PROCEEDINGS OF SOCIETIES. 
227 
printed in the next number of the Journal, and the Fellows would 
be able to read it before the next meeting, at which any discussion 
arising out of the subject could be taken. (The paper will be found 
printed at p. 186.) 
The paper was then taken as read, and a vote of thanks to the 
authors unanimously passed. 
The Secretary announced that in consequence of the large hall of 
the college being required for other purposes, the Society would in 
future hold its meetings in the library. The scientific evening would 
also be held in the library and adjoining suite of rooms on the 21st 
instant, and the Council hoped that as many as possible of the 
Fellows would bring their instruments and objects of interest on that 
occasion. 
The President, H. C. Sorby, Esq., F.RS., then read a paper " On 
some new contrivances for the study of the Spectra, and for applying 
the mode of Spectrum Analysis to the Microscope." He first exhibited 
and explained the apparatus used in his experiments and investi- 
gations, showing the new arrangement for employing an ordinary 
eye-piece in connection with a slit and prisms ; and also the c(m- 
struction of the binocular spectrum microscope, and the method of 
comparing the spectra of two objects in the field of that instrument. 
The importance of obtaining equal illumination in both spectra was 
pointed out, and the means of regulating the light was also described. 
The measurement of the position of absorption bands by means of the 
quartz interference scale, the spot method, and the wave-length 
method, were explained, and the relative advantages of each were set 
forth. After some interesting observations upon the meaning of the 
absorption bands and the variations produced in their positions by 
acid or alkaline additions to the same solutions, illustrations were 
given by means of coloured diagrams of a few remarkable spectra 
which had recently engaged the attention of the author, and he inti- 
mated his intention to exhibit and further explain the apparatus and 
objects at the forthcoming scientific evening. 
Mr. Slack having proposed a vote of thanks to the President for 
his paper, it was put to the meeting and carried unanimously. 
In consequence of the lateness of the hour the discussion upon the 
President's paper was postponed until the next meeting. (The paper 
will be found printed in extenso at p. 198.) 
Donations to the Library and Cabinet since March 3, 1875 : 
Nature. Weekly The Editor. 
AthenEeum. Weekly ,. Ditto. 
Society of Arts Journal. Weekly Society. 
Journal of the Quekett Club. No. 28 Club. 
Bulletin de la Societe Botanique de France Society. 
Eeport of the East Kent Natural History Society, for 1874 . . . . Ditto. 
Alfred Allen Esq., of Felsted, Essex, was elected a Fellow of the 
Society. 
Walter W. Eeeves, 
Assistant-Secretary . 
