83 
when one’s attention is chiefly devoted to the careful adjust- 
ment of the apparatus connected with the telescope. 
The convenience of the plan adopted may be judged of by 
the fact that on the evening of the partial eclipse of the moon, 
the 4th October last, in four hours I succeeded with the help 
of two assistants in taking no less than twenty negatives, 
and the telescope was several times disturbed to oblige friends 
who desired to see the progress of the eclipse through the in- 
strument, but the apparatus was quickly re-adjusted, although 
possibly in some cases with slight loss of definition in the 
negative, through haste. At a previous meeting, I described 
how these negatives were made, but it may be interesting to 
refer to the fact that while the fifteenth of the series was 
taken the telescope was at rest. The clock had been discon- 
nected for re-adjustment and it was forgotten when the plate 
was ready for exposure, consequently the moon had moved 
partly off the plate, and the negative shows a portion only ; 
but the exposure was so short that the eye fails to detect any 
difference in the sharpness of this and the others, which were 
all taken when the clock had been watched and carefully 
regulated for the moon’s motion. This fact is, I thinh, of 
some interest, as it shows that about the time of full moon 
when the light is of the greatest intensity, pictures may he 
made with telescopes not equatorially mounted. 
My telescope is a refractor of five inches aperture and six 
feet focal length, giving an image of the moon averaging 
about eleven sixteenths of an inch in diameter. The actinic 
focus is one tenth of an inch longer than the visual. The 
object glass is of Munich manufacture, and is mounted by 
Mr. Dancer on the Sisson’s or English plan with double 
polar axis. The hour circle is twenty-six inches in diameter, 
and is used also as the driving wheel, having teeth cut in the 
edge, in which a screw works connected with the driving 
clock by a rod, and which can be instantly disconnected 
by means of a cam. The object glass is an excellent 
one, and the mounting is everything that can be desired. 
