DEPARTMENT OF TERRESTRIAL MAGNETISM. 247 



It is believed that the results of intercomparisons of instruments 

 already published by the Department amply show that the purposes 

 have been accomplished. "VNTiile for obvious reasons it was necessary 

 for the Department to make a provisional choice itself of the magnetic 

 standards to which the existing observational data are to be reduced 

 in the preparation of its own world magnetic charts, that choice was 

 based upon a critical study of the available data from institutions in 

 all parts of the world. When others have adopted our choice, it has 

 been as the result of their own judgment on the basis of the evidence 

 presented and without any soUcitation on our part. By our methods 

 we have been able to disclose important instrumental errors at various 

 observatories. 



The present time is a favorable one for making any required changes, 

 if any mistakes have been made in the conduct of the past work and 

 with regard to the poUcy followed by the Department. The general 

 magnetic-survey work has reached its first stage of completion and 

 we are preparing now to take up some of the other lines of research 

 outlined in the original project and announced in various past annual 

 reports. Both the President of the Institution and the Director of the 

 Department will be pleased to receive at any time suggestions, as well 

 as constructive criticisms, from those interested in the advancement 

 of our knowledge of the physics of the Earth. 



DETAILS OF OBSERVATIONAL WORK. 



OCEAN WORK. 



At the beginning of the fiscal year preparations were being made to 

 start the Carnegie on her homeward cruise from Buenos Aires to an 

 Atlantic port, by way of Cape Horn, the Pacific Ocean, and the 

 Panama Canal. This cruise, designated "Cruise V," began at Buenos 

 Aires on December 4, 1917, the Carnegie having been detained at this 

 port for over 9 months on account of the war. 



The passage around Cape Horn to Talcahuano, Chile, was made 

 in the short time of 38 days, arrival at the latter port occurring on 

 January 11, 1918. Although the usual stormy weather and heavy 

 seas were encountered off Cape Horn, the winds usually drew from 

 favorable directions. The daily average for the 38 days at sea was 102 

 nautical miles, and the usual daily program of magnetic and other 

 work was carried out without serious interruption. 



After a stay of 12 days at Talcahuano, during which time the C. I. W. 

 magnetic stations at Coronel and at Concepcion were reoccupied, the 

 Carnegie sailed again on January 23, 1918, for Callao, Peru. After 

 making a large detour to the westward in order to fill in unsurveyed 

 areas, the vessel arrived at Callao on February 22, 1918, having made 

 a highly successful trip of 30 days. 



