Part 6
DEAR SIR,—I have found no difficulty in putting up the instrument, and the adjustments do not appear to be hard to manage. It is a very beautiful instrument, and the case with which its movements are made is extraordinary.
I am, dear Sir, Yours faithfully, (_Signed_.) Mr. G. CALVER.
* * * * *
_From_ J. SLATER, Esq.
TOWN HALL SQUARE, BOLTON, _September, 1877_.
DEAR SIR,—Last night, through a break in the clouds, I managed to get my first look with the telescope (an 8-1/2″). I turned it on delta Cygni. The definition was rather fluttering, but a 6-1/2 in. stop enabled me to see it well with 170; the first time I have ever divided this star[2] the colour was obvious. I then tried Pi Aquilæ, which was beautifully divided. I am much pleased with the instrument and its performance, and when I do get a fine night I expect great things from my 8-1/2 in.
Yours truly, (_Signed_.) Mr. G. CALVER.
Footnote:
[2] The observer had used an 8-1/2″ reflector, however, for some years.
* * * * *
(_Another Letter from the same Gentleman._)
BOLTON, _December, 1877_.
DEAR SIR,—As to the adjustments of the 8-1/2 in., I have had very little trouble, and I have tried it again on a few objects, a few nights ago, and with a 7 in. stop, and a power of 300, I split Zeta Cancri and the close double _sf_ Castor; with the full aperture they were very easy. I have also split Gamma Andromedæ with 7 in. stop, and on a very fine night. I believe 6-1/2 in. would do it.
I just got a look, on November 7th, at the shadow of Titan, on Saturn’s disc; but was driven inside before I could observe the time of its passing the centre. I have seen the Moon on two occasions with the finest definition I ever saw. Altogether I am highly pleased and proud of my telescope. I have not yet tried many faint objects; still I saw the Crab nebula in Taurus much nearer Lord Rosse’s drawings than Herschel’s, as given by Chambers.
I am, dear Sir, Yours truly, (_Signed_.) Mr. G. CALVER.
* * * * *
_From_ G. BILLINGTON, Esq.
WELLWICK, WENDOVER, _July 19th_.
DEAR SIR,—I am perfectly satisfied with the mirror, a 6-1/2 in., now that I have tried it with _your_ flat, and I have no difficulty in seeing star disks when the air is good.
I am, dear Sir, Yours truly, (_Signed_.) Mr. G. CALVER.
* * * * *
_From_ THE REV. S. TOMLINSON.
CARLISLE TERRACE, MALAHIDE, 1877.
DEAR SIR,—I write to tell you that I was very much pleased indeed with last night’s observations with your 18″. The star disks were good and well condensed, and stray light well gathered in, and when a good night comes I have no doubt of it.
The markings on Mars were well defined. I find the advantage of a large aperture shows itself. I have no doubt I picked up the outer Satellite, but cannot be certain till to-night, if I am permitted to see it. The only objection I have is its short focus, 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 focus; if not I am satisfied and thankful, and must only proceed to the testing process inch by inch.
Yours truly, (_Signed_.) Mr. G. CALVER.
* * * * *
_From the same Gentleman._
CARLISLE TERRACE, MALAHIDE, _November 6th, 1877_.
MY DEAR SIR,—I had intended to write to you before, but, from various duties, I have been obliged to postpone it from day to day. I have been working steadily, however, with your 18″, and I like it the more I use it. The figure is wonderfully perfect, and the definition of planetary details and markings most admirable.
On four occasions I have seen the Satellites of Mars; of these I can feel quite certain of two, for it was held sufficiently long to perceive a marked change in position angle. The intensely small companion to _a_^2 Capricorni I have well seen, cleanly separated, and that in strong daylight. I am anxious for a good night to attack τ Orionis. During these observations I have been using the telescope as a Newtonion during my work at the convexes; but my labours have been pleasantly intercepted by the magnificent and gorgeous views of the star clusters and nebulæ—more beautiful and startling than I could possibly have imagined, and surpassing far anything I had ever pictured to my mind.
