296 CARNEGIE INSTITUTION OF WASHINGTON. 



Further results of line-integrals of the Earth's magnetic force. Louis A. Bauer and W. J. 

 Peters.i Phys. Rev., vol. 19, 428-429 (April 1922). 



Line-integrals of the Earth's magnetic force around ocean areas. Louis A. Bauer and W. J. 

 Peters.^ 



These two papers give additional results as derived from recent computa- 

 tions of line-integrals around circuits formed by the tracks of the magnetic- 

 survey vessel, the Carnegie, and the trips of land expeditions sent out by the 

 Department of Terrestrial Magnetism. 



One of the most interesting circuits was that formed by Cruise III of the 

 Carnegie in the North Atlantic Ocean in 1914, extending from New York to 

 80° north, off the northwest coast of Spitzbergen. This circuit embraces 

 an area of 4,441,176 sq. km. The result of the line-integral around this 

 circuit was such as would be produced by currents of positive electricity pass- 

 ing through the air perpendicularly through the Earth's surface of average 

 strength one-twentieth of an ampere per square kilometer. For the sake of 

 comparison it may be recalled that the line-integrals around the United States, 

 as based upon independent computations of the magnetic data for 1905 and 

 1915, gave a result which could be produced by currents of positive electricity 

 passing through the air perpendicularly through the Earth's surface, having 

 an average strength of about one-thirtieth of an ampere per square kilometer 

 (see Terr. Mag., vol. 25, 145-160, December 1920). 



From the foregoing it is seen that the results of two line-integrals, one over 

 an ocean area exclusively, and the other over a land area exclusivelj'-, are of 

 the same sign and are practically of the same magnitude. On the other hand, 

 the vertical currents as disclosed by atmospheric-electric observations, accord- 

 ing to present methods, over the regions of the two line-integrals, agree in 

 direction with the results of the magnetic line-integrals. Quantitatively, 

 however, there is a pronounced discordance. The strength of the vertical 

 conduction-current of atmospheric electricity is only about one ten-thousandth 

 of the currents indicated by the magnetic line-integrals. 



Another circuit for which the line-integral has been computed is that 

 formed by the track of the Carnegie's first cruise, made in 1909-10. This 

 circuit incloses an ocean area of 13,050,122 sq. km. and extends from New 

 York to England along the track of ocean travel in latitude about 50® N., 

 thence to Madeira, and finally back to New York by way of the sailing routes 

 in latitude 20° N. The result of the line-integral around this circuit is the 

 same as that which would be produced by currents of positive electricity 

 passing from the air perpendicularly through the Earth's surface and having 

 an average strength of one twenty-sixth of an ampere per square kilometer. 

 This is practically the same result as was obtained by the evaluation of the 

 line-integral around the United States. 



The third line-integral is based upon a circuit by the Carnegie in the Indian 

 Ocean, June 6 to September 9, 1911, extending across the Equator. The area 

 inclosed is 11,125,474 sq. km., the resulting line-integral being practically 

 zero. (The indicated upward positive current was less than one-thousandth 

 ampere per square kilometer average strength.) 



The fourth line-integral was computed for a circuit of the Carnegie extending 

 across the Equator and inclosing an area of 13,538,751 sq. km. in the Pacific 

 Ocean, from July 15 to October 22, 1912, and is especially interesting be- 



1 Presented by Louis A. Bauer at the Toronto meeting of the American Physical Society, 

 December 1921. 



2 Presented by Louis A. Bauer at the Rome meeting of the International Section of Terrestrial 

 Magnetism and Electricity, May 1922. 



