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.