OBSERVERS' FIELD REPORTS. 



The following reports, or extracts, will serve to give an idea of the conditions 

 under which the various magnetic surveys, chiefly executed during the period 

 January 1, 1911, to December 31, 1913, have been accomplished. The world-wide 

 scope of the operations is shown by the list of countries in which magnetic observa- 

 tions were made during this period. For various reasons, the reports can not always 

 be published in full as submitted by the observers; they frequently contain informa- 

 tion of special concern only to the Department of Terrestrial Magnetism. Then 

 again, as the observers write the reports themselves, they necessarily must minimize 

 their own particular achievements. However, sufficient has been retained under 

 each observer's report to give the reader ample opportunity to judge of the care, 

 skill, courage, and thoroughness with which the work intrusted to the observer was 

 executed. The reports are arranged alphabetically by observers' names. 



J. P. AuLT, ON Magnetic Work in Peru, Bolivia, and Chile, 

 March to August 1912. 



In accordance with instructions of February 27 and March 21, 1912, I left Washington, 

 D. C, for New Orleans on March 21, going by way of Baldwin, Kansas, in order to obtain 

 from Observer C. C. Stewart information regarding conditions in South American coun- 

 tries. Arriving in New Orleans March 28 and being joined the following day by Messrs. 

 Donald MacKenzie and H. R. Schmitt, who had been assigned as members of my party, 

 we sailed March 30 from New Orleans on the United Fruit Company's steamship Atenas. 



The following instrumental outfits were used by the party: J. P. Ault had universal 

 magnetometer No. 14 (with dip needles Nos. 1, 2, 5, and 6, and intensity needles Nos. 3, 4, 

 7, and 8), chronometer No. 677 and watch No. 100, and observing-tent No. 23 provided with 

 sod-cloth; Donald MacKenzie used magnetometer No. 16, dip circle No. 177 (with dip 

 needles Nos. 1, 2, 5, and 6 and intensity needles Nos. 3 and 4), pocket-chronometer Kittel 

 No. 257, and watches Nos. 804 and 811 in leather belt, and observing-tent No. 21 with sod- 

 cloth and hammock; H. R. Schmitt had magnetometer No. 8, dip circle No. 171 (with dip 

 needles Nos. 171.1, 171.2, 177.7, 177.8, and intensity needles Nos. 171.3 and 171.4), chrono- 

 meter No. 1044 andw^atch No. 53, and observing-tent No. 24 with sod-cloth and hammock. 



Upon arrival at Colon, Panama, on April 4, our magnetic station was reoccupied on 

 that day. The party sailed from Balboa for Callao on the Pacific Steam Navigation Com- 

 pany's steamship Guatemala on April 8, arriving at Callao and Lima, Peru, on April 15. 

 After two weeks spent in preliminary arrangements, instructions, and practice, Mr. Mac- 

 Kenzie left Lima on May 28 for Antofagasta and La Paz. After arriving at the latter place 

 on May 25, having established 3 complete and 2 incomplete stations, he resigned and returned 

 to his home. In the meanwhile arrangements were being made for the trip to Masisea on 

 the L^cayali River, and instructions and practice were given to Mr. Schmitt. I was planning 

 to make this trip myself, but, upon receipt of cabled advice from the Director, the plans 

 were changed and Mr. Schmitt was sent instead on May 20, while I accompanied him as 

 far as Tarma. LTpon arrival at La Merced on May 26 he found that chronometer No. 677 

 had stopped. He was instructed to return to Oroya, where 1 delivered to him on May 31 

 chronometer No. 1044. For an account of Mr. Schmitt's trip, see his separate report. 



In accordance wath cabled instructions received after my return from Oroya, I left 

 Lima on June 10 and arrived at La Paz on June 15 and took charge of Mr. MacKenzie's 



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