/ -^ 



i^oy^z 



SCIENCE 



New Series. 

 Vol. VII. No. 173. 



Friday, April 22, 1898. 



Single Copies, 15 cts. 

 Annual Subschiption, 85.00. 



General Electric Co.'s 



NEW X=Ray Tube 



WITH AUTOMATIC VACUUM REGULATOR. 



Simple. Efficient. Long-lived. Cannot run too high in vacuum. 



Roentgen Ray Apparatus, catalogue Nr- 7.050. Minia- 

 ture, Candelabra, Decorative Lamps, catalogue No. 9,044. 



Elisoit Decoiative it piimaluie Lamp Departieot, 



{GENERAL ELECTRIC COMPANY.) 



HARRISON. N. J. 



Rare Minerals. 



THAUMASITE from West Paterson, N. J., a unique compound of the 

 sulphate, silicate and. carbonate of calcium with 42 per cent, of water. 

 An excellent, attractive, cabinet size specimen, postpaid for 14 cents, 

 CKYSTALI.IZED AKSKMC from Japan, in balls % to i^^-inch diameter, postpaid, 16 cents. CONTACT TWINS OF 

 QUARTZ, postpaid, Sl.OO. TWISTED STIBNTTE crystals and groups, 28 cents, postpaid. MOUNTAIN LEATHER, a 

 great novelty, postpaid, lie., 16c., 22c. and 27c. 134-page Catalogue, describing every mineral, 25c. in paper ; 50c. in cloth 

 44-page Price-List, 4c. Bulletins and Circulars Free. 



GEO. li. ENGLISH & CO.. Mineralogists, 64 £. 12th St.. New York. 



MAX KOHIi^ Ghexnnitz^ G-ermany^ 



FIRST ETTROPEAN MAKER OF 



Physical and Ellectrical Instruments 



special Manufacturer of Kqentgen X-Ray Outfits. 



Apparatus for Experiments witli Currents of HigU Frequence and Tension, 



Apparatus for the Experiments according to Hertz. 



Apparatus for Marconi's Wireless Telegraphy. 



Price List No. 10 of Physical Instruments ; nearly 400 pages and more than 1300 engravings (in German, English 

 and French). Special List of X-Ray Apparatus containing numerous testimonials as well as estimates for complete 

 outfits, explicit directions for use, etc., in English language. ' 



jm- REFERENCES FROM LEADING EXPERTS. -^^^ 



Representative: Messps. EIMER & AMEND, 205-211 Third Avenue, New York. 



