172 PROCEEDINGS OF SOCIETIES. 
instruments. The whole of the arrangements and preparations 
for the Soirée were under the superintendence of Mr. Blenkins, 
one of the Honorary Secretaries, and the company were received, 
on entering, by the President, James Glaisher, Esq., F.R.S.—Mr. 
Williams had charge of the ancient microscopes,’ including the 
large Martin microscope, the property of the Society. This 
collection excited much interest, as showing the gradual improve- 
ment and development of the instrument.—Mr. Wenham exhibited 
an improved form of binocular microscope for the highest powers, 
starting from the recent idea brought out by Messrs. Powell and 
Lealand of obtaining the whole aperture of the object-glass in 
each eye by means of the direct transmission and partial reflection 
from an inclined plate of glass placed behind the object-glass. It 
seems most desirable to increase, if possible, the quantity of hght 
in the reflected image, as when the disc of plate glass is inclined 
at an angle of 45° the quantity of light is less than jth part of 
the incident rays. Mr. Wenham has succeeded in effecting this 
by reducing the number of transmitting surfaces and obtaining 
the light in the inclined tube by means of two reflectors. A 
small prism is used, in form and size resembling the common 
binocular prism, but with the two reflecting surfaces more inclined, 
so as to be beyond the angle of total reflection. In contact with 
the first reflecting surface is another small triangular prism, 
whose upper plane is parallel with the base of the main prism ; the 
rays from the object-glass will then pass direct through without 
refraction, and the same rays are reflected from the two contact 
surfaces in the inclined body in the usual way. The arrangement 
nearly equalises the amount of light in each eye—Mr. Browning 
exhibited some of his now celebrated micro-spectroscopes, such 
as has been so successfully applied by Dr. Bird Herapath to the 
detection of blood-stains in the Ash murder case. Mr. Browning 
also exhibited some very beautiful, curious, and interesting 
spectra, among which we noticed Cochineal, Brazilwood, and, most 
curious of all, Sumach.—Mr. Conrad W. Cooke exhibited an in- 
strument designed by him, and to which he has given the name 
of “ Micrographic Camera;” one of the purposes for which it is 
intended, being to facilitate the figuring of microscopic objects to 
any desired scale. By this instrument an image (with perfect 
definition) can be thrown on a sheet of paper placed in a hori- 
zontal or slanting position, so that an uneducated eye can appre- 
ciate the form, and any one may trace the outlines and detail, 
with a fair amount of accuracy, on the paper. It is useful also 
for purposes of demonstration, for two or more persons may at 
the same time conveniently examine the image formed on the 
paper: this, for the explanation of minute organic structure to 
students and others, may be found of value. This instrument 
may be worked as well in an illuminated room as in a dark one, 
because the head of the observer is isolated from external light by 
means of a curtain which falls over the back of his chair. 
Measurement of the objects shown in this camera may very easily 
