DEPARTMENT OF TERRESTRIAL MAGNETISM.* 



L. A. Bauer, Director. 



GENERAL SUMMARY. 



The operations and chief results of the Department during the period 

 November i, 1911, to October 31, 1912, in brief were: 



CONTINUATION OF THE MAGNETIC SURVEY OE THE OCEANS WITH THE AID OF 

 THE NON-MAGNETIC VESSEL, THE "CARNEGIE." 



At the end of the last fiscal year the vessel had completed her projected 

 circumnavigation cruise as far as Batavia, Java. She sailed from there on 

 November 21, 191 1, bound for the eastern part of the Indian Ocean, and 

 went thence to Manila, Philippine Islands, where she arrived on February 3, 

 1912; the total distance covered on this leg of the cruise was 8,292 miles 

 and the time at sea was 75.5 days. The cruise continued from Manila to 

 Suva, Fiji ; thence to Papeete, Tahiti, from which port the Carnegie sailed 

 on October 15, bound for Coronel, Chile. It is expected that the present 

 circumnavigation cruise will be completed by the end of 1913. The total 

 distance covered during the present fiscal year will be about 28,000 nautical 

 miles ; the magnetic declination was determined at about 260 points along 

 the tracks of the vessel, and the magnetic dip and intensity at about 180 

 points. 



The errors in the charts of the lines of equal magnetic declination used 

 by mariners, as disclosed by the observations on board the Carnegie in the 

 eastern part of the Indian Ocean, reached nearly the same magnitude as 

 those found in the western part of this ocean, viz, 3 to 5 , according to 

 the chart used; the errors were again systematic. However, in the China 

 Sea and that part of the Pacific Ocean between Manila and Suva the chart 

 errors in magnetic declination have been gratifyingly small, usually less 

 than i°. The latter regions had already been partially covered by the work 

 of our previous vessel, the Galilee, and the results of the observations had 

 been supplied to the leading hydrographic establishments. On the passage 

 from Suva to Tahiti the errors in the charts of the lines of equal magnetic 

 declination amounted to nearly 2°. 



All the results of observations on board the Carnegie of the magnetic ele- 

 ment of chief interest to the mariner, the magnetic declination, obtained on 

 her first cruise as well as on her second, up to arrival at Suva on June 7, 

 1912, have already appeared in print; the results for the passage from Suva 



* Address : The Ontario, Washington, District of Columbia. Grant No. 750. $97,810 

 for investigations and maintenance during 1912. (For previous reports see Year Books 

 Nos. 3-10.) 

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