JVIAGNETIC SURVEY OF THE OCEANS 



55 



effects of smoke and exhaust gases. Furthermore, 

 it would be necessary to repeat such work and 

 control of such conditions on many vessels in order 

 to accomplish the requisite distribution of observa- 

 tions over the oceans. Despite the considerable 

 expense that would be incurred, the accumulated 

 data would be subject to many uncertainties and 

 would involve an expenditure of time for reductions 

 in the office out of all proportion to that required 

 were there a survey-vessel available. 



Because of the great desirability of continuing the 

 operation conducted for a quarter-century by the 

 vessels of the Carnegie Institution of Washington, 



in certain regions been determined. One of the first 

 tasks, therefore, of the Research will be the repeti- 

 tion of the observations of the Carnegie in these 

 regions to determine the secular change so that 

 the isogonic charts may be corrected to date and 

 prepared for succeeding epochs. This vessel is to 

 be of the same beam as the Carnegie and .slightly 

 greater overall length. The proposed instrumental 

 equipment will parallel closely that used on the 

 Carnegie as it has not appeared advisable to depart 

 from designs gradually evolved from the experience 

 of many years of observational work at sea. 



With the completion of the Research and its 



Fig. 8. Showing Oceanic Areas (Shaded) between Parallels of 60° North and South Latitude for Which Secular 

 Variation op Magnetic Elements Could Not be Controlled by Land Stations 



ON Continents and Islands 



it is gratifying that, in view of the Institution's 

 decision not to replace the Carnegie by a similar 

 vessel, the British Admiralty has designed and in 

 September 1936 placed a contract to build a non- 

 magnetic vessel, to be named Research. The 

 chief reason for this action on the part of Great 

 Britain was found in her world-wide maritime in- 

 terests. Magnetic charts published for the last 

 two decades by the American, British, French, 

 German, and other governments for use at sea have 

 been based in an increasingly large degree upon data 

 obtained by the Carnegie. There are now serious 

 gaps in the present data which would have been 

 filled had the Carnegie completed her last cruise 

 and had the rapid change in the secular variation 



continuation of the oceanic survey we may look 

 forward to further advance of geophysical research. 

 Not only will the resulting additional observations 

 increase the opportunities of geophysical investiga- 

 tions but they will enhance the value of the earlier 

 data. 



The task of the geophysical survey of the oceans 

 is so great that other hydrographic services of mari- 

 time nations should be stimulated by the action 

 of the British Admiralty to provide similar vessels 

 wath equipment and personnel to take their appro- 

 priate share in the execution and in the coordination 

 of such service. Resolutions adopted after thor- 

 ough discussions by the Commission of Terrestrial 

 Magnetism and Atmospheric Electricity of the Inter- 



