I 



DEPARTMENT OF TERRESTRIAL MAGNETISM. 275 



LAND MAGNETIC SURVEY.^ 



Magnetic changes. — The endeavor was made, while the Carnegie was out 

 of commission, to concentrate the work of the available observers upon secur- 

 ing magnetic observations in land areas where further information was ur- 

 gently needed, especially with regard to secular changes. A sufficient time 

 had elapsed to make it worth while to repeat observations at a carefully 

 selected number of our earher established stations and thus determine the 

 magnetic changes which had occurred during the elapsed interval. These 

 magnetic changes, as accurate observations have multiplied, are proving to 

 be of a more complicated character than at times realized. Similar experi- 

 ence is encountered by other magnetic services. Thus recent magnetic 

 observations of the United States Coast and Geodetic Survey have shown 

 that the rate of change of the magnetic declination, or direction of the com- 

 pass, "has varied so much recently that values carried forward from 1915 

 are in some cases not dependable." 



Along with the desired repeat observations, important magnetic data were 

 likewise obtained in regions requiring filling in. The main expeditions during 

 the year were as follows: 



1. Africa. — Mr. W. C. Parkinson made comparisons of the instruments used by him 

 with those of the Helwan Observatory, Egypt. While en route to Spain for further 

 observatory comparisons, he reoccupied stations of the Department in Egypt, Sinai Penin- 

 sula, Tunisia, and Algeria; observations were made also at Bouzareah Observatory near 

 Algiers. 



2. Asia. — Observer Frederick Brown, while en route from Australia to China, reoccupied 

 Department stations and established a new station at Singapore. During February to 

 July 1922, he made weekly observations at the station of the Department on the grounds 

 of the Canton Christian College, Canton, China. Resuming his field work on July 11, he 

 made repeat observations at six C. I. W. stations in China and comparisons of his instru- 

 ments with the electric magnetometers of Professor Watanabe and with the standard 

 observatory instruments at Kakioka, Japan. He then proceeded to Washington, where he 

 arrived early in September. 



Dr. P. H. Dike, of the staff of Robert College, Constantinople, formerly an observer of the 

 Department, was engaged temporarily for three months from the first of June, making 

 magnetic observations on expeditions into Asia Minor, Syria, and the islands of the 

 eastern Mediterranean. 



Mr. W. C. Parkinson reoccupied the C. I. W. station at Jidda, Arabia, and established 

 new stations at Yambo, El Wedj, and Jidda, in Arabia. Dr. H. U. Sverdrup (Amundsen 

 Expedition) reoccupied the station at Kain-ge-skon, Siberia. 



3. Australasia. — Mr. Frederick Brown, accompanied by Assistant Observer J. Shearer of 

 the Watheroo Magnetic Observatory, during the early part of November 1921 reoccupied 

 three C. I. W. stations in Western Australia and established a new station at Bunbury. 

 Mr. Brown left Fremantle November 9, for China, occupying en route four additional C. I. W. 

 stations and one new station in Western Australia. Mr. Shearer spent the remainder of 

 November reoccupying Department stations at Northam, Southern Cross, and Cool- 

 gardie, returning to Watheroo on November 26. 



Observer Donald G. Coleman, at the conclusion of his work in the Fiji Islands, while en 

 route to Melbourne, occupied four stations in New South Wales. During February Mr. 

 Coleman compared his instrument with those of the Melbourne Observatory and at the 

 Observatory's new site, Toolangi, and assisted Dr. Baldwin in the transfer from the old site 

 and in mounting of instruments at the new site. He then occupied 10 stations in New 

 Zealand. At the conclusion of his work in the Pacific Islands in July, he returned to Sydney 

 via New Zealand, reoccupying the Auckland station en route and about 10 stations in New 

 South Wales and Queensland. During the total solar eclipse of September 21, 1922, he 

 made observations at Coongoola in accordance with a special program. 



' From the report of the chief of the section, H. W. Fisk. 



