532 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
cod cave perforated mirror could be slid into a notch in the lower face 
of the ring. The details are shown in separate cuts : o in the left-hand 
lowest cut is the lens. There was no eye-piece, the length of the tube 
being merely a guide for the position of the observer’s eye. 
The lamp and stand, depicted in fig. 129, appear to have been 
Kusswurm’s idea, although (as he admits) the glass globe filled with 
water was adapted from the method of Hooke (1660). 
The date of the letter in which Russwurm sends the drawings of his 
Microscope to Lederm filler is December 5, 1761. 
Adams’ Compendious Pocket Microscope. — The cut of this old 
Microscope (fig. 130) is copied from the ‘ Micrographia Illustrata ’ by 
G. Adams, 4th edition, 1771. It is interesting to note that this is the 
model to which Beni. Martin added his improvements in 1776.* It will 
Fig. 128. 
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be observed that both have folding tripod feet ; both have compass joints 
at their bases for inclination ; both are body focussers by rack-and- 
pinion ; both have body movements over the stage by lateral swing in 
arc and sliding bar, after the plan of Ellis’ Aquatic Microscope (made 
by Cuff in 1755). Adams calls this Microscope an abridgment of his 
Variable Microscope ; now this Variable Microscope, which was first 
described in this same edition of the 1 Micrographia,’ was, we are told 
by Adams, designed by a nobleman who did not wish his name to be 
published ; and as this Variable Microscope more nearly conforms to 
the Microscopes of the present day than any of those preceding it, 
microscopists ought to be much indebted to this anonymous nobleman 
for the form of the instruments they now use. 
The main alteration that we find in the Compendious Pocket Micro- 
scope is a radical one, and consists in the transference of the compass 
* See this Journal, ante, p. 326, fig. 73. 
