DEPARTMENT OF TERRESTRIAL MAGNETISM. 281 



have been traversed by the observers without loss of life, though some 

 of the routes followed were both difficult and fraught with danger. 



The Department has furthermore cooperated with five Arctic 

 expeditions and one Antarctic expedition, supplying instruments 

 and instructions, training observers, and reducing the observations 

 whenever necessary. 



Besides the magnetic data obtained, geographic positions have been 

 determined which have been furnished to cartographers for preparation 

 of maps of more or less unsurveyed regions. Information of interest 

 to geographers and travelers, collected by the observers, has been 

 furnished freely by various persons and organizations upon request. 



OBSERVATORY WORK. 



Watheroo Magnetic Observatory, Western Australia. — ^As stated in 

 the annual report of last year, the continuous photographic registration 

 of the manifold changes experienced in the Earth's magnetic field 

 during the day and year was begun on January 1, 1919. Since then 

 this important work has been uninterruptedly in progress ; the results 

 are pro\ing of such value as to justify amply the choice of location, 

 which, it may be of interest to note, is almost antipodal to Washington. 

 The remarkably brilliant display of the aurora borealis witnessed at 

 Washington and elsewhere on March 22, 1920, it was found had its 

 counteipart at the Watheroo Observatory as the aurora austrahs. 

 Mr. Edward Kidson assumed full charge of the observatory early in 

 November 1919, after Mr. WaUis's departure for Washington. (For 

 details of work accomphshed and results obtained see pp. 295 and 

 318.) The erection of the structures required for the observational 

 work in terrestrial electricity (atmospheric electricity and earth cur- 

 rents) has had to be deferred until 1921. 



Huancayo Magnetic Observatory, Peru. — In spite of delays of various 

 kinds and difficult conditions, excellent progress has been made in 

 the erection of the various observatory buildings, under the immediate 

 charge of Dr. H. M. W. Edmonds, assisted by Mr. Albert Smith as 

 foreman-carpenter. The observatoiy site of about 25.5 acres has an 

 elevation above sea-level approximately 11,000 feet and is about 

 125 miles east of Lima. It is hoped that observational work may be 

 begun about the middle of 1921. (For details, see pp. 294 and 296.) 



Washington, District of Columbia. — ^The required standardizations 

 of magnetic instruments have been made from time to time in the 

 Standardizing Magnetic Observatory (see p. 302). For an account 

 of the atmospheric-electric work in the deck observatory, see p. 308. 



Miscellaneous. — Matters relating to the stmctural and observational 

 work at Watheroo and Huancayo, which received attention at Wash- 

 ington, are briefly stated on page 297. 



