320 CARNEGIE INSTITUTION OF WASHINGTON. 



A brief synopsis of the chief expeditions, 1908 to 1915, was given. The 

 results and descriptions of stations up to 1913, inclusive, have been pub- 

 lished in two volumes, issued by the Carnegie Institution of Washington.^ 

 The subsequent data are now being reduced, and it is hoped the volume to 

 contain them can appear in 1917. 



The next step will be to refer all the observations to the same date by 

 means of the data obtained at the repeat stations and at the magnetic observ- 

 vatories, of which, alas, there are too few in South America. Argentina and 

 Brazil are the only countries at present in which such observatories are being 

 maintained. 



The construction of new magnetic charts for the entire globe, as based 

 upon the data accumulated since 1905, is in progress. 



Throughout the entire work in South America every assistance possible 

 has been rendered in the furtherance of the Institution's magnetic work by 

 the various South American Governments, and by private individuals who 

 became interested in the work of the Department of Terrestrial Magnetism. 

 For this invaluable cooperation, grateful acknowledgment is here made. 



Concomitant changes in terrestrial magnetism and solar radiation. L. A. Bauer. Proc. 

 Nat. Acad. Sci., vol. 2, 24-27 (Jan. 1916). Washington. 



An abstract of a paper presented before the National Academy of Sciences 

 at the New York meeting, November 17, 1915 (see abstract, "Solar radiation 

 and terrestrial magnetism," page 330, Annual Report for 1915 published in 

 Year Book No. 14). 



Corresponding changes in the Earth's magnetic field and the solar radiation. L. A. Bauer. 

 (Presented before the Philosophical Society of Wasliington, January 22, 1916.) 



Investigations with the aid of more recent solar and magnetic data have 

 confirmed the author's preliminary conclusions of 1914 and 1915.^ It is 

 again found in the majority of cases (about 80 per cent), that increased 

 intensity of solar radiation, as shown by changes in solar-constant values 

 possessing the accuracy of those of the Smithsonian Institution, is accom- 

 panied by an appreciable decrease in the constant used as a measure of the 

 intensity of the Earth's magnetic field. While the magnetic effect, observed 

 on the average, is such as accompanies the heating of a magnet, it is, appar- 

 ently, not to be referred to such a cause. A preliminary examination of the 

 magnetic effects in different parts of the Earth indicates that the seat of the 

 system of forces causing the effects is not within the Earth itself, but in the 

 regions above us. 



In conclusion, it was pointed out that, from the standpoint of terrestrial 

 magnetism, observations dependent solely upon the thermal energy of solar 

 radiation can not be given any greater significance than that they may indi- 

 cate some change in solar activity. Thus changes in the solar constant may 

 not be regarded as a true or adequate measure of the various ionizing agencies 

 (ultra-violet light, corpuscular radiations, electrons impinging upon our 

 atmosphere, etc.) which are, at present, believed to be ultimately the cause 

 of the magnetic effects. To the pyrheliometer, the bolometer, and meteor- 

 ological appliances, must be added the magnetic needle, if we wish to get as 

 complete a representation as possible of the many and different effects attrib- 

 utable to our Sun, directly or indirectly. 



'Land Magnetic Observations, 1905-1910, bj' L. A. Bauer; Land Magnetic Observation-i, 

 1911-1913, and Reports on Special Researches, by L. A. Bauer and J. A. Fleming. 

 'Published in Terr. Mag., vol. 19, 119-124, 1915, and vol. 20, 143-158, 1916. 



