246 ANNUAL REPORT SMITHSONIAl^ INSTITUTION, 1925 



AVliile ill charge of the magnetic work of the Coast and Geodetic 

 Survey, liauer had satisfied liimself of the feasibility of making; mafj- 

 netic observations at sea Avith nearly the same accuracy as on land, 

 if a suitable vessel could be obtained. His plan for the Avorld survey, 

 therefore, included j)rovisi()n for a magnetic survey of the ocean 

 areas by means of a non-magnetic vessel. This work at sea was car- 

 ried on successfully from 1905 to 1921, first on the Galilee^ a chartered 

 sailing vessel, and later on the Caimegie, a sailing vessel with 

 auxiliary power, built for the purpose so nearly free of magnetic 

 material as to practically eliminate the need of taking account of 

 deviation corrections. 



While this worlc* at sea was carried on primarily for scientific 

 purposes, it had great immediate practical value in that it provided 

 the means for correcting the existing world isogonic charts, which 

 were found to be seriously in error because of the insufficient data 

 on which they Avere based. 



At the same time magnetic observers were sent to nearly all ac- 

 cessible regions Avhere magnetic surA^eys Avere not being made under 

 other auspices and to some regions usually thought of as inaccessible. 

 Asia, Africa, South America, Central America, Mexico, were all the 

 field of these far-reaching operations. In some instances, as in 

 Canada, one season's Avork by an observer of the Department of Ter- 

 restrial Magnetism of the Cainegie Institution of Washington Avas 

 sufficient to stimulate local interest to a point where means Averc 

 provided for continuing the work under local auspices. Advantage 

 was taken of these Avorld-Avide traAels to secure comparisons of in- 

 struments with the standards of the A^arious magnetic observatories 

 and other agencies engaged in making magnetic surveys, thus insur- 

 ing a greater homogeneity of results, in some cases calling attention 

 to defective instruments and in general emphasizing the importance 

 of better instruments and methods. 



Some idea of the magnitude of the Avork done in this Avorld mag- 

 netic surA'Cy may be gained from the statement that it covered all 

 the ocean areas from latitude 70° north to 60° south, nearly all of 

 the land areas from 30° north to 60° south, excepting India and the 

 Dutch East Indies, and in addition parts of China, Persia, and 

 Canada. 



During the same period gOA'^ernmental magnetic surveys have been 

 made in India, New Zealand, Dutch East Indies, South Africa, 

 Canada, and Russia (including Siberia), and resurA^eys haA^e been 

 made of Japan and the British Islands, and in France, Prussia, 

 and other European countries. Thus it Avill be seen that during the 

 ])ast 2.5 years there has been executed a Avorld magnetic survey 



