Besides the two observers of terrestrial magnetism to be supplied by the Coast Survey, there will be a physician fitted by education and habits of study to take charge of some scientific portion of the work, in which he will be specially instructed by the Superintendent of the Coast Survey or his assistant. There will also be three sailors selected from the whaling fleet, who will have charge of the three whale boats belonging to the outfit, and act as assistants to the several observers. The writer of this article, by reason of his experience in Arctic travel, will have charge of the expedition in all except the scientific work, the reports on which will be turned over directly to the officers of the United States Coast and Geodetic Survey for reduction and discussion upon the return of the party from the field.
The scheme of work has already been prepared by Professor Charles A. Schott, who is looked upon as probably the best informed on all the details of terrestrial magnetism of all men in this or any other country. In the course of his exhaustive report upon this subject he says: “The magnetic observations proper will comprise the measure of the three elements, the declination, the dip, and the intensity, which fully define the magnetic force at a place. The measures will be partly absolute and partly differential, and will be considered under two heads; those to be taken while travelling, and those to be attended to at winter quarters.” Detailed instructions for this work are given which are too technical to be interesting except to the specialist. He recommends that a single cocoon thread carrying a sewing needle shall be used to observe the declination where by proximity to the Magnetic Pole the horizontal force is weak. For it must be borne in mind that the Magnetic Pole is the point where the vertical force, called “dip,” is greatest—represented by 90°—while the horizontal force, called “declination,” is 0°.
DIAGRAM OF THE NORTH MAGNETIC POLE REGION.
The observations for dip, naturally the most important of the survey, will be made with a Kew Dip Circle employing two needles; the usual reversals of circle, face, and polarity should be attended to at each station, to place the instrument in the plane of the magnetic meridian. The usual method of finding the plane of the meridian will probably not answer in that part of the world for want of sufficient accuracy; the direction of the magnetic 162 meridian should, therefore, be taken as indicated by the delicately suspended needle of the declination instrument, and, where this method fails, dip observations should be made in any two planes 90° apart, of which the first plane is preferably that of the meridian as guessed at.
It is proposed to charter a steam whaler to take the party from St. John’s, Newfoundland, to the northern part of Repulse Bay, which, being directly connected with Hudson’s Bay, is the nearest point to the pole-containing area that is accessible any year. There a permanent station is to be erected where regular observations will be continued all the time and from which each spring a field party (perhaps two) will start to locate the geographical position of the pole.
PROFESSOR C. A. SCHOTT.