SCIENCE—ADVERTISEMENTS 
Spencer Microscopes 
Our entire output of Microscopes is 
temporarily taken by the Medical Divi- 
sions of the U.S. Government. Weare 
happy to thus dedicate our facilities to 
the winning of the war. 
Although unable to accept further 
orders just now for Compound Micro- 
scopes, we are able to supply a limited 
number of Microscope Accessories, 
Microtomes, Dissecting Instruments, 
etc. Information given on request. 
. SPENCER LENS COMPANY 
ald EUFFALO, N. Y. 
Northrup Alternating 
Current Galvanometer 
The “Detroit” 
Combination Gas Machine 
Automatically makes the best 
and cheapest gas for 
Laboratory Uses of Every Character 
Heating—Cooking—Lighting 
Over 30,000 in daily use 
Descriptioe catalogue and names of users in your 
locality sent on request 
Described in Circular No. 7 
i THE DETROIT HEATING & 
Pyrolectric Instrument Co, LIGHTING Co. 
148 E. State St. Trenton, N. J. 612 Wight St. Detroit, Mich. 
Established 1868 
