ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
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giving the proper angle. A glass stage If by lj in. is adjustable in 
a groove near the top of the box, and can be replaced by a glass stage 
with cell, opal glass stage, or black glass stage, of the same size. 
Bausch and Lomb’s Educational Dissecting Microscope. — The 
popularity of this instrument has induced the makers to bring out an 
improved form (fig. 4). The base is of japanned metal, very heavy 
to secure stability. All other parts are heavily nickelled to prevent 
erosion by reagents. The stage is of large size, and the opening is 
provided with a glass disc. The lenses are carried by a metal arm 
movable about the stage, and are focussed by means of the knob shown 
at the side of the pillar, this method being entirely satisfactory for 
lenses of the powers used. Triplet, Coddington, or doublet lenses are 
supplied, but the two first are recommended on account of their superior 
defining power. 
Improved Stage Construction. — Messrs. Bausch and Lomb have 
been paying special attention to this part of the instrument, and con- 
sider that their new stages are exactly at light angles to the optical 
axis, perfectly rigid under manipulation, possess perfectly plane surfaces, 
and are not affected by reagents. The surfaces of all stages, except in 
the cheaper stands, are of hard rubber. The metal part of the stage is 
recessed and covered with beaded studs. The rubber is forced into 
this depression while in a plastic condition, and vulcanised in such a 
manner that not only a mechaiical but a chemical union takes place 
