104 THE AMERICAN MONTHLY [Apr 
Notes on Microscopy. 
F. SHILLINGTON SCALES, F.R.M.S. 
Royal MrcrRoscoPicaAL Socir—ETy.—On November 21st, 
Mr. Wm. Carruthers, F.R.S., President, in the Chair. 
Mr. Nelson exhibited and described an erect-image dis- 
secting microscope by Leitz, sent for exhibition by Mr. 
Baker. The erection of the microscope image, effected by 
means of Porro prisms, was first described by Behrens 
in the Journal of the Society in 1888. This instrument 
was valuable as a dissecting microscope ;it was provided 
with hand-rests and three objectives having a very long © 
working distance. Mr. Disney exhibited a diffraction plate, 
having the lines ruied in concentric circles, by which the 
diffraction bands were separated with great clearness. 
The rulings were about 7,000 to the inch. He also exhib- 
ited a steel brooch, the surface of which had been ruled 
in the same way. The method by which the lines were 
produced was at present a secret. The articles were of 
English manufacture, and had been lent to him by Messrs. 
Townson and Mercer. Mr. C. F. Rousselet exhibited an 
electric lamp for use with the microscope. After six 
months’ trial he had found it very satisfactory for work 
with low and medium powers. It was manufactured by . 
Edison Swan Co., and was called the “Focus” lamp. The 
President called attention to the exhibition that evening 
of a number of slides from the Society’s cabinet, prepared 
by the late Dr. Carpenter in connection with bis investi- 
gations into the shells of the mollusca. Mr. B. B. Wood- 
ward, who has given much attention to this subject, had 
also brought down some valuable preparations for exhi- 
bition. Mr. Vezey, at the request of the President, read 
a short abstract, copied from the Report of the British 
Association for 1846, which was a resume of the original 
/ communication on shel] structure made to that Associa- 
tion by the late Dr. Carpenter, to illustrate which the 
