August 3, 1902.] 



SCIENCE. 



181 



ent form was exhibited and the functions of 

 its various parts explained. 



Absorption Spectra of the Permanganates: 

 B. E. Moore, University of Nebraska. 

 Read by title. 



The Index of Kefraction and the Absorp- 

 tion of Fuchsine: W. B. Cartmel, Uni- 

 versity of Nebraska. Read by title. 



Determination of Dispersion by Means of 

 Channeled Spectra: S. R. Williams, 

 University of Nebraska. Read by title. 

 E. F. Nichols, 

 Secretary Section B. 



SECTION B. 



IN SESSION WITH THE AMERICAN PHYSICAL 



SOCIETY. 



The meeting was held in the Middle Lec- 

 ture Room of the Carnegie Institute, July 

 2, 1902. Professor W. Le Conte Stevens 

 was elected chairman pro tern. The pro- 

 gram follows : 



Results of Recent Magnetic Investigations : 

 L. A. Bauer, U. S. Coast and Geodetic 

 Survey, Washington, D. C. 

 The paper was illustrated by charts 

 which exhibited the results of reeeat re- 

 searches in terrestrial magnetism conducted 

 by the U. S. Coast and Geodetic Survey. 

 Several recording magnetic instruments of 

 modern construction were described and 

 methods of standardization discussed. 

 Lantern slides of the new magnetic observ- 

 atories of the survey were shown. 



Some Recent Interesting Magnetic Dis- 

 turbances Registered at the Coast and 

 Geodetic Survey, Magnetic Observa- 

 tories : L. A. Bauer. ~ 

 The records of a number of recent mag- 

 netic disturbances taken at the different 

 magnetic observatories of the Coast Survey 

 ■were shown by lantern slides and the sig- 

 nificance of the results obtained was dis- 



cussed. Both of the foregoing papers will 

 appear in the Journal of Terrestrial Mag- 

 netism and Atmospheric Electricity. 



On the Relation between Thermoelectric 

 Power and Change of Length, caused by 

 Magnetization: Edward Rhodes, Haver- 

 ford College. 



A thermoelectric pile of fourteen iron 

 wires, 40 cm. long, thirteen copper wires, 

 15 cm. long, and one bar of a special alloy 

 of antimony and zinc, was built up. The 

 alloy has the property that its thermo- 

 electromotive force with iron is such as to 

 counteract that of the thirteen copper iron 

 junctions. 



When this pile has steam and cold water 

 jackets placed over its ends and is inserted 

 in a suitable solenoid, a curve may be ob- 

 tained showing the thermoelectric power, 

 at the mean temperature, of magnetized, 

 against unmagnetized iron, as the field is 

 varied. 



A cyclic curve of this kind was taken and 

 proved to be of the peculiar and distinct- 

 ive type of the cyclic change of length 

 curves. 



In order that the two curves should 

 agree, however, it is necessary to correct 

 the change of length curve for the contrac- 

 tion B'' l4cnY, where Y is Young's modulus. 

 A similar thermopile was constructed 

 of nickel wires. In this case only the 

 first ascending branch of the curve was 

 taken. This was of the same type as the 

 change of length curve for nickel, which is 

 altogether different from that for iron. 



The existence of this relation seems to 

 open the way to a large amount of further 

 work on the nature of magnetism. 



The complete paper -will appear in the 

 Physical Revieiv. 



Experiments on the Electrolysis of Radio- 

 active Solutions: Geo. G. Pegram, Co- 

 lumbia University. Read by title. 



