SCIENCE 
NEW SERIEs. ‘SINGLE COPIES, 15 CTS. 
VoL. X. No. 256. FRipay, NOVEMBER 24, 1899. ANNUAL SUBSCRIPTION, $5.00 
TH REE ELE MENTS OF OUR SUCCESS 
Have been the three LENSES with which 
our most popular Microscopes are equipped 
‘oo > 
Li (unm ‘J 
% inch Objective. % 1nch Objective. zs inch Oil Immersion Objective. 
The 2-3 inch Objective possesses the large field, depth of focus, and 
high resolving 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. 
MERE aren icaatieaieace: N. St. Paul Street, ROCHESTER, N. Y. 
