SCIENCE 



AUG 2.3 ig 



New Series 

 Vol. LII, No. 1338 



Friday, August 20, 1920 



If _^, Single Copies, 15 Cts. 



Annual "jubscription, $6.00 



The First of the 

 Five Senses 



is sight — and it is the result of first impressions received 

 through the eye that there is implanted in student and 

 adult alike the desire for further knowledge. 

 That this desire may be the more readily created and fos- 

 tered, many schools, colleges and societies are using the 



Bausch"[omb 



BALOPTICON 



THE PERFECT STEREOPTICON 



The Balopticon is invalualjle for classroom, laboratory 

 and auditorium. Models are made for showing either 

 lantern slides or opaque objects, or both — photo prints, 

 •post cards, specimens, etc. 



The Balopticon " speeds up " impressions and 

 makes them everlasting. The name of the 

 maker assures the quality and length of the 

 Balopticon's service. 



Bausch ^ Ipmb Optical ©. 



552 ST. PAUL STREET 



ROCHESTER, N. Y. 



Leading American Makers of Photographic Lenses, Microscopes, Projection Apparatus 

 (Balopticons), Ophthalmic Lenses arid Instruments, Phoiomicrographic Apparatus, Range 

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

 Binoculars, Magnifiers and other High-Grade Optical Products. 



