SCIENCE 



New Series 



Vol. LIU, No. 1377 



Friday. May 20. 1921 



Single Copies, 16 Cts. 

 Annual Subscription, 86.00 



BAUSCH & LOMB 

 Portable Balopticon 



Ipnal Miise^iJ^- 



Practical P ^^^uoility 

 without sacrifice of 

 Projection Efficiency 



New Model A 



THIS new Balopticon will be welcomed by every institute worker or traveling lecturer. It is 

 truly portable, yet has all the optical and mechanical features necessary to insure best pro- 

 jection results. The projection lens is our regular quality Balo lens; the lamp house accom- 

 modates a 400-watt Madza lamp, or special illuminant w^hen required, and condensers are of 

 full 4f\ inch diameter. 



The case, of leatheret-covered wood, is an integral part of the outfit, shutting off light flare 

 and serving as a supporting base for instrument in operation. The equipment is unusually well 

 balanced, making it very easy to carry. 



Write for booklet on this new Balopticon. 



gausch ^ Ipmb Optical ©. 



Neiv York 



552 St. Paul Street ROCHESTER, N. Y. 



Chicago Washington Saa Francisco London 



Leading American Makers of Photographic Lenses, Microscopes, Projection Apparaiui 

 {Balopticons), Ophthalmic Lenses and Instruments, Photomicrographic Apparatus, Rang* 

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

 Binoculars, Magnifiers, and other high-grade Optical Products 



