SCIENCE 



New Series 

 Vol.. LI, No. 1316 



Friday, March 19, 1920 



Single Copies, 15 Cts. 

 Anhuai, Suescbiption, $6.00 



The Royal Road 

 to the Mind 



'T'HERE may be "no royal road to learning' 

 but the path through the eye is certainly 

 shorter. Students reason first with their sight; 

 their judgment is actuated by the visual powers. 



Just consider, then, how invaluable the 

 BAUSCH & LOME BALOPTICON is in 

 classroom, laboratory and auditorium. Models 

 are made for showing either lantern slides or 

 opaque objects (photo prints, postcards, speci- 

 mens, etc.) or both. 



The Balopticon "speeds up" im- 

 pression making and makes it ever- 

 lasting. The name of the maker 

 is your guarantee of long thorough 

 service. 



BAUSCH & LOME OPTICAL CO. 



New York 

 Chicago 



Washington 

 ROCHESTER, N. Y. 



San Francisco 

 London 



Leading American Makers of Photographic Lenses, Microscopes, Projection Ap- 

 paratus {Balopiicons) , OphthalnUc Lenses and Instruments, Photornicrograpkic Ap- 

 paratus, Range Finders and Gun Sights for Army and Navy, Searchlight Re- 

 jectors, Stereo-Prism Binoculars, Magnifiers and other High-Grade Opticat 

 Products, 



