332 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
MICROSCOPY. 
A. Instruments, Accessories, &c.* 
(1) Stands. 
Evolution of the Microscope.t — Mr. E. M. Nelson, on behalf of 
a sub-committee of the Quekett Microscopical Club, proposes in a 
series of articles : — (a) to investigate a good type of instrument ; ( b ) to 
give a study of modern instruments, showing wherein, and why, they 
either follow or depart from the selected type; (c) to collate the other 
material bearing on the development of modern Microscopes, though not 
falling within the limits of a and b. For the type, Powell’s No. 1 is to 
be taken, since to this the best modern Microscopes are more and more 
conforming ; and, as it has remained 
Fig. 21. in its present form for upwards of 
twenty years, it is a permanent type. 
In the present paper several old 
forms, which are of importance in 
the evolution of the Microscope, and 
which have probably influenced the 
design of Powell’s No. 1, are de- 
scribed. Figures are given of the 
instruments of Jansen (about 1660), 
Descartes (1637), Hooke (1665), 
Divini (1667), Cherubin d’Orleans 
(1671), Bonanni (1691), Hartsoeker 
(1694), and John Marshall (1704). 
Of importance are Hooke’s, Bon- 
anni’s, and Marshall’s. 
Simple Microscope for Direct 
Observation and for Photography.^ 
• — Herr C. Leiss describes the in- 
strument shown in fig. 21, which is 
made by Fuess. The arm o, sup- 
porting the lens, is rigidly fixed to 
the foot, and the stage and mirror 
are made movable. Above the lens 
the small camera T may be fixed by 
the screw S. For direct observation, 
and for photographs which need not 
be very sharp, ordinary Steinlieil 
lenses are used ; but for better photographic work, two photographic 
objectives of 41 and 25 mm. focus are supplied; these fit into the arm o. 
* This subdivision contains (1) Stands; (2) Eye-pieces and Objectives; (3) Illu- 
minating and other Apparatus; (4) Photomicrography; (5) Microscopical Optics 
and Manipulation ; (6) Miscellaneous. 
t Journ. Quekett Micr. Club, vi. (1897) pp. 349-56 (9 figs.). 
X Zeitschr. f. angew. Mikr., iii. (1897) pp. 39-40 (1 fig.). 
