612 



SCIENCE. 



[N. S. Vol. XXIV. No. 620. 



Magnetograph Records of Earthquakes 

 with Special Reference to the San Fran- 

 cisco Earthquake of April 18, 1906: L. 

 A. Bauer, Magnetic Survey, Washing- 

 ton. 



Rotation and Elliptic Polarization pro- 

 duced hy Iron Films in a Magnetic 

 Field: W. D. Harris, University of Ne- 

 braska. 



Films were obtained on microscope cover 

 glass by cathode deposit in vacuo. The 

 rotation of the plane of polarization was 

 measured by use of a Lippich half-shade 

 Nicol prism, and the ellipticity of the light 

 by means of a Brace half-shade elliptic 

 polarizer and compensator. Films deposit- 

 ed in hydrogen exhibited a rotation rising 

 gradually from zero in the violet to a maxi- 

 mum value in the red. The same films 

 showed an ellipticity of the transmitted 

 ray increasing from a zero value in the 

 violet to a maximum at about 600 ixfx, then 

 a gradually decreasing value toward the 

 red end of the spectrum. With age the 

 values for the longer wave-lengths dropped 

 to a marked extent. A film of same density 

 deposited in nitrogen produced a smaller 

 rotation as well as smaller ellipticity, the 

 latter possessing a maximum value at about 

 560 [xfi. A film deposited in oxygen gave 

 no rotation for any wave-length, but a 

 slight ellipticity, this being a maximum at 

 about 540 [xfx and dropping rapidly to zero 

 in passing toward either end of the spec- 

 trum. All films showed marked polarity 

 when suspended in a magnetic field. 



The film deposited in hydrogen tested for 

 variation in ellipticity with the strength of 

 field showed this to be proportional to the 

 field up to about 8,000 C.Gr.S. units, after 

 which there was but a small increase as the 

 field was intensified. 



The reflected light exhibited in no case 

 any observable ellipticity, although three 

 per cent, of that observed in case of trans- 



mitted light would have been readily de- 

 tected. 



Cobalt and nickel films deposited in hy- 

 drogen showed a rotation similar to iron, 

 but no ellipticity. 



Coefficient of Linear Expansion at Low 

 Temperatures: H. G-. Dorset, Cornell 

 University, 



New Diffraction Spirals: A. G. Webster, 

 Clark University. 



The Calibration of Capillary Tubes: Wil- 

 LARD J. Fischer, Cornell University. 



The Latent Heat of Recalescence in Iron 

 and Steel: Frank H. Bailey, Clark Uni- 

 versity. 



Thermal and Electrical Effects in Soft Iron 

 between 100° and 218° : Edwin H. Hall, 

 Harvard University. 



This will give the results of a continua- 

 tion of the study which my colleagues and 

 I have already published, in the Proceed- 

 ings of the American Academy for May, 

 1906. The general method followed has 

 been the same as before and the results 

 obtained are in general accord with those 

 which we have before obtained at a lower 

 temperature. 



Note on Certain Aspects of Drude's Elec- 

 tronic Theory of Metallic Conduction: 

 Edwin H. Hall, Harvard University. 

 I wish to raise the question whether the 

 expansion of metals is to be accounted for 

 by the expansive force of the imprisoned 

 electrons and what effect these electrons 

 should have on the specific heat of metals. 



The Capacity and Resistance of Aluminum 



Anode Films: C. McC. Gordon, Central 



University of Kentucky. 



Films were formed on aluminum anodes 

 with a direct current of known voltage and 

 their capacity measured in the Wheatstone 

 bridge with a small alternating current. 



As was reported in a previous paper, the 



