56 Land Magnetic Observations, 1905-10 



regions; it is the hope that with the effective cooperation of the existing magnetic 

 institutions, sufficient data on land and ocean will be available to make possible 

 some time after 1913 the construction of new magnetic charts for the epoch 1910. 

 The total number of different stations occupied during the six years' work embraced 

 in the present publication and as shown by Table 5 is 1298, of which 69, however, 

 have been reoccupied more than once in order to obtain secular variation data; 

 thus the total number of actual occupations of primary points has been 1391. 

 Furthermore, more or less extensive magnetic observations were made at over 100 

 auxiliary stations, some of which were established in connection with standardi- 

 zations or determination of instrumental constants; most of them, however, were 

 for the purpose of investigations of local disturbances thus there were about 80 

 of these in the Bermudas and about 25 in the vicinity of the local magnetic pole 

 near Treadwell, Alaska. The grand total of occupations of magnetic stations on 

 land between 1905 and 1910 was, accordingly, about 1500, or on the average, 

 about 250 per annum. Out of the total number there are but 102 for which, owing 

 to some reason, the magnetic observations were not quite complete; that is to say, 

 not all three elements were secured. These were chiefly secondary or auxiliary 

 stations, the element most generally lacking being, of course, the declination because 

 of failure to secure azimuth determinations on account of overcast skies. 



In addition to the 69 C. I. W. secular variation stations, there were re-occupied 

 about 125 other points at which the magnetic elements had been observed pre- 

 viously by other organizations or observers, thus not onlj' furnishing additional 

 secular variation data, but also the data required if use is to be made of previous 

 magnetic operations. It is the endeavor to secure secular variation and correlation 

 data at about 10 to 20 per cent of the points occupied each year. Thus the distri- 

 bution and the secular variation work are being prosecuted together. Twenty- 

 three of the stations have been at magnetic observatories very widely scattered 

 over the Earth from which the data for correlation of magnetic standards of all 

 countries have been obtained. 



It may also be mentioned that in cooperation with other organizations, in 

 particular with governmental institutions in Mexico and in Canada, the Depart- 

 ment has furnished instrumental and other assistance and has thus aided in the 

 securing of magnetic data which will be published by the respective institutions 

 concerned. Thus, for example, a cooperative arrangement was entered into in 

 1908 with the Canadian Department of Marine and Fisheries for securing magnetic 

 and allied observations on an eighteen months' cruise of the Arctic (formerly the 

 GaM55), commanded by Capt. J. E. Bernier, to Baffin Land, Davis Strait, Lancaster 

 Sound, Barrow Strait, and Melville Sound. The Department supplied the outfit 

 of magnetic and electric instruments, gave such additional training to the observer 

 of the Canadian Meteorological Service, Mr. W. E. W. Jackson, at Washington, 

 as he required, and furnished all necessary observation forms and data, as also 

 full directions for the work, which was confined chiefly to work ashore and on 

 the ice. 



