252 CARNEGIE INSTITUTION OF WASHINGTON. 



paper contains comments, based on the experience of the Department of 

 Terrestrial Magnetism, with respect to questions and subjects of discussion 

 according to the printed agenda, distributed before the meeting at Rome. 



Proposed magnetic and allied observations during the total solar eclipse of September 10, 

 1923. Louis A. Bauer and J. A. Fleming. Terr. Mag., vol. 28, 29, 30 

 (March- June 1923). 



Magnetic observations during the total solar eclipse. Louis A. Bauer and J. A. Fleming. 

 Science, vol. 58, 62, 63 (July 27, 1923). 



A proposed general program for field-station and observatory work, includ- 

 ing magnetic, atmospheric-electric, and meteorological observations is out- 

 lined. The general circumstances of the eclipse are given and also a list of 

 references giving detailed information with respect to meteorological and 

 living conditions at places within the belt of totality. 



On the physical interpretation of results of line integrals of the Earth's magnetic force.^ 

 Louis A. Bauer and W. J. Peters. Phys. Rev., vol. 21, 388 (March 1923). 



At the Toronto meeting of the American Physical Society in 1921, the 

 authors gave the results of line integrals of the Earth's magnetic force, taken 

 around various complete circuits over ocean and land areas. The results 

 were of such a magnitude and of such a character as not to be readily ascrib- 

 able to observational errors.^ In accordance with usual theory, the line- 

 integral results would be regarded as indicating the existence of electric 

 currents passing perpendicularly through the area inclosed by the circuit. 

 The current density thus indicated would be about 10,000 times that shown 

 by atmospheric-electric observations. The first author some years ago 

 suggested another physical interpretation which has been reexamined in the 

 light of the more recent data and on the basis of a new analysis of the Earth's 

 magnetic field. It is found that the line-integral results reveal, in part at 

 least, an effect similar to a deviation of the compass needle as though caused 

 by forces set in operation during the Earth's rotation; the north end of the 

 compass needle is found to be deflected along a parallel of latitude, on the 

 average, between 5° north and 45° north about one-tenth of a degree toward 

 the east, and for the corresponding region in the southern hemisphere about 

 one-tenth of a degree towards the west (see also p. 266). 



Formula for scale-value determination of declination variometers. H. M. W. Edmonds. 



During April and May two formulae that have been in use for determining 

 the effective distance, R, between the movable mirror of the declination 

 variometer and the recording drum of the magnetograph, were considered 

 and tested experimentally. Lamont^ corrected the measured distance for 

 torsion and subtracted one-third the thickness of all intervening glass plates 

 or lenses. 



Kohlrausch* found that the effect of the variometer lens eliminates the 

 distance between the lens and mirror. This led to the adoption of the formula 



where D = distance from back of lens to magnetogram; w = mirror thickness, 



* Presented at the Boston meeting of the American Physical Society, December 28, 1922; a 

 fuller publication will be made in the Journal of Terrestrial Magnetism and Atmospheric Elec- 

 tricity. 



» See Phys. Rev., vol. 19, 427, 428 (April 1922). 



' J. Lamont, Handbuch des Erdmagnetismus, Berlin, 1849 (90-96). 



^ F. Koblrausch, Ueber die Correctionen bei einer Winkelmessung mit Spiegel und Scala, 

 Ann. Pbysik u. Chemie, N. F,, vol. 31, 1887 (95-100). 



