Faithfully yours, (_Signed_.) Mr. G. CALVER.
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 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.
