustrations1 being entirely different from any other book on machine shop practice4 ,departing from conventional style1 the author avoids universal or common shop usage and limits his work to showing special ways of doing things better1 more cheaply and more rapidly than usual4 ,as a result the advanced methods of representative establishments of the world are placed at the disposal of the reader4 ,this book shows the proprietor where large savings are possible1 and how products may be improved4 ,to the employee it holds out suggestions that1 properly applied1 will hasten his advancement4 ,no shop can afford to be without it4 ,it bristles with valuable wrinkles and helpful suggestions1 ,it will benefit all1 from apprentice to proprietor4 ,every machinist1 at any age1 should study its pages4 ,fifth ,edition4 ,price #b4ej ,,threads ,,and ,,thread ,,cutting4 ,by ,,colvin and ,,stabel4 ,this clears up many of the mysteries of thread-cutting1 such as double and triple threads1 internal threads1 catching threads1 use of hobs1 etc4 ,contains a lot of useful hints and several tables4 #crd ,edition4 ,price #be cents4 ,,tools ,,for ,,machinists ,,and ,,wood ,,workers1 ,,including ,,instruments ,,of ,,measurement4 ,by ,,joseph ,g4 ,,horner4 ,the principles upon which cutting tools for wood1 metal1 and other substances are made are identical1 whether used by the machinist1 the carpenter1 or by any other skilled mechanic in their daily work1 and the object of this book is to give a correct and practical description of these tools as they are commonly designed1 constructed1 and used4 #cdj pages1 fully illustrated4 ,price #c4ej ,,manual ,,training ,,economics ,,of ,,manual ,,training4 ,by ,,louis ,,rouillion4 ,the only book published that gives just the information needed by all interested in ,manual ,training1 regarding ,buildings1 ,equipment1 and ,supplies4 ,shows exactly what is needed for all grades of the work from the ,kindergarten to the ,high and ,normal ,school4 ,gives itemized lists of everything used in ,manual ,training ,work and tells just what it ought to cost4 ,also shows where to buy supplies1 etc4 ,contains #agd pages1 and is fully illustrated4 #bnd ,edition4 ,price #a4ej ,,marine ,,engineering ,,marine ,,engines ,,and ,,boilers1 ,,their ,,design ,,and ,,construction4 ,by ,dr4 ,g4 ,,bauer1 ,,leslie ,s4 ,,robertson1 and ,s4 ,,bryan ,,donkin4 in the words of4 ,dr4 ,bauer1 the present work owes its origin to an oft felt want of a ,condensed ,treatise1 embodying the ,theoretical and ,practical ,rules used in ,designing ,marine ,engines and ,boilers4 ,the need for such a work has been felt by most engineers engaged in the construction and working of ,marine ,engines1 not only by the younger men1 but also by those of greater experience4 ,the fact that the original ,german work was written by the chief engineer of the famous ,vulcan ,works1 ,stettin1 is in itself a guarantee that this book is in all respects thoroughly up-to-date1 and that it embodies all the information which is necessary for the design and construction of the highest types of marine engines and boilers4 ,it may be said that the motive power which ,dr4 ,bauer has placed in the fast ,german liners that have been turned out of late years from the ,stettin ,works1 represent the very best practice in marine engineering of the present day4 ,this work is clearly written1 thoroughly systematic1 theoretically sound2 while the character of its plans1 drawings1 tables1 and statistics is without reproach4 ,the illustrations are careful reproductions from actual working drawings1 with some well-executed photographic views of completed engines and boilers4 #eej illustrations and numerous tables4 #i4jj net ,,modern ,,submarine ,,chart4 ,a cross-section view1 showing clearly and distinctly all the interior of a ,submarine of the latest type4 ,you get more information from this chart1 about the construction and operation of a ,submarine1 than in any other way4 ,no ,details omitted-everything is accurate and to scale4 ,it is absolutely correct in every detail1 having been approved by ,naval ,engineers4 ,all the machinery and devices fitted in a modern ,submarine ,boat are shown and to make the engraving more readily understood all the features are shown in operative form with ,officers and ,men in the act of performing the duties assigned to them in service conditions4 ,this ,,chart ,,is ,,really ,,an ,,encyclopedia ,,of ,a ,,submarine4 ,it is educational and worth many times its cost4 ,mailed in a ,tube for #be cents4 #gdd pages4 ,,mining ,,ore ,,deposits1 ,,with ,a ,,chapter ,,on ,,hints ,,to ,,prospectors4 ,by ,j4 ,p4 ,,johnson ,this book gives a condensed account of the ore-deposits at present known in ,south ,africa4 ,it is also intended as a guide to the prospector4 ,only an elementary knowledge of geology and some