PROCEEDINGS OF SOCIETIES. 
273 
Since the doctrine in view will prove more valid than Dr. Eoyston- 
Pigott now seems inclined to concede, and in future, I think, will be 
considered as of some importance in the theory of optical instruments, 
many readers of the ' Monthly Microscopical Journal ' will take in- 
terest in a clear statement of its origin. On that account I hope you 
will grant a place in your Journal to these remarks, and thereby induce 
Dr. Koyston-Pigott to reveal his knowledge of the hitherto unknown 
writings of Lagrange he refers to, in kindly naming paper and page, 
where Lagrange has applied the wave-principle to the problems of 
vision, — has investigated the dioptrical performance of high-angled 
systems,— and has advanced the principles from which the formula 
quoted could be derived. 
I am, Sir, yours obediently. 
Dr. Ernst Abbe. 
PliOCEEDINGS OF SOCIETIES. 
KoYAL Microscopical Society. 
King's College, October 4, 1876. 
H. C. Sorby, Esq., E.E.S., President, in the chair. 
The minutes of the preceding meeting were read and confirmed. 
A list of presents to the Society was read, and the thanks of the 
meeting were voted to the donors. 
A paper was read by Mr. Thomas Palmer, " On a New Method of 
Measuring and Eecording the Bands in Spectra," the subject being 
illustrated by drawings placed in the hands of the President, and by 
the exhibition of the apparatus described, showing the application of 
the micrometer scale to the spectrum of a solution of nitrate of 
didymium. (The paper will appear in our next number.) 
The President proposed a vote of thanks to Mr. Palmer, which was 
carried unanimously. He expressed the pleasure which he felt at 
finding that some further attention was being given to this subject, 
and thought he need hardly say that he had listened to the paper 
with very great interest. There were a number of points in it which 
were worthy of notice, and he could not help saying that he was 
exceedingly pleased that Mr. Palmer had seen the desirability of 
reducing his measurements to wave-lengths. He judged, from the 
descriptions given, that the scale would have to be altered if a dif- 
ferent prism were used, and asked Mr. Palmer if that were not so. 
Mr. Palmer said that of course the actual measurements would 
only apply to the same prism, or to one with the same refractive 
index. 
The President said it appeared to him that in every case they 
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