Yours very truly, (_Signed_.) Mr. G. CALVER.
* * * * *
_From_ MAJOR-GENERAL ADDISONS, C.B.
MELTON, 1878.
SIR,—You will be glad, I know, to hear that I had a very satisfactory evening with the 18 in. equatorial yesterday, and the clock kept it in the field without vibration of any sort.
Yours obediently, (_Signed_.) Mr. G. CALVER.
* * * * *
_From_ J. T. STEVENSON, Esq.
AUCKLAND, NEW ZEALAND, 1877.
DEAR MR. CALVER,—Since writing to you I have been observing with the 6-1/2 in. equatorial telescope, and I have much pleasure in informing you that I am greatly pleased with its performance. The definition of the planets is beautiful.
I am happy to inform you that I have found a most minute crater in Picard _a_, it is much smaller than the test crater (mentioned in Cel. Obj., by WEBB, page 83) in same formation. I wrote to Mr. WEBB about it, and since then I have seen it distinctly; it is another proof of the excellence of your telescope.
Yours truly, (_Signed_.) Mr. G. CALVER.
* * * * *
_From_ J. C. HARKER, Esq.
KENDAL, 1878.
DEAR SIR,—After four months use of the telescope I had of you (an 8-1/2 in.), I am able to tell you that I am much pleased with its great excellence. The definition of the mirror is very fine, and its performance on the Moon being superb, with so high a power as 700. The stand I find very steady and convenient, and the screw motions very smooth.
I am, dear Sir, Yours truly, (_Signed_.) Mr. G. CALVER.
* * * * *
_From_ E. A. FRY, Esq.
BIRMINGHAM, 1878.
DEAR SIR,—I write to tell you that I like the telescope very much (5-1/4 in. equatorial); the mirror is, as you say, a gem, and it is quite a treat to look at the mysteries above. Saturday was a glorious night, though the Moon was rather too bright. Altogether I am quite satisfied with the telescope, and the finish is first-rate.
Yours truly, (_Signed_.) Mr. G. CALVER.
* * * * *
_From_ THE REV. J. M. COATES.
THE GODDARDS, MOULTON, SPALDING.
DEAR SIR,—I am able to report satisfactorily on the mirror. On Saturday night last I divided μ^2 Boötis, power 300, with the 8-1/2″.
Yours truly, (_Signed_.) Mr. G. CALVER.
* * * * *
_From the same Gentleman._
THE GODDARDS, MOULTON, SPALDING, _January 18th, 1879_.
DEAR SIR,—I have been waiting for opportunities for testing observations, but there have been few nights when the weather and leisure time have concurred in giving me a chance. However, I can say this much, that in lunar work I have had much pleasure from the excellent definition given by the 8-1/2 in. I had some fine views of Copernicus under high powers not long since, and am anxiously awaiting opportunities for closer study of a particular region.
Yours truly, (_Signed_.) Mr. G. CALVER.
* * * * *
_From_ FRANK C. DENNETT, Esq.
10, TERMINUS TERRACE, SOUTHAMPTON, _December 10th, 1878_.
DEAR SIR,—The 5-1/4 in. is beautiful. Last night there was a slight frosty fog, and the air was very very steady, in fact I only remember about one such night since November, 1875. Saturn was sharp and hard, and the shadow of the ring intensely black, with all powers from 168 to 372, and even with 550, obtained by removing the field lens of 372. The very broad polar caps presented a bluish grey, rendered more visible by contrast with a fine penumbral line of a very slightly brownish grey close to the south border of the ring, and which seemed to be diffused on the south border (_i.e._, the line was diffused). I should fancy the line here referred to was less than 1″ of arc broad; considerably less!
Turning from Saturn, I looked at ε Arietis, the present distance of which is only 1″·17; with all powers, from 213 upwards, the components were visible as two tiny points of light thoroughly divorced, and with 288 power, reminding one of ε^2 Lyræ, as seen with 120 on a 2-3/4 in. achr., only the discs seemed freer from rings.
