ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
24] 
The focusing lens is adjusted over a glass square, on the underside 
of which is fixed a fragment of a fly’s wing, and the image produced in 
the Microscope is focused on the plane of the fly’s wing. The focusing 
lens and the glass square are then removed, and a sensitive plate is 
substituted, being covered by a small cap of obvious construction ; the 
incandescence lamp is then set in action as required, care being taken 
that no actinic light strikes the sensitive plate except during the 
required exposure in the Microscope. 
Roux’s Lantern for Photomicrography. — Dr. Roux has devised the 
lantern for photomicrography shown in flg. 27. 
A small ball of magnesia, 5-6 mm. in diameter, is placed in the 
lantern D, which is rendered incandescent by an oxy-hydrogen jet. A 
Fig. 27. 
condenser E concentrates the light on the stage G of the Microscope. 
Behind the ball is a mirror adjustable by the rod F. The screws at B 
and C enable the lantern to be centered vertically and horizontally. 
Care is required in heating the ball, which must be brought to 
1890. R 
