DEPARTMENT OF TERRESTRIAL MAGNETISM. 259 



vioiisly occupied by observers of the Department, and all of which 

 were in the jungle regions of the Amazon or the Guianas. As must be 

 expected in such cases, some time was lost on account of sickness from 

 malaria and other tropical disorders, but, largely on account of the 

 close observance of precautions recommended for traveling in such 

 regions, the sickness was never severe and the loss of time was com- 

 paratively small. 



ABSTRACTS OF PUBLICATIONS AND INVESTIGATIONS. 



Sea surface-temperature and meteorological observations made on the Carnegie during 

 her sub-Antarctic cruise, December 6, 1915, to April 1, 1916. J. P. Ault. 

 Terr. Mag., vol. 22, 183-189 (December 1917), Washington. 



This paper contains the results of sea surface-temperature and meteoro- 

 logical observations made on board the Carnegie during her sub-Antarctic 

 cruise, December 6, 1915-ApriI 1, 1916, from Lyttelton (New Zealand) to 

 South Georgia and Lyttelton. Reports that have thus far come from this 

 region are few and incomplete, and as the part of the Great Southern Ocean 

 traversed is the scene of such rapid and extreme changes in meteorological 

 conditions, any additional information on the subject is of interest. The 

 Carnegie made a complete circumnavigation of the globe from west to east, 

 mainly between the parallels of latitude 50° and 60° south, in one season, 

 the summer of 1915-16, during which Sir Ernest Shackelton's expedition 

 was meeting with such serious reverses. The m-eteorological observations 

 made by the two parties of his expedition, and those obtained on the Carnegie, 

 are especially valuable because they are contemporaneous records of the 

 conditions prevailing in different parts of the southern regions at that time. 



Relation between the secular variation of the earth's magnetism and solar activity. L. A. 

 Bauer. Terr. Mag., vol. 23, 1-22, 61-68 (March and June 1918), Washington. 



In a previous paper entitled "Solar radiation and terrestrial magnetism," 

 the possibility was pointed out that irregularities in the annual changes of 

 the Earth's magnetic elements, the so-called secular variation, might be 

 associated with such manifestations of solar activity as are revealed to us 

 by changes in the solar constant of radiation.* As the result of a preliminary 

 investigation, the following conclusion was reached in that paper: 



If the quiet-day magnetic effect were to persist throughout the year, 

 it would cause a secular variation fully 10 times that generally observed. 

 However, the quiet days are in the minority, being exceeded 3 tinies 

 and more by unquiet days, on which the magnetic effect is of an opposite 

 kind to that of the quiet day. Since these acyclic effects appear to be 

 associated with solar changes and since the latter are not periodic, but more 

 or less sporadic, there is an outstanding effect at the end of the year which 

 causes an irregularity in the regularly progressing secular change. Accord- 

 ingly, there should be found some correspondence between annual changes 

 of the solar constant and annual magnetic changes. This is found to be the 

 case. Since the solar-constant changes occur only approximately in accord- 

 ance with sun-spot activity, and since the magnetic changes are found to 

 conform closely to those in the solar constant, an explanation is found as 

 to why the irregularities in the magnetic secular change do not always syn- 

 chronize with changes in solar activity as measured by the sun-spot numbers, 

 nor correspond in magnitude to them. 



*Terr. Mag., vol. 20, 1915, pp. 155 and 157. 



