nd a considerable part of
Hudson's Bay. While the iso-dynamic lines of 1-85/100, and 1-875/1000, are
smaller ovals, included within the former. Such, at least, is the present
belief from such investigations as have been made. (See an article by
Professor Loomis, American Journal of Science, new series, vol. iv. p.
192.)

Our subject demands a still closer examination of the elements of
magnetism and its associated electricities, and their influence upon
climate and the atmosphere with a view to the solution of the questions in
hand, and we will pursue the inquiry in the present chapter.

Waiving, for the present, any further notice of the fact that the
counter-trades are concentrated over, and contiguous to, this area of
intensity, for the purpose of examining the magnetic phenomena
independently, and intending to return to a consideration of their
connection with it, we observe:--That it is now well settled that the
iso-geothermal lines, or lines of equal terrestrial heat, are coincident,
or nearly so, with the lines of equal magnetic intensity. The points where
the magnetic intensity is at a minimum, on the magnetic meridian, are the
warmest points of that meridian, and those where it is most intense, the
coldest.

The magnetic elements of a place may be computed from its thermal ones.
The laws producing or governing the distribution of one, have an intimate
physical relation with those producing or governing the other. Professor
Norton ably sums up a discussion of the subject (in the American Journal
of Science for September, 1847), omitting the theoretic propositions, as
follows:

"1. All the magnetic elements of any place on the earth may be
deduced from the thermal elements of the same; and all the great
features of the distribution of the earth's magnetism may be
theoretically derived from certain prominent features in the
distribution of its heat.

"2. Of the magnetic elements, the horizontal intensity is nearly
proportional to the mean temperature, as measured by Fahrenheit's
thermometer; the vertical intensity is nearly proportional to the
difference between the mean temperatures, at two points situated at
equal distances north and south of the place, in a direction
perpendicular to the iso-geothermal line; and, in general, the
direction of the needle is nearly at right angles to the
iso-geothermal line, while the precise course of the infl