SCIENCE 



New Series ^ Ji Tr'p,,-..v MABriwr IQC)^ Single. Copies, 15 Cts. 



Vol. XXI. No. 531. D xs O \ -CKlUAl, iViAKOtl Oy l.iJKJO. Annual Subscription, 85.00 



PHYSICAL APPARATUS FROM MAX KOHL 



By special arrangement with Max Kohl I am able to import his Physical Laboratory Apparatus on the 

 most favorable "duty free" basis. The quality of Kohl apparatus is attested by the awarding of one 

 "Grand Prize" and a "Gold Medal" at the recent St. Louis World's Fair. 



Also, I have unexcelled facilities for procuring instruments from other European makers, including 

 Cambridge Scientific Co., Societe Genevoise, Carl Zeiss, R. Fuess, A Kruss, Otto WolflF, Hartmann & Braun, 

 Siemens and Halske, M. Th. Edelmann, Nalder Bros. & Co., Robert W. Paul, Kelvin and James White, etc. 



Be sure to correspond with me concerning apparatus for the equipment of high class Physical and 

 Electrical Engineering Laboratories. Write for Pamphlet 530. 



JAMES G. BIDDLE, 1114 Chestnut Street, Philadelphia 



y FREE import scientific instruments free of dut\) for col- 



leges and uni'versities from Societe Gene-voise, Cam- 



IMP O R TA TIO N ^^^^^^ Scientific Instrument Co. , Max Kohl, Carl Zeiss 

 jn. I iK^iy ^^^.^^^ ^^^^^^ ^-^/e/mann. Otto Wolff, 



Hartmann & Braun, Siemens & Halske, and many other sources. 



We shall endea'vor to secure your business on the basis of moderate prices and to 

 keep it on the score of good service. An inquiry 'will recei've a prompt reply. 



THE SCIENTIFIC SHOP albert b. porter 

 SCIENTIFIC INSTRUMENTS 322 Dearborn Street, CHICAGO 



Spheroidal Granite from Alichigan 



(See article by J. F. Kemp in this journal. Vol. XVIII., p. 503, October W. 1U03.) 



We have remaining a few fine museum slabs from this unique boulder. Such of these 

 as are not sold immediately will be cut into smaller cabinet specimens at from $5 to $10 

 each. As the supply is strictly limited to our present holdings, we advise our friends to 

 order at once. Photogi-aphs will be sent for inspection, on request, to accredited parties. 



WARD'S NATURAL SCIENCE ESTABLISHMENT, 76 College Ave., Rochester, N. Y. 



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i Apparatus for Buectro=Chemists | 



= We have recently established a department to include instruments for i 



z electro-chemical investigations and solicit correspondence. E 



= We make a most complete line of POTENTIOMETERS, COIL SLIDE BRIDGES, COIL i 

 I AND SLIDE RHEOSTATS ELECTROMETERS, CONDENSERS, KEYS, Etc. = 



I The Willyoung CAPILLARY ELECTROMETER j 



E is now ready==the perfected result of much study and experiment==invaluable to Electro- E 

 E Physicists. Excels in convenience, sensitiveness, and freedom from error. {Circular 536) = 



1 THE WILLYOUNG & GIBSON CO., 40 West Thirteenth Street, New York City | 



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