,,new ,,edition ,,of ,,hints ,,on ,silvered-,glass ,reflecting ,,telescopes ,,manufactured ,,by ,,mr4 ,g4 ,,calver1 ,f4,r4,a4,s4 ,,with ,,directions ,,for ,,silvering1 ,,adjusting1 c4 #ahgg4 ,,george ,,calver1 ,,hill ,,house1 ,,widford1 ,,chelmsford1 ,,essex4 ,illustration3 decorative ,,hints ,,on ,silvered-,glass ,reflecting ,telescopes4 ,of the various forms of ,telescopes now in use1 each has its own peculiar advantages2 but the ,silvered-,glass ,reflector is undoubtedly gaining favour among our practical observers4 ,a well-figured speculum1 being perfectly free from chromatic aberration1 gives1 in a proper condition of the atmosphere1 the finest possible definition of the ,moon and planets1 the markings and colours of these objects being excellently seen2 while coloured stars1 such as ,albireo 7 ,cygni71 or ,almaach 7 ,andromed71 are exceedingly well shown1 the beautiful contrast of the stars in the former being especially noticeable in a reflector4 ,the advice of 8,f4,r4,a4,s40 7in the 8,english ,mechanic10 ,march #bast1 #ahgc7 as to the choice of a ,telescope1 may here appropriately be quoted4 ,after expressing a preference for refractors when measuring close double-stars1 he says1 8,but should the object of your correspondent be merely to regard the wonders and beauties of the ,heavens1 or notably1 should he purpose to devote himself to the study of the physical structure of the ,moon and planets1 then by all means let him obtain the largest reflector he can afford2 its absolute achromatism tells most astonishingly on these last-named objects40 ,this is the opinion of one who has great practical knowledge of the different forms of ,telescopes4 ,if ,achromatic ,telescopes of large aperture could be made as cheaply as reflectors1 and in as convenient a form1 they would doubtless be preferred for general star-work1 although the aberrations1 especially that of colour1 cannot be so perfectly corrected4 ,a silvered-glass reflector is1 however1 much cheaper than a refractor1 and1 when the aperture exceeds five or six inches1 is much handier to work1 and occupies less space1 being only about half the length of an achromatic of the same aperture4 ,it is true that a reflector will give less light than an achromatic of equal aperture--but this is1 in certain conditions of the atmosphere1 a distinct advantage1 the extra aperture to give the same light adding to the definition and penetrating power4 ,an example of this is seen in the beautiful definition given by an unsilvered mirror on brilliant objects1 as the ,sun1 ,moon1 and ,venus4 ,in large achromatics1 the distressing excess of light has often to be reduced by diminishing the aperture or using a higher power than is convenient2 and in such cases a lower and more suitable power can be employed with a reflector4 ,when the air is unsteady1 the definition of ,reflectors1 owing to their tubes being open1 is more liable to fluctuate than that of refractors1 although when a reflector does not give good definition on account of the atmosphere1 a refractor of the same aperture will certainly not perform satisfactorily4 ,sir ,john ,herschel has shown that when the air in the tube of even an achromatic is disturbed in turning from one object to another1 good definition does not return until it is brought to rest4 ,in order to reduce the vibration of the air in the open tube1 and also that of the stand1 to a minimum1 reflectors require to be very firmly and steadily mounted1 and to have iron tubes4 ,many of the specula made by me are now in observatories1 where they have been compared with achromatics of first-rate quality with the most satisfactory results4 ,for instance1 several #f-a_/b inch specula were tried with two excellent achromatics of #d-a_/b and #f inches aperture1 when the planetary definition was considered to be superior with the reflectors2 and the appearance of the star-discs1 with equal apertures1 differed little from the beauty and hardness of the images given by the achromatics4 ,in viewing stars of great altitude1 the use of the refractor is extremely inconvenient to the observer1 whose position is necessarily very uncomfortable1 while with the ,newtonian reflector any part of the heavens may be observed with the same ease and comfort4 ,in short1 a good speculum1 well mounted and situated1 is sure to be both pleasing and satisfactory4 ,it is perhaps unnecessary to remind the reader that1 when the defining powers of a telescope are put to the test1 as much depends on the acuteness of the observer's eye and the practice he has had1 as upon the perfection of the instrument and the fineness of air4 ,it is a mistake to suppose that when the stars appear to be the brightest to the unaided eye1 definition will be at its best1 though this may happen2 when it does so1 the astronomer should make the most possible use of the opportunity1 as such nights are very scarce4 ,as a rule1 the best nights are those when there is the slightest possible mistiness of the atmosphere1 and for the faintest stars absence of bright moonlight4 ,the #e inch mirror is guaranteed to divide stars one second apart with ease1 and closer ones in very fine air4 ,the #h-a_/b will split such difficult pairs as #b ,andromed1 and #b ,botis4 ,an acute eye will master these stars with even a less aperture on very favourable occasions1 #b ,andromed having been seen with a #g-;inch stop of a #aj-;inch mirror1 and ,mr4 ,sadler1 of ,honiton ,rectory1 has split this star with his #f-a_/b-;inch telescope4 ,it sometimes happens on favourable nights that the most difficult objects will be seen with the same telescope1 which on other occasions had failed to show them as well as a much smaller aperture had done in very fine air4 ,these remarks equally apply to the observation of minute stars and planetary detail4 ,the amateur must follow the advice of the ,rev4 ,t4 ,w4 ,webb1 given in 8,celestial ,objects0 7pages #ae-ag71 and must cultivate that virtue applicable to all scientific investigation1 namely1 patience4 ,the following interesting and difficult objects may be looked for1 the powers used for their observation should vary from #aej to #cjj1 and for the very closest stars up to #ejj1 or even still higher4 ,,tests ,,for ,,specula4 ,,light ,,tests4 #id ,ophiuchi4 #e 3 #g1 #ac4 #eh ,ceti4 #ce 3 #fe1 #ad4 ,crateris4 #c 3 #d1 #ad4 #ae ,monocerotis4 #be1 #ae 3 #f1 #ie1 #ae4 ,orionis4 #ae1 #bj 3 #d1 #ae1 #ab4 ,ceti4 #f 3 #de1 #ae4 ,trianguli4 #e 3 #ee1 #ae4 #agi ,piscium4 #c 3 #he1 #ae4 #aaj ,herculis4 #ee 3 #e1 #af4 ,andromed4 #de 3 #d1 #af4 ,equulei4 #ce1 #c1 #ej 3 #e1 #ac1 #af1 #ad4 #he ,virginis4 #cj 3 #f1 #af4 #ee ,andromed4 #be 3 #ee1 #af4 #agh;a ,delphini4 #bj 3 #ge1 #af4 #bab ,libr4 #bj1 #aj 3 #f1 #af1 #h4 #ad ,monocerotis4 #aj 3 #f1 #af4 #id ,ceti4 #e 3 #ee1 #af4 ,aquil4 #ae 3 #ce1 #af4 ,,separating ,,tests4 #cc ,orionis4 #b 3 #f1 #h4 #eb ,orionis4 #ah 3 #f1 #h4 ,cygni4 #ah 3 #ce1 #i4 #b ,camelopardi4 #ag 3 #ee1 #ge4 ,aquil4 #ag 3 #f1 #g4 #b ,cancri4 #ad 3 #ee1 #g4 #i ,leonis4 #ab 3 #ge1 #ge4 ,orionis4 #a 3 #d1 #e4 ,arietis4 #a 3 #e1 #fe4 #d ,lyncis4 #a 3 #f1 #ge4 #cg ,pegasi4 #jh 3 #f1 #ge4 #gdi ,tauri4 #jh 3 #ga1 #gb4 #df ,arietis4 #jh 3 #h1 #i4 a ,cygni4 #jg3 #e1 #f4 ,delphini4 #jg 3 #e1 #ee4 #bj ,draconis4 #jg 3 #g1 #ge4 #bhg ,draconis4 #jg 3 #g1 #h4 #agh;b ,delphini4 #jf 3 #de1 #f4 ,draconis4 #jf 3 #de1 #fe4 #b ,andromed4 #jf 3 #he1 #i4 #b ,botis4 #je 3 #h1 #he4 a ,botis4 #je 3 #de1 #de4 #g ,tauri4 #je 3 #f1 #fe4 #ajh ,draconis4 #je 3 #i1 #i4 ,herculis4 #jc 3 #c1 #h4 #db ,com ,berenices4 #jc 3 #de1 #e4 ,leonis4 #jc 3 #fe1 #ge4 ,since writing the first edition of my catalogue1 the writer has received many gratifying accounts of the success of the 8,silvered-,glass ,reflector40 ,many private letters have been received by him from observers1 expressing their delight and satisfaction4 ,this has been so encouraging that no pains have been spared1 nor any opportunities neglected1 in turning to the best purpose every valuable lesson that continued practice and experience may have suggested in the manipulation of specula from time to time1 in order to secure the best means for obtaining the highest excellence of defining power4 ,many modifications and improvements have been made in working and testing mirrors1 and special machinery and appliances constructed for large sizes4 ,but to complete my conditions suitable for truly figuring and testing specula of considerable size1 ,i found it necessary to remove from the traffic and tremor of a town to a still and tranquil situation in the country4 ,the truth of the curve is so sensibly and seriously affected by vibration constantly going on in and near a town1 that it is liable to a variety of defects1 and the surface becomes wavy and 8plucked40 ,as an instance1 ,i may mention that my first and most convincing proof of the advantage of the stiller situation was tested by an #ah-;inch speculum 7on which much labour had been bestowed72 it was laid aside1 but successfully finished after removal1 and without undulations or any perceptible defect1 and the ,observer wrote me1 that in good air1 he 8saw ,sirius as a brilliant white dot1 without a ray or appendage of any kind1 and celestial photographs obtained with it are very fine40 ,such results were exceedingly gratifying1 as they were obtained with much less labour and uncertainly1 and the tedious process of the final touches had not to be repeated so many times4 ,it is said that the celebrated ,alvan ,clarke1 from the same effects of tremor1 never finished an object-glass to his satisfaction above-ground2 and ,dr4 ,draper1 testing his mirrors at the centre of curvature1 to avoid draughts1 c4 in an ordinary apartment1 resorts to an underground one4 ,in this little book of 8,hints0 it may be useful to remind those who possess a speculum of fine quality that they are not produced by a 8rule of thumb0--so to speak--and that the difference between a speculum and a really fine one1 giving a maximum of defining and illuminating power1 is the result of considerable labour and thought1 and deserves careful usage4 ,the ,rev4 ,cooper ,key1 an amateur of much experience1 writes in the 8,english ,mechanic10 that he was eight months 7working sometimes eight hours a day71 giving his #ah inch speculum its final touches and corrections4 ,a well known correspondent of the 8,english ,mechanic10 8,hyperion10 tells us he found it impossible to test his #h-a_/b inch mirror in an ordinary room1 and had to resort to a tunnel under the clay of his garden4 ,those who have the means and perseverance to make their own mirror1 should be careful not to proceed with the finishing touches until an hour at night when their workshop1 if in a town1 is free from tremor4 ,first secure a well-ground and carefully-centred disc1 let the polish be as perfect as possible before any attempt is made to figure4 ,care must be taken that every square or portion of the polisher is of the same consistency and temperature1 that the disc may not be acted on irregularly4 ,to give the pitch this quality it must be well boiled and 8pulled10 so that no air bubbles are in the squares1 as these cause expansion or contraction as the temperature of the apartment varies1 or that of the pitch and glass from friction4 ,it is much the best plan to keep the workshop to the same uniform temperature as the polisher was made for1 allowing no draughts to pass over the mirror while working1 nor the gas or lamp to be near4 ,when the polisher is warmed--which it should be after laying aside for any time--it should be warmed equally4 ,neglect of the above in making the polisher1 or any incautious handling of either the disc or polisher1 will be sure to cause defects1 which cannot be cured but by retracing the early steps in the fine grinding with an accurately centered tool4 ,the polishing successfully accomplished1 the process of correcting for parallel rays is next proceeded with4 ,at every step all possible care must be taken to prevent the mirror from running into an irregular curve4 ,the importance of this cannot be too strongly urged1 if a speculum capable of doing the best work is desired1 as the curve must be true1 regular1 or uniform1 to give the highest defining and illuminating power4 ,an under-corrected mirror1 if of a regular curve1 will perform much better than a compound correction1 exhibiting at the focal point much less lateral aberration4 ,a brief explanation of this may be of use as far as the limits of these pages will admit4 ,it would be impossible to teach1 by a mere description of methods1 how to commence and finish off a speculum of good quality1 even if every working secret and minute detail were unreservedly explained4 ,the only way is to master sufficient theory1 and the rest will come by prolonged care and perseverance4 ,i state this because amateurs who have been desirous of enjoying the gratification of observing with a mirror of their own making have written for information which they have been quite willing even to pay for liberally1 but have felt disappointed1 and perhaps thought it somewhat discourteous1 on being told that what they wanted was impracticable and could not be satisfactorily attempted by the ,optician in writing4 ,in some cases ,i have finished amateurs' work on agreeable terms1 and which has led to a pleasant correspondence or acquaintance4 ,these remarks may prevent some future disappointment4 ,every one is familiar with the fact that the parabola is the only concave surface that can reflect rays of light falling on its surface from an object at an infinite distance--such as the stars and planets practically are--to one common focus1 or without aberration4 ,this series or column of rays 7which is equal in diameter to the opening of the speculum71 reach the mirror without making an angle to it or to each other1 they travel side by side1 they are all of one length1 and are reflected to a point1 and are therefore all of the same length at the proper focal distance1 viz41 half the radius of the curvature of the concave4 ,the properties of the parobola make the nearest possible approach to it of the utmost importance4 ,it has been said that a considerably under-corrected surface1 if of a true and uniform curve1 is better than one with less aberration1 with zones or sections of various curves4 ,to explain this1 let us suppose an artificial star at some short distance1 say #ej yards1 the parabola would not form an image of this at the eye-piece without aberration2 it has for this distance too short a focus for the central rays1 and the best disc is inclined to the inner focus1 because the rays from the object diverge towards it1 instead of travelling parallel2 and they reach the surface 7the central rays compared with the marginal71 at an angle equal to the semi-diameter of the mirror4 ,but1 if instead of a parabolic mirror an elliptical one be used1 which has one of its foci at #ej yards' distance1 the image will be perfect4 ,now place the artificial star at #ejj yards1 the image will now be attended with perceptible aberration4 ,the longer focus of the ellipse must be worked further and further from the mirror by shortening the focus of the central rays4 ,correct it for this distance1 and again remove the artificial star to a still greater distance1 repeating the corrections as before and carrying the outer focus towards the object1 and the inner towards the mirror1 until the rays from the object become more and more parallel1 and the curve is nearer and nearer to the parabola1 or that eccentricity of ellipse which acts better and better for distant objects or parallel rays4 ,it is evident from this that if the ellipse is corrected very considerably towards the parabola1 without irregularities1 and every part of the surface corrected regularly from the centre to the edge 7no part hastening more than another71 that such a surface1 though under-corrected1 is much better than if one portion is fully and another under-corrected1 especially if the more imperfect portion is towards the edge4 ,such a compound correction may show little or no outstanding aberration at the focal point1 but the rays do not find a focus at the same regular pace as they would from a regular curve--one edge of a zone will be coming into focus when another would be going out4 ,with the focussing screw they are focussed to the place where they appear to collapse1 and are most satisfactory1 though1 in reality1 the rays at the best place bend over each other1 and the definition is imperfect4 ,from a star1 which is only a point1 this may be more tolerated1 but on the planets1 where the image has a sensible diameter1 and is perhaps magnified many times1 this imperfect curve is very inferior to the regular one1 whose error is all of one kind4 ,the light is all there somewhere1 but not with any good effect4 ,there is no proper illumination or definition1 as rays are employed which are crossing the optical axis at varying angles1 and the result is confusion4 ,so the amateur who sets himself the pleasant task of making his own speculum 7for there are many who can better afford the labour than the capital to purchase1 and whose capabilities are thus superior to their means71 need not be discouraged and give up the pursuit because he cannot obtain the best results by getting a perfectly parabolic glass4 ,but if he has been successful in removing a considerable amount of the spherical error1 and advanced to the elongated ellipse by maintaining a truthful curve1 8let well alone0 with this disc1 and proceed no further1 but commence another1 taking care not to alter the first until the second is better1 and then an improvement of the first may be attempted4 ,in the second attempt1 should the amateur lose control over the regularity of the surface1 let him try it as an experiment against the first on the planets1 and he will not fail to appreciate the difference1 and will be stimulated by fresh courage to get as near to the parabola as possible with the same accurate curve4 ,to produce a true and uniform curve is1 however1 the acme of troubles1 whether it is desired to obtain the spherical1 or parabola1 or any other curve4 ,it is generally supposed that the spherical curve is a very easy matter1 so easy indeed that it is difficult to avoid4 ,this is a very great mistake--a spherical curve of undeviating truth is as difficult a problem as a true parabola4 ,the spherical curve is the only uniform curve1 it has but one focus1 and the polisher must coincide with1 and be of the same radius as the glass1 at every instant4 ,this is why the optician strives to obtain a semi-polish with the grinder to lessen the risk of losing his curve on the polisher1 for the curves of an object glass are spherical4 ,the curve most liable to be obtained by the amateur is the spheroidal1 a curve with its marginal rays shorter than the central1 or half the radius of curvature4 ,there are no means with the telescope of telling the spheroidal1 approximating to the sphere1 from the sphere4 ,there are no means of analyzing the exact character of a curve equal to certain methods at the centre of the curvature1 but to accomplish this requires much practice and observation1 with 8surroundings0 perfectly free from vibration4 ,if the amateur can overcome this1 and lives in or very near a town1 he should only work at the polishing and figuring during the late hours of the night1 when traffic1 c4 have subsided4 ,then1 by carefully preventing any draughts in the apartment1 and with the mirror of the same temperature as the air in the room1 he will then be able to see how varied and numerous are the chances of error in working a mirror1 and the great care necessary to avoid or cure them4 ,he will find the surface exceedingly prone to receive zones and irregularities during work1 and much more so than to 8work true40 ,the necessity for avoiding incautious