438 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
ments, placed outside in tlie sunlight, and workable from the interior by 
means of cords and pulleys. The screen is a broad frame covered with 
bleached sheeting. On one end of the screen is a small mirror, so 
fastened as to indicate, by the sun’s reflection, when the screen is re- 
flecting the maximum amount of sunlight. This light reflected from the 
screen is superior to the proverbial white cloud, and eclipses any artificial 
light. 
“ I feel sure that, in the right hands, the appliances I have here de- 
scribed, if patented, could be made a source of profit ; and the moral right 
to so use them is hereby freely given to whomsoever chooses to accept. 
“ It is with much pleasure that I acknowledge the aid, during the 
last few years, of Mr. E. M. Grosse in executing a number of the details 
of this system of using the Microscope. The accompanying illustrations 
are from his hand.” 
(3) Illuminating' and other Apparatus. 
Projection Lantern.*— M. H. Mohlenbruck describes an ordinary 
form of projection lantern for showing microscopic preparations and 
photographs. 
Light-Filters and Colour-Screens. | — Dr. A. C. Stokes points out 
the unsatisfactory nature of the ordinary coloured glasses and fluid-cells. 
The best he has used is Clifford’s malachite-green screen, but for con- 
tinual use the light of this is trying to the eyes. For general use the 
author has a particular kind of blue glass (from Lovibond’s tintometer) 
coated with a layer of “Walpole green” cement; this is pleasanter to 
the eyes, but does not give so good a definition as the Clifford screen. 
Simple Machine for Micrometer Rulings.} — Mr. D. W. .Smith has 
devised a simple inexpensive machine for producing fine rulings, up to 
Fig. 37. 
thirty or forty thousand to the inch, on glass. The micrometer-screw A 
(fig. 37), with graduated head E, imparts a longitudinal motion to a 
metal wedge B, which, for each turn of the screw, gives a lateral motion 
* Arch. Sci. Pliys. et Nat., iii. (1897) pp. 590-3. 
f Journ. New York Micr. Soc., xiii. (1897) pp. 5G-63. 
X Tom. cit., pp. 53-5 (1 fig.). 
