SCIENCE 



N«w 8KBIM FrtfiAV NnVFMRB-n 9^ 1Q17 Single Copiki, 15Ct8. 



V0L.XLVI. N0.1195 FRIDAY, IN OVEMBER /d, iyi^ annual Subsoeiption, 85.00 



Optical Efficiency 



THE SUPREME TEST of any optical 

 instrument lies in its lens components. 

 This is especially true of the microscope. 

 No matter how many elaborate styles and 

 devices may be introduced to influence 

 the buyer, the main question still persists, 

 How well can I see with this instrument ? 



Bausch & Lomb Microscopes predomin- 

 ate in the laboratories of the coimtry be- 

 cause Bausch & Lomb quality is an im- 

 varying quantity. 



" 8 reasons Why You Should Buy Bausch 

 & Lomb Microscopes " is a circular which 

 explains the design and construction of 

 our microscopes — with reasons. 



Write for it. 



Bausch ^\pmb Optical (5. 



552 ST. PAUL STREET ROCHESTER, N.Y, 



New York Washington Chlcaeo San Francisco 



Leading American Makers of Microscopes, Pholomicrographic and Projection Apparatus 



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



and other High Grade Optical Products. 