handling or heating may be realized by the following little experiment when one can manage and understand it3--,place the tip of one finger on the surface1 as it hangs in the dark room ready for testing1 and with very gentle pressure let it remain long enough to spell one's name2 it will then be seen that the feeble heat of the finger has1 by expansion1 raised a mound on the surface of the glass1 and though this amount of swelling must be very small1 yet it is enough to cast a shadow across the surface1 as if something were laid on it1 and quite ten minutes will elapse before the heat will leave this spot and the surface again become level4 ,now if the polisher were placed on the glass while this hillock was there1 a permanent hollow would be the result4 ,for a full account of these methods 7of which ,foucault was the discoverer7 the reader is referred to ,sir ,john ,herschel's and ,dr4 ,draper's works on the telescope4 ,care must be taken not to leave too much aberration1 as then the central disc is formed too positively outside the focus1 and the rest of the light from the object appears as obtrusive rings and false light4 ,the over-correction is bad1 and acting as a negative lens the disc is formed too near the mirror4 ,such a correction1 besides being objectionable on almost all classes of objects1 prevents the use of the 8,barlow0 lens1 and acts badly with all kinds of positive or ,ramsden eye-pieces1 which improve under-corrected1 but 8make bad worse0 with over-corrected surfaces4 ,if these few and brief hints should stimulate the industrious and persevering student to make his own telescope1 and thus enjoy the fruits of his own labours 7which may add a relish and a pleasure to his astronomical work71 they will have served the purpose for which they are written4 ,after a 8,hint0 on the choice of focus for the mirror1 it only remains to say a few words about the plane1 as this1 with the large speculum1 are the only parts that need be home-made as far as the optical work is concerned4 ,never adopt a 8dumpy0 for general use where high powers are sometimes wanted1 for small and moderate sizes1 say #h to #ab diameters1 and for large sizes not less than about #f diameters of the mirror1 as the larger ones practically admit of a shorter focus4 ,the short ones can be mounted somewhat cheaper1 but never choose them on this account1 they will not make so satisfactory an instrument1 and no adaptation of 8,barlow's0 will make it so4 ,to make the plane1 provide three well-turned metal discs of #g inches or #i inches diameter4 ,iron is the best1 as the work will go down closer1 and the plates or discs may be very thick--say an inch--and not so liable to 8spring40 ,these turned discs must be scraped and ground perfectly flat on each other1 until they are in good contact all over1 so that there is nothing between the faces when testing them4 ,in the earlier stage of 8truing10 oil and colour can be used4 ,when these discs are proved true1 a disc of plate glass1 same size1 is cemented with pitch on one of them1 or on a thick disc of glass1 and care must be taken that it is not strained while on the block during working4 ,truly grind this plate on one of the tools to a fine semi-polish4 ,polish on the same tool with a piece of thick silk or alpaca1 laid over and cemented down by a solution of resin dissolved in turpentine 7as much resin as the turpentine will dissolve71 then1 with the tip of the finger1 thinly smear over the tool and bind round the edge with cord1 and the silk will keep in place4 ,fill up the texture of the silk or alpaca evenly with damp rouge1 keep it uniformly damp1 and never let the rouge and water work about4 ,it may be polished on very hard strained pitch1 but pitch for the amateur is not so safe1 as it is liable in his hands to alter its form and destroy the truth of the plane1 but it is the quickest and handiest if it can be managed4 ,after the polish is perfect remove the plate from the support and cut into squares a little larger than the size of the intended flat4 ,test these in the telescope on a star4 ,if one plane turns out bad1 the whole will most likely be so1 and another plate must be worked with renewed energy and care1 for a bad plane will spoil the action of the speculum however good1 for there is no way of counteracting the curved surface of the flat or second reflector4 ,the edge of the plate for about an inch should not be used4 ,when a good plane is found it can be edged by turning a piece of wood a little less in diameter than the minor axis of the plane required1 turn the end square1 and mark a line around it distant from the end equal to the diameter1 and cut through to the opposite edge1 and it will give the oval and will appear round at #de1 this will mount nicely in brass tubes of the proper size1 and a cover should be made to fit easy4 8,,the ,,equatorial40 ,fig4 #a is a modification of the ,german principle1 and it should be a sufficient recommendation to remark that it is the principle used by a maker of such experience as ,mr4 ,john ,browning1 and is1 without doubt1 the very best style of mounting for a fixed equatorial1 especially when clockwork is employed1 because clock power is applied to the polar axis itself direct from the driving worm4 ,the driving part1 viz41 the worm and wheel1 which is out of the observer's way 7being between the standards71 is not liable to meet with accident1 and the driving wheel being near the lower end of the axis1 is at the most rigid part1 viz41 the foundation of the instrument4 ,as it has a long and very firm polar axis1 and is connected with the foundation plate1 it secures the utmost steadiness and freedom from strain4 ,an equatorial mounting1 with two long and stiff shafts for the axes1 has always the advantage of firmness2 the holding portions of the instrument being in masses1 are not liable to receive injury from blows1 and thus be put radically out of order4 ,no means should be resorted to to make an equatorial of light weight2 an instrument cannot be light and slim and at the same time firm and steady--no amount of steadying rods1 splines or strings1 will make a slender tripod for a refractor so steady as a firmly made one1 with proper size and weight in the parts4 ,another important advantage of this kind of mount for a large size is1 that although it has considerable weight1 it is very convenient to move and set up1 being built of convenient parts1 which are easy of separation and removal4 ,the uprights or standards are separate1 and are bolted to the bed-plate1 the upper and lower discs are readily detached from the stand4 ,the cradle and tube are in this construction separable4 ,the tube of the telescope being suspended over the side of the stand1 is in the most convenient position for observing objects at any altitude1 as the stand is out of the way and clear of the telescope4 ,the various disadvantages and objections to the driving clock being carried by the telescope are here avoided4 ,the clock1 which is large and very powerful1 is bolted down to the iron bed-plate1 and the telescope1 not having to carry the clock or weight1 the balance is never altered nor the rate of the clock disturbed1 and thus a strong clock1 keeping regular time1 and working much longer can be used4 ,they will drive #b-a_/b hours4 ,it will be readily understood that a driving clock to enable the instrument to do the most exact and best work must be powerful and a good time-keeper4 ,lord ,lindsay has said that 8the clock should have twice as much power as is used10 otherwise the spindles1 c4 are pent up1 and it is moreover sensible to any extra weight or work being put upon the instrument4 ,to give an idea of the efficiency and regularity of this clock1 ,i may mention that a ,newtonian telescope of #ah inches aperture1 intended to carry a photographic camera of #aab lbs4 weight1 needed no additional provisions to do the extra work1 the rate and power not being affected4 ,there is a mechanism in the clock 8for making up of time0 and in setting the hour circle can be used with a joint handle or hooks as a fine screw-motion1 and can be applied whether the clock is going or not4 ,there is also a provision at the foundation for throwing the instrument out of the meridian1 to follow the motion of the moon or planets with the clock and 8maker up40 ,the above mounting is equally suitable for 8,cassegrains0 and 8,newtonians10 to both of which forms it has been successfully applied up to #ah inches of aperture4 ,it is well suited for large telescopes4 ,fig4 #b is a mounting on the same principle1 but with a shorter polar axis1 and the column is in one casting4 ,it is well suited for moderate sizes1 and the circles1 c4 are applied exactly as in ,fig4 #a1 but when a clock is wanted there is no mounting equal to the former4 ,the 8,educational0 is a plain #f-a_/b inch1 of #d to #f feet focus1 and is made to this pattern1 with revolving body and screw-motion for following4 ,it is made as portable as it can be1 and is a steady1 good-working instrument1 and much approved of4 ,,the ,,universal ,,alt-,,azimuth4 7,,fig4 #c47 ,in this mounting ,i have seen little or no alteration needful1 except that the tube is now made to balance so that the eye-tube can be reached for objects in the zenith without the observer having to elevate himself1 and the elevating rod can be clamped without the lever1 the legs of the stand are more curved and have more spread in them4 ,this 8,alt-,azimuth0 stand has met with much approval2 and where portability is of consideration and the observer has to set up and remove the entire instrument after every night's work1 this1 or the ,angle-,block stand1 will be found the most convenient1 more so than an equatorial in any form4 ,there is much less weight to remove1 and being in three convenient parts is more readily put together and separated in the dark4 ,if the stand and trunnions can be left in the open air a very small covering will serve to protect them1 and then the tube alone has to be removed4 ,the equatorial cannot be too highly recommended where it can be a fixture and undisturbed1 as when once got into proper adjustments its advantages can then be realised1 but not unless it is a permanent fixture4 ,the circles of a portable equatorial can only be used for very rough reading1 and consequently the adjustments are never in order1 and the readings are of very limited use indeed4 ,,the ,,improved 8,,angle-,,block0 ,,stand4 7,,fig4 #d47 ,with respect to the tube1 it is mounted like the ,alt-,azimuth1 but with the plane of the horizontal movement corresponding to the latitude of the place of observation1 and therefore following objects with one screw movement is in reality a telescope with equatorial motions4 ,it need not be of heavier construction than the ,alt-,azimuth1 and there is not the double weight of counterpoising1 c4 as in the equatorial1 and when circles are not desired this will be the most economical1 handiest1 and easily managed instrument1 as it partakes of the equatorial form or motions4 ,the telescope tube is well balanced1 and the declination movement is easy and free1 and fitted with a clamp screw1 so that when the instrument is turned on an object that object can then be followed by an endless screw4 ,it can be made to suit any latitude1 and by the addition of foot screws on a level floor1 can be got into suitable adjustments1 and if it has to be removed 7for the stand is very little heavier than an ordinary ,alt-,azimuth71 8guides0 can be provided1 so that it can go very approximately into the exact place again when brought out for use4 ,they are made1 when desired1 with a revolving body and fine screw-motion in declination4 ,,the 8,,popular ,,reflector40 ,,with ,,angle-,,block ,,stand4--7,,fig4 #d47 ,the speculum is #e-a_/d inch diameter1 and carefully figured1 and is recommended as a very useful instrument4 ,the size and power of this telescope has been adopted as that most likely to meet the means and requirements of a large number of amateurs4 ,many prefer to commence astronomical observations with 8something inexpensive10 and are led to begin with the popular and well advertised #c inch refractor at #e4 ,these1 except in a few chance cases1 are sure to prove disappointing1 and are perhaps the cause of their giving up any further attempts to follow up the subject of astronomy1 which may otherwise be so pleasantly and profitably pursued with a reliable instrument4 ,it is well known that a less aperture than #d-a_/b inches is insufficient to give the observer a satisfactory idea of the varied and most interesting details of the planets1 and the ever-changing outline and tone of the belts and markings of ,jupiter1 ,saturn1 and ,mars4 ,large apertures bring out details when the smaller ones can only show a general outline4 ,the former also delineates more with a lower power1 providing the focus is of proper length4 ,the planets and nebul cannot be seen to advantage without aperture and focal length4 ,the field of view is then flat1 the object is properly illuminated1 with sharp and crisp definition1 and is also much less subject to annoyance from tremour1 through the necessity for constant adjustments in the fields1 c41 as is the case with small apertures1 for the object is magnified more in proportion4 ,a certain magnifying power is necessary in order that the object may be sufficiently large to scrutinize2 and this1 whether the aperture is large or small1 must be from about #aej to about #cjj times for the planets4 ,but #aej on a #c inch is a high power for the quantity of light obtained1 to say nothing of the separate consideration and advantage of long focus4 ,aperture is a quality or function of the telescope considered separately from light or focus4 ,for instance1 suppose a #e inch speculum is so thinly silvered that it gives the exact degree of light as a #b-a_/b inch refractor1 the defining and separating power of the #e inch aperture would be very superior to the #b-a_/b inch4 ,the 8,popular ,reflector10 with #e-a_/d inch speculum of #e1 #e-a_/b1 to #f feet focus1 will be found very suitable1 and if its illuminating power is not greater than a #d-a_/b inch refractor1 its defining and dividing powers are superior4 ,by choosing the above focal lengths1 according to circumstances1 the observer can reach the eye-tube1 while standing erect for objects in the zenith1 and it is a great mistake to suppose that the shorter the tube the more handy it becomes4 ,these foci will not require a 8,barlow0 lens to flatten the field4 ,the 8,barlow0 is very useful for short foci when the aperture is considerable1 as it improves the imperfect correction for spherical error1 but this is much better corrected in the mirror itself than by a 8,barlow0 lens1 which cannot be used without more than one disadvantage4 ,there must1 by its insertion1 be some loss of light1 which can ill be spared with small instruments1 and when used to obtain magnifying power there is some disturbance of colour1 and this subtracts from the beauty and purity of the definition of a reflector4 ,there is nothing equal to a good eye-piece to obtain power1 and flatness of field by the curve of the speculum4 ,with the 8,popular ,reflector0 and an outlay of a few shillings on some popular books1 such as the excellent work 8,celestial ,objects10 by the ,rev4 ,t4 ,w4 ,webb1 and some first-class publications by ,mr4 ,r4 ,a4 ,proctor1 especially his smaller star atlas1 c41 the amateur can compare the work he is then capable of doing with a large and expensive refractor which might be beyond his reach4 ,,the ,,adjustments ,,of ,,the ,,equatorial4 ,when the inexperienced amateur purchases an equatorial with circles1 he should not be without the third edition of 8,chamber's ,handbook of ,descriptive ,astronomy10 which1 besides being an excellent book in other respects1 is a really practical guide to the use and application of the ,equatorial1 and is indispensable to the beginner4 ,he will there find the fullest details of the adjustments to any degree of exactness4 ,besides many other matters he will be instructed in the use and application of apparatus to the perfect ,equatorial1 including all kinds of eye-pieces1 micrometers1 c41 c41 as well as other optical instruments and accessories4 ,the ,equatorials described in this catalogue are provided with every means of adjustment4 ,the cradle contains powerful screws to set the line of sight at right angles to the declination axis1 and shifting screws to place the polar axis in the meridian and to the correct elevation1 and with care and a few experiments with the adjustments1 and by observations of some catalogue stars1 the various adjustments will soon be correctly made1 and the verniers set accordingly4 ,,the ,,cassegrain4 ,this is a form of reflecting telescope but little known4 ,this is rather strange1 since it is a very much better principle than the 8,gregorian10 so well known to the old observers4 ,herschel says it admits of a theoretically perfect telescope4 ,compared with the 8,newtonian0 it has its advantages and disadvantages4 ,its principal advantages are1 first1 the shortening of the tube1 which in large telescopes is sometimes very important4 ,secondly1 the observer has not to ascend to the eye-tube1 the observations being made at the lower end1 as with a refractor4 ,the 8,cassegrain0 has a flatter field of view1 owing to the action of the curve of the second reflector causing the rays to travel twice the distance1 and1 adding the element of magnifying power1 the eye-pieces need not be composed of small lenses4 ,the adjustments are perhaps a little more trouble1 as the line of collimation must be carefully attended to1 this requiring only a little more care can soon be accomplished1 and then the definition of a good 8,cassegrain0 is very pleasing4 ,amongst its disadvantages is the necessity for the observer to gaze upwards as with refractors1 which1 when the object is at a considerable altitude1 is distressing1 this is one of the reasons why the 8,newtonian0 is so pleasant to use1 on account of the natural and easy position of the observer4 ,the eye-piece being a fixture1 it is not quite so convenient to use some of the accessories of the telescope4 ,but there are means to overcome these drawbacks1 and so make the 8,cassegrain0 even more handy than the 8,newtonian40 ,i have mounted an #ah inch speculum of #ab feet focus in the 8,cassegrain0 form1 so that objects at any altitude could be observed with the greatest possible ease4 ,a plane was fixed near the large mirror to receive the rays from the convex reflector and to throw them out to the side1 illuminating apparatus were fixed here1 and micrometers1 c4 used1 as if it were a 8,newtonian02 the tube was thus made shorter1 and the flat field of a long focus realised1 but there would be a little loss of light in consequence of an extra reflection1 but this1 with a large aperture 7and the fact that the 8,cassegrain0 gives a little more light than the 8,newtonian07 can better be spared1 considering the convenience gained4 ,the observer is not elevated for any altitudes1 and a large telescope is actually occupying less room than a small one4 ,it can be used with or without the diagonal4 ,i have1 by request1 fitted the 8,cassegrain0 with means for two observers to view the same object at the same time4 ,a perforated plane was arranged to receive a portion of the converging rays and throw them to the side of the tube into an eye-tube1 and the remainder passing on to the eye-tube at the proper place1 two images are thus formed1 and can be magnified at will and viewed simultaneously4 ,the perforated plate was so arranged that it could be removed at pleasure4 ,illustration3 ,,fig4 #a4 ,illustration3 ,,fig4 #b4 ,illustration3 ,,fig4 #c4 ,illustration3 ,,fig4 #d4 ,,the ,,alt-,,azimuth ,,stand4 ,fig4 #c4 ,the ,telescope1 being balanced on trunnions1 can be moved from an elevation approaching the zenith to an almost horizontal position4 ,in order that it may be secured anywhere between these extremes1 attached to the upper part of the telescope is an iron rod1 which1 sliding through the end of the arm of the stand1 can be there clamped4 ,the telescope will now be clamped in ,altitude4 ,as the progression of celestial objects will apparently be very slow1 resource must be had to the smoothness of motion obtained by a screw4 ,the upper end of the ,altitude rod is therefore tapped to receive a long screw with a large milled head1 jointed to the telescope body2 by revolving this head the telescope is raised or depressed accordingly as the screw is unscrewed1 or the reverse4 ,it is necessary that the screw should be withdrawn some way from the rod before clamping it1 preparatory to following an object which has passed the meridian1 or is setting2 as perhaps1 just when the clearest vision is obtained1 the observer may be annoyed by the screw action being suddenly stopped by the milled head coming in contact with the top of the rod4 ,when viewing objects near the zenith1 and the focus long1 the handle attached to the clamp will be found useful1 as it can thereby be reached without leaving the finder4 ,the handle may be so placed that a downward push should clamp1 and an upward pull release4 ,the second motion in the ,alt-azimuth ,stand1 namely1 ,azimuth1 is obtained as follows3--,the strong iron disc which forms the upper fitting of the legs has its surface accurately turned4 ,on this revolves an iron disc1 rather less in diameter1 to which the trunnions which support the telescope are attached4 ,the main axis of this disc passes through the centre of the lower disc1 and then through a hollow bearing tube1 a continuation of it4 ,all these fittings having been most carefully turned and ground together1 great steadiness1 combined with facility of horizontal movement1 is ensured4 ,in order that this motion can be communicated as evenly as possible1 resource must be again had to a screw which is thus applied4 ,just within the circumference of the lower disc is a narrow groove1 turned to such a depth that the ring which is thus separated from the main disc is still firmly held to it by the uncut portion4 ,an iron clamp grooved to this ring holds the nut of a long screw1 the plain end of which is jointed to the upper disc4 ,when this clamp is fixed to the ring1 any motion given to the screw will act on the upper disc1 and cause it to revolve1 and thus the whole telescope will be slowly moved in ,azimuth4 ,the advantages of this plan are many1 the most important being the rapidity and ease with which the telescope can be shifted from one object to another1 even to those in contrary directions2 all that is necessary being to release the clamp and turn the telescope to the object required4 ,the clamp being carried round with the upper disc1 can be fixed directly the desired position is obtained1 when the screw is at once in action4 ,should it happen1 whilst following an object1 that the screw becomes exhausted from the joint and clamp coming together1 the clamp should be released1 and the screw turned sufficiently in the reverse way to bring it into action1 the weight on the upper disc keeping the telescope meanwhile in position4 ,if this operation be rapidly performed1 the whole length of screw can be brought in play before the object has left the field of view of the finder1 and can thus be easily refound with the higher power of the telescope4 ,motion is applied to the screw by means of a ,hook's joint1 named thus from its inventor4 ,this joint being furnished with a long handle1 enables the observer1 by means of it1 to move the ,telescope in ,azimuth at any rate1 and without removing his eye from the eye-piece4 ,it will be seen from the preceding remarks that by means of the vertical and horizontal screw motions1 the telescope1 when clamped1 can be moved in any direction with the greatest facility1 permitting a celestial object to be observed with high powers for a considerable time1 and with the greatest pleasure and comfort to the observer4 ,illustration3 decorative ,illustration3 decorative ,,adjustments4 ,these instruments are always sent out in correct adjustment1 and with moderate care during transit1 and afterwards1 will remain so1 but as the performance of the instrument greatly depends on the accuracy of the adjustments the following instructions will enable the observer not only to ascertain whether they are perfect1 but also to render them so if found defective4 ,these adjustments are by no means difficult1 and will be easily understood by attention to the following remarks3-- ,into the draw tube screw the 8adjusting piece10 which is a small brass circle with a hole in its centre about #a_/bj of an inch in diameter4 7,the draw tube should be in about the same position as when at focus with an eyepiece47 ,place the large mirror in its cell in the tube or body of the telescope1 taking care that the three bayonet-joint pins are correctly placed1 that is1 with grooves pointing downward4 ,they will be found to drop easily into their corresponding holes2 care must however be taken that the grooves have gone well home4 ,both the speculum and small mirror1 or 8flat10 must be uncovered4 ,on looking through the aperture of the adjusting piece1 if the mirrors are in correct adjustment their reflections will be seen as follows3--the small oval mirror being placed at an angle of #de will appear circular1 and reflected exactly in the centre of this circle will be seen the bright image of the large mirror with a dark round spot in its centre1 as shown by ,fig4 #a4 ,this dark spot is the double reflection of the 8flat10 and should be concentric with both the bright reflection of the large mirror and the circular outline of the 8flat40 ,all these should also be perfectly concentric with the circle given by the stop in the draw tube4 ,should these circles not be all central the adjustments are not perfect and must be rectified as follows4 ,to adjust the 8,flat0 or small diagonal ,mirror4 ,if the bright reflection of the large mirror is seen as a perfect circle1 but not exactly in the centre of the 8flat10 the latter requires adjustment2 for this purpose loosen the milled head screw at the middle of the back of the 8flat0 which in large instruments is made sufficiently heavy to act as a counterpoise to prevent vibration4 ,this will allow the 8flat0 to be rotated by the hand vertically with respect to the tube of the telescope4 ,bring the bright circular reflection of the mirror exactly central in this direction1 and fasten in position by screwing up the milled head screw or counterpoise4 ,if the circular reflection is quite central no further adjustment is required1 but if not1 then1 after completing the vertical adjustment1 as described1 proceed to make the horizontal adjustment by turning in one or other direction the milled head of the horizontal adjustment screw1 situated in front of the vertical adjustment screw2 this will bring the circle of light exactly into its proper horizontal and central position1 and the adjustments are then completed4 ,if the bright reflection of the large mirror is not seen as a perfect circle1 and the small dark spot not in the centre1 the speculum is out of adjustment1 and consequently the adjustment of the 8flat0 is best performed by removing the large mirror or speculum with its cell and so arranging the body of the telescope that on looking through the 8adjusting piece0 a large sheet of white paper spread on the ground a short distance from the open end appears as a white circle of light reflected in the 8flat40 ,now bring this white circle exactly into the centre of the flat precisely in the way described above1 and on this being accomplished replace the speculum uncovered with its cell1 and proceed4 ,to adjust the large ,mirror or ,speculum4 ,illustration3 ,fig4 #a4 ,fig4 #b4 ,fig4 #c4 ,fig4 #d4 ,when in perfect adjustment the large mirror viewed through the 8adjusting piece0 should appear as before stated1 as a complete bright circle1 with the image of the 8flat0 as a smaller dark circular spot exactly in the centre 7,fig4 #a74 ,should this not be the case it must be rectified by means of the three adjusting screws at the back of the cell4 ,proceed as follows3--,first unloose 7by a few turns7 the small clamping screws which pass through the larger hollow adjusting ones2 then1 on looking through the adjusting piece the relative position of the image of the 8flat0 should be carefully noted4 ,if the dark spot is nearer the bottom1 and consequently more of the top part of the bright circle is seen 7,fig4 #b71 the mirror reflects too much of the upper part of the tube1 and therefore the top of the mirror leans too far back and must be pushed more forward by screwing in the top adjusting screw 7a ,fig4 #a7 a little at a time till the dark spot is central4 ,should the spot be towards the top 7,fig4 #b inverted71 the reverse holds good and the top adjusting screw 7a7 must be unscrewed or the two other adjusting screws turned in4 ,should the spot be towards the left 7,fig4 #c71 screw up the right adjusting screw 7c ,fig4 #a74 ,if towards the right 7,fig4 #d71 screw up the left adjusting screw 7b ,fig4 #a74 ,the dark spot is always furthest away from that part of the tube which is too much reflected1 and from the adjusting screw that must be turned in to correct it4 ,when all the adjustments are considered perfect1 as in ,fig4 #a1 the small screws are to be clamped up to keep the adjusting screws in position4 ,if1 after the greatest care has been taken in adjustment1 a flare should appear on looking at a star 7say of the second magnitude7 with an eye-piece of a high power1 and the diffraction rings are not quite concentric1 it can generally be rectified by turning the large screws of the mirror round in cell a little at a time4 ,if this does not remove the flare the adjustment of the 8flat04 is not sufficiently correct and must be altered by means of the screws at its back4 ,if the flare is at the top or bottom of the star the 8flat0 must be very slightly revolved by the hand1 after unloosing the middle screw1 and when correct reclamping it4 ,if at either side1 namely1 in the direction of the major axis of the 8flat0 and in a line with the tube1 the 8flat0 must be altered by the long screw4 ,it is always advisable to leave the telescope for a short time undisturbed1 especially if1 on first looking at a star1 a flare should appear1 as these appendages often vanish when the instrument has been for a short time in the air4 ,these adjustments may at first appear somewhat difficult1 but are rendered remarkably easy by observing how the different screw movements alter the positions of the reflections4 ,a useful test as to the correctness of the adjustments may be obtained by viewing a star with a high power eye-piece out of focus4 ,when in the centre of the field it should appear as a bright luminous circle with a circular dark spot in the centre1 the size of the bright circle diminishing as the focus is approached and the dark spot remaining central4 ,the cell mount of the large mirror can be removed from the tube and replaced without disturbing its adjustments1 but it is very advantageous if the entire instrument can always be left undisturbed when not in use in an observatory of light construction1 having a skeleton revolving dome1 covered with well oiled canvas or calico1 and made with a wide opening and large shutters4 ,the ,rev4 ,e4 ,l4 ,berthon has described in the 8,english ,mechanic10 ,october #acth1 #ahga1 an observatory of this kind most admirably suited to shelter a reflector1 as the temperature inside would be as nearly as possible that of the external air1 and no annoyance from damp would be experienced4 ,where an observatory is not practicable the telescope might be protected by a close fitting covering of like make4 ,both the large and small mirrors should be protected by their covers 7with which they are provided71 when not in use1 especially if left in the open air4 ,the larger sized tubes have a door large enough to admit the cover and so allow of its being put on the large mirror without the necessity of the speculum being removed from the body of the telescope4 ,to ,adjust the 8,finder40 ,direct the telescope to any bright star 7the ,pole-star being by far the best1 as it has very little apparent motion71 and bring this star into the centre of the field of a low-power eye-piece4 ,now adjust the 8finder0 by means of the three screws bearing on it1 till the star is bisected by the cross wires seen in the focus of the eye-lens of the 8finder40 ,change the low eye-piece to a high one1 and perfect the adjustment as before described4 ,any well-defined terrestrial object at a distance can be employed in the day-time to roughly adjust the 8finder10 leaving the final adjustments to be made by a star4 ,the use of ,stops4 ,a stop #a_/d inch less in diameter than the speculum1 is often useful1 in order to cut off the internal reflections of the tube4 ,with mirrors #f-a_/b inches in diameter and under stops are seldom required2 with the #f-a_/b inch a #e inch stop may however sometimes be used with advantage on very bright objects4 ,with an #h-a_/b inch mirror a #g inch stop often improves planetary definition4 ,with larger sizes than #h-a_/b inches several stops of different diameter may be used1 when experiment will determine what size is best suited to the condition of the atmosphere1 and the character and brilliancy of the object to be observed4 ,these stops can be easily cut out of thin cardboard and afterwards blacked with ,indian-ink or lampblack4 ,on ,observing the ,sun4 ,no larger aperture than #d-a_/b inches should be employed for solar observation1 except with a specially constructed 8,solar ,eye-piece10 as even a #d-a_/b inch speculum often concentrates sufficient heat to crack the coloured glass of an ordinary sun-cap1 if exposed for any length of time4 ,if a 8solar eye-piece0 is employed1 the whole aperture may be used4 ,in viewing the moon a slightly tinted glass is often most useful1 especially to persons with weak sight1 as it takes off a great deal of the glare4 ,,to ,,silver ,,and ,,polish ,,the ,,specula4 ,the cost of silvering is trifling1 and with cleanliness and ordinary care very little difficulty will be experienced4 ,the apparatus and chemicals required consist of the following articles3-- ,,apparatus4--,a ,silvering ,vessel3--,this should be a flat-bottomed circular glass or glazed dish1 #a inch or more larger in diameter than the speculum to be silvered1 and sufficiently deep to allow of a stratum of fluid of an inch or rather more between the face of the mirror and the bottom of the dish1 the top of the mirror being nearly level with the edge of the dish4 ,a ,mixing ,vessel3--,a #dj oz4 glass measure will answer well1 but care should be taken not to scratch the sides whilst stirring1 or the glass is liable to fly4 ,should a measure not be procurable1 any receptacle of sufficient size may be used1 but a glass one is best1 as it will allow of the action of ammonia being better observed4 ,a ,box of ,scales and ,weights4 ,a ,glass funnel and filtering paper4 ,two ,glass ,rods for ,stirring purposes4 ,a ,five-ounce ,glass ,measure4 ,a ,test tube #c_/d or #a inch in diameter4 ,some ,clean ,cotton ,wool4 ,some very fine ,wash-leather4 ,a ,support of ,wood1 on which to cement the speculum1 described further on4 ,all these articles should be perfectly clean and free from dust1 and the ,glass ones well rinsed with distilled water just before using4 ,,chemicals4--,nitrate ,silver4 ,potash pure1 precipitated by ,alcohol4 ,sugar of milk powdered4 ,nitric ,acid1 pure4 ,liquor ,ammoni4 ,distilled water1 pure4 ,pitch4 ,fine ,rouge4 ,turpentine4 ,procure a strip of wood an inch or so less in diameter than the mirror1 and of sufficient length to rest securely on the opposite sides of the silvering vessel4 ,pour on this piece of wood some melted pitch1 and whilst it is still hot1 place on it the back of the speculum moistened with a little turpentine2 when cold1 reverse1 and lay the cemented speculum face downwards1 suspended in the dish4 ,should the distance between the face of the mirror and the bottom of the dish be less than an inch1 raise the mirror by means of thin wedges1 placed between the strip of wood and the edges of the dish4 ,but if1 on the contrary1 the mirror should be considerably more than an inch away from the bottom1 which will occur if the silvering vessel is very deep1 the speculum must be cemented to a block of wood of sufficient height1 screwed to the suspending strip1 instead of being cemented directly to the strip itself4 ,when the speculum is properly placed in the dish1 namely1 with the front surface about one inch from the bottom1 pour in water till the fluid reaches about #a_/d inch up the side of the mirror4 ,measure this quantity1 as it will indicate the total amount of the silvering solution required to be prepared4 ,to prepare the ,silvering ,solutions--make #c standard solutions as follows-- ,no4 #a4 ,nitrate ,silver in crystals #ajj grains4 ,distilled water #d oz4 ,no4 #b4 ,potash pure by alcohol #a oz4 ,distilled water #be oz4 ,no4 #c4 ,powdered sugar of milk #a_/b oz4 ,distilled water #d oz4 ,solution ,no4 #c must be made just before using4 ,the others will keep if the distilled water employed in their preparation is pure1 and the solutions1 when made1 are kept in glass stoppered bottles4 ,suppose it is desired to silver an #h-a_/b inch mirror1 proceed as follows3--the total amount of solution required having been ascertained1 as before described1 pour #b ozs4 of solution ,no4 #a into the mixing vessel previously well washed and rinsed with distilled water1 and cautiously add ,liquor ,ammoni4 ,a grey precipitate will be formed2 continue to add the ammonia1 drop by drop1 till the precipitate is just dissolved and the solution becomes clear4 ,the solution should be well stirred with a glass rod whilst adding the ammonia4 ,now add #d oz4 of solution ,no4 #b1 and re-dissolve the brown precipitate which is produced with ,liquor ,ammoni as before described4 ,there will now be about #f-a_/b oz4 of solution4 ,subtract the #f-a_/b oz4 from the total amount previously ascertained to be required1 and the remainder will be the amount of distilled water to be added4 ,add half this quantity of distilled water to the #f-a_/b oz4 of solution1 and add a drop at a time of solution ,no4 #a1 till there is a slight precipitate1 which cannot be re-dissolved by a considerable amount of stirring 7say for #b or #c minutes72 then add the remaining half of distilled water and cover up from dust the vessel containing the solution1 so as to allow the slight precipitate to settle4 ,there is a point of importance to be attended to1 namely1 that no more ammonia is employed than is absolutely necessary4 ,the total amount of ammonia required in the #f-a_/b oz4 of solution is about #b drs4 ,to ,clean the ,mirror4 ,fill the end of a test tube with cotton wool1 leaving plenty outside the tube4 ,having poured a small quantity of strong nitric acid on the front of the mirror1 rub the acid well all over the front and sides with the cotton wool brush4 ,place the speculum under a water tap for a few minutes till the acid is washed away1 and finally well rinse with distilled water2 then place it in the silvering vessel 7previously thoroughly cleansed7 and pour in distilled water till it reaches #a_/h inch up the side of the speculum4 ,to ,mix the ,solutions4 ,the precipitate having settled1 pour into a clean vessel all that is clear of the solution1 leaving about #b oz4 behind1 which will be turbid with the precipitate1 and therefore useless4 ,the total amount will be afterwards made correct by the addition of the same quantity of solution ,no4 #c4 ,having filtered solution ,no4 #c1 warm it to about #ajj ,f4 by allowing the bottle to stand in warm water1 or by heating in a small flask4 ,when everything is quite ready1 add #b oz4 of the filtered solution ,no4 #c1 whilst warm1 to the clear solution described above1 and thoroughly mix4 ,to immerse the ,mirror4 ,remove the mirror from the distilled water1 taking care not to touch the surface of the mirror1 and wipe the back and edge with some clean cotton wool4 ,if this precaution is not taken the water is liable to drain down the sides of the mirror whilst silvering1 and cause streaks at the edge of the film4 ,having poured away the distilled water in the silvering vessel1 substitute the mixed solutions1 and directly the solution becomes slightly inky1 gently immerse the mirror1 taking care that no air bubbles1 or specks of any kind1 remain between the surface of the mirror and the solution4 ,the mirror should not be removed from the bath until all the silver has been exhausted from the solution4 ,this may be known by the solution being clear below the silver film on the surface of the liquid4 ,the time required will vary from #de minutes on a hot summer's day1 to #ij minutes when the thermometer shows a low degree of temperature4 ,in the latter case it is better to have the silvering bath in a warm room4 ,immediately the mirror is removed from the bath1 the silvered surface should be well washed by allowing ordinary water to flow on it from a tap1 for five minutes or more1 then finally rinse with distilled water and place the mirror to dry with the silvered surface resting on some blotting paper4 ,it is as well if the mirror can be left undisturbed for a day or two1 as the film will be firmer1 but it may be polished1 if desired1 after drying for a few hours4 ,to ,polish the ,silvered ,surface4 ,make a couple of polishing pads by filling two pieces of very soft wash-leather about six inches square loosely with cotton wool1 and tie them into balls4 ,gently remove any dust that may have settled on the film with some loose cotton wool1 and then go over it with one of the pads in small circular strokes for about #ae minutes4 ,this will consolidate the film and fit it for polishing4 ,spread a little of the finest rouge on a sheet of writing paper1 and impregnate the other pad with it4 ,go over the film with the rouged rubber with the same circular strokes till it is perfectly polished1 which will take another #ae minutes or so4 ,never commence with the rouged pad1 as the surface may be injured4 ,when once the film has been consolidated it will remain so1 and can be repolished many times with the rouged pad should it get tarnished4 ,the pads should be kept from dust in wide-mouthed bottles for future use4 ,with care the film will last for a long time1 especially if it is not allowed to get damp1 and consequently the mirrors should never be brought uncovered from the cold air to a warmer temperature4 ,the 8flat0 may be silvered and polished in the same way as the speculum1 using a smaller appropriate vessel for the silvering solution4 ,to ,separate the mirror from the ,wooden ,support4 ,should the mirror be attached directly to its support1 insert a chisel between them1 when one or two gentle blows will cause them to separate1 but1 should the mirror be cemented to a block1 stand the mirror on edge1 when a slight tap on the block will detach it4 ,scrape off any pitch that remains on the back of the mirror1 using finally some turpentine to wipe it clean4 ,great care should be taken not to finger the film4 ,martin's process for ,silvering4 ,prepare four solutions of any quantity4 ,keep in stoppered bottles4 ,solution #a4--;,dissolve #age grains of pure nitrate of silver in #aj oz4 of distilled water4 ,solution #b4--;,dissolve #bfb grains of pure nitrate of ammonia in #aj oz4 of distilled water4 ,solution #c4--;,dissolve #a oz4 avoirdupois of pure caustic potash 7prepared by alcohol7 in #aj oz4 of pure distilled water4 ,solution #d4--;,dissolve #a_/b oz4 avoirdupois of pure sugar candy in #e oz4 of distilled water1 then add #cb grains of tartaric acid and boil in a flask or other clean glazed vessel for #aj minutes1 when cool add #a oz4 of alcohol and then dilute with distilled water1 so as to make up the volume to #aj oz4 ,for silvering use equal parts of each1 mix solutions #a and #b together1 and #c and #d2 when the mirror is ready mix the whole together in the silvering vessel and quickly suspend the mirror4 ,in the summer time1 if the solution cannot be kept in a very cool place1 the mirror must be quite ready to be placed in the bath1 as the solutions turn instantly when mixed together4 ,illustration3 decorative ,,selected ,,testimonials #aa1 ,,wellington ,,park ,,terrace1 ,,belfast1 ,july #gth1 #ahgf4 ,,dear ,,sir1--,the night before last was a clear night and ,i got the #f-a_/b inch out1 and though the air was not good when using a #c-a_/d inch refractor1 ,i was much pleased with the performance of the mirror4 ,mr4 ,w4 came up about #aa o'clock and stayed till one1 we got it on ,saturn1 and although rather low it was really a fine sight1 ,mr4 ,w4 was much pleased4 ,the moon being near to full we could not do much with faint points of light4 ,yours sincerely1 ,w4 ,e4 ,,parkinson4 ,mr4 ,g4 ,,calver4 99 99 99 99 99 #gd1 ,,hagley ,,road1 ,,edgbaston1 ,november #bgth1 #ahgf4 ,,dear ,,sir1--,i have now got the #e-;inch speculum fairly into adjustment1 and ,i am well pleased with it4 ,last night1 the sky being clear for a short time1 ,i turned it on the moon1 the definition of minute craters was all that could be desired4 ,i hope to have better opportunities4 ,i am1 ,yours truly1 ,f4 ,g4 ,l4 ,mr4 ,g4 ,,calver4 99 99 99 99 99 #gd1 ,,hagley ,,road1 ,,edgbaston1 ,november #bast1 #ahgf4 ,,dear ,,sir1--,i have mounted the #e-;inch speculum on a simple equatorial and it works well4 ,i am sure it will turn out a fine glass and ,i shall not regret the time and pains ,i have spent over it4 ,it is not quite in adjustment yet1 when it is it will afford me a treat4 ,i have just tried it once on the ,orion ,nebula and ,trapezium1 details of ,nebula well seen1 and the #eth star in ,trapezium easy4 ,i am1 ,yours truly1 ,f4 ,g4 ,l4 99 99 99 99 99 ,,dowlais1 ,december #bgth1 #ahgf4 ,,dear ,,sir1--,i have thoroughly tested the speculum1 and am pleased to tell you it stood its trials well4 ,yours truly1 ,d4 ,c4 ,c4 ,mr4 ,g4 ,,calver4 99 99 99 99 99 ,,st4 ,,denies1 ,,southampton1 ,august #adth1 #ahgf4 ,,dear ,,sir1--,with reference to your enquiry as to the performance of the #f-a_/b in4 reflector4 ,i have pleasure in stating that ,i am perfectly satisfied4 ,it readily divides the test objects and shows delta ,cygni with as low a power as #afj4 ,the comes to ,sirius may be considered an atmospheric test1 perhaps1 but ,i have repeatedly seen it4 ,your stand ,i find very steady and convenient2 altogether ,i can fairly say that ,i consider that ,i have an instrument of considerable power at a comparatively small cost4 ,i now find the attempt to observe with a refractor the reverse of pleasant4 ,the owner of a #c-;inch refractor1 after using my reflector1 writes that he envies me its power1 ease1 definition1 and comfort in observing4 ,i am1 ,dear ,sir1 ,yours truly1 ,a4 ,h4 ,s4 99 99 99 99 99 ,,hilgay ,,rectory1 ,february #bjth1 #ahgg4 ,,dear ,,mr4 ,,calver1--,the sky last night cleared up in places and enabled me to try the #aj-;inch2 there was a slight haze1 but ,i never saw discs so perfect and neat4 ,i felt certain it would divide anything divisible4 ,clouds came up and put an end to work4 ,i am1 ,dear ,sir1 ,yours sincerely1 ,st4 ,v4 ,b4 99 99 99 99 99 #be1 ,,hamilton ,,terrace1 ,,st4 ,,john',s ,,wood1 ,may #bfth1 #ahgg4 ,,my ,,dear ,,sir1--,i have much pleasure in informing you that the very first time ,i saw ,saturn through your #f-a_/b-;inch reflector1 the definition of the planet was far superior to anything ,i had observed before1 even with a good #d-a_/d-;inch refractor2 and on another occasion ,i was greatly pleased with the clear and easy view of the 8,comes0 to ,botis4 ,but even without including the stars1 the views of ,saturn and ,jupiter through my #f-a_/b-;inch mirror do alone 7in my opinion7 well repay the cost of the telescope4 ,yours truly1 ,,wm4 ,l4 ,,lancaster4 ,mr4 ,g4 ,,calver4 99 99 99 99 99 #cg1 ,,eaton ,,rise1 ,,ealing1 ,february #acth1 #ahgg4 ,,dear ,,sir1--,i like the #ah-;inch speculum1 and ,i think it as good as it can be1 and if the larger one is as good ,i shall be delighted with it4 ,it gives beautiful star images3 ,i see ,sirius as a brilliant dot1 a glorious object without ray or flares of any kind4 ,i never saw it so well before4 ,yours truly1 ,a4 ,a4 ,c4 ,mr4 ,g4 ,,calver4 99 99 99 99 99 #cg1 ,,eaton ,,rise1 ,,ealing1 ,february #crd1 #ahgg4 ,,dear ,,sir1--,i have tried the #ah-;inch speculum on some tests1 and especially the satellites of ,uranus1 and it appears fine1 very fine4 ,what ,i have done in photography promises well4 ,yours truly1 ,a4 ,a4 ,c4 ,mr4 ,g4 ,,calver4 99 99 99 99 99 ,,southend ,,on ,,sea1 ,march #agth1 #ahgg4 ,,my ,,dear ,,sir1--,circumstances have prevented me from making many observations of late1 but ,i am more confirmed in my opinion that my telescope of your make is a very fine instrument4 7,a #f-a_/b-;inch47 ,i heartily wish you success1 which ,i feel sure you will obtain1 as you are so painstaking and turn out a thoroughly reliable article4 ,i shall be curious to compare my brother's telescope with mine4 ,sincerely yours1 ,j4 ,l4 ,l4 ,mr4 ,g4 ,,calver4 99 99 99 99 99 ,,gorlestone1 ,march #cjth1 #ahge4 ,,dear ,,sir1--,you have asked me for my opinion of the #aj-;inch speculum4 ,i have tested it1 and can speak in the highest terms of its performance4 ,definition in good air is as near perfection as it is possible to imagine4 ,such tests as ,cancri1 #b ,andromed are well divided4 ,the #fth star in the trapezium stands out well clear of its brighter neighbour4 ,on the moon any power may be applied1 only lessening the light1 but retaining sharpness of outline4 ,i have tried a good many telescopes1 but never yet saw these #aj-;inch mirrors surpassed4 ,the image of a star disc expanded on each side of the focus is of as nearly the same appearance as possible4 ,yours truly1 ,w4 ,p4 ,,matthews4 99 99 99 99 99 #daf1 ,,brixton ,,road1 ,april #bjth1 #ahge4 ,,dear ,,sir1--,in compliance with your request1 ,i send particulars of my observation on ,draconis4 ,it was about #ab4de this morning when ,i directed my #h-a_/b-;inch to this object1 the air was very unsteady1 in fact not nearly so good as some nights lately1 and ,i well divided it with a power of #dej4 ,i then used a #f-a_/b-;inch stop1 which ,i found very much increased the steadiness of definition4 ,yours very respectfully1 ,p4 ,h4 99 99 99 99 99 #ajth ,july1 #ahgd4 ,,dear ,,sir1--,i tried the #f-a_/d-;inch mirror ,i had from you for the first time last night4 ,the night was not a good one for definition1 but ,i was very much pleased indeed with its performance4 ,yours truly1 ,c4 ,h4 ,w4 99 99 99 99 99 ,,honiton ,,rectory1 ,dec4 #bcrd1 #ahgd4 ,,dear ,,sir1--,i have been wishing to tell you how pleased ,i am at the performance of your mirror4 ,many thanks for your kind offer to change the mirror if needful1 but ,i think it could hardly be better than it is1 its performance on different double stars is most excellent4 ,i have examined nearly #ajj of these since ,september with the #f-a_/b-;inch1 most of them very difficult1 but the mirror came out well under all tests4 ,i send you a list of some of the objects ,i have examined4 ,yours truly1 ,h4 ,,sadler4 ,aquil4--,divided1 power #hj4 #ad-m4 ,webb might have been rated #ae-m4 #f-m41 #g-m4 #ae4 ,a ,b ,c ,a-,b ,a-,c ,aquil4--#c-a_/b1 #af1 #ad1 #if1 #aid4 ,comites easy1 #c other excessively minute ones1 not shown by the #aa-;in4 refractor with which ,p4 ,smyth measured ,b4,c4 ,found #f-a_/b-;in4 ,sept4 #abth1 est4 #ag mag4 #ajj to #aaj4 ,persei4--,my friend 8,linea0 sees two minute stars with #dbh-;in4 ,wray1 not in ,webb1 and ,wray himself sees an excessively difficult companion4 ,i see these #c stars easily with #f-a_/b-;in4 7,wray says his companion is 8very difficult with #g-;in4 refractor1 really only a glimpse star1 even with the best atmosphere071 and have added two more stars to the group4 ,delphini4--,close double discovered by ,burnham1 est4 #jg4 ,in contact #f-a_/b-;in41 power #dcj4 ,coron ,borealis4--,very low1 long past meridian1 in contact #afd power4 a b c ,b a-b a-c b-,b ,equalei4--#e-a_/b1 #ac1 #ad1 #af3 #ce1 #ej1 #c4 #af-m4 not seen1 ,webb #i-a_/c-;in4 ,just divided #afd1 easy #dcj power4 ,two other companions 7not seen by ,smyth or ,webb87 ,andromed4--,the #af-m4 comes1 a very difficult test1 easy2 other comites 7not seen by ,smyth or ,webb87 seen4 ,companion to ,vega pretty easy1 ,nov4 #abth1 #cgm4 after sunset4 a b c ,b a-b b-,b a-c ,p4 #agh xx4 ,delphini4--#g-a_/b1 #h1 #af1 #i3 #adc1 #jg1 #bj4 ,smyth #af by evanescent glimpses2 easy #afd power1 #f-a_/b-;in4 #h-m4 well elongated in direction of #bcj1 power #dcj4 99 99 99 99 99 ,,regent ,,road1 ,,great ,,yarmouth1 ,october #bdth1 #ahgd4 ,,dear ,,sir1--,doubtless you have anticipated hearing from me1 relative to the #aj-;inch telescope1 but the weather has been so indifferent for delicate astronomical work that it has not yet had a fair trial4 ,in middling good air1 when ,i could use a reduced aperture with satisfactory results1 the star images reminded me of the #f-a_/b-;inch1 which ,i considered so superb a mirror that nothing could surpass its fine performance either on stars or planets4 ,with the recollections of the truly splendid views ,i had of ,jupiter last season1 ,i count much to see him with the #aj-;in4 ,yours truly1 ,h4 ,,blyth4 99 99 99 99 99 ,,regent ,,road1 ,,great ,,yarmouth4 ,february #bnd1 #ahge4 ,,dear ,,sir1--,in reply to yours1 ,i have not had a really good night to test severely the defining powers of the #aj-;inch mirror1 but judging from the few difficult objects ,i have seen1 the mirror promises well1 and ,i have no doubt of its excellence4 ,i had a fine view of the grand nebula in ,orionis1 and noticed that the #eth and #fth stars were quite plainly seen1 when the aperture was reduced to #e-a_/b-;inches4 ,i consider your stand a great improvement1 being very convenient and steady4 ,yours truly1 ,t4 ,,ayers4 ,illustration3 decorative ,,catalogue ,,of ,silvered ,glass ,reflecting ,telescopes1 c41 ,,and ,,their ,,accessories1 ,,june1 #ahgg4 ,g4 ,calver1 while introducing the list of prices below1 has the greatest confidence in calling the attention of the practical astronomer and the amateur to the very moderate prices charged1 considering the principle and style of the mounting1 and the firm and well-fitted arrangements in all the parts4 ,the principle of the mounting is that which is the most convenient to use1 and with the greatest degree of steadiness with the easiest movements4 ,fig4 #a is the best mounting ever applied to the ,reflecting ,telescope4 ,he is also able to state1 that with his processes and special facilities for working large specula1 and substantially mounting them1 he is prepared to construct automatic equatorials of large sizes1 and with any special arrangements that may be required4 ,,silvered ,,glass ,,equatorial ,,telescopes1 very substantially and well-fitted1 as 7,fig4 #b74 ,all these equatorials have revolving body4 s4 d4 #e-a_/d inch ,speculum from #d to #f feet focus1 with #h inch hour circles reading to #e seconds of time1 and declination circle reading to #a minute1 two powers #cj #j #j #f-a_/b inch ,speculum of from #e to #f-a_/b feet focus1 #aj inch rotating hour circle1 reading to #e seconds of time1 and declination circle to #a minute of arc1 with #c powers--#ajj to #ejj #de #j #j #h-a_/b inch ,speculum as above with #ab inch circles1 #d powers #gj #j #j #i-a_/d inch ,speculum as above with #ab inch circles1 #e powers #gh #j #j #aj inch ,speculum as above with #ab inch circles1 #e powers #ij #j #j #ab-a_/b inch ,speculum as above with #ab inch circles1 #e powers #abj #j #j ,any of the above sizes mounted on ,stand 7,fig4 #a71 from #e per cent4 extra4 ,fig4 #a is a very excellent stand1 and admirably suited for large instruments with clock power1 and is convenient to remove and adapt to different latitudes1 c41 see p4 #bj4 s4 d4 #ad1 #ae1 to #af inch ,speculum mounted as 7,fig4 #a71 with rotating hour circle reading to #e seconds and declination to #a minute 7the diameter of the circles never less than that of the ,speculum and often larger7 #h powers from #ej to #gjj1 with first-rate and very powerful driving clock1 first-class instrument1 and complete from #bbj to #ccj #j #j #ag1 #ah1 to #bj inch ,speculum1 with #aj powers1 from #ej to #hjj1 including ,kellners1 ,huyghenians1 and ,achromatics1 from #cej to #ejj #j #j #bb to #bd inch ,speculum from #eej to #gej #j #j #cj inch ,speculum1 with #ab powers and position micrometer1 and transit eye-pieces #ajjj #j #j ,prices will be forwarded for special arrangements in any of these large sizes4 ,the ,,cassegrain ,,telescope is a very convenient form1 and perfect in performance1 and in this form a very large instrument requires comparatively a much smaller observatory1 and is more conveniently worked4 ,they can be made so that the image is thrown out at the side and viewed diagonally1 as with the ,newtonian1 see p4 #ce4 ,cassegrains from #e per cent4 extra4 s4 d4 ,driving ,clocks for #f to #aj inch #ce #j #j #ab #ah #dj #j #j #bj #cj #ej #j #j ,the ,,educational ,,reflector is a plain and very steady and satisfactory instrument1 mounted on 7,fig4 #b7 stand1 without circles1 has revolving body1 and made so as to be portable4 s4 d4 #f-a_/b inch ,speculum 7clear aperture71 and of #d to #f-a_/b feet focus1 has screw-motion in right ascension1 #b powers #be #j #j #h-a_/b inch speculum as above1 with #c powers #dj #j #j ,any of these equatorials can be1 according to wish1 fitted without the circles1 c41 and dispensing with that which is not needed1 so as to reduce the price to suit circumstances and convenience4 ,the ,,popular ,,reflector1 with ,angle-,block ,stand1 with endless screw-motion to follow the stars with equatorial motion4 s4 d4 #e-a_/d inch ,speculum1 of from #d to #f feet focus1 with #b powers #ae #ae #j 7,see p4 #bj1 ,fig4 #d74 ,reflecting ,telescope on ,alt-azimuth ,stand1 as described at page #ac1 fitted with ,silvered ,glass ,speculum1 and provided with ,two ,eye-pieces4 s4 d4 #e-a_/d inch ,speculum1 #d to #f feet focus #ai #aj #j #f-a_/b #d #f-a_/b #bd #j #j #h-a_/b #f-a_/b #cc #aj #j #aj #g #de #j #j #ab-a_/b #h #gj #aj #j ,reflecting ,telescope on ,cradle ,stand1 and provided with ,two ,eye-pieces4 s4 d4 #e-a_/d inch ,speculum1 #d to #f feet focus #ba #j #j #f-a_/b #d #f-a_/b or #e feet focus #bg #j #j #h-a_/b #f-a_/b #cf #j #j #aj #g #di #j #j #ab-a_/b #h #gf #j #j ,,silvered-,,glass ,,specula 7unmounted74 ,,the ,,finest ,,quality ,,guaranteed4 s4 d4 #e-a_/d inch diameter #d to #f feet focus #e #j #j #f-a_/b #d #f-a_/b #f #e #j #h-a_/b #f-a_/b #ac #j #j #aj #g #be #j #j #ab-a_/b #h #ch #aj #j #ad #h #ee #j #j #af #aj #ge #j #j #ah #ab #ajj #j #j #bj #ab #acj #j #j #bb #ae #afe #j #j #bd #ah #bjj #j #j #bf #bej #j #j #cj #cjj #j #j #cf #djj #j #j ,,silvered-,,glass ,,diagonal ,,mirrors 7unmounted74 ,,finest ,,quality ,,guaranteed4 s4 d4 #a inch in the minor axis1 or narrowest diameter of the ellipse #a #j #j #a-a_/b ditto ditto ditto #a #aj #j #b ditto ditto ditto #b #j #j #b-a_/b ditto ditto ditto #b #aj #j #c ditto ditto ditto #c #c #j #c-a_/b ditto ditto ditto #d #d #j #d ditto ditto ditto #e #e #j ,,silvering ,,and ,,polishing ,,specula4 s4 d4 #e inch #j #f #j #f-a_/b #j #h #j #h-a_/b #j #aj #f #aj #j #ae #j #ab-a_/b #a #a #j ,diagonal ,planes #cs4 to #j #e #j ,,astronomical ,,eye-,,pieces4 ,,of ,,best ,,quality4 ,huyghenian ,construction of the following magnifying powers on a #f-a_/b feet focus object-glass3-- s4 d4 #ce1 #fj1 #ij1 #acj1 #ahj1 #bjj each #j #ae #j #cbj1 #dej #a #a #j #faj #a #g #f ,all fitted with ,sunshades4 ,improved ,achromatic1 ,ramsden's ,construction4 s4 d4 #ij1 #acj each #a #j #j #ahi1 #bej #a #aj #j #cbj1 #dej #a #ab #f #faj1 #gej #a #ae #j #hej #b #b #j ,kellner's ,construction4 s4 d4 #cj1 #eh1 and #hj each #a #e #j ,,solar ,,eye-,,pieces4 s4 d4 ,solar ,diagonal1 with true plane #a #ab #f ,dawes' ,solar ,eye-piece #h #j #j ,barlow's ,lens #a #a #j ,day ,erecting ,eye-piece #a #e #j ,coloured ,eye-piece ,cap for observing the ,moon #j #d #j ,transit ,eye-pieces1 for use with ,equatorials #a #as4 to #b #b #j ,adjusting ,piece #j #b #f ,,micrometers4 s4 d4 ,parallel ,wire ,micrometer #e #e #j ,position ,micrometers #h #hs4 to #ae #ae #j ,double ,image ,micrometer #h #h #j ,illuminating ,apparatus from #h #j #j ,good ,instruments will be taken in exchange and liberally allowed for4 ,,george ,,calver1 ,,hill ,,house1 ,,widford1 ,,chelmsford1 ,,essex4 ,illustration3 decorative ,,appendix ,,to ,hints on ,silvered ,glass ,reflecting ,telescopes4 ,the object of this pamphlet is to give some new and additional advice not contained in my 8,hints on ,silvered ,glass ,reflecting ,telescopes10 on silvering and adjusting them2 and1 as the results of continued and recent experience1 it is hoped they may be useful1 and may prove an acceptable appendix to my little book of ,hints4 ,the first thing to do after fastening the mirror to the wooden support1 is to suspend it in the dish in which it is to be silvered1 and so to adjust it that there shall be one inch between the bottom of the mirror and the bottom of the dish2 then pour in water to come a quarter of an inch up the sides of the glass--the quantity thus found is to be measured1 and will be the exact amount of the bath when all the solutions are mixed2 this will prevent any hitch at an important moment1 and the glass can be immersed without delay or disturbance4 ,next proceed to wash the surface with nitric acid1 taking care that the acid does not run down the sides1 as it is not so easily removed from the fine ground sides as it is from the polished surface4 ,after gently but thoroughly rubbing the surface1 add a little water1 and again go over2 then wash all off1 and take a large piece of cotton wool and well sponge the surface and sides with plenty of water1 and suspend in a dish or plate with water in it4 ,,to ,,prepare ,,the ,,solutions4 ,the plan ,i adopt is this1--,i dissolve a large quantity of the chemicals required in one-fourth or one-eighth the quantity of water employed by ,martin1 so that in a ,winchester quart stoppered bottle ,i can keep a large supply ready4 ,i make the silver and ammonia solutions eight times the original strength1 the potash and sugar solutions four times only1 as these latter solutions require more water to properly prepare them4 ,enough solutions to silver a #f-a_/b in4 mirror1 eight times are to be made4 ,dissolve #adjj grains of nitrate of silver in #aj ounces of water 7it may be clean fresh rain water filtered1 if distilled is difficult to obtain1 and it will act very well71 but do not put the silver into the exact #aj ounces1 but make up to exact #aj ounces after the silver is dissolved4 ,it is thus condensed eight times4 ,do the same with the nitrate of ammonia1 by dissolving #bjif grains4 ,next prepare the potash and sugar solutions1 condensed to four times the initial strength4 ,dissolve #h ounces of potash1 and make up to exactly #bj ounces of water2 if this is dissolved in a glass measure it will evolve sufficient heat to break it2 it is safely done in a clean white jug4 ,lastly1 dissolve #d ounces of white sugar candy with #daf grains of tartaric acid1 and boil ten minutes in a clean glazed vessel2 when cold1 add #h ounces of alcohol1 and make up to #bj ounces with water4 ,do not use the solutions till all are of the same temperature1 nor on the same day as they are made2 and do not silver until the glass1 and everything used are of the same temperature4 ,to insure this1 get the mirror ready and suspend in water1 with the solutions all collected in the room in which the silvering is to be done1 and let them remain until next day4 ,now1 remembering how many ounces were needed to leave one inch of solution under the surface and a quarter of an inch up the sides of the #f-a_/b in4 mirror1 using a vessel about #b inches larger in diameter than the mirror1 pour into a glass measure #aj drams of the silver solution1 add next #aj drams of the ammonia1 then #bj drams of potash2 if the potash turns the mixture thick1 pour it backwards and forwards into another vessel1 or stir it with a strip of glass1 or a glass rod1 for half a minute2 if the mixture does not turn clear 7which it will not do if it has turned very thick on adding the potash71 add cautiously1 drop by drop1 some of the ammonia solution1 agitating it till it just clears2 do not filter unless there are a great many floating particles through using unfiltered water1 the floating particles cause minute black spots1 which are1 however1 of little consequence1 as their action is only the loss of so much light4 ,measure #bj drams of the sugar--and the mirror being ready to dip 7the amount with the sugar added must be the required quantity previously ascertained71 add the sugar1 stir well1 and immerse when the mixture begins to turn dark ink colour4 ,when silvered1 well wash the mirror with water of the same temperature as itself 7it may be safely sponged with a lump of cotton wool71 and stand it on its edge on blotting-paper to dry4 ,drops of water standing long on it when drying will cause stains1 which will not readily polish off1 and indeed these should not be polished1 as it is not right to polish one part more than another2 so it is best to leave them1 or if this is objected to1 re-silver the mirror1 when standing it in the sun and wind will soon dry the surface1 but be careful not to let the dust settle on it4 ,do not warm anything2 if the weather is cold1 everything may be left many hours in a warm room1 but the equal temperature is of the utmost importance--the actual temperature is not of much consequence4 ,more failures are due to unequal temperature than any other cause in the hands of the amateur4 ,one careful and clever amateur informed me that he had failed six times1 but on the seventh1 by attending to the advice given above1 the silvering was a perfect success1 and all seemed then as easy and certain as it had before seemed uncertain and difficult4 ,,the ,,final ,,adjustment ,,of ,a ,,newtonian ,,reflector ,,on ,a ,,star4 ,the adjustments being as near correctness as can be seen by the usual method of procedure--of which the fullest details are given in my little book1 the telescope is ready to try on a star4 ,if all does not appear satisfactory on first observing the star1 do not disturb the adjustments for a while1 but wait until the air is steadier1 when perhaps it will be quite satisfactory4 ,if not1 turn it on a bright star2 if the adjustments are at fault1 the black shadow of the flat1 when the star is out of focus1 will not be central in the slightly expanded image1 but will be on one side of the expanded disk4 ,use a power of #bjj to #cjj4 ,if the black spot is near one of the sides corresponding with major axis of flat1 the side screw will put it right4 ,we will assume that the black spot is nearer the edge of flat nearest the mirror1 and that the eyepiece is beyond the focus proper for the star2 then unscrew the side screw4 ,if the spot is nearer the other edge of flat1 screw it up little by little1 taking the hand out of the telescope each time1 and see what the effect is4 ,the movement and alteration can be watched while the hand is in the tube4 ,if the spot is seen either the top or bottom of the flat that is in the direction of the diameter of tube1 the middle screw must be slightly loosened and the flat revolved4 ,let the screw just bite so as to hold1 and tighten it when correct4 ,the definition of a star should now be perfect1 and by daylight observe the adjustments2 it may appear that the reflected circles are not concentric1 but if the definition on a star is good in still air1 consider the appearances correct adjustments1 except that the reflection of the black spot on mirror may be made concentric4 ,it sometimes happens that a persistent and rigid centreing of the reflections on face of flat are not the positions for best definition1 perhaps from a slight optical eccentricity somewhere in the instrument4 ,the adjustments of a reflector are soon familiar and easy1 and there is this to be said1 the adjustments can be manipulated upon to any amount without the slightest injury to the instrument2 there is no danger of any sort1 and the instrument can be perfected in its adjustments by daylight1 and this makes it both pleasant and convenient to leisurely work at1 for experience sake4 ,the instrument need not be out of doors either1 unless an artificial star from a black pin's head--which is better in strong sunlight than a thermometer bulb--is to be used instead of a star at night1 if so let it be as high as possible4 ,be careful not to screw up the small screws too tight1 as the fine threads are liable to be spoiled and the screw made useless4 ,,the ,,durability ,,of ,,silver ,,films4 ,it sometimes happens that the films do not last so long as they are expected to do1 that is1 they sometimes lose their splendid lustre sooner than they should do4 ,when it is remembered that though the process of silvering is an easy operation to perform1 yet it is a delicate chemical one1 in which good results are best obtained when several good conditions all meet together1 this is not to be wondered at1 but it is certain the instructions given above will reduce the chances of failure to a minimum1 and imperfect results will be rare4 ,the silver usually lasts a long time4 ,i know silver films that have been in use for ten years4 ,do not suppose that a long and badly worn surface will fail to show the detail and colours of the planets1 the fullest detail also of the moon or the stars4 ,it is surprising how long a silvered surface will continue to do its full work while its appearance is much deteriorated2 picking up faint points of light that are near the very limit of its aperture and power1 seem alone to require the perfect and fresh film4 ,i know silver films that have been in use for seven years and have not been ever re-polished4 ,that the ,silvered ,glass ,reflecting ,telescope is giving satisfaction and is capable of performing the best work of a telescope--being durable1 convenient1 and perfectly efficient--may be gathered from the selection of a very large number of satisfactory and most gratifying letters received by the writer2 and it has been most encouraging to find in all cases the observer is most eager to express his entire satisfaction1 and especially so where so many have been prejudiced1 in the absence of experience1 with feelings of doubt as to their complete efficiency1 and many1 again1 having used fine refractors4 ,it will be seen1 too1 that many have commenced with a small sized reflector1 and gone on increasing their optical power until they have obtained a large and powerful instrument1 imposing indeed as compared with what was considered a powerful instrument less than half a century ago1 and at a fraction of its cost4 ,the gratifying success which ,i have achieved1 attested by the universal satisfaction given by the instruments supplied by me1 is the result of unwearying labour and untiring patience2 every speculum1 large or small1 being figured with my own hands4 ,i have every facility for setting up instruments1 and for testing1 working1 and regulating them in every part on celestial objects4 ,the optical parts are1 therefore1 not merely tested separately and subsequently mechanically adjusted1 but each and every instrument is put together and optically and mechanically tested1 as a whole1 before it is permitted to leave the workshop4 ,every speculum is most carefully figured1 and confidently guaranteed perfect to the extreme edge4 ,the employment of 8stops0 of any kind is quite unnecessary1 except on bad nights1 when the aperture must of course be suited to the degree of steadiness of the air4 ,for1 whether the instrument be a reflector or a refractor1 the aperture and power used must of necessity be limited by the atmospheric conditions under which observations are made4 ,it should1 however1 be remembered that the reflector having not only a much larger aperture than a refractor of same focal length1 and1 being open to the influence of the external air1 is not only affected by a relatively larger column of air1 but is affected in a different way4 ,it frequently happens that reflectors of #f in4 to #ah in4 aperture1 are of same focal length as #e or #f inch refractors4 ,these considerations will explain the occasional use of stops1 and the expediency of having them ready to use when they can be of temporary advantage4 ,there are nights in our climate when a #f inch aperture may be the largest that can be used with satisfaction or advantage2 indeed it used to be accepted as an incontrovertible fact that an aperture of ,g inches was the largest that could be used on average nights in our country4 ,but there are also not a few nights when large apertures1 bring great gain to their fortunate possessors4 ,it is obvious that1 mutatis mutandis1 these conditions must affect refractors as well as reflectors1 with perhaps this difference1 that in the case of a reflector the rays pass down the tube and infringe on the speculum as a column of parallel rays2 consequently all the external rays of the column travel near the surface of the tube for its entire length4 ,this being so1 it is obvious that until the internal and external air and the metal tube have time to equalize in temperature1 it will be advantageous1 in all work requiring high powers1 such as the examination of difficult double stars1 to 8stop off0 for a time the extreme edge by a small diaphragm4 ,this will occur especially on frosty nights after a warm fine day4 ,when the telescope is in the open air1 ice will not infrequently form on the top of the tube1 and the effect will be at once obvious in the irregularity of a star image at the edge corresponding to the top of the tube4 ,the use of a small diaphragm will at once obviate this defect and give perfect images4 ,on such nights a wooden tube is preferable to a metal one4 ,it has been frequently my experience1 when finally testing an instrument1 that when ,i have been dissatisfied with its performance1 and in order to trace the cause of the apparent defect1 have removed the mirrors to my wooden testing tube1 ,i have found every defect removed1 and imperfect replaced by perfect images4 ,the explanation is simple4 ,not only is the wooden tube much larger in diameter than the specula1 but wood is of itself less sensible than metal to differences of temperature4 ,to make the tubes some #b or #c inches larger in diameter than the speculum would cure this evil1 but it would involve various inconveniences and expenses in structure1 which would more than outweigh the advantage of overcoming a hindrance which is after all only temporary and occasional4 ,the experiment of perforating or ventilating tubes has now been thoroughly and exhaustively tried1 with the result that there is a fairly general consensus of experienced opinion against their use4 ,the advantages are merely theoretical2 the disadvantages are grave4 ,among them are the admission of cross reflections in every direction1 the admission of dust1 imperfect protection of the mirrors1 and a decided loss of strength and rigidity to the tube4 ,,catalogue ,,of ,silvered ,glass ,reflecting ,telescopes1 c41 ,,and ,,their ,,accessories1 ,,october1 #ahhj4 ,g4 ,calver1 while introducing the list of prices below1 has the greatest confidence in calling the attention of the practical astronomer and the amateur to the very moderate prices charged1 considering the principle and style of the mounting1 and the firm and well-fitted arrangements in all the parts4 ,the principle of the mounting is that which is the most convenient to use1 and with the greatest degree of steadiness with the easiest movements4 ,fig4 #a is the best mounting ever applied to the ,reflecting ,telescope4 ,he is also able to state that1 with his processes and special facilities for working large specula1 and substantially mounting them1 he is prepared to construct automatic equatorials of large sizes1 and with any special arrangements that may be required4 ,fig4 #a is a very excellent mounting1 and admirably suited for large instruments1 especially when clock-power is applied2 and as now manufactured by ,g4 ,,calver1 is the most complete and reliable1 its details of construction being such as to give the greatest freedom of motion and steadiness4 ,for large sizes the top of polar axis works on friction rollers2 and1 as a superior ,german stand1 its arrangements and means of astronomical as well as optical adjustments1 are such as to make it an instrument of precision4 ,to ensure these qualities many well considered arrangements--entailing careful and expensive workmanship--must be provided2 details that do not easily admit of description in an ordinary catalogue1 or can be shown in an engraving1 but are duly appreciated by the observer1 who will find their value by practice4 ,the cradle bar is compound with fine screw movement for perfecting collimation1 but to make this adjustment perfect1 the telescope tube must be centred in a powerful lathe1 and the cradle and solid metal rings in which the tube revolves 7see illustration7 has to be turned and fitted with true flanges or working bearings2 the mechanical and optical centres will then coincide4 ,the hour circle1 to be truly divided1 must be truly made1 and is a solid wheel of good substance1 working on a secondary axis1 and rotated by mechanical means1 truly concentric1 with a very strong polar axis4 ,the declination circle has fine tangent screw movement1 with double action for setting the readings by milled-headed screw1 and also long driving rod from the eye-piece to set and adjust the object in centre of field4 ,there is slow hand motion1 by a separate wheel in right ascension4 ,the clock-power is connected and disconnected instantly1 by touching with the finger a small lever1 conveniently placed at a small door in the clock case4 ,the clock will go at exactly the same rate1 whether it is driving the telescope or not1 and the latter begins to move at the proper speed the instant the lever is moved1 and the connection of the telescope and clock made1 which is instantly effected by another lever4 s4 d4 #ad1 #ae1 to #af inch ,speculum mounted as 7,fig4 #a71 with rotating hour circle reading to #e seconds and decimation to #a minute 7the diameter of the circles never less than that of the ,speculum1 and often larger7 #h powers1 from #ej to #gjj1 with first-rate and very powerful driving clock1 first-class instrument1 and complete from #bej to #cej #j #j #ag1 #ah1 to #bj inch ,speculum1 with #aj powers1 from #ej to #hjj1 including ,kellners1 ,huyghenians1 and ,achromatics1 from #cfj to #ejj #j #j #bb to #bd inch ,speculum from #fjj to #gjj #j #j #cj inch ,speculum1 with #ab powers and position micrometer1 and transit eye-pieces #ajjj #j #j ,prices will be forwarded for special arrangements in any of these large sizes4 s4 d4 ,driving ,clocks for #f to #h inch #ce #j #j #ab #ah #dj #j #j #bj #cj #ej #j #j ,these are fitted with governor1 regulator1 and self-adjusting break4 ,they are made of gun metal and