otice to Reader.—When you finish reading 
this magazine, place a 1 cent stamp on this notice, 
mail the magazine, andit willbe placedin the 
hands of our soldiers or sailors destined to pro- 
ceed overseas. No wrapping—-No Address. As 
S. Burleson, Postmaster-General. 
SCIENCE 
New SERIES 1s S4 Co; |. 
Dee Sri took Fripay, Aucust 23, 1918 «Sree Ree dee Sees 00 
Bausch Jomb 
BALOPTICON 
THE PERFECT STEREOPTICON 
y 
: 
Invaluable for instruction and lecture work 
—an ideal projection lantern for class room, 
laboratory or auditorium. 
Models for either lantern 
slides or opaque objects 
(photo prints, post cards, 
specimens, etc.) or both. 
Equipped with the new gas- 
filled mazda lamp, absolutely 
automatic. More complete 
models for microscopical and 
Combined Balopticon . all known forms of optical 
projection. 
Because of the demands made upon our resources for some of the government’s 
most important military needs, we are unable to make Balopticon deliveries for 
the present. While proud to be of service in this world crisis, we shall expect 
to serve our other patrons even more efficiently than before, when the world is 
again at peace. 
Bausch €3 lomb Optical ©. 
552 ST. PAUL STREET ROCHESTER, N.Y. 
New York Washington Chicago San Francisco 
Leading American Makers of Microscopes, Projection Apparatus, (Balopticons), Photographic 
and Ophthalmic Lenses, Binoculars, Range Finders, Gun-Sights, Searchlight 
Reflectors, and other High-Grade Optical Products 
