SCIENCE 



New Sebies 



Vol. XLVI. No. 1187 



Friday, September 28, 1917 



Single Copies, 15 Ctb. 

 Annual SuBaoKipriON, S5.00 



STEREO-PROJECTION 



The Ideal Illustrative Method — 



Stereopticon pictures that 

 have depth, reHef, solid- 

 ity — stereoscopic pic- 

 tures — can now be pro- 

 jected with our regular 

 BB Balopticon. The 



method is simple and practical; no special equipment 



is required other than the glass filters. 



One projection lens of the Balopticon has a red, the 

 other a green filter attached. The stereoscopic images 

 are projected on the screen approximately superim- 

 posed, one being red, the other green by virtue of the 

 filters. The observers wear green and red glasses in 

 spectacle frames, so that one eye sees the green, the 

 other the red image on the screen. The images fuse in 

 the brain to form one three-dimensional percept, as in 

 normal binocular vision. The colors being complemen- 

 tary, the resultant image is the ordinary monotone. 



Stereoscopic negatives for lantern slides can be made 

 with a regular stereoscopic view camera, or with a single 

 lens camera, bj^ shifting slightly between exposures. 

 BB Balopticon with lens filters, $71.00. Observers' 

 spectacles, $1.00 per pair. 



Write for special Circular 



Bausch ^ Ipmb Optical (o. 



552 ST. PAUL STREET ROCHESTER, N. Y. 



New York Washingrton Chicaso Sa.n Francisco 



Leading American Makers of Photographic Lenses, Microscopes, Projection Lanterns 

 (Balopticons) Stereo-Prism Binoculars and other High-Grade Optical Products 



GRAND PRIX— PANAMA-PACIFIC EXPOSITION 



