' 7 



SCIENCE 



New Series. 

 Vol. IX. No. 228. 



TTdtti 4v lVr4v19 1 ^QQ Single Copies, 15 CTS. 



X'itiUAY, iVXAl J-Z,, i.ouj. Annual SuBscEipTioN, $6.00 



Queen Engineering Instruments 



Transits 



Levels 



Complete Catalogue of Engineering and Mathematical Instruments sent on Application. 



59 Fifth Avenue 



NEW YORK 



QUEEN & CO., INC. 



Optical and Scientific Instrument Works 



1010 Chestnut St.. Philadelphia 