Later in the evening, when the definition was more fluttery, η Orionis shared the same fate as ε Arietis, being well separated with the same powers. The present distance of this star is only 1″·12. Recently I divided this star with a 4-1/2 in. stop on the mirror, power 288. I have seen ε Arietis well with the same stop too. I think I have told you before that the 5-1/4 in., with 372 power, was successful in dividing ε Equulei, whose distance is only 0″·97. This is the closest star I have yet divided.
The Moon is fine too! Last night I caught a large ring close to the terminator, near the south pole (for the Moon was only about 2-1/2 hours past full), which was looked at over the northern wall; the view was beautiful, such gradations of light and shade, interspersed with greys of different hues, which render the object scarcely describable. The finest clefts and tiniest craterlets are rendered visible. It is a puzzle to me how anyone in the possession of £16 or £17 can go buying a refractor of from 2-1/2 to 3-1/4 in. aperture in preference to a silvered mirror. It must be from sheer ignorance of the beautiful views given by the latter, which is superior in every way.
I do not think there is any other point on which I need touch now, so I must beg to remain,
Dear Sir, Yours very truly, (_Signed_.) Mr. G. CALVER.
* * * * *
_From_ THE REV. JEVON J. MUSCHAMP PERRY, M.A., F.R.A.S.
ST. PAUL’S VICARAGE, ALNWICK, _December 20th, 1879_.
MY DEAR SIR,—I was very much interested in reading your account of the grinding and polishing of the 37″ speculum, in this week’s E. M., copied from the “Monthly Notices” of the R. A. S. Had I only the wealth of my neighbours, I would give you an order for the largest telescope you could construct. Every really good night gives me some fresh proof of the great excellence of the 6-1/2 in. For instance, on December 15th, I clearly and steadily saw _Enceladus_. I could not, of course, have recognized it had it not been that this month’s “Observatory” gave diagrams of the positions of the five inner sats. of Saturn, for 8 p.m. on every day of this month, and a careful search for Encel. was fully rewarded by a clear and steady view of it at that time in its proper place. On this feat the Rev. T. W. WEBB warmly congratulated me, and said that he had seen Encel. with his 9-1/3″ “With,” but only when Saturn was hidden behind a bar. I saw it clearly in exactly its proper position _without_ hiding the planet—power 400. I have also had several good views of Mr. WEBB’S new nebula in Cygnus, and have sent him drawings of the field, which he confirms. I have also made some fine drawings of Jupiter and Mars. On December 12th, 11 p.m., I tackled σ 749 (in Taurus), a very difficult test for my aperture, only 0·8″, and _perfectly_ split it with power 300. The night was superb. When you consider that the theoretical limit of dividing power for a 6-1/2″ is only 0·7″, I think I have done well to split a star 0·8″ in our climate.
Faithfully yours, (_Signed_.) Mr. G. CALVER.
* * * * *
_From_ G. FERGUSON, Esq., M.D.
ALTIDORE VILLA, PITTVILLE, CHELTENHAM, _June 26th, 1879_.
MY DEAR SIR,—I write to tell you that Thursday night being very fine, I had a good opportunity of trying the (an 8-1/2″) mirror on Jupiter, although this planet was lower than it should have been to give the fairest trial. Well, I can only assure you that, despite the low position, I never saw it so beautifully before. The contour of the clouds, particularly one orange one, _sf_, the delicate lines, and the colouring of the belts, were all seen with a sharpness which I had believed scarcely attainable, and proving that the result of your labours has been to effect a very real improvement in the speculum. Notwithstanding the good planetary definition, the air was not tranquil enough for seriously attacking really difficult doubles; still I was much pleased with its performance on π Aquilæ.
Yours truly, (_Signed_.) Mr. G. CALVER.
