TERRESTRIAL MAGNETISM 179 



The recent development of the organisation has 

 been in the way of making the observations more 

 uniform and accurate, and of applying them to the 

 elucidation of problems of distribution which are of 

 equal scientific and economic importance. 1 Steps 

 were taken in 1910 by Dr. H. R. Mill, who had 

 conducted the organisation since 1901, to establish 

 it on a permanent basis as a voluntary scientific 

 institution under the control of trustees ; but in 

 1919 the failure of his health, and circumstances 

 arising from the war, led the trustees to transfer the 

 organisation to the Meteorological Office, so that it 

 now forms an integral part of the meteorological 

 service of the country, while continuing to make full 

 use of the voluntary labours of the army of observers. 



TERRESTRIAL MAGNETISM 



The study of terrestrial magnetism has been 

 fostered in so many directions by the Association 

 that the references to this subject in the list of grants 

 in Appendix I form insufficient evidence by them- 

 selves, and (at the risk of a little repetition) it is 

 appropriate here to review the whole matter. So 

 far as the following statement applies to events down 

 to 1858, it is an abridgment of a report to the 

 Council by Sabine in 1859. 



The first occurrence, it is believed, of a survey 

 being undertaken for the express purpose of determin- 

 ing the positions and values of the isomagnetic lines 

 of declination, dip, and force corresponding to a 

 particular epoch over the whole face of a country 

 or state, was the magnetic survey of the British 



1 Dr. H. R. Mill. 



