Pa ENCE 
SINGLE Copi&s, 15 cts, 
ANNUAL SUBSCRIPTION, $5.00 
THREE ELEMENTS ex ovr success 
Have been the three LENSES with which 
our most popular Microscopes are equipped 
NEw SERIES. 
VoL. XIII. No. 317. FRIDAY, JANUARY D5), 1901. 
al 
=e 
% inch Objective % inch Objective. yz inch Oil Immersion Objective. 
The 2=3 inch Objective possesses the large field, depth of focus, and 
high resolying power which make a low-power lens desirable. 
The 1=6 has remarkable working distance, making it especially adapted 
to general laboratory work, and at the same time resolving, magnifying, and 
illuminating power equal to the best. 
The 1-12 inch Oil Immersion has so many excellent features that 
only a trial can demonstrate them. Unusually long working distance, ex- 
treme flatness of field, high resolving power, and absolute permanency of the 
materials of construction are a few of the good qualities. Our method of 
mounting the delicate hemispherical front lens secures the greatest possible 
permanency and the least lability to leakage. 
Bausch & Lomb Optical Co. 
NEW YORK and CHICAGO N. St. Paul Street, ROCHESTER, N. Y. 