steel1 and every wheel is cut4 ,they drive with most excellent regularity1 and are1 when desired1 made to beat seconds on a bell4 ,the whole is enclosed in a mahogany frame1 with glass panels4 ,fig4 #b admits of equal completeness1 c41 but the stand is not so convenient for clock-power4 ,,silvered ,,glass ,,equatorial ,,telescopes1 very substantially and well fitted as 7,fig4 #b74 ,all these equatorials have revolving body4 s4 d4 #e-a_/d inch ,speculum1 from #d to #f feet focus1 with #g inch hour circles1 reading to #e seconds of time1 and declination circle reading to #a minute1 #b powers #cj #j #j #f-a_/b inch ,speculum1 of from #e to #f-a_/b feet focus1 #aj inch rotating hour circle1 reading to #e seconds of time1 and declination circle to #a minute of arc1 with #c powers--#ajj to #ejj #de #j #j #h-a_/b inch ,speculum1 as above1 with #aj inch circles1 #d powers #gj #j #j #aj inch ,speculum1 as above1 with #aj inch circles1 #e powers #ij #j #j #ab-a_/b inch ,speculum1 as above1 with #aj inch circles1 #e powers #abj #j #j ,the ,,educational ,,reflector is a plain and very steady and satisfactory instrument1 mounted on 7,fig4 #b7 stand1 without circles1 has revolving body1 and made so as to be portable4 s4 d4 #h-a_/b inch ,speculum as above1 with #c powers #dj #j #j ,the ,,popular ,,reflector 7,fig #c71 with ,angle-,block stand1 with endless screw-motion to follow the stars with equatorial motion4 s4 d4 #e-a_/d inch ,speculum1 of from #d to #f feet focus1 with #b powers #ae #ae #j ,these are also made with rotating body4 ,reflecting ,telescope on ,alt-azimuth ,stand1 fitted with silvered glass ,speculum1 and provided with two eye-pieces4 s4 d4 #e-a_/d inch ,speculum1 #d to #f feet focus #ai #aj #j #f-a_/b #e #f-a_/b #be #j #j #h-a_/b #f-a_/b #cc #aj #j #aj #g #ej #j #j #ab-a_/b #h #gj #aj #j ,silvered-,glass ,specula 7unmounted74 ,,the ,,finest ,,quality ,,guaranteed4 s4 d4 #e-a_/d inch diameter1 #d to #f feet focus #e #j #j #f-a_/b #d #f-a_/b #f #e #j #h-a_/b #f-a_/b #ac #j #j #aj #g #be #j #j #ab-a_/b #h #ch #aj #j #ad #h #ee #j #j #af #aj #ge #j #j #ah #ab #ajj #j #j #bj #ab #acj #j #j #bb #ae #afe #j #j #bd #ah #bjj #j #j #bf #bej #j #j #cj #cjj #j #j #cf #djj #j #j ,silvered-,glass ,diagonal ,mirrors 7unmounted74 ,,finest ,,quality ,,guaranteed4 s4 d4 #a inch in the minor axis1 or narrowest diameter of the ellipse #a #j #j #a-a_/b ditto ditto ditto #a #aj #j #b ditto ditto ditto #b #j #j #b-a_/b ditto ditto ditto #b #aj #j #c ditto ditto ditto #c #c #j #c-a_/b ditto ditto ditto #d #d #j #d ditto ditto ditto #e #e #j ,silvering and ,polishing ,specula4 s4 d4 #e inch #j #f #j #f-a_/b #j #h #j #h-a_/b #j #aj #f #aj #j #ae #j #ab-a_/b #a #a #j ,diagonal ,planes #cs4 to #j #e #j ,,astronomical ,,eye-,,pieces4 ,,of ,,best ,,quality4 ,huyghenian ,construction of the following magnifying powers on a #f-a_/b feet focus object-glass3-- s4 d4 #ce1 #fj1 #ij1 #acj1 #ahj1 #bjj each #j #ae #j #cbj1 #dej #a #a #j #faj #a #g #f ,all fitted with ,sunshades4 ,improved ,achromatic1 ,ramsden's ,construction4 s4 d4 #ij1 #acj each #a #j #j #ahi1 #bej #a #aj #j #cbj1 #dej #a #ab #f #faj1 #gej #b #b #j #hej #b #b #j ,kellner's ,construction4 s4 d4 #cj1 #eh1 and #hj each #a #e #j ,solar ,eye-,pieces4 s4 d4 ,solar ,diagonal1 with true plane #a #ab #f ,barlow's ,lens #a #a #j ,day ,erecting ,eye-piece #a #e #j ,coloured ,eye-piece cap for observing the ,moon #j #d #j ,transit ,eye-pieces1 for use with ,equatorials #a #as4 to #b #b #j ,adjusting ,piece #j #b #f ,good ,instruments will be taken in exchange1 and liberally allowed for4 ,,george ,,calver1 ,,hill ,,house1 ,,widford1 ,,chelmsford1 ,,essex4 ,,letters ,,and ,,extracts ,,from ,,the ,,following ,,gentlemen4 ,from ,w4 ,e4 ,,parkinson1 ,esq4 #aa1 ,,wellington ,,park ,,terrace1 ,,belfast1 ,july #gth1 #ahgf4 ,,dear ,,sir1--,the night before last was a clear night1 and ,i got the #f-a_/b inch out1 and though the air was not good when using a #c-a_/d inch refractor1 ,i was much pleased with the performance of the mirror4 ,mr4 ,w4 came up about eleven o'clock and stayed till one2 we got it on ,saturn1 and although rather low it was really a fine sight--,mr4 ,w4 was much pleased4 ,the moon being near to full we could not do much with faint points of light4 ,yours sincerely1 7,signed47 ,mr4 ,g4 ,,calver4 99 99 99 99 99 ,from ,f4 ,g4 ,,lemman1 ,esq4 #gd1 ,,hagley ,,road1 ,,edgbaston1 ,november #bgth1 #ahgf4 ,,dear ,,sir1--,i have now got the #e inch speculum fairly into adjustment1 and ,i am well pleased with it4 ,last night1 the sky being clear for a short time1 ,i turned it on the moon2 the definition of minute craters was all that could be desired4 ,i hope to have better opportunities4 ,i am1 ,yours truly1 7,signed47 ,mr4 ,g4 ,,calver4 99 99 99 99 99 7,from the same ,gentleman47 #gd1 ,,hagley ,,road1 ,,edgbaston1 ,november #bast1 #ahgf4 ,,dear ,,sir1--,i have mounted the #e inch speculum on a simple equatorial1 and it works well4 ,i am sure it will turn out a fine glass1 and ,i shall not regret the time and pains ,i have spent over it4 ,it is not quite in adjustment yet1 when it is it will afford me a treat4 ,i have just tried it once on the ,orion ,nebula and ,trapezium1 details of ,nebula well seen1 and the #eth star in ,trapezium easy4 ,i am1 ,yours truly1 7,signed47 99 99 99 99 99 ,from ,d4 ,c4 ,,carmichael1 ,esq4 ,,dowlais1 ,december #bgth1 #ahgf4 ,,dear ,,sir1--,i have thoroughly tested the speculum1 and am pleased to tell you it stood its trials well4 ,yours truly1 7,signed47 ,mr4 ,g4 ,,calver4 99 99 99 99 99 ,,st4 ,,denies1 ,,southampton1 ,august #adth1 #ahgf4 ,,dear ,,sir1--,with reference to your enquiry as to the performance of the #f-a_/b inch reflector1 ,i have pleasure in stating that ,i am perfectly satisfied4 ,it readily divides the test objects1 and shows delta ,cygni with as low a power as #afj4 ,the comes to ,sirius may be considered an atmospheric test1 perhaps1 but ,i have repeatedly seen it4 ,your stand ,i find very steady and convenient2 altogether ,i can fairly say that ,i consider that ,i have an instrument of considerable power at a comparatively small cost4 ,i now find the attempt to observe with a refractor the reverse of pleasant4 ,the owner of a #c inch refractor1 after using my reflector1 writes that he envies me its power1 ease1 definition1 and comfort in observing4 ,i am1 dear ,sir1 ,yours truly1 ,a4 ,h4 ,s4 99 99 99 99 99 ,from ,w4 ,l4 ,,lancaster1 ,esq4 #be1 ,,hamilton ,,terrace1 ,,st4 ,,john',s ,,wood1 ,may #bfth1 #ahgg4 ,,my ,,dear ,,sir1--,i have much pleasure in informing you that the very first time ,i saw ,saturn through your #f-a_/b inch reflector1 the definition of the planet was far superior to anything ,i had observed before1 even with a good #d-a_/d inch refractor2 and on another occasion ,i was greatly pleased with the clear and easy view of the 8,comes0 to ,botis4 ,but even without including the stars1 the views of ,saturn and ,jupiter through my #f-a_/b inch mirror do alone 7in my opinion7 well repay the cost of the telescope4 ,yours truly1 7,signed47 ,mr4 ,g4 ,,calver4 99 99 99 99 99 ,from ,a4 ,a4 ,,common1 ,esq41 ,f4,r4,a4,s4 #cg1 ,,eaton ,,rise1 ,,ealing1 ,february #acth1 #ahgg4 ,,dear ,,sir1--,i like the #ah inch speculum1 and ,i think it as good as it can be1 and if the larger one is as good ,i shall be delighted with it4#a ,it gives beautiful star images2 ,i see ,sirius as a brilliant dot1 a glorious object without ray or flares of any kind4 ,i never saw it so well before4 ,yours truly1 7,signed47 ,mr4 ,g4 ,,calver4 ,footnote3 #a ,this alludes to the #cg inch1 then under consideration2 and ,i may now add that ,mr4 ,common is perfectly satisfied with it1 and 8consider it a very fine mirror40 99 99 99 99 99 7,from the same ,gentleman47 #cg1 ,,eaton ,,rise1 ,,ealing1 ,february #crd1 #ahgg4 ,,dear ,,sir1--,i have tried the #ah inch speculum on some tests1 and especially the satellites of ,uranus1 and it appears fine1 very fine4 ,what ,i have done in photography promises well4 ,yours truly1 7,signed47 ,mr4 ,g4 ,,calver4 99 99 99 99 99 ,from ,j4 ,l4 ,,lancaster1 ,esq4 ,,southend-,,on-,,sea1 ,march #agth1 #ahgg4 ,,my ,,dear ,,sir1--,circumstances have prevented me from making many observations of late1 but ,i am more confirmed in my opinion that my telescope of your make is a very fine instrument 7a #f-a_/b inch74 ,i heartily wish you success1 which ,i feel sure you will obtain1 as you are so painstaking and turn out a thoroughly reliable article4 ,i shall be curious to compare my brother's telescope with mine4 ,sincerely yours1 7,signed47 ,mr4 ,g4 ,,calver4 99 99 99 99 99 ,from ,the ,,rev4 ,w4 ,p4 ,,matthews4 ,,gorlestone1 ,march #cjth1 #ahge4 ,,dear ,,sir1--,you have asked me for my opinion of the #aj inch speculum4 ,i have tested it1 and can speak in the highest terms of its performance4 ,definition in good air is as near perfection as it is possible to imagine4 ,such tests as ,cancri1 #b ,andromed are well divided4 ,the #fth star in the ,trapezium stands out well clear of its brighter neighbour4 ,on the moon any power may be applied1 only lessening the light1 but retaining sharpness of outline4 ,i have tried a good many telescopes1 but never yet saw these #aj inch mirrors surpassed4 ,the image of a star disc expanded on each side of the focus is of as nearly the same appearance as possible4 ,yours truly1 7,signed47 99 99 99 99 99 #daf1 ,,brixton ,,road1 ,april #bjth1 #ahge4 ,,dear ,,sir1--,in compliance with your request1 ,i send particulars of my observation on ,draconis4 ,it was about #ab4de this morning when ,i directed my #h-a_/b inch to this object1 the air was very unsteady1 in fact not nearly so good as some nights lately1 and ,i well divided it with a power of #dej4 ,i then used a #f-a_/b inch stop1 which ,i found very much increased the steadiness of definition4 ,yours very respectfully1 ,p4 ,h4 99 99 99 99 99 ,july #ajth1 #ahgd4 ,,dear ,,sir1--,i tried the #f-a_/d inch mirror ,i had from you for the first time last night4 ,the night was not a good one for definition1 but ,i was very much pleased indeed with its performance4 ,yours truly1 ,c4 ,h4 ,w4 99 99 99 99 99 ,from ,h4 ,,sadler1 ,esq41 ,f4,r4,a4,s4 ,,honiton ,,rectory1 ,december #bcrd1 #ahgd4 ,,dear ,,sir1--,i have been wishing to tell you how pleased ,i am at the performance of your mirror4 ,many thanks for your kind offer to change the mirror if needful1 but ,i think it could hardly be better than it is1 its performance on different double stars is most excellent4 ,i have examined nearly #ajj of these since ,september with the #f-a_/b inch1 most of them very difficult1 but the mirror came out well under all tests4 ,i send you a list of some of the objects ,i have examined4 ,yours truly1 ,h4 ,,sadler4 99 99 99 99 99 ,aquil4--,divided1 power #hj4 #ad-m4 ,webb might have been rated #ae-m4 #f-m41 #g-m4 #ae4 ,a ,b ,c ,a-,b ,a-,c ,aquil4--#c-a_/b1 #af1 #ad1 #if1 #aid4 ,comites easy1 #c other excessively minute ones1 not shown by the #aa inch refractor with which ,p4 ,smyth measured ,b4,c4 ,found #f-a_/b in4 ,sept4 #abth1 est4 #ag mag4 #ajj to #aaj4 ,persei4--,my friend 8,linea0 sees two minute stars with #dbh in4 ,wray1 not in ,webb1 and ,wray himself sees an excessively difficult companion4 ,i see these #c stars easily with #f-a_/b in4 7,wray says his companion is 8very difficult with #g in4 refractor1 really only a glimpse star1 even with the best atmosphere071 and have added two more stars to the group4 ,delphini4--,close double discovered by ,burnham1 est4 #jg4 ,in contact #f-a_/b in41 power #dcj4 ,coron ,borealis4--,very low1 long past meridian1 in contact #afd power4 a b c n ,equalei4--#e-a_/b1 #ac1 #ad1 #af3 a-b #ce1 a-c #ej b-,b #c4 #af-m4 not seen1 ,webb #i-a_/c in4 ,just divided #afd1 easy #dcj power4 ,two other companions 7not seen by ,smyth or ,webb87 ,andromed4--,the #af-m4 comes1 a very difficult test1 easy2 other comites 7not seen by ,smyth or ,webb87 seen4 ,companion to ,vega pretty easy1 ,nov4 #abth1 #cgm4 after sunset4 a b c ,b a-b b-,b a-c ,p4 #agh xx4 ,delphini4--#g-a_/b1 #h1 #af1 #i3 #adc1 #j4g1 #bj4 ,smyth #af by evanescent glimpses2 easy #afd power1 #f-a_/b in4 #h-m4 well elongated in direction of #bcj1 power #dcj4 99 99 99 99 99 ,from ,h4 ,,blyth1 ,esq4 ,,regent ,,road1 ,,great ,,yarmouth1 ,october #bdth1 #ahgd4 ,,dear ,,sir1--,doubtless you have anticipated hearing from me1 relative to the #aj inch telescope1 but the weather has been so indifferent for delicate astronomical work1 that it has not yet had a fair trial4 ,in middling good air1 when ,i could use a reduced aperture with satisfactory results1 the star images reminded me of the #f-a_/b inch1 which ,i considered so superb a mirror that nothing could surpass its fine performance either on stars or planets4 ,with the recollections of the truly splendid views ,i had of ,jupiter last season1 ,i count much to see him with the #aj inch4 ,yours truly1 7,signed47 99 99 99 99 99 ,from ,t4 ,,ayers1 ,esq4 ,,regent ,,road1 ,,great ,,yarmouth1 ,february #bnd1 #ahge4 ,,dear ,,sir1--,in reply to yours1 ,i have not had a really good night to test severely the defining powers of the #aj inch mirror1 but judging from the few difficult objects ,i have seen1 the mirror promises well1 and ,i have no doubt of its excellence4 ,i had a fine view of the grand nebula in ,orionis1 and noticed that the #eth and #fth stars were quite plainly seen1 when the aperture was reduced to #e-a_/b inches4 ,i consider your stand a great improvement1 being very convenient and steady4 ,yours truly1 7,signed47 99 99 99 99 99 ,from ,,the ,,rev4 ,a4 ,p4 ,,arnott4 ,,am ,,street1 ,,edinburgh1 #h-a_/b ,,alt4 ,,azimuth4 ,february #beth1 #ahgh4 ,,dear ,,sir1--,i have found no difficulty in putting up the instrument1 and the adjustments do not appear to be hard to manage4 ,it is a very beautiful instrument1 and the case with which its movements are made is extraordinary4 ,i am1 dear ,sir1 ,yours faithfully1 7,signed47 ,mr4 ,g4 ,,calver4 99 99 99 99 99 ,from ,j4 ,,slater1 ,esq4 ,,town ,,hall ,,square1 ,,bolton1 ,september1 #ahgg4 ,,dear ,,sir1--,last night1 through a break in the clouds1 ,i managed to get my first look with the telescope 7an #h-a_/b74 ,i turned it on delta ,cygni4 ,the definition was rather fluttering1 but a #f-a_/b in4 stop enabled me to see it well with #agj2 the first time ,i have ever divided this star#b the colour was obvious4 ,i then tried ,pi ,aquil1 which was beautifully divided4 ,i am much pleased with the instrument and its performance1 and when ,i do get a fine night ,i expect great things from my #h-a_/b in4 ,yours truly1 7,signed47 ,mr4 ,g4 ,,calver4 ,footnote3 #b ,the observer had used an #h-a_/b reflector1 however1 for some years4 99 99 99 99 99 7,another ,letter from the same ,gentleman47 ,,bolton1 ,december1 #ahgg4 ,,dear ,,sir1--,as to the adjustments of the #h-a_/b in41 ,i have had very little trouble1 and ,i have tried it again on a few objects1 a few nights ago1 and with a #g in4 stop1 and a power of #cjj1 ,i split ,zeta ,cancri and the close double sf ,castor2 with the full aperture they were very easy4 ,i have also split ,gamma ,andromed with #g in4 stop1 and on a very fine night4 ,i believe #f-a_/b in4 would do it4 ,i just got a look1 on ,november #gth1 at the shadow of ,titan1 on ,saturn's disc2 but was driven inside before ,i could observe the time of its passing the centre4 ,i have seen the ,moon on two occasions with the finest definition ,i ever saw4 ,altogether ,i am highly pleased and proud of my telescope4 ,i have not yet tried many faint objects2 still ,i saw the ,crab nebula in ,taurus much nearer ,lord ,rosse's drawings than ,herschel's1 as given by ,chambers4 ,i am1 dear ,sir1 ,yours truly1 7,signed47 ,mr4 ,g4 ,,calver4 99 99 99 99 99 ,from ,g4 ,,billington1 ,esq4 ,,wellwick1 ,,wendover1 ,july #aith4 ,,dear ,,sir1--,i am perfectly satisfied with the mirror1 a #f-a_/b in41 now that ,i have tried it with your flat1 and ,i have no difficulty in seeing star disks when the air is good4 ,i am1 dear ,sir1 ,yours truly1 7,signed47 ,mr4 ,g4 ,,calver4 99 99 99 99 99 ,from ,,the ,,rev4 ,s4 ,,tomlinson4 ,,carlisle ,,terrace1 ,,malahide1 #ahgg4 ,,dear ,,sir1--,i write to tell you that ,i was very much pleased indeed with last night's observations with your #ah4 ,the star disks were good and well condensed1 and stray light well gathered in1 and when a good night comes ,i have no doubt of it4 ,the markings on ,mars were well defined4 ,i find the advantage of a large aperture shows itself4 ,i have no doubt ,i picked up the outer ,satellite1 but cannot be certain till to-night1 if ,i am permitted to see it4 ,the only objection ,i have is its short focus1 as it seriously complicates my labours in matching the secondary convexes for the ,cassegrain form--if you can help me in the matter of a longer focus2 if not ,i am satisfied and thankful1 and must only proceed to the testing process inch by inch4 ,yours truly1 7,signed47 ,mr4 ,g4 ,,calver4 99 99 99 99 99 ,from the same ,gentleman4 ,,carlisle ,,terrace1 ,,malahide1 ,november #fth1 #ahgg4 ,,my ,,dear ,,sir1--,i had intended to write to you before1 but1 from various duties1 ,i have been obliged to postpone it from day to day4 ,i have been working steadily1 however1 with your #ah1 and ,i like it the more ,i use it4 ,the figure is wonderfully perfect1 and the definition of planetary details and markings most admirable4 ,on four occasions ,i have seen the ,satellites of ,mars2 of these ,i can feel quite certain of two1 for it was held sufficiently long to perceive a marked change in position angle4 ,the intensely small companion to a#b ,capricorni ,i have well seen1 cleanly separated1 and that in strong daylight4 ,i am anxious for a good night to attack ,orionis4 ,during these observations ,i have been using the telescope as a ,newtonion during my work at the convexes2 but my labours have been pleasantly intercepted by the magnificent and gorgeous views of the star clusters and nebul--more beautiful and startling than ,i could possibly have imagined1 and surpassing far anything ,i had ever pictured to my mind4 ,yours very truly1 7,signed47 ,mr4 ,g4 ,,calver4 99 99 99 99 99 ,from ,,major-,,general ,,addisons1 ,c4,b4 ,,melton1 #ahgh4 ,,sir1--,you will be glad1 ,i know1 to hear that ,i had a very satisfactory evening with the #ah in4 equatorial yesterday1 and the clock kept it in the field without vibration of any sort4 ,yours obediently1 7,signed47 ,mr4 ,g4 ,,calver4 99 99 99 99 99 ,from ,j4 ,t4 ,,stevenson1 ,esq4 ,,auckland1 ,,new ,,zealand1 #ahgg4 ,,dear ,,mr4 ,,calver1--,since writing to you ,i have been observing with the #f-a_/b in4 equatorial telescope1 and ,i have much pleasure in informing you that ,i am greatly pleased with its performance4 ,the definition of the planets is beautiful4 ,i am happy to inform you that ,i have found a most minute crater in ,picard a1 it is much smaller than the test crater 7mentioned in ,cel4 ,obj41 by ,,webb1 page #hc7 in same formation4 ,i wrote to ,mr4 ,,webb about it1 and since then ,i have seen it distinctly2 it is another proof of the excellence of your telescope4 ,yours truly1 7,signed47 ,mr4 ,g4 ,,calver4 99 99 99 99 99 ,from ,j4 ,c4 ,,harker1 ,esq4 ,,kendal1 #ahgh4 ,,dear ,,sir1--,after four months use of the telescope ,i had of you 7an #h-a_/b in471 ,i am able to tell you that ,i am much pleased with its great excellence4 ,the definition of the mirror is very fine1 and its performance on the ,moon being superb1 with so high a power as #gjj4 ,the stand ,i find very steady and convenient1 and the screw motions very smooth4 ,i am1 dear ,sir1 ,yours truly1 7,signed47 ,mr4 ,g4 ,,calver4 99 99 99 99 99 ,from ,e4 ,a4 ,,fry1 ,esq4 ,,birmingham1 #ahgh4 ,,dear ,,sir1--,i write to tell you that ,i like the telescope very much 7#e-a_/d in4 equatorial72 the mirror is1 as you say1 a gem1 and it is quite a treat to look at the mysteries above4 ,saturday was a glorious