328 PROCEEDINGS OF THE SOCIETY. 



Professor Frederic J. Cheshire, C.B.E., F.Inst.P., F.R.M.S., 

 read a number of holograph letters written about 1876 by the late 

 Professor Abbe to J. W. Stephenson, on the subject of Abbe's diffrac- 

 tion theory of microscope vision ; and exhibitions of interference 

 and diffraction experiments were given by Mr. J. E. Barnard, Mr. J. 

 Rheinberg, Dr. Clay, Mr. H. Emsley, Mr. L. C. Martin, Mr. F. Harrison 

 Grlew, Mr. B. K. Johnson, and Professor Cheshire. Mr. Fredk. W. 

 Shurlock, B.A., B.Sc, F.Inst.P., Principal of the Derby Technical 

 College, exhibited in the form of lantern projections some of his 

 diffraction photographs. 



As the President had to leave at this stage, the Chair was occupied 

 by Mr. Earland and afterwards by Dr. Murray. 



Professor Rama, Mr. Rheinberg and Mr. Conrad Beck took part in 

 the discussion that ensued. 



A hearty vote of thanks was accorded to Professor Cheshire and to 

 those gentlemen who had assisted him with exhibits. 



Thanks were also accorded to Mr. H. C. Whitfield for his kindness 

 in operating the lantern. 



It was announced from the Chair that the next meeting would be 

 held on October 19, and that the Rooms would be closed for th& 

 Summer Vacation from August 15 to September 10 inclusive. 



The business proceedings then terminated. 



