120 



PROCEEDINGS OF THE SOCIETY. 



MEETING 



Held on the 21st of Decembee, 1904, at 20 Hanover Square, W. 

 G. C. Karop, Esq., M.R.C.S., m the Chair. 



The Minutes of the Meeting of the 16th of November, 1904, were 

 read and confirmed, and were signed by the Chairman. 



The List of Donations to the Society since the last Meeting,. 

 exclusive of exchanges and reprints, was read, and the thanks of the 

 Society were voted to the donors : 



George C. Whipple, Eeport of the Commission on Additional Water I 



Supply for the City of New York. Appendix VI. Chemistry and> The Author. 

 Biology. (No date) J 



Records of the Egyptian Government School of Medicine. Vol. II. \ mj, n- / 

 Edited by the Director. (4 to, Cairo, 1904) j i ne director 



The Chairman said that, in consideration of the atmospheric condi- 

 tions existing that evening, and the consequent difficulty which the 

 Fellows might experience in reaching their homes, the Council had 

 decided that any discussion which might arise on the paper to be read, 

 should not be protracted beyond half -past nine. 



Mr. A. E. Conrady read a short paper on an experiment shown in 

 the room by means of Abbe's Demonstration Microscope, which proved 

 by a change in the apparent -position of the lines of a grating brought 

 about by changing from direct to dark-ground illumination, that two. 

 successive spectra from that grating were opposed to each other in 

 phase, as he had predicted theoretically in his paper read at the 

 November meeting of the Society. He thought this conclusively 

 showed that correctly worked out deductions from the undulatory theory 

 could always be depended upon to be borne out by experiment. 



Mr. Rheinberg said he was profoundly impressed by the way in 

 which the points referred to had been brought out in this paper. He 

 '.oil been present when the experiment proposed by Mr. Conrady was. 

 made, and it w T as quite startling to see how exactly his prediction had 

 been verified, and how by the mere shifting of a diaphragm they could 

 make the image of one set of alternate black and white lines shift its. 

 position, whilst another nearly similar set — in view at the same time— 



