if 



SCIENCE 



New Series 



Vol. LA'I, Xo. Hd; 



Friday, Novembek 17, 1922 



Annual Wubsckiption, $6.00 

 Single Copiks, 15 Os. 



A Bausch & Lomb 

 BALOPTIGON 



Designed Especially for Schools 



riiHE Model BC Balopticon 

 -*- is an unusually practical 

 outfit for classrooms or me- 

 dium size school auditoriums, 

 as it can be used for long pro- 

 jection distances when neces- 

 sary. It is equipped with a 

 600-watt Mazda lamp, the 

 most powerful that can be at- 



tached to an ordinary lamp 

 socket, so that it can be used 

 where only regular current is 

 available. 



Operation is entirely au- 

 tomatic. The construction 

 throughout is of the same 

 high standard that character- 

 izes all Bausch & Lomb pro- 

 jection ap]3aratus. 



Bausch & Lomb Optical Company 



409 St. Paul Street, Rochester, N. Y. 



New York 



Washington 



Chicago 



San Francisco 



London 



Leading American Malters of Optical Measuring Instruments, Photomicrographic Apparatus. Photographi< 



Lenses, Microscopes, Projection Apparatus (Balopticons), Ophthalmic Lenses and Instruments. 



Range Finders and Gun-Sights for Army and Navy, Searchlight Reflectors, Stereo-Prism 



Binoculcirs, Telescopes, Magnifiers, Automobile Lenses and other High-Grade 



Optical Products. 



£=.. — that &es may see 



'er and fan 



