40 
MECHANICAL PORTION OF THE MICROSCOPE. 
attached by a bayonet joint, and can be removed to allow of 
packing in a convenient case. Polarizing apparatus and other 
accessories, are furnished to order with this instrument. 
57. A more complete Inverted HIicro§cope is mounted 
on a revolving foot, has coarse and fine adjustments of focus, 
a stage movable by a lever, and a column with rack and pinion 
movement to carry either the illuminator, polarizing apparatus, 
or oblique condenser. It can be furnished with all the accesso- 
ries supplied with other instruments. 
The especial use of the inverted microscope is for investigation 
of chemical substances, but it also afibrds advantages in exam- 
ining all objects contained in fluids, for however deep the cell, 
the object lying at the bottom is seen as though mounted in the 
shallowest cell. By this instrument small insects, animalculse 
and infusorise, as Desmidise and Diatomaceae are viewed from 
their under surface, which often materially aids in investigating 
their structure. 
58. OBJECT-OliASSE§. Our achromatic object-glasses 
range from 2 inch to ^^2 i^ch focus, with magnifying powers 
varying from 20 to over 1600 diameters, which may be in- 
creased, by extending the draw-tube of the microscope, to 2000 
diameters. A table containing a list of our objectives, with 
the angular aperture and magnifying power of each, with 
the different eye-pieces, will be found in connection with the 
Price List at the end of this Catalogue. 
To suit the requirements of different observers, we furnish two 
classes of achromatic objectives. Our objectives of the First 
Class have very large angular aperture, with the most perfect cor- 
rection of spherical and chromatic aberration, and are mounted 
in the best manner, and in the most improved style, and are at- 
tached to the microscope with a bayonet join t."^ The-|, J, J, and 
^ inch objectives of this class are furnished with Mr. Wenham’s 
form of adjustment for correcting the aberration produced by 
* Our objectives will be attached to the microscope by a screw, for those who 
prefer that mode of attachment. 
J. & W. GRUNOW & GO’S ILLUSTRATED 
