Containing a Magnetic Survey of a considerable portion of the North American Continent.
From the moment that the fact was known, that the locality of the maximum of the magnetic Force in a hemisphere is not coincident, as was previously supposed, with the locality where the dip of the needle is 90°, researches in terrestrial magnetism assumed an interest and importance greatly exceeding that which they before possessed; for it was obvious that the hypothesis which then generally prevailed regarding the distribution of the magnetic Force at the surface of the globe, and which had been based on a too-limited induction, was erroneous, and that even the broad out line of the general view of terrestrial magnetism had to be recast. The observations on which this discovery rested, (being those which I had had an opportunity of making in 1818, 1819 and 1820 within the Arctic Circle, and at New York in 1822,) were published in 1825*; they constituted, I may be permitted to say, an important feature in the views, which led the British Association in the year 1835 to request that a report should be prepared, in which the state of our knowledge in respect to the variations of the magnetic Force at different parts of the earth’s surface should be reviewed, and, as is customary in the reports presented to that very useful institution, that those measures should be pointed out which appeared most desirable for the advancement of this branch of science. In the maps attached to the report, the isodynamic lines on the surface of the globe were drawn simply in conformity with observations, and unmixed with hypothesis of any sort. The observations collected for that purpose were not those of any particular individual or of any single nation, but embodied the results obtained by all persons who up to that period had taken part in such researches, subjected to such amount of discussion only as conveyed a knowledge of the modes of observation severally employed, and reduced the whole to a common unit.
J.E. Bernier’s Claims to Fame