SCIENCE 



Niw SiKiu 



Vol. XLVII No. 1217 



Friday, April 26, 1918 



SiNOLB Copies, 16 Cts. 

 Annual Bubsokiptiom, tS.W 



^auscK |omb 



Microscopes 



1. OPTICS 



To produce a really good micro- 

 scope objective is one of the most 

 difficult tasks imaginable. It re- 

 quires skill and experience in equal 

 measure — mathematical skill to 

 compute the corrections and tech- 

 nical skill and skill of hand to re- 

 produce those corrections in the 

 ground and polished lenses. For 

 the mathematical skill we have drawn upon the universities of both the Old 

 and the New World. Our technical experience has been growing ever 

 since John J. Bausch built with his own hands the first power grinding 

 and polishing plant used in America. 



Bausch & Lomb objectives are true to focus and resolving power. The 

 corrections of these lenses are explained in our microscope catalog. You 

 require a good objective to do good work. See that your lenses have the 

 name Bausch & Lomb engraved on the mount. 



Bausch ^Ipmb Optical (o. 



409 ST. PAUL STREET ROCHESTER, N.X 



New York 



Washinfipton 



Chicaeo 



San Francisco 



Leading American Makers of Microscopes, Photomicrographic and Projection Apparatus 



(Balopticons), Photographic and Ophthalmic Lenses, Stereo-Prism Binoculars 



and Other High Grade Optical Products 



