ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
2(33 
Laving a shutter, with a continuously intermittent release, each move- 
ment of which simultaneously caused a circular sensitive plate to 
advance by a sector. Of this camera only the shutter in the front of 
the apparatus was retained. This was fixed to the plate of a camera 
similar to that described in (1). The two special slides designed by the 
author have a clockwork movement. The one for use with a glass 
sensitive plate consists of a rectangular box 20 cm. by 20 cm. and 5 cm. 
deep. At the centre of the box is a metal wheel, put in motion by a 
clockwork arrangement at the back of the slide, which is provided with 
an escapement pneumatically regulated. In the metal wheel are fixed 
the sensitive plates, of the same size as those used in the Stirn camera. 
This part of the slide is protected from light by a screen, which is placed 
on a frame in such a way as not to interfere with the movement of the 
wheel. The screen is pierced with a circular aperture of 5 cm., placed 
in a line with the aperture of the shutter. The focusing is effected 
either by Moitessier’s method, or by the substitution of a ground glass 
for the slide. When the slide has been placed in position, the finder, 
previously described, is fixed by a screw* tube in the shutter. As 
soon as focusing is finished, the slide is charged with the sensitive plate, 
and successive photographs are taken of the movements of the object on 
the stage, while it is kept under observation the whole time with the 
finder. The disadvantage of this slide is that with it only a very limited 
number of proofs can be obtained. The apparatus devised by the author 
to remedy this defect can give theoretically 250 impressions of 9 cm. by 
9 cm. in a minute. This second slide is a modified form of that of East- 
man.* A band of very sensitive negative paper is rolled in turn on two 
cylinders. A powerful clockwork arrangement placed at the top of the 
slide effects the movement of the sensitive paper. A lever, pneumatically 
regulated by a caoutchouc ball, communicates with the spring which sets 
the clockwork in motion. The rest of the apparatus is in all respects 
similar to that first described. 
The first of the two slides was constructed at Milan by Mr. Oscar 
Pettozzi, and the second at Genoa by Mr. Ettore Guelfi. 
New Flash-light for Photography, j — Dr. Thomas Taylor made an 
exhibition of his new discovery before the Washington Chemical Society, 
which, it is believed, will supersede several now in use for photographing 
at night. The composition consists largely of charcoal made from the 
silky down of the milk- weed — a form of carbon which he prefers to all 
others, because of its freedom from ash. A few grains being placed on 
tissue paper and ignited by a punk match, produces a prompt and 
blinding flash, while it was observed that the paper on which the powder 
rested was not even scorched, thus demonstrating the greater security 
from accidents. 
Notes on Photomicrographic Prints exhibited at Meeting of 
R.M.S. on 19th November, 1890. — Mr. A. Pringle writes as follows 
regarding the remarks made on his prints by Dr. Dallinger and 
Mr. E. M. Nelson. J 
(1) Photographs of B. termo . — Mr. G. F. Dowdeswell, F.R.M.S., is 
* M. A. Londe’s ‘ La Photographie Moderne,’ 1888, p. 22. 
t Microscope, x. (1890) p. 190. \ See this Journal, 1890, pp. 836 -7. 
