ii SCIENCE—ADVERTISEMENTS 
Build up Your Projection Lantern for all Forms 
of Projection as You See Fit. This is 
a Possibility with 
Sag 
(Convertible) 
Bausch lomb 
Balopticons 
Convertible and Universal Medels 
They are constructed with a system of interchangeable parts which can 
be readily adjusted for the projection of lantern slides, opaque objects or fluid 
objects, also for microscopic, polariscopic or spectroscopic projection as desired. 
Pages from a book can be so projected as to be perfectly readable. Photo- 
graphs, engravings, maps and even solid objects can be shown in their true 
form and coloring with sharply margined fields. 
Years of experience have shown Bausch & Lomb Balopticons to be 
thoroughly practicable for all these forms of projection. 
Send for descriptive catalog 15 D. 
Bausch £7 lomb Optical ©. 
NEW YORK WASHINGTON CHICAGO SAN FRANCISCO 
LONDON ROCHESTER. NY. FRANKFORT 
