Observers' Field Reports 109 



e. kidson, on the general magnetic survey of australia, 1911 to 1913. 



The general magnetic survey of Australia, which will be practically completed by the 

 enn of 1914, was begun the middle of July 1911, the plan followed being that contained in 

 the Director's instructions of June 21, 1911, and subsequent supplementary ones. Quoting 

 from the Director's article in the September 1911 issue of Terrestrial Magnetism and Atmos- 

 pheric Electricity, page 215: 



"Australia is at present (1911) the largest land area in which so comparatively few magnetic 

 observations have been made. With the exception of the portion of Victoria, of which a magnetic 

 survey embracing aljout 2.35 points was carried out by the indefatigable Neumayer, between 18.58 

 and 1864, the preliminary magnetic survey of Tasmania by McAulay and Hogg in 1901, and some 

 isolated observations along the coasts, such magnetic results as exist in the interior are confined, well- 

 nigh exclusively, to compass observations by survej''ors. 



"If it be remembered that the total area involved is over three-fourths that of entire Europe, and 

 is practically equal to that of the United States (exclusive of Alaska) , it ^vill readily be appreciated 

 that there remains here an important field for magnetic exploration. And the importance does not 

 arise merely from purely scientific considerations, but from practical ones as well navigation, sur- 

 vej'ing, and exploration of the great interior reaches. The prevalence of local disturbances at some 

 of the ports of call is well known, and mention should be made here of the remarkable local disturb- 

 ances revealed at Port Walcott on the northwest coast, by the admirable work of H. M. S. Penguin, 

 1890-93." 



As the result of the Director's conferences with various government officials and men 

 of science at Sydney, Melbourne, Adelaide, and Perth, in May and June 1911, the much 

 desired general magnetic survey of Australia was organized, the Melbourne Magnetic 

 Observatory, under the direction of Professor Baracchi, serving as the principal base-station 

 throughout. The wTiter, at Colombo, Ceylon, on .June 21, 1911, was relieved of ocean 

 dutj' aboard the Carnegie, and was placed by the Director in charge of the proposed survey, 

 serving throughout the work in this capacity. The total expenses of the work have been 

 borne by the Department of Terrestrial Magnetism of the Carnegie Institution of Washing- 

 ton. The cordial assistance received at all times from government authorities and from 

 others too niunerous to mention by name, deserves mention and is here gratefully and 

 appreciatively acknowledged. The thanks of the Department are especially due Professor 

 Baracchi for looking after the forwarding of the mail to the observers in the field and for 

 facilitating the work in many ways. 



The general plan was for the Department of Terrestrial Magnetism to observe the 

 magnetic elements, with every precision possible, at stations spaced, on the average, about 

 100 miles apart, i. e., about 1 station to every 10,000 square miles. As the area of Australia 

 and outlying possessions is practically 3,000,000 square miles, a general magnetic survey 

 would impl}' 300 stations; there were 394 different stations at the end of 1914. Up to the 

 end of 1913 there had already been 247 stations; during 1914, 3 additional observers were 

 assigned, so that 4 parties could be put in the field. The detailed work, it is hoped, will 

 be undertaken by the Commonwealth itself or by interested persons. 



It is not necessary in this general report to enumerate the stations up to the end of 

 1913, since they will all be found tabulated in the "Table of Results, pp. 36-^2." A 

 summary of preliminary ^-alues of the magnetic elements was presented before the Aus- 

 tralasian Association for the Advancement of Science at the January 1913 meeting in 

 Melbourne and printed in the Report of the Association, Vol. XIV, pp. 20-23. 



Those, besides myself, engaged in the work here described, were: E. N. Webb, tem- 

 porar>- observer, July to October 1911; F. W. Cox, assistant observer. May 1912 to Feb- 

 ruary 1913; F. Brown, assistant observer, July to December 1913. 



The distribution of the instrumental outfits used during the several years is indicated 

 in the following paragraphs. 



