Bausch & Lomb Optical Co., 
MANUFACTURERS OF \ ff 
The Leading American MICROSCOPES 
OBJECTIVES AND ACCESSORIES, 
Photographic Lenses, and other Optical Instruments. 
NEW PETROGRAPHICAL MICROSCOPE, 
Constructed by advice and assistance of Prof. George H. Williams, 
Johns Hopkins University. 
Complete Illustrated Catalogue on Application .. 
Factory and Main Office: 
531-543 North St. Paul Street, 
ROCHESTER, N. Y. 
Branch. Office : 
48 and 50 Maiden Lane * 
NEW YORK 
