Meanwhile an investigation of a totally different character, and conducted by totally different means, 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, Göttingen 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 Göttingen 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 Göttingen 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 daily variation that Lamont found to increase and diminish once in every 10-1/3 years.
