334 ANNUAL, REPORT SMITHSONIAN INSTITUTION, 1910. 



Southern Hemisphere, and the plans at first contemplated three 

 stations: in Sydney, Australia; Capetown, Africa; and Santiago, 

 Chile. It was pointed out, however, b}^ Dr. Helmert that better re- 

 sults could be secured, as far as the evaluation of the so-called Ki- 

 mura-term in the latitude equation was concerned, by two stations 

 placed as exactly as possible on opposite sides of the earth. Ac- 

 cordingly, after correspondence with authorities in Australia and 

 the Argentine Eepublic, two cites were chosen in 1905 which satisfy 

 this condition, and are, in addition, admirably situated as regards 

 climatic advantages. Both are in south latitude 31° 55' 15", and 

 differ 179° 36' in their longitudes. The Australian installation is in 

 charge of Dr. Hessen, formerly of Berlin, and is located at Bays- 

 water. West Australia, about 4 miles from Perth, the capital. The 

 Argentine station is under the direction of Dr. Luigi Camera, form- 

 erly occupied in similar observations at Carloforte, and is located at 

 Oncativo, about 45 miles from Cordoba. 



Both of these stations commenced observations in 1906, and the 

 work has been prosecuted with great energy since that date. 1 The 

 results thus far secured are enabling us to draw more accurate con- 

 clusions with regard to these supplementary, exceedingly minute 

 movements of the earth's axis. 



The formula for the variation of latitude is ordinarily expressed 

 by the equation 



(f)—(f)'=x cos X -\- y sin X -f~ s, 

 where aj and y are the components of the variation in the planes of 

 zero longitude and that perpendicular to this, while the term s, called 

 the Kimura-term from the Japanese astronomer who suggested its 

 introduction denotes that part of the variation which is common to 

 all the stations, corresponding to an apparent movement of the center 

 of gravity of the earth toward one or the other pole. The results 

 from the northern stations have revealed the interesting fact that the 

 value of s is periodic, with a period of one year, reaching its zero 

 values about March 9 and September 12, and its maximum and 

 minimum values on June 10 and December 10, these points coming, 

 then, about 10 days before the solstitial points. The preliminary 

 results from the southern stations coincide almost exactly with those 

 from the northern stations with respect to the magnitudes of x and y, 

 and show, in addition, that the value of the s-term is of the same 

 magnitude and algebraic sign as that derived from the northern re- 

 sults. This 2-term is very small, oscillating only 0."046 on each side 

 of the mean, which, if real, would correspond to a movement of the 

 center of gravity of the earth of about 4| feet toward the North or 

 the South Pole. The temptation is very strong to seek a meteoro- 



X 



1 The observations at Bayswater were discontinued in January, 1909 ; the station at 

 Oncativo has been taken over by the Government of the Argentine Republic. 



