22 
Transactions of the Society . 
The idea is not a new one, for it was suggested for micrometric pur- 
poses by Mr. Gr. Burch.* Without discussing the respective capa- 
bilities of that and the one now before you, I think you will admit 
that the new one is the simpler and less cumbersome of the two. 
My new camera merely consists of a small piece of common 
looking-glass, such as is used for the plane mirror of a Microscope, 
fixed at an angle of 45° to an eve-piece cap. This, when the Micro- 
scope is placed in a horizontal position, reflects the rays horizontally 
and at right angles to the optic axis; these rays then fall on a 
piece of neutral tint placed at an angle of 45° to these rays, so as to 
reflect them upwards to the eye. 
Fig. 1. 
The mirror corrects the transposition, and the neutral tint the 
inversion ; an erect image is therefore seen on the table. In other 
words, the image is precisely the same as the object on the stage of 
the Microscope. (But any one who possesses a right-angled prism 
and places it anywhere between the objective and the eye-piece — 
maintaining, of course, a horizontal position for the reflected ray — 
can use any ordinary Beale camera on the eye-piece.) 
The neutral tint is mounted on a pivot, so that it may be turned 
round through a right angle ; this i3 to adapt the instrument for use 
with either the right or left eye. Of course it would be simpler and 
cheaper to make it immovable, adapting it for the eye which the 
observer is in the habit of using. 
By this device the simplicity of the Beale’s neutral tint is main- 
tained, while the serious disadvantage spoken of above is removed. 
The rules for working this instrument are precisely the same as 
those for Beale’s neutral tint. The old caution, however, may as weil 
* Journ. Quek. Micr. Club, v. (1878) p. 47. 