mining experience are necessary in order to understand this work4 ,with these qualifications1 it will materially assist one in his search for metalliferous mineral occurrences and1 so far as simple ores are concerned1 should enable one to form some idea of the possibilities of any he may find4 ,among the chapters given are3 ,titaniferous and ,chromiferous ,iron ,oxides-,nickel-,copper-,cobalt-,tin-,mo lybdenum-,tungsten-,lead-,mercury -,antimony-,iron-,hints to ,prospectors4 #b4jj ,,physics ,,and ,,chemistry ,,of ,,mining4 ,by ,t4 ,h4 ,,byrom4 ,a practical work for the use of all preparing for examinations in mining or qualifying for colliery managers' certificates4 ,the aim of the author in this excellent book is to place clearly before the reader useful and authoritative data which will render him valuable assistance in his studies4 ,the only work of its kind published4 ,the information incorporated in it will prove of the greatest practical utility to students1 mining engineers1 colliery1 managers1 and all others who are specially interested in the present-day treatment of mining problems4 ,among its contents are chapters on3 ,the ,atmosphere2 ,laws ,relating to the ,behavior of ,gases2 ,the ,diffusion of ,gases2 ,composition of the ,atmosphere3 ,sundry ,constituents of the ,atmosphere2 ,water2 ,carbon2 ,fire-,damp2 ,combustion2 ,coal ,dust and ,its ,action2 ,explosives2 ,composition of ,various ,coals and ,fuels2 ,methods of ,analysis of ,coal2 ,strata ,adjoining the ,coal ,measures2 ,magnetism and ,electricity2 ,appendix2 ,useful ,tables1 etc42 ,miscellaneous ,questions4 #afj pages4 ,illustrated4 #b4jj ,,practical ,,coal ,,mining4 ,by ,t4 ,h4 ,,cockin4 ,an important work1 containing #dbh pages and #bac illustrations1 complete with practical details1 which will intuitively impart to the reader1 not only a general knowledge of the principles of coal mining1 but also considerable insight into allied subjects4 ,this treatise is positively up to date in every instance1 and should be in the hands of every colliery engineer1 geologist1 mine operator1 superintendent1 foreman1 and all others who are interested in or connected with the industry4 #bnd ,edition4 #b4ej ,,pattern ,,making ,,practical ,,pattern ,,making4 ,by ,f4 ,w4 ,,barrows4 ,this is a very complete and entirely practical treatise on the subject of pattern making1 illustrating pattern work in wood and metal4 ,from its pages you are taught just what you should know about pattern making4 ,it contains a detailed description of the materials used by pattern makers1 also the tools1 both those for hand use1 and the more interesting machine tools2 having complete chapters on the band saw1 ,the ,buzz ,saw1 and the ,lathe4 ,individual patterns of many different kinds are fully illustrated and described1 and the mounting of metal patterns on plates for molding machines is included4 ,rules1 ,formulas and ,tables are included1 containing simple and original methods for finding the weight of castings1 both from the pattern itself and from the drawings4 ,this section contains some new and practical formulas1 which will be found very useful in estimating weights1 with the accuracy required for quotations to prospective customers4 ,ali of these rules are simple1 and can be put to practical use by the ordinary1 every-day man1 and they have been proved by years of actual use4 ,plain rules for keeping down the cost of patterns1 with a complete system for checking the cost of and marking the patterns1 and a card record showing what the pattern is1 material used1 where located in safe1 with its cost and date of production1 is included4 ,the book closes with an original and practical method for the inventory and valuation of patterns4 ,containing #cbf pages and #aej detailed illustrations4 ,price #b4jj ,,perfumery ,,henley',s ,,twentieth ,,century ,,book ,,of ,,receipts1 ,,formulas ,,and ,,processes4 ,edited by ,g4 ,d4 ,,hiscox4 ,the most valuable ,techno-chemical ,receipt ,book published4 ,contains over #aj1jjj practical receipts1 many of which will prove of special value to the perfumer1 a mine of information1 up-to-date in every respect4 ,price1 ,cloth1 #c4jj2 half morocco #d4jj ,,perfumes ,,and ,,their ,,preparation4 ,by ,g4 ,w4 ,,askinson1 ,perfumer4 ,a comprehensive treatise1 in which there has been nothing omitted that could be of value to the ,perfumer4 ,complete directions for making handkerchief perfumes1 smelling-salts1 sachets1 fumigating pastilles3 preparations for the care of the skin1 the mouth1 the hair1 cosmetics1 hair dyes and other toilet articles are given1 also a detailed description of aromatic substances3 their nature1 tests of purity1 and wholesale manufacture4 ,a book of general1 as well as professional interest1 meeting the wants not only of the druggist and perfume manufacturer1 but also of the general