ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
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geological purposes. The foot and column are east in one piece, so 
that the instrument can safely be held and carried by the upper portion. 
Roberval’s micrometer-screw is used for the fine adjustment, this being 
an advantage in small, though not in large, stands. The usual acces- 
sories for parallel and convergent polarised light are added. 
Method of Using the Microscope.* — Mr. N. A. Cobb describes, in 
the following terms, an apparatus which he has found useful in the 
application of the Microscope to agricultural inquiries: — 
“ The apparatus I have to describe has been so very useful to me 
that I cannot but think it will be also useful to others in this and other 
countries, engaged as I am on the various scientific problems presented 
by agriculture ; and if it turns out useful to them, even the farmer, who 
looks upon this technical article as of no service to him, will — whether 
he knows it or not— be indirectly benefited. 
“ This method of mounting and using a Microscope is one that has 
been gradually perfected through almost daily use since 1888. I have 
frequently been asked to publish the details, and have so far refrained 
from doing so only because I found that on each new Microscope mounted 
I was enabled to make a number of improvements ; and so long as this 
was the case, any description would soon be antiquated, and so become — 
to me, at least — only a source of annoyance. On no less than ten 
separate occasions has this device been remodelled to suit differing cir- 
cumstances, and it now stands in five laboratories under my supervision, 
viz. Sydney, Moss Yale, Wagga, Bathurst, and Pymble. 
“ The following is a key to the illustration (fig. 34) 
a a a, architrave of a window facing the sun. 
bbb, 1/4-in. runners, 4 in. wide, in which the blind d slides. 
c c, runners for the arm j, which carries the camera m. 
d , perfectly opaque blind, made of American leather or enamelled cloth 
running on a spring roller at the top of the window. By raising this 
blind the whole apparatus may be flooded with sunlight if necessary. 
e, a 1/4-in. board, 8 in. wide, hanging in an inch-deep slot in the board/, 
and riveted to the blind d, and hence rising and lowering with the 
blind. This board e slides in the runners bbb. 
f f, an inch board, 8 in. wide, fitted to the side of the window and receiving 
the board e, into a median slot 1/4 in. -wide, and 1 in. deep in its 
upper edge. 
{/, two sliding pieces of thin ebonite, placed one behind the other, each with a 
diamond-shaped opening cut out in the middle. By sliding these 
ebonite shutters, the opening h can be made of various sizes. 
i i, the runners in which the two ebonites g slide. Behind the ebonites an 
elongated opening is cut in the board e , and this opening has a ground 
glass sliding over it in runners similar to ii, but fastened to the back 
side of e. All these latter appliances are for the purpose of varying 
the amount and character of the light coming through the diamond- 
shaped opening h. 
j , wooden arm,. 1 in. thick and 3 in. wide, carrying the micro-camera m, and 
sliding in the ways c c, capable of being clamped by the set-screws w. 
Any position of j may be recorded by means of scales marked on c c. 
7;, photographic plate-holder, half-plate size, as used on an ordinary tripod 
camera. 
7, frame iuto which the slide It is pushed, in construction similar to the back 
of an ordinary tripod camera. 
in, leather bellows of micro-camera, capable of extension to four or five feet. 
* Reprint from Agric. Gaz. N.S. Wales, March 1897. 
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