/ 
60 Tue MICROSCOPE. 
that would show but “four moons belonging to Jupiter, while 
a friend of his owned one that would show eleven.” Let us 
have plenty of questions and plenty of answers. The lady de- 
siring to know about the “tube cast,” was enlightened, while 
the other parties probably do not know, to this day, that they 
made f. s of themselves in trying to show their wisdom, 
Something in regard to the programme will be given soon. 
——ao >. 
SMALL PHOTO-MICROGRAPHIC CAMERA. 
BY FREDERICK W. MERCER, M. D., F. R. M.S. 
AS introductory argument in favor of photo-micrography is 
unnecessary, as the science has received such general re- 
cognition, that it only remains to point to changes and improve- 
ments in apparatus, and leave the rest to the observer. 
The little instrument illustrated here, was described in the 
Journal of the Royal Microscopical Society, and is now intro- 
duced to the notice of your readers, because a description of it 
has not appeared in any American periodical devoted to mi- 
croscopy. Since first described this camera has been quite thor- 
oughly tested by a number of competent workers; their favor- 
able judgment, and frequent inquiry from others as to its ma- 
nipulation, has made it seem that some general answer in this 
way might be gratified. 
The camera is made by several manufactures of photo- 
graphic apparatus, in this country, chiefly by the Blair Co., and 
the Scoville Co. It is made to take plates 22x34, or 5}x44. 
The former sized plate is the one most generally adopted, and 
should be of extra thin glass as supplied by Mr. Corbett, of 
Philadelphia, Lantern slide 34x44 can be made directly from 
these. 
The whole apparatus is exceedingly portable; measuring, 
with draw-tube inverted, 44x44x 9 inches. It can be attached 
to and used with the microscope in any position, but a few 
minutes time being necessary for its adjustment. It is in- 
tended for use with eye-piece or amplifier; it can, however, 
be used without either. The small negative made by this 
camera can be enlarged without perseptible deterioration. 
