248 CARNEGIE INSTITUTION OF WASHINGTON. 



purpose, when he obtained for iron and nickel results similar to those later 

 obtained b}'^ Beck and by Arvidsson, to which Braunbek refers, and very 

 recently by Chattock and Bates. ^ 



The earliest successful experiments in this field were experiments on the 

 magnetization of steel by rotation, of which the above-mentioned effect is the 

 converse, made by L. J. H. Barnett and myself ^ and presented to the American 

 Physical Society in 1914. They have been followed ^ by experiments of the 

 same kind on soft iron, cobalt, nickel, cold-rolled steel, and Heusler alloys, for 

 each one of which, on the assumption of a single type of magneton, such as the 

 complex magneton of Richardson, with the axes of the rotating elements fixed 

 in the atom, the ratio of the angular momentum to the magnetic moment has 

 been found equal or nearly equal to w/e, the value found for steel in 1914, 

 instead of 2ml e. 



Richardson's theory calculates the ratio of angular momentum to magnetic 

 moment, which is the quantity (on the simplest hypothesis) sought in all these 

 experiments. His formula fits the experimental facts when the rotation of the 

 positive nucleus (or part thereof) is opposite to that of the negative electrons 

 in motion, and when the magnetic moments, or the real velocities of the posi- 

 tive protons, are negligible. It is interesting to note that the nucleus cuts 

 down the ratio of angular momentum to magnetic moment characteristic of the 

 electron orbits, not by affecting the magnetic moment, but by decreasing the 

 angular momentum, so that the rotation of neutral bodies in the nucleus, if 

 that were possible, would suffice for the purpose. 



While the negative-and-positive magneton hypothesis will account for the 

 experimental results, it is also possible to account for them on the hypothesis 

 that a single type of purely negative magneton is involved with a ratio of 

 angular momentum to magnetic moment equal to mje. In this connection 

 we may observe that the Lorentz-Abraham uniformly and superficially charged 

 electron in rotation about its axis has just this ratio w/e, as shown by Abra- 

 ham ^ in 1903. Both hypotheses have advantages and both are difficult to 

 reconcile with some of the facts. 



Chief results of a preliminary analysis of the Earth's magnetic field for 1922. No. I: 



Zonal harmonics and uniform magnetic field. No. II : Non-potential system. 



Louis A. Bauer. Terr. Mag., vol. 28, 1-28 (March- June 1923). 

 Summary of results of a recent analysis of the Earth's magnetic field for 1922.^ Louis A. 



Bauer. 

 Similarities in the magnetic fields of the Earth and the Sun. Louis A. Bauer. Pop. Astron., 



vol. 31, 186 (March 1923). 

 On the physical composition of the Earth's magnetic field in 1922. Louis A. Bauer. Phys. 



Rev., vol. 21, 370 (March 1923). 

 Some physical aspects of a recent analysis of the Earth's magnetic field.^ Louis A. Bauer. 



Science, vol 58, 113-115 (August 17, 1923). 

 The Earth's magnetic field for 1922. Louis A. Bauer. Nature, vol. 112, 295-298 (August 



25, 1923). 



These papers, of which the first mentioned is the principal one, present 

 various aspects of the chief results of the author's preliminary analysis of the 

 Earth's magnetic field for 1922, made as free as possible without assumptions 

 as to the composing systems and restricted to the region of the Earth (86 per 



1 Roy. Soc. Proc. A., Nov. 16, 1922 (see Nature, Nov. 25, 1922). 



» S. J. Barnett, Phys. Rev., vol. 6, 1915 (239). 



» S. J. Barnett, Phys. Rev., vol. 10, 1917 (7); S. J. Barnett and L. J. H. Barnett, Phys. Rev., 

 vol. 17, 1921 (404, 405), and vol. 20, 1922 (90, 91). See also S. J. Barnett, Bull. Nat. Res. Coun- 

 cil, vol. .3, 1922 (235). 



* M. Abraham, Ann. Physik, vol. 10, 1903 (151, 159, 171). 



* Presented at the annual meeting of the Section of Terrestrial Magnetism and Electricity 

 of the American Geophysical Union, Washington, April 18, 1923. 



* Presented at the meeting of the American Philosophical Society, Philadelphia, April 21, 1923 



