SCIENCE 



New Series. 



Vol. VIII. No. 190. 



TToT-rvAAT ATTr^TTCjrn 1Q 1QQQ SINGLE COPIES, 15 CIS. 



I?ixiJJAY, i:i.U(jUhJ. lO, lOdO. Annual SuBSCMPTiON, 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 No. 9,050. Minia- 

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



ElisoQ DecDiative aDl mmiatuie Lam Depaitmeiit, 



(GENERAL ELECTRIC COMPANY.) 



HARRISON, N. J. 



f^ I fiA' lOxl ^^^ pages, 40 splendid engi-avings. Con- 



UUIIIUlulU Isllliuiul UdlUlU&Udl ment bringing °b^e°woiku™ to date. %Iet%'fc 



I vl classification showing what minerals contain 



each element. Alphabetical index of names. Lists giving the specimen values of minerals, etc., etc. For teachers, students, 



collectors, mining experts, chemists, and others. Postpaid; Paper, 35 cents ; Cio^^, 50 cents; Galf,inierleavedj%^,QQ^ 



DR. A. E. FOOTE, 1317 Arch Street, Philadelphia, Pa, U.S.A. Established me . 



COLLECTIONS OF MINERALS FOR STUDY OR REFERENCE. CABINET SPECIMENS. GEMS. 



MAX KOHLa^ Chemnitz^ Grerxnany^ 



FIRST EUROPEAN MAKER OF 



Physical and iElectrical Instruments 



special Manufacturer of Koentgeii X-ISay Outfits. 



Apparatus for Experiuients witU Currents of High Frequence and. Tension. 



Apparatus for the Experiments according to Hertz. 



Apparatus for Marconi's Wireless Telegraphy. 



Price List No. 10 of Physical Instruments ; nearly -100 pages and more than 1300 engravings {in German, English 

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

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



M^ REFERENCES FROM LEADING EXPERTS, "m^ 



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



