BL ENCE 
NEw & SINGLE CoPiEs, ; 
Vou. XIIL No. 819. Fray, Fepruary 8, 1901. Annaanceese nes eon $5.00. 
Queen Instruments 
Lummer Brodhun punt onctee Screen 
An indispensable accessory when accurate photometric work is done. 
The QUEEN form excels all others in: 
REVERSIBILITY 
ACCURACY OF ADJUSTMENT 
SIMPLICITY OF CONSTRUCTION 
GENERAL FINISH 
We are the only makers who guarantee their Lummer Brodhun Screens to reverse within 3 mm. 
INDUCTION COILS PHOTOMETERS X-RAY TUBES 
PHYSICAL AND ELECTRICAL APPARATUS 
QUEEN & CO., INc. 
. GRAY, President 
1010 CHESTNUT STREET, 
59 Fifth Avenue, New York PH | LADELPH IA 
480 Monon Bldg., Chicago 