* * * * *
_From the same Gentleman._
_July 27th._
Yours of July 25th duly to hand. I have the speculum adjusted in the “pink” of accuracy. Star discs are small and round, with concentric diffraction rings, and quite rayless except in the case of the very brightest stars, and even with these the rays are very trifling. But for the diffraction rings, which I fancy a really good night will mostly get rid of, I should, I feel sure, have readily divided η Coronæ.
The Moon last night, though very low, was seen with most gratifying ease and sharpness. Altogether you will gather that I am more than satisfied. I am greatly gratified, and will look forward to great pleasure as the season advances.
Yours faithfully, (_Signed_.) Mr. G. CALVER.
* * * * *
_From_ THE REV. JEVON J. MUSCHAMP PERRY, M.A., F.R.A.S.
ST. PAUL’S VICARAGE, ALNWICK, _August 8th, 1880_.
MY DEAR SIR,—You have indeed surpassed yourself, and your performance is better than your promise. The mirror arrived safely yesterday, and when I unpacked it I was exceedingly pleased with its surface and general appearance, but of course that was a small matter. I waited till night to test it on a close double.
I first tried it on ε Boötis, and although the night was very bad the definition it gave of the two stars with 450 and full aperture was admirable, considering the night. After waiting a long time for clouds to clear away, I turned the tube on that exceedingly difficult test, δ Cygni. I consider this star to be one of the severest tests for any telescope, reflector, or refractor of any aperture in the whole heavens. The performance of the mirror upon it, with the _full_ aperture, was simply MAGNIFICENT, the small close companion standing out clearly, well separated from its bright primary, although the night was not good. I hardly thought it possible that the fine 18 inch mirror could be excelled. I am bound to confess that you have excelled it.
To say that I am extremely grateful to you is a very poor expression of my feelings. I am pleased and delighted _beyond measure_ with the _super-excellent_ 18-1/4 in. mirror you have sent me. Clouds put an end to my work last night, but I have no doubt that in the future every night’s observations will only accumulate proofs of the exquisite perfection of your handiwork.
Very faithfully yours, (_Signed_.) Mr. G. CALVER.
* * * * *
_Extract from the “English Mechanic,” September 3rd, 1880_.
“The telescope is a silvered-glass Newtonian reflector. There are two specula, one of 18 in. in diameter, figured by the celebrated WITH, in 1878, and is a magnificent specimen of that eminent maker’s handiwork. In fact, I am given to understand that Mr. COOPER KEY considered that he had attained perfection in this mirror, and of all men then living there was no better judge than he. The other is 18-1/4 in. in diameter, and was originally figured by Mr. COOPER KEY himself; but it was only perfect over the interior 14 in., and, consequently, while the whole aperture could be used on the moon and planets, this was all of it that could be used upon close doubles. I determined, therefore, to give this mirror to Mr. CALVER to re-figure, and, if possible, excel Mr. WITH’S speculum.
“In order that Mr. CALVER might know the extent of his task, I returned home through London and Chelmsford, bringing with me both mirrors, which Mr. CALVER tested for himself at the centre of curvature. After the trial was over, he pronounced Mr. WITH’S mirror to be an exceptionally fine one, and heartily congratulated me on the possession of such a beauty. I left the other one with him to be re-figured.
