240 DEPARTMENT OF TERRESTRIAL MAGNETISM. 



Survey control at Washington and cooperative work. — Considerable time was 

 required to plan the work undertaken, to test and standardize outfits, to 

 coordinate the Department's field activities with those of other organizations 

 so as to prevent duplication, and to arrange for cooperative work with ex- 

 ploratory expeditions. In addition to the cooperation with special expedi- 

 tions referred to under the head "Field operations," arrangements were 

 made also with Mr. L. C. Daves, chief engineer of the Liberian Boundary 

 Survey, to obtain magnetic observations at stations on the Liberian boundary. 

 He and Mr. C. T. Bussell, his chief assistant, were instructed during Novem- 

 ber and December in the use of the magnetometer and dip circle and a com- 

 plete outfit for magnetic observations was supphed. 



Reductions of field observations. — The necessary computations and revisions 

 of observations and the preparation of manuscript giving the results of land 

 magnetic observations during 1921 and 1922 were about 90 per cent com- 

 pleted at the end of October; this work was carried out by Mr. Fisk, with 

 the assistance of Mr. F. C. Brown, temporary computer. 



The land magnetic results of the MacMillan Baffin Land expedition of 

 1921 to 1922 were revised and compiled, chiefly by Mr. H. F. Johnston. A 

 general account of the geophysical work of the expedition, including a sum- 

 mary of the results, was prepared by Mr. Fleming for publication as an 

 appendix to Dr. MacMillan's narrative. 



Excellent progress was made in the compilations of the extensive observa- 

 tions of the Bermuda magnetic survey of 1922, and papers were prepared 

 on (a) the magnetic survey of Bermuda and (6) the Bermuda magnetic anom- 

 aly and possible effect on secular changes (see abstract, pp. 253-254). In con- 

 nection with these compilations, Mr. Fisk took up an investigation of methods 

 to determine, by least squares, from observed ocean data, the normal distribu- 

 tion over large areas, in this case that between 24° and 40° north latitude and 

 between 284° and 306° east longitude; a note on this investigation and a 

 suggested method of adjustment is abstracted on pages 254 to 255. The 

 detailed data resulting from the survey were supplied Captain H. P. Douglas, 

 R. N., in charge of the Bermuda Hydrographic Survey under the auspices 

 of the British Admiralty, at his request. 



OBSERVATORY WORK.^ 



The following abstracts summarize briefly the work done at the observa- 

 tories and at Washington: 



Watheroo Magnetic Observatory, Western Australia. — Dr. G. R. Wait con- 

 tinued in charge of the observatory throughout the year, with the assistance 

 of Mr. J. Shearer, observer, and, since November 29, also of Mr. J. E. I. Cairns, 

 observatory aid. The magnetographs and conductivity apparatus No. 6 for 

 recording both positive and negative conductivity of the atmosphere were in 

 continuous operation. The installations of two overhead earth-current 

 lines, each 2 miles long, and of two underground earth-current lines, each a 

 mile long, the two systems paralleling each other from the southwest corner 

 of the site to the north and to the east, respectively, were completed; the 

 necessary recording apparatus was installed in the atmospheric-electric and 

 earth-current house. It is hoped that this equipment will be regularly in 

 operation before the close of the year. The program of limited meteorological 

 observations was continued and data were supplied monthly, as in the past, 



^ From the reports of J. A. Fleming, assistant director, and of the observers in charge. 