public4 ,third edition4 #cab pages4 ,illustrated4 #c4jj ,,plumbing ,,mechanical ,,drawing ,,for ,,plumbers4 ,by ,r4 ,m4 ,,starbuck4 ,a concise1 comprehensive and practical treatise on the subject of mechanical drawing in its various modern applications to the work of all who are in any way connected with the plumbing trade4 ,nothing will so help the plumber in estimating and in explaining work to customers and workmen as a knowledge of drawing1 and to the workman it is of inestimable value if he is to rise above his position to positions of greater responsibility1 ,among the chapters contained are3 #a4 ,value to plumber of knowledge of drawing2 tools required and their use2 common views needed in mechanical drawing4 #b4 ,perspective versus mechanical drawing in showing plumbing construction4 #c4 ,correct and incorrect methods in plumbing drawing2 plan and elevation explained4 #c4 ,floor and cellar plans and elevation2 scale drawings2 use of triangles4 #e4 ,use of triangles2 drawing of fittings1 traps1 etc4 #f4 ,drawing plumbing elevations and fittings4 #g4 ,instructions in drawing plumbing elevations4 #h4 ,the drawing of plumbing fixtures2 scale drawings4 #i4 ,drawing of fixtures and fittings4 #aj4 ,inking of drawings4 #aa4 ,shading of drawings4 #ab4 ,shading of drawings4 #ac4 ,sectional drawings2 drawing of threads4 #ad4 ,plumbing elevations from architect's plan4 #ae4 ,elevations of separate parts of the plumbing system4 #af4 ,elevations from architect's plans4 #ag4 ,drawing of detail plumbing connections4 #ah4 ,architect's plans and plumbing elevations of residence4 #ai4 ,plumbing elevations of residence 7continued72 plumbing plans for cottage4 #bj4 ,plumbing elevations2 roof connections4 #ba4 ,plans and plumbing elevations for six-flat building4 #bb4 ,drawing of various parts of the plumbing system2 use of scales4 #bc4 ,use of architect's scales4 #bd4 ,special features in the illustrations of country plumbing4 #be4 ,drawing of wrought iron piping1 valves1 radiators1 coils1 etc4 #bf4 ,drawing of piping to illustrate heating systems4 #aej illustrations4 ,price #a4ej ,,modern ,,plumbing ,,illustrated4 ,by ,r4 ,m4 ,,starbuck4 ,this book represents the highest standard of plumbing work4 ,it has been adopted and used as a reference book by the ,united ,states ,government1 in its sanitary work in ,cuba1 ,porto ,rico1 and the ,philippines1 and by the principal ,boards of ,health of the ,united ,states and ,canada4 ,it gives connections1 sizes and working data for all fixtures and groups of fixtures4 ,it is helpful to the master plumber in demonstrating to his customers and in figuring work4 ,it gives the mechanic and student quick and easy access to the best modern plumbing practice4 ,suggestions for estimating plumbing construction are contained in its pages4 ,this book represents1 in a word1 the latest and best up-to-date practice1 and should be in the hands of every architect1 sanitary engineer and plumber who wishes to keep himself up to the minute on this important feature of construction4 ,contains following chapters1 each illustrated with a full-page plate3 ,kitchen sink1 laundry tubs1 vegetable wash sink2 lavatories1 pantry sinks1 contents of marble slabs2 bath tub1 foot and sitz bath1 shower bath2 water closets1 venting of water closets2 low-down water closets1 water closets operated by flush valves1 water closet range2 slop sink1 urinals1 the bidet3 hotel and restaurant sink1 grease trap2 refrigerators1 safe wastes1 laundry waste2 lines of refrigerators1 bar sinks1 soda fountain sinks2 horse stall1 frost-proof water closets2 connections for ,s traps1 venting2 connections for drum traps2 soil pipe connections2 supporting of soil pipe2 main trap and fresh air inlet2 floor drains and cellar drains1 subsoil drainage2 water closets and floor connections2 local venting2 connections for bath rooms2 connections for bath rooms1 continued2 connections for bath rooms1 continued2 connections for bath rooms1 continued2 examples of poor practice2 roughing-work ready for test2 testing of plumbing system2 method of continuous venting2 continuous venting for two-floor work2 continuous venting for two lines of fixtures on three or more floors2 continuous venting of water closets2 plumbing for cottage house2 construction for cellar piping2 plumbing for residence1 use of special fittings2 plumbing for two-flat house2 plumbing for apartment building2 plumbing for double apartment building2 plumbing for office building2 plumbing for public toilet rooms2 plumbing for public toilet rooms1 continued2 plumbing for bath establishment2 plumbing for engine house1 factory plumbing2 automatic flushing for schools1 factories1 etc42 use of flushing valves2 urinals for public toilet rooms2 the ,durham system1 the destruction of pipes by electrolysis2 construction of work without use of lead2 ,automatic sewage lift1 automatic sump tank2 country plumbing2 construction of cesspools2 septic tank and automatic sewage siphon2 country plumbing2 water supply for country house2 thawing of water mains and service by electricity2 double boilers2 hot water supply of large buildings2 automatic control of hot water tank2 suggestions for estimating plumbing construction4 #djj octavo pages1 fully illustrated by #ee full-page engravings4 ,price #d4jj ,,standard ,,practical ,,plumbing4 ,by ,r4 ,m4 ,,starbuck4 ,a complete practical treatise of #dej pages covering the subject of ,modern ,plumbing in all its branches1 a large amount of space being devoted to a very complete and practical treatment of the subject of ,hot ,water ,supply and ,circulation and ,range ,boiler ,work4 ,its thirty chapters include about every phase of the subject one can think of1 making it an indispensable work to the master plumber1 the journeyman plumber1 and the apprentice plumber1 containing chapters on3 the plumber's tools2 wiping solder1 composition and use2 joint wiping2 lead work2 traps2 siphonage of traps2 venting2 continuous venting2 house sewer and sewer connections2 house drain2 soil piping1 roughing2 main trap and fresh air inlet2' floor1 yard1 cellar drains1 rain leaders1 etc42 fixture wastes3 water closets2 ventilation2 improved plumbing connections2 residence plumbing2 plumbing for hotels1 schools1 factories1 stables1 etc42 modern country plumbing2 filtration of sewage and water supply2 hot and cold supply2 range boilers2 circulation2 circulating1 pipes2 range boiler problems2 hot water for large buildings2 water lift and its use2 multiple connections for hot water boilers2 heating of radiation by supply system2 theory for the plumber2 drawing for the plumber4 ,fully illustrated by #cdg engravings4 ,price #c4jj ,,receipt ,,book ,,henley',s ,,twentieth ,,century ,,book ,,of ,,receipts1 ,,formulas ,,and ,,processes4 ,edited by ,,gardner ,d4 ,,hiscox4 ,the most valuable ,techno-chemical ,receipt ,book published1 including over #aj1jjj selected scientific1 chemical1 technological1 and practical receipts and processes4 ,this is the most complete ,book of ,receipts ever published1 giving thousands of receipts for the manufacturer of valuable articles for everyday use4 ,hints1 ,helps1 ,practical ,ideas1 and ,secret ,processes are revealed within its pages4 ,it covers every branch of the useful arts and tells thousands of ways of making money an just the book everyone should have at his command4 ,modern in its treatment of every subject that properly falls within its scope1 the book may truthfully be said to present the very latest formulas to be found in the arts and industries and to retain those processes which long experience has proven worthy of a permanent record4 ,to present here even a limited number of the subjects which find a place in this valuable work would be difficult4 ,suffice to say that in its pages will be found matter of intense interest and immeasurable practical value to the scientific amateur and to him who wishes to obtain a knowledge of the many processes used in the arts1 trades and manufactures1 a knowledge which will render his pursuits more instructive and remunerative4 ,serving as a reference book to the small and large manufacturer and supplying intelligent seekers with the information necessary to conduct a process1 the work will be found of inestimable worth to the ,metallurgist1 the ,photographer1 the ,perfumer1 the ,painter1 the ,manufacturer of ,glues1 ,pastes1 ,cements1 and ,mucilages1 the ,compounder of ,alloys1 the ,cook1 the ,physician1 the ,druggist1 the ,electrician1 the ,brewer1 the ,engineer1 the ,foundryman1 the ,machinist1 the ,potter1 the ,tanner1 the ,confectioner1 the ,chiropodist1 the ,manicure1 the ,manufacturer of ,chemical ,novelties and ,toilet ,preparations1 the ,dyer1 the ,electroplater1 the ,enameler1 the ,engraver1 the ,provisioner1 the ,glass ,worker1 the ,goldbeater1 the ,watchmaker1 the ,jeweler1 the ,hat ,maker1 the ,ink ,manufacturer1 the ,optician1 the ,farmer1 the ,dairyman1 the ,paper ,maker1 the ,wood and ,metal ,worker1 the ,chandler and ,soap ,maker1 the ,veterinary ,surgeon1 and the ,technologist in general4 ,a mine of information1 and up-to-date in every respect4 ,a book which will prove of value to ,,everyone1 as it covers every branch of the ,useful ,arts4 #hjj pages4 ,price #c4jj ,,what ,,is ,,said ,,of ,,this ,,book3 ,your ,twentieth ,century ,book of ,receipts1 ,formulas and ,processes duly received4 ,i am glad to have a copy of it1 and if ,i could not replace it money couldn't buy it4 ,it is the best thing of the sort ,i ever saw4 7,signed7 ,m4 ,e4 ,,trux1 ,sparta1 ,wis4 ,there are few persons who would not be able to find in the book some single formula that would repay several times the cost of the book4 ,merchant's ,record and ,show ,window4 ,,rubber ,,rubber ,,hand ,,stamps ,,and ,,the ,,manipulation ,,of ,,india ,,rubber4 ,by ,t4 ,o',,conor ,,sloane4 ,this book gives full details on all points1 treating in a concise and simple manner the elements of nearly everything it is necessary to understand for a commencement in any branch of the ,india ,rubber ,manufacture4 ,the making of all kinds of ,rubber ,hand ,stamps1 ,small ,articles of ,india ,rubber1 ,u4 ,s4 ,government ,composition1 ,dating ,hand ,stamps1 the ,manipulation of ,sheet ,rubber1 ,toy ,balloons1 ,india ,rubber ,solutions1 ,cements1 ,blackings1 ,renovating ,varnish1 and ,treatment for ,india ,rubber ,shoes1 etc42 the ,hektograph ,stamp ,inks1 and ,miscellaneous ,notes1 with a ,short ,account of the ,discovery1 ,collection1 and ,manufacture of ,india ,rubber are set forth in a manner designed to be readily understood1 the explanations being plain and simple4 ,including a chapter on ,rubber ,tire ,making and ,vulcanizing2 also a chapter on the uses of rubber in ,surgery and ,dentistry4 ,third revised and enlarged edition #age pages4 ,illustrated4 #a4jj ,,saws ,,saw ,,filings ,,and ,,management ,,of ,,saws4 ,by ,,robert ,,grimshaw4 ,a practical hand book on filing1 gumming1 swaging1 hammering1 and the brazing of band saws1 the speed1 work1 and power to run circular saws1 etc4 ,a handy book for those who have charge of saws1 or for those mechanics who do their own filing1 as it deals with the proper shape and pitches of saw teeth of all kinds and gives many useful hints and rules for gumming1 setting1 and tiling1 and is a practical aid to those who use saws for any purpose4 ,new edition1 revised and enlarged4 ,illustrated4 ,price #a4jj ,,steam ,,engineering ,,american ,,stationary ,,engineering4 ,by ,w4 ,e4 ,,crane4 ,this book begins at the boiler room and takes in the whole power plant4 ,a plain talk on every-day work about engines1 boilers1 and their accessories4 ,it is not intended to be scientific or mathematical4 ,all formulas are in simple form so that any one understanding plain arithmetic can readily understand any of them4 ,the author has made this the most practical book in print2 has given the results of his years of experience1 and has included about all that has to do with an engine room or a power plant4 ,you are not left to guess at a single point4 ,you are shown clearly what to expect under the various conditions2 how to secure the best results2 ways of preventing shut downs and repairs2 in short1 all that goes to make up the requirements of a good engineer1 capable of taking charge of a plant4 ,it's plain enough for practical men and yet of value to those high in the profession4 ,a partial list of contents is3 ,the boiler room1 cleaning boilers1 firing1 feeding2 pumps2 inspection and repair2 chimneys1 sizes and cost2 piping2 mason work2 foundations2 testing cement2 pile driving2 engines1 slow and high speed2 valves2 valve setting2 ,corliss engines1 setting valves1 single and double eccentric2 air pumps and condensers2 different types of condensers2 water needed2 lining up2 pounds2 pins not square in crosshead or crank2 engineers' tools2 pistons and piston rings2 bearing metal2 hardened copper2 drip pipes from cylinder jackets2 belts1 how made1 care of2 oils2 greases2 testing lubricants2 rules and tables1 including steam tables2 areas of segments2 squares and square root2 cubes and cube root2 areas and circumferences of circles4 ,notes on3 ,brick work2 explosions2 pumps2 pump valves2 heaters1 economizers2 safety valves2 lap1 lead1 and clearance4 ,has a complete examination for a license1 etc41 etc4 ,second edition4 #bhe pages4 ,illustrated4 ,price #b4jj ,,eminent ,,engineers4 ,by ,,dwight ,,goddard4 ,everyone who appreciates the effect of such great inventions as the ,steam ,engine1 ,steamboat1 ,locomotive1 ,sewing ,machine1 ,steel ,working1 and other fundamental discoveries1 is interested in knowing a little about the men who made them and their achievements4 ,mr4 ,goddard has selected thirty-two of the world's engineers who have contributed most largely to the advancement of our civilization by mechanical means1 giving only such facts as are of general interest and in a way which appeals to all1 whether mechanics or not4 #bhj pages4 #ce illustrations4 ,price #a4ej ,,engine ,,runner',s ,,catechism4 ,by ,,robert ,,grimshaw4 ,a practical treatise for the stationary engineer1 telling how to erect1 adjust and run the principal stearn engines in use in the ,united ,states4 ,describing the principal features of various special and well-known makes of engines3 ,temper ,cut-off1 ,shipping and ,receiving ,foundations1 ,erecting and ,starting1 ,valve ,setting1 ,care and ,use1 ,emergencies1 ,erecting and ,adjusting ,special ,engines4 ,the questions asked throughout the catechism are plain and to the point1 