I f OH 10 



SCIENCE 



Friday, March 4, 1898. 



Single Copies, 15 cts. 

 Annual Suesceiption, $5.00. 



General Electric Co.s 



FLUOROSCOPES 



Platino=cyanide of Barium, or Tungstate of Calcium Screens. 



NEW X=RAY TUBE 



EFFICIENT. 



WITH AUTOMATIC 



VACUUM REGULATOR. 



LONG-LIVED. 



ROENTGEN RAY APPARATUS of all kinds. 



Catalogue No. 9050. 



Candelabra, Miniature and Decorative Lamps. 



Catalogrue No. 9044. 



EOlsoii Decorative U piiQlalure Lamp oepartineiit, 



(GENERAL ELECTRIC COMPANY,) 



HARRISON, N. J. 



Minerals. 



VAKISCITE and WAKDITE, 60 cents to S2. VTVIANITE, Mul- 

 lica Hill. N. J., good specimens, 2.5 cents to 81. I,ODK>TONE, 

 strong, 25 cents to 60 cents. " HELL FIKE ROCK," 50 cents to 

 SI HESSITE, crystallized, S2 to $10. OPALS, Australia, $1 to 86. 



FLEXIBLE SANDSTONE, best quality, 50 cents to S3. KUTJLATED tJUABTZ, S2 to $10. 



STAUROLITES, various localities, 10 cents to 60 cents. CLAY IBONSrONK CONCRETIONS, 



natural rattles, 25 cents to $1. Write for Circulars. 



Ward's Xatural Science EstablisliineiLt, 



18 to 28 College Ave., Rochester, N. Y. 



Thompson's 90° Arc Lamp 



FOR OPTICAL PROJECTION. 



jGrreatly increased illumination as compared with 

 ' ' vertical " or " inclined ' ' carbons. The latest develop- 

 ment in Projection Apparatus. Especially suited to Pub- 

 lic"and Class-room Lectures. Complete Lantern Outfits 

 at right ^'prices. Ask for special pamphlet, No. 250. 



JAMES G. BIDDLE,' 909 Drexel Bailding, Philadelphia. 



