570 PROCEEDINGS OF THE SOCIETY. 



small thickness. But they led to some very distinct indications about 

 the question which he (Dr. Czapski) believed to be the most interesting : 

 the correctness of microscopical vision under the various circumstances 

 and the factors upon which this correctness depended. He (Dr. Czapski) 

 could not go further into the matter then, and regretted that his com- 

 mand of the English language was not sufficient to enable him to 

 express himself as clearly as could be wished, but he should like to 

 have an opportunity at some future time of returning to the subject 

 and of bringing some objects in illustration. 



Mr. E. M. Nelson gave a brief abstract of his paper on "Micro- 

 metry," showing that the size of the antipoint had to be allowed for, 

 especially in the measurement of minute objects, otherwise an error 

 might be introduced that sometimes amounted to over 100 p.c. 



The following papers were, owing to the lateness of the hour, taken 

 as read : — " On the ' Lag ' in Microscopic Vision " (continued) ; " An 

 Improved Horse-shoe Stage " ; "A Micrometric Correction for Minute 

 Objects " ; and " An old Non-achromatic Simple Microscope," by Mr. E. 

 M. Nelson. " A Method of Mounting Bacteria from Fluid Media," by 

 Mr. J. A. Hill. 



The Chairman said they were greatly indebted to Lord Rayleigh, 

 Dr. Siedentopf, and Mr. Nelson for the very interesting papers read, 

 and to the visitors and Members for the learned remarks made in the 

 discussion on the subject. He also emphasised their indebtedness to 

 the firm of Messrs. Carl Zeiss for sending to England for their inspec- 

 tion the valuable apparatus by which the results of Dr. Siedentopf's 

 investigations and discoveries had been demonstrated to the Fellows. 



The thanks of the Meeting were then very heartily voted to the 

 gentlemen referred to. 



The Meeting was then adjourned to October 21st, and it was 

 announced that the Society's Rooms would be closed from August 14th 

 to September 14th. 



New Fellows. — The following were elected Ordinary Fellows : — 

 Messrs. Alfred Chaston Chapman, Raymond B. Fitz-Randolph, and 

 Jas. Wm. Johnson. 



The following Objects, Instruments, &c, were exhibited : — 



The Society : — An old Non-achromatic Simple Microscope, pre- 

 sented by Mr. E. M. Nelson. Two Micrometers, one ruled with lines 

 T ^u in. apart, and the other ruled with lines 5 -J-g- in. apart, presented by 

 Mr. E. M. Nelson. 



Mr. F. "VV. "Watson Baker for Messrs. "Wm. Watson & Sons : — A 

 new Portable Microscope ; and a new Mechanical Stage. 



Mr. Conrad Beck : — Sir Wm. Crookes' Spinthariscope. 



Dr. J. Charlton Briscoe : — A new Portable Microscope. 



