had been prosecuted to a very
similar conclusion. Two years after Schwabe began his solitary
observations, Humboldt gave the first impulse, at the Scientific
Congress of Berlin in 1828, to a great international movement for
attacking simultaneously, in various parts of the globe, the complex
problem of terrestrial magnetism. Through the genius and energy of
Gauss, Gottingen became its centre. Thence new apparatus, and a new
system for its employment, issued; there, in 1833, the first regular
magnetic observatory was founded, whilst at Gottingen was fixed the
universal time-standard for magnetic observations. A letter addressed by
Humboldt in April, 1836, to the Duke of Sussex as President of the Royal
Society, enlisted the co-operation of England. A network of magnetic
stations was spread all over the British dominions, from Canada to Van
Diemen's Land; measures were concerted with foreign authorities, and an
expedition was fitted out, under the able command of Captain (afterwards
Sir James) Clark Ross, for the special purpose of bringing intelligence
on the subject from the dismal neighbourhood of the South Pole. In 1841,
the elaborate organisation created by the disinterested efforts of
scientific "agitators" was complete; Gauss's "magnetometers" were
vibrating under the view of attentive observers in five continents, and
simultaneous results began to be recorded.

Ten years later, in September, 1851, Dr. John Lamont, the Scotch
director of the Munich Observatory, in reviewing the magnetic
observations made at Gottingen and Munich from 1835 to 1850, perceived
with some surprise that they gave unmistakable indications of a period
which he estimated at 10-1/3 years.[356] The manner in which this
periodicity manifested itself requires a word of explanation. The
observations in question referred to what is called the "declination" of
the magnetic needle--that is, to the position assumed by it with
reference to the points of the compass when moving freely in a
horizontal plane. Now this position--as was discovered by Graham in
1722--is subject to a small daily fluctuation, attaining its maximum
towards the east about 8 A.M., and its maximum towards the west shortly
before 2 P.M. In other words, the direction of the needle approaches (in
these countries at the present time) nearest to the true north some four
hours before noon, and departs farthest from it between one and two
hours after noon. It was the _range_ of this da