214 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
a “ Pocket Reflecting Microscope,” * an account of which was published 
in 1739.f 
In the library of the Society is a collection of B. Martin’s tracts 
(1765), in which an improvement of hiS" a Pocket Reflecting Microscope” 
is figured, pi. 2, fig. 13. This improvement consisted in prolonging the 
tube, and placing below the stage 
a mirror, capable of being inclined, 
for the purpose of illuminating 
transparent objects. Note that the 
term “ reflecting ” applies solely 
to the mirror used for the pur- 
pose of illuminating transparent 
objects, and does not imply that 
the instrument was on the cata- 
dioptric principle. 
Martin’s improved Microscope 
is now known as the drum-foot ; 
it is still made in France, and is 
occasionally to be seen in our 
toy shops. This form of Micro- 
scope was adopted by Fraun- 
hofer (1816)4 Oberhauser (1835, 
patented 1837), Lerebours (1838). 
Martin’s second improvement 
consisted in the adaptation of the 
Culpeper and Scarlet tripod foot, 
a form which has long since passed 
away. This is figured in his 
‘ Optical Essays,’ fig. 21, no date 
(bound up with liis tracts). 
The Microscope in fig. 46 is 
a later form of his drum Microscope, further improved by the addition 
of a rackwork coarse adjustment. This Microscope is neither signed nor 
dated. B. Martin died in 1782, and the instrument appears to bo of 
a much later date than that. The box contains a cut of the instrument, 
with a descriptive text, in which it is called Martin’s Microscope ; but 
it does not appear to be older than the first half of the present century. 
Early Form of Ross Microscope. — Messrs. Watson and Son have 
very generously presented an interesting and early form of a Ross 
Microscope to the Society (fig. 47). The Microscope is on the Lister 
model, fitted with a rack-and-pinion coarse, and a short-lever nose-piece 
fine adjustment, the fine adjustment screw being at the side, instead of 
in its usual position, the front of the body. 
The stage has rectangular mechanical movements, both being per- 
formed by rack-and-pinion, the heads of both the pinions being placed 
* This Microscope is figured in a book in the library of the Society, viz. ‘ A 
Treatise on the Microscope,’ by B. Martin, 1742, fig. 1 ; also in Journ. Queketfc Micr. 
Club, vii. (1898) p. 11, fig. 20. 
f For this date see ‘Adams on the Microscope,’ second edition, 1798, p. 21, foot- 
note. 
X For this date see ‘ Les Microscopes et de leur usage,’ 0. Chevalier, 1S39, R.M.S. 
library. 0 
Fig. 46. 