“And now to come to the most important part of all—the performance of the 18 in. WITH mirror upon close double stars. Since the telescope came into my possession, I have never had a thoroughly good night; but even on an indifferent one, I have, with the _full aperture_, divided such extremely difficult tests as η Coronæ, μ^2 Herculis, and δ Cygni; 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 mirror. In fact, the definition it gave one night, when the Scottish Astronomer Royal was staying with me of ε Boötis, was such, that the Professor told me I could not expect any telescope, reflector, or refractor, upon the same object, and on the same night, to do better. However, I knew Mr. CALVER was doing his very utmost in the honourable and praiseworthy competition to attain perfection, to give me a mirror which would bear favourable comparison with Mr. WITH’s. It reached me about a week ago, 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 telescope, reflector or refractor, in the northern heavens, that is δ Cygni[3]. To make the test as severe as possible, I applied the _whole_ aperture at once, with a power of 347. I was surprised and delighted _beyond measure_ with the result. The small star stood out clearly separated from its bright primary, and there were two or three diffraction rings round the latter _unbroken_ in any part, and _equally_ bright all round. I consider the results which Mr. CALVER has attained in this mirror cannot possibly be excelled. I measured this star on two separate nights, and the mean results are pos. 328·9°, dist. 1·29″. I also measured, with this mirror, another difficult star of the same character, namely, with a bright primary and small companion, ζ Herculis, with the following results, pos. 111·3°, dist. 1·03″. I make the companion of this star a dusky blue, or lavender. As regards the light-grasping power of the mirror, I turned it, the other night, on the minute pair between β^1 and β^2 Capricorni, which Sir John Herschel gave as the test of the power of any telescope and eye to observe the satellites of Uranus. The night was very unsteady, but the minute stars of the pair were most conspicuous.”
Footnote:
[3] NOTE.—Mr. Perry does not mean that δ Cygni is one of the most difficult tests as regards the distance of the components. He has often seen it with his 6-1/2″ Silvered Glass Reflector, and even with a stop of 5-1/2″ on the same instrument; 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 perfection.
* * * * *
_From_ THOS. WESTLAKE, Esq.
FORDINGBRIDGE, _June, 1880_.
MY DEAR SIR,—I wrote you last evening, and afterwards had my first trial with the telescope (a 10 in. Alt Azimuth). It turns out a beauty. I had the full aperture on all the evening, the air was very good, but not perfect. Alpha Lyræ was a splendid object with all powers, a most brilliant disk with just indications of circular rings—no wings or rays. I turned it on B Cygni, and the beauty of the mirror stood revealed, both stars _perfect disks_, with _just_ the indication of perfect circular defraction rings, and the colours were most beautiful,—nothing could possibly appear finer. I consider the mirror perfect, and the stand most convenient and smooth and pleasant in action.
I am, dear Sir, Yours truly, (_Signed_.) Mr. G. CALVER.
* * * * *
_From_ THE REV. E. H. LOWE.
WILMCOTE, _April, 1880_.
DEAR Mr. CALVER,—I have been exceedingly occupied, as there has been a succession of gloriously fine nights, and I have secured the Nebulæ diagrams I so much wished for Mr. WEBB,—and I would allow nothing to divert me from them—but I put it (a 15-1/2 in. equatorial) on Zeta Cancri, and it was shown beautifully. I have been working at the driving clock, and it is under capital control. The great cluster 13 M., is a glorious object, and magnificently resolved. I see all I look for on the Moon.
Faithfully yours, (_Signed_.) Mr. G. CALVER.
* * * * *
_From_ W. SCOTT, Esq.
SOUTHWICK, SUNDERLAND, _July, 1880_.
DEAR SIR,—Dr. Blacklock, and also Mr. Bell, have seen the mirror, and pronounce it perfect, and it performs admirably.
Yours truly, (_Signed_.) Mr. G. CALVER.
* * * * *
_From_ JAMES L. MCCANCE, Esq., F.R.A.S.
PUTNEY HILL, S.W., _October 23rd, 1879_.
DEAR Mr. CALVER,—Weather and circumstances have been very unfavourable for doing much work with the 10 inch reflector since I got it from you. But with what I have seen with it I am very pleased; in good weather the views of the planets, Jupiter and his “Great Red Spot” especially, were grand. The mounting (equatorial) is quite satisfactory, and the movements work smoothly and well.
Yours very truly, (_Signed_.)
* * * * *
_From_ FRANK C. DENNETT, Esq.
10, TERMINUS TERRACE, SOUTHAMPTON, _July 11th, 1880_.
DEAR SIR,—It is a long time ago that you asked me to write and let you know how I liked the 9-1/2 in. I have not done so because I wished first to see what was to be made of the planets.