236 REPORTS ON INVESTIGATIONS AND PROJECTS. 



TERRESTRIAL MAGNETISM. 



DEPARTMENT OF RESEARCH IN TERRESTRIAL MAGNETISM.* 



By L. a. Bauer, Director. 



Owing to the great amount of field work in operation, which was under- 

 taken on account of the reasons given in the report of the previous year, the 

 office investigations have of necessity been curtailed. The progress made 

 during the year in the office and in the field is as follows : 



OFFICE WORK. 



Investigation I. — Study of the secular variation and compilation of data 

 preparatory to publication on a uniform plan. — As related in the heading 

 "Field work" a number of secular variation stations have been established. 

 The compilation and the discussion of data have been continued as oppor- 

 tunity offered. For certain countries the compilations have been completed. 



Investigation II. — Discussion and publication of the data on the magnetic 

 perturbations observed during the eruption of Mont Pelee, Martinique, igo2. — 

 This work is about 80 per cent completed; the final discussion had to be 

 temporarily discontinued by reason of the more pressing duties, but it is 

 confidently expected that the investigation can soon be brought to a close. 



Investigation III. — A general study of the laws of the diurnal variation 

 to serve as a basis for determining corrections and their reliability for the 

 reduction of Held observations. — Work along this line has been confined 

 chiefly to the collection of data. The Department has also secured the 

 results of the valuable series of declinations obtained by Mr. W. J. Peters 

 while in charge of the scientific work of the Second Ziegler Polar Expe- 

 dition in the Franz Josef Archipelago in 1903 and 1904. 



Investigation IV. — Special investigation of magnetic storms, with the 

 view of determining a working method for the discussion and analysis of 

 such fluctuations. — These studies have been continued under the direction 

 of Prof. Adolf Schmidt, in charge of the Potsdam Magnetic Observatory, 

 with the aid of funds supplied, with the approval of the Executive Com- 

 mittee, by the Department. Owing to Professor Schmidt's multitudinous 

 duties during the present year, it has not been possible for him to do more 

 than make a preliminary report. 



Investigation V. — Discussion of the magnetic and electric observations 

 made during the total solar eclipse of August jo, 1905. — During the year 

 considerable progress has been made in the reduction of the observations 

 made by the Department at its stations, Battle Harbor, Labrador ; Turnavik, 

 Labrador; Black Point, Nova Scotia; Missinaibi, Canada, and TripoH, 



* Report for the year ending October 31, 1906. Grant No. 312. $56,000 for investiga- 

 tions and maintenance. (For previous reports see Year Book No. 3, pp. 68-74, and 

 Year Book No. 4, pp. 264-274.) 