night1 though the ,moon was rather too bright4 ,altogether ,i am quite satisfied with the telescope1 and the finish is first-rate4 ,yours truly1 7,signed47 ,mr4 ,g4 ,,calver4 99 99 99 99 99 ,from ,,the ,,rev4 ,j4 ,m4 ,,coates4 ,,the ,,goddards1 ,,moulton1 ,,spalding4 ,,dear ,,sir1--,i am able to report satisfactorily on the mirror4 ,on ,saturday night last ,i divided #b ,botis1 power #cjj1 with the #h-a_/b4 ,yours truly1 7,signed47 ,mr4 ,g4 ,,calver4 99 99 99 99 99 ,from the same ,gentleman4 ,,the ,,goddards1 ,,moulton1 ,,spalding1 ,january #ahth1 #ahgi4 ,,dear ,,sir1--,i have been waiting for opportunities for testing observations1 but there have been few nights when the weather and leisure time have concurred in giving me a chance4 ,however1 ,i can say this much1 that in lunar work ,i have had much pleasure from the excellent definition given by the #h-a_/b in4 ,i had some fine views of ,copernicus under high powers not long since1 and am anxiously awaiting opportunities for closer study of a particular region4 ,yours truly1 7,signed47 ,mr4 ,g4 ,,calver4 99 99 99 99 99 ,from ,,frank ,c4 ,,dennett1 ,esq4 #aj1 ,,terminus ,,terrace1 ,,southampton1 ,december #ajth1 #ahgh4 ,,dear ,,sir1--,the #e-a_/d in4 is beautiful4 ,last night there was a slight frosty fog1 and the air was very very steady1 in fact ,i only remember about one such night since ,november1 #ahge4 ,saturn was sharp and hard1 and the shadow of the ring intensely black1 with all powers from #afh to #cgb1 and even with #eej1 obtained by removing the field lens of #cgb4 ,the very broad polar caps presented a bluish grey1 rendered more visible by contrast with a fine penumbral line of a very slightly brownish grey close to the south border of the ring1 and which seemed to be diffused on the south border 7i4e41 the line was diffused74 ,i should fancy the line here referred to was less than #a of arc broad2 considerably less6 ,turning from ,saturn1 ,i looked at ,arietis1 the present distance of which is only #aag2 with all powers1 from #bac upwards1 the components were visible as two tiny points of light thoroughly divorced1 and with #bhh power1 reminding one of #b ,lyr1 as seen with #abj on a #b-c_/d in4 achr41 only the discs seemed freer from rings4 ,later in the evening1 when the definition was more fluttery1 ,orionis shared the same fate as ,arietis1 being well separated with the same powers4 ,the present distance of this star is only #aab4 ,recently ,i divided this star with a #d-a_/b in4 stop on the mirror1 power #bhh4 ,i have seen ,arietis well with the same stop too4 ,i think ,i have told you before that the #e-a_/d in41 with #cgb power1 was successful in dividing ,equulei1 whose distance is only #jig4 ,this is the closest star ,i have yet divided4 ,the ,moon is fine too6 ,last night ,i caught a large ring close to the terminator1 near the south pole 7for the ,moon was only about #b-a_/b hours past full71 which was looked at over the northern wall2 the view was beautiful1 such gradations of light and shade1 interspersed with greys of different hues1 which render the object scarcely describable4 ,the finest clefts and tiniest craterlets are rendered visible4 ,it is a puzzle to me how anyone in the possession of #af or #ag can go buying a refractor of from #b-a_/b to #c-a_/d in4 aperture in preference to a silvered mirror4 ,it must be from sheer ignorance of the beautiful views given by the latter1 which is superior in every way4 ,i do not think there is any other point on which ,i need touch now1 so ,i must beg to remain1 ,dear ,sir1 ,yours very truly1 7,signed47 ,mr4 ,g4 ,,calver4 99 99 99 99 99 ,from ,,the ,,rev4 ,,jevon ,j4 ,,muschamp ,,perry1 ,m4,a41 ,f4,r4,a4,s4 ,,st4 ,,paul',s ,,vicarage1 ,,alnwick1 ,december #bjth1 #ahgi4 ,,my ,,dear ,,sir1--,i was very much interested in reading your account of the grinding and polishing of the #cg speculum1 in this week's ,e4 ,m41 copied from the 8,monthly ,notices0 of the ,r4 ,a4 ,s4 ,had ,i only the wealth of my neighbours1 ,i would give you an order for the largest telescope you could construct4 ,every really good night gives me some fresh proof of the great excellence of the #f-a_/b in4 ,for instance1 on ,december #aeth1 ,i clearly and steadily saw ,enceladus4 ,i could not1 of course1 have recognized it had it not been that this month's 8,observatory0 gave diagrams of the positions of the five inner sats4 of ,saturn1 for #h p4m4 on every day of this month1 and a careful search for ,encel4 was fully rewarded by a clear and steady view of it at that time in its proper place4 ,on this feat the ,rev4 ,t4 ,w4 ,,webb warmly congratulated me1 and said that he had seen ,encel4 with his #i-a_/c 8,with10 but only when ,saturn was hidden behind a bar4 ,i saw it clearly in exactly its proper position without hiding the planet--power #djj4 ,i have also had several good views of ,mr4 ,,webb',s new nebula in ,cygnus1 and have sent him drawings of the field1 which he confirms4 ,i have also made some fine drawings of ,jupiter and ,mars4 ,on ,december #abth1 #aa p4m41 ,i tackled #gdi 7in ,taurus71 a very difficult test for my aperture1 only #jh1 and perfectly split it with power #cjj4 ,the night was superb4 ,when you consider that the theoretical limit of dividing power for a #f-a_/b is only #jg1 ,i think ,i have done well to split a star #jh in our climate4 ,faithfully yours1 7,signed47 ,mr4 ,g4 ,,calver4 99 99 99 99 99 ,from ,g4 ,,ferguson1 ,esq41 ,m4,d4 ,,altidore ,,villa1 ,,pittville1 ,,cheltenham1 ,june #bfth1 #ahgi4 ,,my ,,dear ,,sir1--,i write to tell you that ,thursday night being very fine1 ,i had a good opportunity of trying the 7an #h-a_/b7 mirror on ,jupiter1 although this planet was lower than it should have been to give the fairest trial4 ,well1 ,i can only assure you that1 despite the low position1 ,i never saw it so beautifully before4 ,the contour of the clouds1 particularly one orange one1 sf1 the delicate lines1 and the colouring of the belts1 were all seen with a sharpness which ,i had believed scarcely attainable1 and proving that the result of your labours has been to effect a very real improvement in the speculum4 ,notwithstanding the good planetary definition1 the air was not tranquil enough for seriously attacking really difficult doubles2 still ,i was much pleased with its performance on ,aquil4 ,yours truly1 7,signed47 ,mr4 ,g4 ,,calver4 99 99 99 99 99 ,from the same ,gentleman4 ,july #bgth4 ,yours of ,july #beth duly to hand4 ,i have the speculum adjusted in the 8pink0 of accuracy4 ,star discs are small and round1 with concentric diffraction rings1 and quite rayless except in the case of the very brightest stars1 and even with these the rays are very trifling4 ,but for the diffraction rings1 which ,i fancy a really good night will mostly get rid of1 ,i should1 ,i feel sure1 have readily divided ,coron4 ,the ,moon last night1 though very low1 was seen with most gratifying ease and sharpness4 ,altogether you will gather that ,i am more than satisfied4 ,i am greatly gratified1 and will look forward to great pleasure as the season advances4 ,yours faithfully1 7,signed47 ,mr4 ,g4 ,,calver4 99 99 99 99 99 ,from ,,the ,,rev4 ,,jevon ,j4 ,,muschamp ,,perry1 ,m4,a41 ,f4,r4,a4,s4 ,,st4 ,,paul',s ,,vicarage1 ,,alnwick1 ,august #hth1 #ahhj4 ,,my ,,dear ,,sir1--,you have indeed surpassed yourself1 and your performance is better than your promise4 ,the mirror arrived safely yesterday1 and when ,i unpacked it ,i was exceedingly pleased with its surface and general appearance1 but of course that was a small matter4 ,i waited till night to test it on a close double4 ,i first tried it on ,botis1 and although the night was very bad the definition it gave of the two stars with #dej and full aperture was admirable1 considering the night4 ,after waiting a long time for clouds to clear away1 ,i turned the tube on that exceedingly difficult test1 ,cygni4 ,i consider this star to be one of the severest tests for any telescope1 reflector1 or refractor of any aperture in the whole heavens4 ,the performance of the mirror upon it1 with the full aperture1 was simply ,,magnificent1 the small close companion standing out clearly1 well separated from its bright primary1 although the night was not good4 ,i hardly thought it possible that the fine #ah inch mirror could be excelled4 ,i am bound to confess that you have excelled it4 ,to say that ,i am extremely grateful to you is a very poor expression of my feelings4 ,i am pleased and delighted beyond measure with the super-excellent #ah-a_/d in4 mirror you have sent me4 ,clouds put an end to my work last night1 but ,i have no doubt that in the future every night's observations will only accumulate proofs of the exquisite perfection of your handiwork4 ,very faithfully yours1 7,signed47 ,mr4 ,g4 ,,calver4 99 99 99 99 99 ,extract from the 8,english ,mechanic10 ,september #crd1 #ahhj4 8,the telescope is a silvered-glass ,newtonian reflector4 ,there are two specula1 one of #ah in4 in diameter1 figured by the celebrated ,,with1 in #ahgh1 and is a magnificent specimen of that eminent maker's handiwork4 ,in fact1 ,i am given to understand that ,mr4 ,,cooper ,,key considered that he had attained perfection in this mirror1 and of all men then living there was no better judge than he4 ,the other is #ah-a_/d in4 in diameter1 and was originally figured by ,mr4 ,,cooper ,,key himself2 but it was only perfect over the interior #ad in41 and1 consequently1 while the whole aperture could be used on the moon and planets1 this was all of it that could be used upon close doubles4 ,i determined1 therefore1 to give this mirror to ,mr4 ,,calver to re-figure1 and1 if possible1 excel ,mr4 ,,with',s speculum4 8,in order that ,mr4 ,,calver might know the extent of his task1 ,i returned home through ,london and ,chelmsford1 bringing with me both mirrors1 which ,mr4 ,,calver tested for himself at the centre of curvature4 ,after the trial was over1 he pronounced ,mr4 ,,with',s mirror to be an exceptionally fine one1 and heartily congratulated me on the possession of such a beauty4 ,i left the other one with him to be re-figured4 8,and now to come to the most important part of all--the performance of the #ah in4 ,,with mirror upon close double stars4 ,since the telescope came into my possession1 ,i have never had a thoroughly good night2 but even on an indifferent one1 ,i have1 with the full aperture1 divided such extremely difficult tests as ,coron1 #b ,herculis1 and ,cygni2 and these results were quite sufficient to show me that the very high reputation of its excellent maker is worthily and proudly maintained by this mirror4 ,in fact1 the definition it gave one night1 when the ,scottish ,astronomer ,royal was staying with me of ,botis1 was such1 that the ,professor told me ,i could not expect any telescope1 reflector1 or refractor1 upon the same object1 and on the same night1 to do better4 ,however1 ,i knew ,mr4 ,,calver was doing his very utmost in the honourable and praiseworthy competition to attain perfection1 to give me a mirror which would bear favourable comparison with ,mr4 ,,with's4 ,it reached me about a week ago1 and on the same evening ,i had an opportunity of testing it upon what ,i consider to be one of the very severest tests that can be applied to any telescope1 reflector or refractor1 in the northern heavens1 that is ,cygni#c4 ,to make the test as severe as possible1 ,i applied the whole aperture at once1 with a power of #cdg4 ,i was surprised and delighted beyond measure with the result4 ,the small star stood out clearly separated from its bright primary1 and there were two or three diffraction rings round the latter unbroken in any part1 and equally bright all round4 ,i consider the results which ,mr4 ,,calver has attained in this mirror cannot possibly be excelled4 ,i measured this star on two separate nights1 and the mean results are pos4 #cbhi1 dist4 #abi4 ,i also measured1 with this mirror1 another difficult star of the same character1 namely1 with a bright primary and small companion1 ,herculis1 with the following results1 pos4 #aaac1 dist4 #ajc4 ,i make the companion of this star a dusky blue1 or lavender4 ,as regards the light-grasping power of the mirror1 ,i turned it1 the other night1 on the minute pair between #a and #b ,capricorni1 which ,sir ,john ,herschel gave as the test of the power of any telescope and eye to observe the satellites of ,uranus4 ,the night was very unsteady1 but the minute stars of the pair were most conspicuous40 ,footnote3 #c ,,note4--,mr4 ,perry does not mean that ,cygni is one of the most difficult tests as regards the distance of the components4 ,he has often seen it with his #f-a_/b ,silvered ,glass ,reflector1 and even with a stop of #e-a_/b on the same instrument2 but he was surprised at the beauty and perfection of the images--perfect and unbroken rings--and he knew that these appearances could not have presented themselves had not the figure of the mirror been of extraordinary perfection4 99 99 99 99 99 ,from ,,thos4 ,,westlake1 ,esq4 ,,fordingbridge1 ,june1 #ahhj4 ,,my ,,dear ,,sir1--,i wrote you last evening1 and afterwards had my first trial with the telescope 7a #aj in4 ,alt ,azimuth74 ,it turns out a beauty4 ,i had the full aperture on all the evening1 the air was very good1 but not perfect4 ,alpha ,lyr was a splendid object with all powers1 a most brilliant disk with just indications of circular rings--no wings or rays4 ,i turned it on ,b ,cygni1 and the beauty of the mirror stood revealed1 both stars perfect disks1 with just the indication of perfect circular defraction rings1 and the colours were most beautiful1--nothing could possibly appear finer4 ,i consider the mirror perfect1 and the stand most convenient and smooth and pleasant in action4 ,i am1 dear ,sir1 ,yours truly1 7,signed47 ,mr4 ,g4 ,,calver4 99 99 99 99 99 ,from ,,the ,,rev4 ,e4 ,h4 ,,lowe4 ,,wilmcote1 ,april1 #ahhj4 ,,dear ,mr4 ,,calver1--,i have been exceedingly occupied1 as there has been a succession of gloriously fine nights1 and ,i have secured the ,nebul diagrams ,i so much wished for ,mr4 ,,webb1--and ,i would allow nothing to divert me from them--but ,i put it 7a #ae-a_/b in4 equatorial7 on ,zeta ,cancri1 and it was shown beautifully4 ,i have been working at the driving clock1 and it is under capital control4 ,the great cluster #ac ,m41 is a glorious object1 and magnificently resolved4 ,i see all ,i look for on the ,moon4 ,faithfully yours1 7,signed47 ,mr4 ,g4 ,,calver4 99 99 99 99 99 ,from ,w4 ,,scott1 ,esq4 ,,southwick1 ,,sunderland1 ,july1 #ahhj4 ,,dear ,,sir1--,dr4 ,blacklock1 and also ,mr4 ,bell1 have seen the mirror1 and pronounce it perfect1 and it performs admirably4 ,yours truly1 7,signed47 ,mr4 ,g4 ,,calver4 99 99 99 99 99 ,from ,,james ,l4 ,,mccance1 ,esq41 ,f4,r4,a4,s4 ,,putney ,,hill1 ,s4,w41 ,october #bcrd1 #ahgi4 ,,dear ,mr4 ,,calver1--,weather and circumstances have been very unfavourable for doing much work with the #aj inch reflector since ,i got it from you4 ,but with what ,i have seen with it ,i am very pleased2 in good weather the views of the planets1 ,jupiter and his 8,great ,red ,spot0 especially1 were grand4 ,the mounting 7equatorial7 is quite satisfactory1 and the movements work smoothly and well4 ,yours very truly1 7,signed47 99 99 99 99 99 ,from ,,frank ,c4 ,,dennett1 ,esq4 #aj1 ,,terminus ,,terrace1 ,,southampton1 ,july #aath1 #ahhj4 ,,dear ,,sir1--,it is a long time ago that you asked me to write and let you know how ,i liked the #i-a_/b in4 ,i have not done so because ,i wished first to see what was to be made of the planets4 ,last night1 at #ad;h #cjm1 ,i had my first peep at ,jupiter through it1 and a grand sight it was2 his belts coloured1 though not so vivid as they are sometimes1 were fine in the extreme2 and1 though the power employed was only the achromatic #bae1 the satellites were beautiful little discs1 one especially showing the tint of its surface4 ,a quarter of an hour later ,saturn was in the field of view2 a grand object1 several of the satellites surrounding it4 ,a little cloud was coming up over it1 so ,i could not see so much of this planet as ,i should have liked1 though amply sufficient to prove incontestably its high class4 ,with double stars ,i have not attempted much1 though on turning it on #b ,botis ,i found the division easy1 the components being respectively slightly orange1 and dullish white or pale yellow4 ,i have had lots of grand views of the wonders of the 8star depths10 clusters1 and nebul1 notably #eg ,messier1 the ,ring nebula1 in ,lyra1 the great ,orion nebula1 and the marvellous ,whirlpool nebula1 the chief outlines of which were well shown4 ,hitherto the instrument has been chiefly employed on the ,moon1 the details of which come out hard and sharp in a beautiful manner1 with all powers up to #eae1 the highest ,i have4 ,the #e-a_/d in4 pleased me very much1 but the #i-a_/b in4 delights me4 ,yours faithfully1 7,signed47 ,mr4 ,g4 ,,calver4 99 99 99 99 99 ,from ,g4 ,w4 ,,royston ,,pigott1 ,esq41 ,m4,d41 ,f4,r4,s41 ,f4,r4,a4,s41 c4 ,,eastbourne1 ,july1 #ahhj4 ,,dear ,,sir1--,there has been but little weather for testing4 ,mr4 ,slack has been staying with me2 we are delighted with the #h-a_/b1 and think it a great beauty4 ,i can hardly imagine any mirror much better1 and ,i expect great precision from it4 ,i find its focus to be #fe inches1 not quite so much as my fine ,dollond glass1 of #c-c_/d in4 aperture4 ,yours truly1 7,signed47 ,mr4 ,g4 ,,calver4 99 99 99 99 99 ,from ,a4 ,,williams1 ,esq4 ,,clarence ,,lodge1 ,,grafton ,,street1 ,,brighton1 ,august1 #ahhj4 ,,dear ,,sir1--,i had intended writing to you to express my pleasure in my #e-a_/d in4 telescope nearly a month ago1 but thought ,i would have another look first1 and the more ,i look the more ,i am pleased with it4 ,i cannot now imagine anyone preferring a #c-a_/d in4 refractor to one of these4 ,i have had no trouble at all with the adjustments1 and if was to get out of adjustment1 it could be rectified in about five minutes4 ,notwithstanding the unsettled weather 7giving on an average only about one fine night in eight71 ,i have examined nearly two hundred double stars in the last three months1 some of them very difficult4 ,i enclose a list of a few1 which will show very well the capabilities of the instrument4 ,yours truly1 7,signed47 ,mr4 ,g4 ,,calver4 ,,list ,,of ,,objects ,,seen ,,with ,a #e-a_/d ,,inch ,,reflector4 ,scorpii 7#e1 #eb 3 #ac7 clearly divided1 #ahf power4 ,lyr4 ,debilissima quite easy2 #ahf1 #chj powers1 though nearly half ,moon4 #a ,herculis 7#id1 #aj 3 #ajd74 ,just divided1 #chj4 ,very difficult1 owing to its faintness4 ,vega4 #aa mag41 comes quite plain1 only #dg minutes before sunrise2 powers #aaj1 #ahf4 ,virginis 7#e1 #ac 3 #dbg74 ,comes plain1 #aaj1 #ahf4 ,scorpii1 the close pair 7#d1 #e 3 #jh71 well elongated1 power #chj2 small star 7#g1 #h 3 #afh7 divided1 #aaj4 ,botis 7#d1 #e 3 #jhh7 elongated #ahf1 notched #chj1 and with field lens removed1 all but divided4 ,cygni 7#c1 #i 3 #afc71 #i plain1 #chj on several occasions4 ,antares is chiefly an atmospheric test1 but the companion was quite plain on one occasion out of the three ,i looked for it4 #b ,botis 7#ge1 #h 3 #jfc71 considerably elongated1 #chj4 ,coron 7#ee1 #f 3 #jfb71 slightly elongated1 #chj2 but not nearly so much as #b ,botis4 #ef ,herculis 7#fe1 #ac 3 #ae71 #ac easy1 all powers4 ,aquil 7#f1 #g 3 #ae74 ,just separated1 #aaj2 #ad mag4 7,webb71 just visible1 #ahf4 ,equulei4 ,just divided1 #ahf 7#eg1 #fb 3 #aj74 99 99 99 99 99 ,from ,d4 ,,traill1 ,esq4 ,,balham1 ,march #eth1 #ahhj4 ,,my ,,dear ,,sir1--,i have at present to use the telescope1 an #h-a_/b in4 ,alt ,azimuth1 out of a window1 and so at a great disadvantage1--in fact cannot give it a fair trial till ,i have the house ready for it1 meanwhile ,i use it as occasions offer1 and have been highly pleased with it4 ,the views of the nebular in ,orion resemble those of ,,bond',s drawings1 and shows immeasurably above my #c-a_/d1 of course4 ,i think the mirror is perfect from its performance on large stars whose disks are small and round1 without rays of any kind4 ,i am thoroughly satisfied4 ,yours truly1 7,signed47 ,mr4 ,g4 ,,calver4 99 99 99 99 99 ,from ,,hugh ,,auld1 ,esq4 ,,grosvenor ,,crescent1 ,,edinburgh1 #ahgi4 ,,dear ,,sir1--,i have not been able to do much with the telescope1 a #e-a_/d ,angle-block1 through the unfavourable weather for the last four months1 but with the opportunities ,i have had its performance is satisfactory2 it performs well on stars with high powers1 and ,i am sure it will bear a good deal higher4 ,i am very well pleased with the instrument4 ,yours truly1 7,signed47 ,mr4 ,g4 ,,calver4 99 99 99 99 99 ,from ,,the ,,rev4 ,,thos4 ,h4 ,,browne1 ,f4,r4,m4,s41 c4 ,,the ,,cedars1 ,,high ,,wycombe1 ,february #bfth1 #ahhj4 ,,dear ,,sir1--,i am exceedingly pleased with the action of your mirror 7an #h-a_/b in4 equatorial72 what ,i have seen of sun1 moon1 planets1 and stars is splendid4 ,i have had a good many telescopes1 but never liked one so well as the one you have sent me4 ,for the first day or two ,i could do nothing but admire it4 ,yours truly1 7,signed47 ,mr4 ,g4 ,,calver4 99 99 99 99 99 ,from ,,the ,,rev4 ,,conybeare ,w4 ,,bruce1 ,m4,a41 ,f4,r4,a4,s4 ,,st4 ,,nicholas' ,,rectory1 ,,cardiff1 ,july #agth1 #ahhj4 ,,my ,,dear ,mr4 ,,calver1--,you will have been looking for some news of me and the #ab4 ,i have purposely delayed writing until ,i was really in a position to say something definite1 and you had already heard my high opinion of the mirror4 ,let me at once say that that opinion has been more than justified4 ,the mirror is a beauty4 ,canon ,beechey and ,i got ,jupiter and ,saturn at #b4cj a4m4 yesterday morning--and they were superb4 ,the ,canon declared enthusiastically1 that he 8had never seen ,saturn anything like that10 and the last thing he said to me on the subject as ,i parted with him to-day was1 8,you have got a very fine instrument indeed40 ,if ,i could add anything more in its praise it would be this1 that ,i am really going to build a new observatory for it--my present one is too small and cramped4 ,sincerely yours1 7,signed47 ,mr4 ,g4 ,,calver4 99 99 99 99 99 7,another ,letter from the same ,gentleman47 ,,st4 ,,nicholas' ,,rectory1 ,,near ,,cardiff1 ,august #bhth1 #ahhj4 ,,dear ,mr4 ,,calver1--,the #ab inch surpasses all my expectations4 ,it has the perfection in figure of the incomparable #aj inch of yours1 which was its immediate predecessor1 and1 in grasp of light1 the difference in favour of the #ab inch over the #aj inch1 a most brilliant mirror1 is simply astounding4 ,you may equal the #ab inch--,i am sure you will1 whenever you make one--but you will not easily beat it4 ,mr4 ,,sadler1 the well-known and most accurate observer1 has himself worked with it1 and writes of it to me as follows3--8,the #ab in4 is considerably superior in light grasping power to ,h#b's #bj ft4 reflector1 and the figure is a much finer one40 ,your skill and kindness has placed me in the front rank among amateur observers1 as far as the possession of optical means is concerned4 ,i was afraid that the ,german ,stand would not prove so convenient as the 8,berthon ,equestrian ,stand10 but ,i find it is and far more so4 ,the ,german ,stand is1 for anything above #f in41 decidedly more solid and dependable1 and far simpler in any case4 ,the merit of the 8,berthon ,equestrian0 form is that it requires a smaller observatory4 ,very sincerely yours1 7,signed47 99 99 99 99 99 ,from ,w4 ,s4 ,,franks1 ,esq41 ,f4,r4,a4,s4 ,,leicester1 ,august #aith1 #ahhj4 ,,my ,,dear ,,sir1--,as the #aa-a_/d in4 speculum has now been in constant use for two years1 ,i may be allowed to express my opinion1 with all due deliberation1 as to its performance4 ,it has been tried upon almost every conceivable object during that period with uniformly good results4 ,having also a #e in4 achromatic of the finest quality1 ,i have been enabled to make a great number of comparisons between the two instruments1 mounted side by side3 and for fine definition1 smallness of star discs1 and freedom from chromatism1 the reflector always came out victorious4 ,upon first mag4 stars1 nothing could surpass the purity of the image in the reflector2 but on immediately turning to the achromatic1 the outstanding violet rays were painfully obtrusive4 ,for red stars1 which are generally small1 the reflector seems especially adapted4 ,i used to be rather sceptical about the tints of red stars1 but must confess1 after seeing the magnificent tints of scarlet and crimson which are shown by a large aperture1 that my doubts have vanished4 ,definition upon the planets1 in good air1 is simply perfect4 ,the detail on ,jupiter and ,saturn reminds one of an exquisite engraving4 ,the far distant ,neptune is perfectly defined as a tiny disc1 and his moon steadily visible with the #aa-a_/d in4 ,the facul and other ,solar detail are brought out with wonderful distinctness4 ,as for the ,moon1 the crispness of definition1 absence of colour1 and immense number of minute objects shown by the reflector1 leave nothing to be desired4 ,the gorgeous views of clusters and nebul3 the brilliantly crowded fields in the galaxy3 and the endless variety of star colours and groups are almost beyond description1 and must be seen to be appreciated4 ,i could fill pages about objects seen with the #aa-a_/d in4 mirror1 but will not occupy more space1 save to thank you for having placed such perfect instruments within the reach of amateurs4 ,yours faithfully1 7,signed47 ,mr4 ,g4 ,,calver4 99 99 99 99 99 ,from ,w4 ,s4 ,,franks1 ,esq41 ,f4,r4,a4,s4 ,,leicester1 ,september1 #ahgh4 ,,my ,,dear ,,sir1--,mr4 ,,burnham is undoubtedly 8facile princeps10 as an observer of double stars4 ,few men could have discovered such difficult objects as he has done with a #f ,o4,g4 ,perhaps1 it ought to be conceded that the usual formula for separating power1 requires modification in his case1 as ,pogson's formula for 8minima visible0 did with ,mr4 ,j4 ,w4 ,,ward1 of ,belfast4 ,apropos of this topic3 do you recollect ,mr4 ,,ward',s discovery of several additional comites to ,pxx #deb ,cygni8 ,one of them ,mr4 ,,burnham only succeeded in seeing with the greatest difficulty with the #f ,o4,g4 when the large star was hidden by a bar4 ,i can see this easily enough with the #aa-a_/d in4 mirror1 in presence of the brighter star4 ,when you have any intending customers halting between two opinions1 or in any way dubious about reflectors--if you will refer them to me1 ,i shall have great pleasure in giving my testimony4 ,reflectors have been very badly used1 and in justice to them ,i shall not hesitate to express my honest conviction whenever it is asked4 ,yours sincerely1 7,signed47 ,mr4 ,g4 ,,calver4 99 99 99 99 99 ,from ,,philip ,,vallance1 ,esq4 ,,cobb ,,court1 ,august #bdth1 #ahhj4 ,,dear ,mr4 ,,calver1--,i write to thank you for the very excellent #ab in4 mirror you have worked for me4 ,you know that ,i have excellent opportunities of testing it by those of ,with1 ,bird1 ,grubb1 ,murrell1 and others2 and also for definition by a capital #f in4 refractor--and ,i can truly say it is surpassed by none1 and equalled by few3 it is quite my favourite instrument1 and has been a source of much enjoyment ever since ,i have had it1 and again ,i thank you for working me such a treasure4 ,i am1 dear ,mr4 ,calver1 ,yours very truly1 7,signed47 99 99 99 99 99 ,from ,,the ,,rev4 ,n4 ,s4 ,,godfrey1 ,f4,r4,a4,s4 ,,st4 ,,bartholomew',s ,,vicarage1 ,,southsea1 ,august #bcrd1 #ahgi4 ,,my ,,dear ,mr4 ,,calver1--,the #ab inch mirror which you worked and mounted for me gives me perfect satisfaction4 ,i think ,i have had sufficient experience with telescopes to justify the expression of a confident opinion1 as at one time or other ,i think ,i have had #ac achromatic telescopes by ,tulley1 ,dollond1 ,simms1 ,jones1 ,cooke1 and ,murrell1 of apertures varying from #b-a_/d to #g inches1 besides #e graduated instruments4 ,the one ,i had before yours was an #h-a_/h ,with-,browning1 which ,with himself considered of as fine a figure as he could work1 and it certainly was a beautiful mirror4 ,your #ab inch is quite as perfect in its definition4 ,i have soon on particularly fine evenings ,castor as two discs1 without wing or ray4 ,i have separated with ease ,leonis1 #b ,botis1 ,coron1 #b ,andromed1 and many others of that class4 ,the planets ,jupiter and ,saturn on fine nights are magnificent4 ,i could go into more detail1 but ,i think the facts ,i have mentioned are sufficient to convey an idea of the performance of the mirror2 and ,i am particular in expressing my opinion thus strongly1 because great names1 with no experience of reflectors1 are committed to their condemnation4 ,i am certain that under favourable circumstances they are quite equal in their performances to refractors4 ,i know my #h-a_/h ,with was in every way equal to my #g inch ,troughton and ,simms1 and in light superior1 when newly silvered4 ,and when the cost is taken into consideration1 ,cooke's price of a #aj inch ,o4,g4 being #cij1 without mounting1 and your price for a #aj inch mirror being only #be1 ,i can only express my astonishment that there can exist any doubt in the scientific mind upon the subject4 ,may ,i say that ,i shall be pleased to answer any questions that any of your intending purchasers may wish to ask4 ,i cannot speak too highly of your mirror4 ,i may add that through the courtesy of its possessor1 ,a4 ,a4 ,,common1 ,esq41 ,i saw ,jupiter magnificently last year in the #cg mirror you worked for him4 ,i am1 my dear ,mr4 ,calver1 ,very truly yours1 7,signed47 99 99 99 99 99 ,from ,,the ,,rev4 ,,canon ,,st4 ,,vincent ,,beechey1 ,f4,b4,a4,s41 c4 ,,hilgay ,,rectory1 ,,downham1 ,,norfolk1 ,june #bbnd1 #ahhj4 ,,my ,,dear ,,calver1--,i really do not know how to thank you enough for all the pleasure you have given me1 and for the excellence of the work you have done for me4 ,i like it more and more6 ,it is really as near perfection as ,i could ever hope for4 ,even at my old age of nearly eighty1 ,i divide #a second stars like two dots1 and ,i used a power of #gjj on my #h foot4 ,what mirror but of great excellence would bear that power1 and give you two dots6 ,i would not part with it for anything4 ,when ,i have been to ,mr4 ,bruce he is coming to me1 and we will try your #ab against my #aj4 ,he will have light1 a great thing for me1 but ,i do think he cannot have better definition4 ,i hope nothing will prevent his getting the #ab in time for us to adjust and try it4 ,my telescope1 now complete1 is a gem1 and has given me more pleasure than any other scientific thing4 ,ever most sincerely yours1 7,signed47 ,mr4 ,g4 ,,calver4 99 99 99 99 99 ,from ,,the ,,rev4 ,j4 ,,gwynne ,,hughes1 ,f4,m4,s41 c4 ,,maldon1 ,august #cjth1 #ahhj4 ,,my ,,dear ,,sir1--,all my friends are greatly pleased with the #aj in4 reflector you have made me--with its general appearance and superior workmanship4 ,the wheel at the foot adds very much to its portability4 ,tho form of its stand is the best ,i have seen1 giving a complete sweep without any fresh adjustment4 ,the cell bearing the reflector drops into its place without any difficulty1 even in the dark4 ,the trials ,i have made of the instrument have revealed a clearness and sharpness of definition far superior to anything of the kind ,i had seen before4 ,i am indebted to you for a source of boundless scientific interest at very moderate expense4 ,with best wishes1 ,i remain1 dear ,sir1 ,yours sincerely1 7,signed47 ,mr4 ,g4 ,,calver4 99 99 99 99 99 ,from ,,walter ,,goodacre1 ,esq4 ,,seven ,,sisters ,,road1 ,may1 #ahgi4 ,,dear ,,sir1--,respecting the #e-a_/d in41 ,i am very much pleased with it2 the definition is very good4 ,as a proof of the excellence of the mirror1 ,i may mention that ,i have on several occasions seen the small crater on the floor of ,helicon1 given by ,,webb as a test for a #i in4 mirror4 ,yours truly1 7,signed47 ,mr4 ,g4 ,,calver4 7,another ,letter from the same ,gentleman47 99 99 99 99 99 ,from ,,rev4 ,n4 ,s4 ,,godfrey1 ,f4,r4,a4,s4 ,october #dth1 #ahhj4 ,,dear ,,sir1--,i have been able to get to use my telescope again1 and send you some of my seeings4 ,june #agth4-- ,herculis4 ,still night1 #aj p4m41 light haze4 ,discs beautifully small4 ,occasionally without any interference ring4 ,july #ahth4-- ,herculis4 ,beautifully seen1 power #dif1 ,cooke4 ,august #afth4--,well seen4 #f4ae p4m41 daylight4 ,august #bfth4-- ,cygni4 ,misty4 ,adjustment beautiful4 ,small star well seen4 ,cassiope4 ,double blue star well divided4 ,august #bgth4-- ,herculis4 ,both stars occasionally without ray or ring4 ,two brilliant dots4 ,colour of companion1 pale lilac4 ,full aperture4 ,power #bjg1 ,cooke4 #f p4m4 ,august #cjth4--,dumb bell nebula4 ,well seen4 ,not at all regular in outline1 as given by ,h4 ,several glimpse stars4 ,september #bdth4-- ,herculis4 ,very fine definition4 ,the difficulty with this star is clearly atmospheric4 ,i saw it well with #h in4 aperture1 power #bjg3 but the interference ring became thicker and continuous all round3 probably owing to the larger size of my diagonal prism1 nearly #b-a_/b in4 ,the planets are now again simply magnificent4 ,all the usual details ,i see splendidly with full aperture of #ab in41 and as sharp as if cut out with a penknife4 ,the great red spot is a wonderful phenomenon4 ,what is it8 ,the great nebula in ,andromeda1 seen through your fine nebula power is a mysterious sight4 ,you seem to be looking at something which eludes your vision 7except the nucleus72 you see it1 and yet1 ghost-like1 you see through it4 ,i long for the great nebula in ,orion4 ,i did not see it last year on account of illness4 ,believe me1 ,my dear ,mr4 ,calver1 ,very truly yours1 7,signed47 ,mr4 ,g4 ,,calver4 99 99 99 99 99 ,from ,t4 ,,hildersley1 ,esq4 #cc1 ,,berwick ,,street1 ,w41 ,september #ith1 #ahhj4 ,,dear ,,sir1--,i am very pleased to be able to tell you that ,i have got the #h-a_/b in4 mirror into very fair adjustment--only a slight flare on one side1 which ,i could correct if clouds had not come up1 and ,i have not had a chance since1 as my time is very limited4 ,as it was1 comes to ,wega came out fine2 also debilissima1 ,botis1 #b ,botis1 was well seen4 ,stops made little improvement4 ,nebula in ,andromeda very fine1 both large and small4 ,clusters in ,hercules well resolved1 and ,jupiter and ,saturn1 though low down1 were grand2 all is clear with any power or aperture4 ,yours truly1 7,signed47 ,mr4 ,g4 ,,calver4 99 99 99 99 99 ,from ,,rev4 ,e4 ,a4 ,,fishbourne1 ,m4,a4 ,,minor ,,canonries1 ,,llandaff1 ,october #dth1 #ahhj4 ,,my ,,dear ,,sir1--,i send you my cheque1 which ,i do with the greatest pleasure4 ,i am delighted with1 the telescope and with its capabilities4 ,faithfully yours1 7,signed47 ,mr4 ,g4 ,,calver4 99 99 99 99 99 ,from ,,walter ,,goodacre1 ,esq4 ,,london1 ,n41 ,september #fth1 #ahhj4 ,,my ,,dear ,,sir1--,the #h-a_/b in4 mirror which you supplied me with during the early part of the year1 ,i have recently mounted as a simple equatorial4 ,and although ,i have had but few opportunities at present of using the same1 they have been sufficiently numerous to prove1 beyond doubt1 the great excellence of the mirror4 ,on the evening of the #crd ,september1 ,i had some beautiful views of ,jupiter and ,saturn4 ,in the former the deep coppery hue of the equatorial belts1 and of the large spot1 at present visible on his southern hemisphere1 were strikingly conspicuous1 as were many minute details of his surface4 ,in the case of ,saturn1 the gradations of light on the rings1 and the delicately tinted belts on the planet itself1 also the sharply defined shadow of the planet on the rings were easily seen4 ,its definition of the most minute portions of the moon's surface1 leaves nothing to be desired1 whilst its performance on double stars is equally satisfactory4 ,yours faithfully1 7,signed47 ,mr4 ,g4 ,,calver4 99 99 99 99 99 ,from ,g4 ,w4 ,,royston ,,pigott1 ,esq41 ,m4,d41 ,f4,r4,s41 ,f4,r4,a4,s41 c4 ,,eastbourne1 ,october #dth1 #ahhj4 ,,dear ,,sir1--,your figuring of the #h-a_/b in4 mirror has given me much satisfaction4 ,i see #a #b ,lyr1 and such stars1 with #fjj1 very sharp and clear4 ,i have counted six satellites of ,saturn1 and the equatorial belt is very distinct4 ,last week ,i happened to observe ,jupiter1 when a black shadow of a satellite was beautifully notching the limb1 at the same time a small pearl-like satellite was about to egress from the belts4 ,i saw1 also1 six spherical cloudlets on the belts4 ,yours faithfully1 7,signed47 ,mr4 ,g4 ,,calver4 99 99 99 99 99 ,from ,,rev4 ,s4 ,,mills1 ,m4,a4 ,,droylsden1 ,september #dth1 #ahhj4 ,,dear ,mr4 ,,calver1--,to-night was an exceptional fine night for the stars1 the like of which ,i have not had since ,i got your #f-a_/b in4 ,i had for a week or so been observing with my home-made #h in41 but to-night again recurred to yours1 and its superiority was all the more conspicuous and gratifying4 ,it quite delighted me afresh6 ,looking at ,cygni1 ,i picked up two1 to me1 new stars1 which ,i think fully completes ,mr4 ,,sadler',s tests in this field4 ,i mark the newly found ones in red4 ,this only shows that one has only patiently to watch and wait for a suitable observing night to get one out of a certain aperture it is capable of showing4 ,the vast superiority of your #f-a_/b in4 has quite put my #h inch out of court66 ,yours faithfully1 7,signed47 ,mr4 ,g4 ,,calver4 99 99 99 99 99 7,from the same ,gentleman47 ,,droylsden ,,rectory1 ,,manchester1 ,july #cjth1 #ahhj4 ,,my ,,dear ,,sir1--,i can scarcely express to you the pleasure ,i have had in the use of your splendid #f-a_/b in4 mirror4 ,both in light grasping power1 and in the separation of close double stars1 it has far surpassed my highest expectations1 and quite removed the prejudice ,i entertained against reflectors4 ,though possessing a first-class #d-a_/d in4 refractor1 equatorially mounted in my observatory1 ,i now use your mirror in preference1 in the more difficult and delicate observations1 and with it am able to master the most severe tests given for #f-a_/b in4 aperture4 ,i would not be without one of your finely figured mirrors1 now that ,i have tested their merits1 for any consideration4 7,signed47 ,mr4 ,g4 ,,calver4 99 99 99 99 99 7,from the same ,gentleman47 ,,the ,,rectory1 ,,droylsden1 ,october #dth1 #ahhj4 ,,my ,,dear ,,sir1--,i have given your #h-a_/b in4 mirror one night's trial1 and it has greatly pleased me4 ,its resolution of the great cluster in ,hercules was truly magnificent1 and the clearness with which it brought out stars very difficult with #f-a_/b in4 was highly gratifying4 ,i hope to turn it to very good account4 ,yours faithfully1 7,signed47 ,mr4 ,g4 ,,calver4 ,illustration3 7,,fig4 #a47 ,illustration3 7,,fig4 #b47 ,illustration3 7,,fig4 #c47 ,printers3 ,,warren ,,hall ,,lovitt1 #hh1 ,camden ,road1 ,london4 ,n4,w4 ,,transcriber's ,,note3 ,the constelation ,botis also appears in the original spelt as ,bootis and ,botis these have all been corrected to ,botis without being noted below4 ,also variations in hyphenation remain unchanged4 ,the following typos are corrected in this e-text and are shown within the text as ,original ,replaced by ,page #d ,many of the speculas ,many of the specula ,page #g on the pitch or the pitch ,page #bd and proceed and proceed4 ,page #bh kept is glass kept in glass ,page #ca ,see p4 #bg1 ,fig4 #d ,see p4 #bj1 ,fig4 #d ,page #ci 7prices for #h-a_/b then #f-a_/b7 7prices for #f-a_/b then #h-a_/b7 7appendix7 ,page #ad ,rev4 ,w4 ,p4 ,,matthews ,,rev4 ,w4 ,p4 ,,matthews ,page #bd 7a #aj in4 ,alt ,azimuth4 7a #aj in4 ,alt ,azimuth74 ,page #cb ,rev4 ,e4 ,a4 ,,fishbourne1 ,m4,a4 ,,rev4 ,e4 ,a4 ,,fishbourne1 ,m4,a4