SCIEN F 
NEw SERIES. SINGLE COPIES, 15 cTs. 
VoL. X. No. 237. FRIDAY, JULY 14, 1899. ANNUAL SUBSCRIPTION, $5.00 
WEEN _. 
IMPROVED STANDARDS 
Perfect Circulation and 1 f | Of 
i ==, © 
Uniform Temperature 50 O 
Guaranteed Accuracy 
1 f Write for Circular No. 494 
50 O O We are offering the above Standards 
at about half the usual price 
QUEEN & CO., inc. 
J. G. GRAY, President 
Electrical and Scientific Instrument Works 
9 Fifth A P 
; NEW YORK 1010 CHESTNUT ST., PHILADELPHIA 
