a, and Hudson's Bay
Companies. But the chart was far from satisfactory, and, in consequence of
the discordant nature of the observations, no dependence could be placed
on it.

No further steps were taken to ascertain the magnetism of the earth until
the close of the last century, when the French government undertook the
first comprehensive experimental inquiry on the subject. When the
exploring expedition of La Perouse was organized, the French Academy of
Sciences prepared instructions for the expedition, containing a
recommendation that observations with the dipping-needle should be made at
stations widely remote, as a test of the equality or difference of the
magnetic intensity; suggesting also, with a sagacity anticipating the
result, that such observations should particularly be made at those parts
of the earth where the dip was greatest, and where it was least. The
experiments, whatever their results may have been, which, in compliance
with this recommendation, were made in the expedition of La Perouse,
perished in its general catastrophe, neither ships nor navigators having
ever been heard of; but the instructions survived.

Our knowledge of the laws of magnetism was not increased until 1811, when,
on the occasion of a prize proposed by the Royal Danish Academy, M.
Hansteen, whose attention had for many years been turned to magnetic
phenomena, undertook its re-examination. With indefatigable labor M.
Hansteen traced back the history of the subject, and filled up the
interval from Halley's time, and even from an earlier epoch (1600). The
results appeared in his very remarkable and celebrated work, published in
1819, entitled, "Upon the Magnetism of the Earth;" in which he clearly
demonstrates, by a great number of facts, the fluctuation which the
magnetical element has undergone during the last two centuries, confirming
in great detail the position of Halley--that the whole magnetical system is
in motion; that the moving force is very great, extending its effects from
pole to pole; and its that motion is not sudden, but gradual and regular.

In the magnetic atlas which accompanies M. Hansteen's work there is a
variation chart for 1787, showing the magnetic force at that period. In
this chart the western line of no variation, or that which passes through
all places on the globe when the needle points to the true north, begins
in latitude 60 deg. to the west of Hudson's Bay; proceeds in a southeast
direction throug