170 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
as I can find no reference to these plates in the advertisement-sheets of 
the Almanac, I have not been able to put them to practical trial. 
To shut off the light preparatory to exposing, I employ simply a 
piece of black velvet gummed on to a visiting card, slipped on top of 
the ring that carries the Abbe condenser ; but it would be undoubtedly 
better to use a flap-shutter working inside the camera just behind the 
eye-piece ; as under all but the highest powers the object is more or 
less visible as an opaque object, after the light has been cut off from 
below ; and though the amount of light so thrown is too small to have 
much effect during the short time that elapses between drawing the 
shutter of the dark slide and exposing, it must have a certain more or 
less fogging effect, and should therefore be avoided by those who have 
sufficient micro work to set aside a camera specially for the purpose. 
As will be seen, the apparatus described need cost but little. 
Simple as it is, it may be further simplified by using a simple wooden 
upright, mortised into the base-board, to carry the camera. One misses 
the great convenience of being able to instantly swing the camera out 
of the way when changing objects and focusing ; but, apart from the 
delay involved in having to unscrew and replace the camera on such 
occasions, such an appliance is quite as efficient as that first described, 
aud reduces the cost of the appliance required to connect one’s camera 
and Microscope to a few pence. 
Many biologists are unhandy with their pencils, and, looking upon 
“ micro ” work as a particularly recondite branch of photography, are 
debarred from employing this means of illustrating their observations. 
If a few such can be induced to discover how simple a matter photo- 
graphic recording can be made, I believe the space I have occupied in 
the Journal will not be wasted. 
Photomicrographs.* — Dr. J. Eismond discusses the pros and cons in 
regard to photomicrographs. He suggests a compromise between them 
and drawings. A faint copy of the negative is taken on platinum paper 
or the like ; and this is touched up with ink, pencil, or colours, so as to 
differentiate any particular structure. 
A Simple Arrangement for taking Slightly Enlarged Stereoscopic 
Photographs.-]- — Dr. W. Gebhart points out that with an ordinary 
stereoscopic camera, in which the two objectives are fixed at only a small 
distance apart, the object cannot be brought close enough to the camera 
to produce an enlarged picture ; this could be done by using two cameras 
having their axes converging to the object, or by moving one camera 
into two positions about a vertical axis passing through the object. In 
the majority of cases (except, for example, with a polished sphere) the 
same result would be obtained if the camera remained fixed and the 
object be turned through a small angle. For this purpose the object is 
placed at the centre of a wooden disc, which can be turned about a 
vertical axis, through the required angle, this angle, of 6-15°, depending 
on the distance of the camera, being indicated by graduations on the 
disc and an index-pointer. 
* Eiol. Centralbl., xvi. (189(5) pp. 864-5. 
f Zeitschr. f. wiss. Mikr., xiii. (1896) pp. 419-23 (1 fig.). 