and the answers are given in such simple language as to be readily understood by anyone4 ,all the instructions given are complete ad up-to-date2 and they are written in a popular style1 without any technicalities or mathematical formulae4 ,the work is of a handy size for the pocket1 clearly and well printed1 nicely bound1 and profusely illustrated4 ,to young engineers this catechism will be of great value1 especially to those who may be preparing to go forward to be examined for certificates of competency2 and to engineers generally it will be of no little service1 as they will find in this volume more really practical and useful information than is to be found anywhere else within a like compass4 #chg pages4 ,seventh edition4 ,price #b4jj ,,engine ,,tests ,,and ,,boiler ,,efficiencies4 ,by ,j4 ,,buchetti4 ,this work fully describes and illustrates the method of testing the power of steam engines1 turbines and explosive motors4 ,the properties of steam and the evaporative power of fuels4 ,combustion of fuel and chimney draft2 with formulas explained or practically computed #bee pages1 #agi illustrations4 #c4jj ,,horsepower ,,chart4 ,shows the horsepower of any stationary engine without calculation4 ,no matter what the cylinder diameter of stroke2 the steam pressure or cut off2 the revolutions1 or whether condensing or non-condensing1 it's all there4 ,easy to use1 accurate1 and saves time and calculations4 ,especially useful to engineers and designers4 #ej cents4 ,,modern ,,steam ,,engineering ,,in ,,theory ,,and ,,practice4 ,by ,,gardner ,d4 ,,hiscox4 ,this is a complete and practical work issued for ,stationary ,engineers and firemen dealing with the care and management of boilers1 engines1 pumps1 superheated steam1 refrigerating machinery1 dynamos1 motors1 elevators1 air compressors1 and all other branches with which the modern engineer must be familiar4 ,nearly #bjj questions with their answers on steam and electrical engineering1 likely to be asked by the ,examining ,board1 are included4 ,among the chapters are3 ,historical2 steam and its properties2 appliances for the generation of steam2 types of boilers2 chimney and its work2 heat economy of the feed water2 steam pumps and their work2 incrustation and its work2 steam above atmospheric pressure2 flow of steam from nozzles2 superheated steam and its work2 adiabatic expansion of steam2 indicator and its work2 steam engine proportions2 slide valve engines and valve motion2 ,corliss engine and its valve gear2 compound engine and its theory2 triple and multiple expansion engine4 steam turbine2 refrigeration2 elevators and their management2 cost of power2 steam engine troubles2 electric power and electric plants4 #dhg pages4 #dje engravings4 ,price #c4jj ,,steam ,,engine ,,catechism4 ,by ,,robert ,,grimshaw4 ,this unique volume of #dac pages is not only a catechism on the question and answer principle2 but it contains formulas and worked-out answers for all the ,steam problems that appertain to the operation and management of the ,steam ,engine4 ,illustrations of various valves and valve gear with their principles of operation are given4 ,thirty-four ,tables that are indispensable to every engineer and fireman that wishes to be progressive and is ambitious to become master of his calling are within its pages4 ,it is a most valuable instructor in the service of ,steam ,engineering4 ,leading engineers have recommended it as a valuable educator for the beginner as well as a reference book for the engineer4 ,it is thoroughly indexed for every detail4 ,every essential question on the ,steam ,engine with its answer is contained in this valuable work4 ,sixteenth edition4 ,price #b4jj ,,steam ,,engineer',s ,,arithmetic4 ,by ,,colvin-,,cheney4 ,a practical pocket book for the steam engineer4 ,shows how to work the problems of the engine room and shows why4 ,tells how to figure horse-power of engines and boilers2 area of boilers2 has tables of areas and circumferences2 steam tables2 has a dictionary of engineering terms4 ,puts you on to all all of the little kinks in figuring whatever there is to figure around a power plant4 ,tells you about the heat unit2 absolute zero2 adiabatic expansion2 duty of engines2 factor of safety2 and #a1jja other things2 and everything is plain and simple--not the hardest way to figure1 but the easiest4 #bnd ,edition4 #ej cents4 ,,steam ,,heating ,,and ,,ventilation ,,practical ,,steam1 ,,hot-,,water ,,heating ,,and ,,ventilation4 ,by ,a4 ,g4 ,,king4 ,this book is the standard and latest work published on the subject and has been prepared for the use of all engaged in the business of steam1 hot water heating1 and ventilation4 ,it is an original and exhaustive work4 ,tells how to get heating contracts1 how to install heating and ventilating apparatus1 the best business methods to be used1 with ,tricks of the ,trade for shop use4 ,rules and data for estimating radiation and cost and such tables and information as make it an indispensable work for everyone interested in steam1 hot water heating1 and ventilation4 ,it describes all the principal systems of steam1 hot water1 vacuum1 vapor1 and vacuum-vapor heating1 together with the new accelerated systems of hot water circulation1 including chapters on up-to-date methods of ventilation and the fan or blower system of heating and ventilation4 ,containing chapters on3 ,i4 ,introduction4 ,,ii4 ,heat4 ,,iii4 ,evolution of artificial heating apparatus4 ,,iv4 ,boiler surface and settings4 ,v4 ,the chimney flue4 ,,vi4 ,pipe and fittings4 ,,vii4 ,valves1 various kinds4 ,,viii4 ,forms of radiating surfaces4 ,,ix4 ,locating of radiating surfaces4 ,x4 ,estimating radiation4 ,,xi4 ,steam-heating apparatus4 ,,xii4 ,exhaust-steam heating4 ,,xiii4 ,hot-water heating4 ,,xiv4 ,pressure systems of hot-water work4 ,,xv4 ,hot-water appliances4 ,,xvi4 ,greenhouse heating4 ,,xvii4 ,vacuum vapor and vacuum exhaust heating4 ,,xviii4 ,miscellaneous heating4 ,,xix4 ,radiator and pipe connections4 ,,xx4 ,ventilation4 ,,xxi4 ,mechanical ventilation and hot-blast heating4 ,,xxii4 ,steam appliances4 ,,xxiii4 ,district heating4 ,,xxiv4 ,pipe and boiler covering4 ,,xxv4 ,temperature regulation and heat1 control4 ,,xxvi4 ,business methods4 ,,xxvii4 ,miscellaneous4 ,,xxvii4 ,rules1 tables and useful information4 #cfg pages4 #cjj detailed engravings4 ,price #c4jj ,,steam ,,pipes ,,steam ,,pipes3 ,,their ,,design ,,and ,,construction4 ,by ,,wm4 ,h4 ,,booth4 ,the work is well illustrated in regard to pipe joints1 expansion offsets1 flexible joints1 and self-contained sliding joints for taking up the expansion of long pipes4 ,in fact1 the chapters on the flow of steam and expansion of pipes are most valuable to all steam fitters and users4 ,the pressure strength of pipes and method of hanging them are well treated and illustrated4 ,valves and by-passes are fully illustrated and described1 as are also flange joints and their proper proportions1 exhaust heads and separators4 ,one of the most valuable chapters is that on superheated steam and the saving of steam by insulation with the various kinds of felting and other materials with comparison tables of the loss of heat in thermal units from naked and felted steam pipes4 ,contains #ahg pages4 ,price #b4jj ,,steel ,,american ,,steel ,,worker4 ,by ,e4 ,r4 ,,markham4 ,this book tells how to select1 and how to work1 temper1 harden1 and anneal steel for everything on earth4 ,it doesn't tell how to temper one class of tools and then leave the treatment of another kind of tool to your imagination and judgment1 but it gives careful instructions for every detail of every tool1 whether it be a tap1 a reamer or just a screw-driver4 ,it tells about tempering of small watch springs1 the hardening of cutlery1 and the annealing of dies4 ,in fact there isn't a thing that a steel worker would want to know that isn't included4 ,it is the standard book on selecting1 hardening1 and tempering all grades of steel4 ,among the chapter headings might be mentioned the following subjects3 ,introduction2 the workman2 steel2 methods of heating2 heating tool steel2 forging2 annealing2 hardening baths2 baths for hardening2 hardening steel2 drawing the temper after hardening2 examples of hardening2 pack hardening2 case hardening2 spring tempering2 making tools of machine steel2 special ,steels2 steel for various tools2 causes of trouble2 high speed steels1 etc4 #cff pages4 ,illustrated4 #b4ej ,,hardening1 ,,tempering1 ,,annealing1 ,,and ,,forging ,,of ,,steel4 ,by ,j4 ,v4 ,,woodworth4 ,a new work treating in a clear1 concise manner all modern processes for the heating1 annealing forging1 welding1 hardening1 and tempering of steel1 making it a book of great practical value to the metal-working mechanic in general1 with special directions for the successful hardening and tempering of all steel tools used in the arts1 including milling cutters1 taps1 thread dies1 reamers1 both solid and shell1 hollow mills1 punches and dies1 and all kinds of sheet metal working tools1 shear blades1 saws1 fine cutlery1 and metal cutting tools of all description1 as well as for all implements of steel both large and small4 ,in this work the simplest and most satisfactory hardening and tempering processes are given4 ,the uses to which the leading brands of steel may be adapted are concisely presented1 and their treatment for working under different conditions explained1 also the special methods for the hardening and tempering of special brands4 ,a chapter devoted to the different processes for ,case-hardening is also included1 and special reference made to the adoption of machinery steel for tools of various kinds4 #dth ,edition #bhh pages4 #bja ,illustrations4 ,price #b4ej ,,turbines ,,marine ,,steam ,,turbines4 ,by ,,dr4 ,g4 ,,bauer and ,o4 ,,lasche4 ,assisted by ,e4 ,ludwig and ,h4 ,vogel4 ,translated from the ,german and edited by ,m4 ,g4 ,s4 ,swallow4 ,this work forms a supplementary volume to the book entitled ,marine ,engines and ,boilers4 ,the authors of this book1 ,dr4 ,g4 ,bauer and ,o4 ,lasche1 may be regarded as the leading authorities on turbine construction4 ,the book is essentially practical and discusses turbines in which the full expansion of steam passes through a number of separate turbines arranged for driving two or more shafts1 as in the ,parsons system1 and turbines in which the complete expansion of steam from inlet to exhaust pressure occurs in a turbine on one shaft1 as in the case of the ,curtis machines4 ,it will enable a designer to carry out all the ordinary calculations necessary for the construction of steam turbines1 hence it fills a want which is hardly met by larger and more theoretical works4 ,numerous tables1 curves and diagrams will be found1 which explain with remarkable lucidity the reason why turbine blades are designed as they are1 the course which steam takes through turbines of various types1 the thermodynamics of steam turbine calculation1 the influence of vacuum on steam consumption of steam turbines1 etc4 ,in a word1 the very information which a designer and builder of steam turbines most requires4 ,the book is divided into parts as follows3 #a4 ,introduction4 #b4 ,general remarks on the design of a turbine installation4 #c4 ,the calculation of steam turbines4 #d4 ,turbine design4 #e4 ,shafting and propellers4 #f4 ,condensing plant4 #g4 ,arrangement of turbines4 #h4 ,general remarks on the arrangement of steam turbines in steamers4 #i4 ,turbine-driven auxiliaries4 #aj4 ,tables4 ,large octavo4 #bad pages4 ,fully illustrated and containing #ah tables4 ,including an entropy chart4 ,price1 net1 #c4fj ,,watch ,,making ,,watchmaker',s ,,handbook4 ,by ,,claudius ,,saunier4 ,this famous work has now reached its seventh edition and there is no work issued that can compare to it for clearness and completeness4 ,it contains #dih pages and is intended as a workshop companion for those engaged in ,watch-making and allied ,mechanical ,arts4 ,nearly #bej engravings and fourteen plates are included4 ,price #c4jj ,,the ,,greatest ,,book ,,ever ,,offered ,,to ,,the ,,public6 ,,new ,,revised ,,edition ,henley's ,twentieth ,century ,book of ,,recipes1 ,,formulas ,,and ,,processes ,edited by ,,gardner ,d4 ,,hiscox1 ,m4 ,e4 ,price #c4jj ,handsome ,cloth ,binding #d4jj ,half ,morocco ,binding #hjj ,large ,octavo 7#f x #i #a_/b7 ,,pages ,contains over #aj1jjj ,selected ,processes1 ,formulas and ,practical ,recipes1 ,including hundreds of so-called ,trade ,secrets for every business ,,how ,,to ,,make ,,money ,this new book of processes and formulas is the latest and greatest compilation of the kind ever published4 ,it is a standard work--an authority--a first aid--and a court of last resort on ,what to ,make and ,how to ,make ,it4 ,it contains more than #aj1jjj practical recipes and formulas for everyday use in business1 at home or in the factory4 ,everything you want to make--,antiseptics1 ,waterproofing1 ,lubricants1 ,rust ,preventives1 ,dyes1 ,filters1 ,cleaning ,preparations1 ,enameling1 ,beverages1 ,inks1 ,adhesives1 ,polishes1 ,disinfectants1 ,flavorings1 ,cosmetics1 ,ceramics1 etc41 etc4 ,photography is treated in all of its various branches1 as are also ,plating1 ,painting1 ,leather ,work1 etc4 ,tests for ,food ,adulterants are fully covered2 how to make fly paper2 to color flowers artifically2 to estimate weight of ice by measurement2 to make materials fireproof2 to work with metals-aluminum1 brass1 etc42 to make anything and everything1 from ,a to ,z4 ,there is not a home1 office1 factory1 or place of business of any kind that does not actually need this book4 ,it is a money saver and a money maker2 it appeals to the young as well as to the old4 ,great business enterprises allow their success to the manufacture or sale of some simple invention or compound--usually the result of an experiment at home4 ,with this latest book of practical formulas the boy of to-day has a far better opportunity than his father--and the mother and sisters can develop an industry of their own that will produce a comfortable income4 ,we live in the most progressive country on the face of the earth4 ,we owe it to ourselves to advance--to learn--to progress4 ,we can't afford to stand still4 ,then learn more1 so you can earn more4 ,profit by the knowledge that has made others successful4 ,now is the time-you can't learn younger4 ,get this book at once4 ,copies of this books sent prepaid to any address on receipt of price4 ,,the ,,norman ,w4 ,,henley ,,publishing ,,co41 #acb ,,nassau ,,street4 ,,new ,,york4