the points of feeblest intensity (Sabine, in the Phil. Transact. for 1846, pt. iii, p. 254, and in the Manual of Scient. Inquiry for the use of the British Navy, 1849, p. 17).

1828-1829. The voyage of Hansteen and Due: Magnetic observations in European Russia and in Eastern Siberia as far as Irkutsk.

1828-1830. Adolf Erman's voyage of circumnavigation, with his journey through Northern Asia, and his passage across both oceans, in the Russian frigate Krotkoi. The identity of the instruments employed, the uniformity of the methods and the exactness of the astronomical determinations of position will impart a permanent scientific reputation to this expedition, which was equipped at the expense of a private individual, and conducted by a thoroughly wellinformed and skilful observer. See the general declination Chart, based upon Erman's observations in the Report of the Committee relat. to the Arctic Expedition, 1840, pl. 3.

1828-1829. Humboldt's continuation of the observations begun in 1800 and 1807, at the time of the solstices and equinoxes regarding horary declination and the epochs of extraordinary perturbations, carried on in a magnetic pavilion specially erected for the purpose at Berlin, and provided with one of Gambey's compasses. Corresponding measurements were made at St. Petersburgh, Nikolajew, and in the mines of Freiberg, by Professor Reich, 227 feet below the surface of the soil. Dove and Riess continued these observations in reference to the variation and intensity of the horizontal magnetic force till November 1830 (Poggend. Annalen. Bd. xv, s. 318-336; Bd. xix, s. 375-391, with 16 tab.; Bd. xx, s. 545–555).

1829-1834. The botanist David Douglas, who met his death in Owhyhee, by falling into a trap in which a wild bull had previously been caught, made an admirable series of de Humboldt's original station in South America has been inferred to be 1.372 to 1.000. This is the origin of the number 1.372, which has been generally employed by British observers. By absolute measurements we are not only enabled to compare numerically with one another the results of experiments made in the most distant parts of the globe, with apparatus not previously compared, but we also furnish the means of comparing hereafter the intensity which exists at the present epoch, with that which may be found at future periods." Sabine, in the Manual for the use of the British Navy, 1849, p. 17.

observations on declination and intensity along the northwest coast of America, and upon the Sandwich Islands as far as the margin of the crater of Kiraueah (Sabine, Rep. of the Meeting of the British Association at Liverpool, pp. 27 -32).

1829. Kupffer, Voyage au Mont Elbrouz dans le Caucase, pp. 68-115.

1829. Humboldt's magnetic observations on terrestrial magnetism with the simultaneous astronomical determinations of position in an expedition in Northern Asia undertaken by command of the Emperor Nicholas, between the longitudes 11° 3′ and 80° 12′ east of Paris, near the Lake Dzaisan as well as between the latitudes of 45° 43′ (the island of Birutschicassa in the Caspian Sea) to 58° 52' in the northern parts of the Ural district near Werchoturie (Asie Centrale, t. iii, pp. 440-478).

1829. The Imperial Academy of Sciences at St. Petersburgh, acceded to Humboldt's suggestion for the establishment of magnetic and meteorological stations in the different climatic zones of European and Asiatic Russia, as well as for the erection of a physical central observatory in the capital of the empire under the efficient scientific direction of Professor Kupffer. (See Cosmos, vol. i, p. 184. Kupffer Rapport adressé à l'Acad. de St. Pétersbourg relatif à l'Observatoire physique central, fondé auprès du Corps des Mines, in Schum. Astr. Nachr. No. 726; and in his Annales Magnétiques, p. xi) Through the continued patronage, which the Finance Minister, Count Cancrin, has awarded to every great scientific undertaking, a portion of the simultaneously corresponding observations 72 between the White Sea and

72 The first idea of the utility of a systematic and simultaneously conducted series of magnetic observations is due to Celsius, and, without referring to the discovery and measurement of the influence of polar light on magnetic variation, which was, in fact, due to his assistant, Olav Hiörter (March, 1741), we may mention that he was the means of inducing Graham, in the summer of 1741, to join him in his investigations for discovering whether certain extraordinary perturbations, which had from time to time exerted a horary influence on the course of the magnetic needle at Upsala had also been observed at the same time by him in London. A simultaneity in the perturbations afforded a proof, he said, that the cause of these disturbances is extended over considerable portions of the earth's surface, and is not dependent upon accidental local actions (Celsius, in Svenska Veten

the Crimea, and between the Gulf of Finland and the shores of the Pacific in Russian America, were begun as early as 1832. A permanent magnetic station was established in the old monastery at Pekin, which, from time to time since the reign of Peter the Great, has been inhabited by monks of the Greek Church. The learned astronomer, Fuss, who took the principal part in the measurements for the determination of the difference of level between the Caspian and the Black Sea was chosen to arrange the first magnetic establishments in China. At a subsequent period Kupffer in his voyage of circumnavigation compared together all the instruments that had been employed in the magnetic and meteorological stations as far east as Nertschinsk in 119° 36′ longitude, and with the fundamental standards. The magnetic observations of Fedorow, in Siberia, which are no doubt highly valuable, are still unpublished.

1830-1845. Colonel Graham of the topographical engineers of the United States, made observations on the magnetic intensity at the southern boundary of Canada (Phil. Transact. for 1846, pt. iii, p. 242).

1830. Fuss, Magnetic, Astronomical, and Hypsometrical Observations on the journey from the Lake of Baikal, through Ergi-Oude, Durma, and the Gobi, which lies at an elevation of only 2525 feet, to Pekin, in order to establish the magnetic and meteorological observatory in that city, where Kovanko continued for 10 years to prosecute his observations (Rep. of the Seventh Meeting of the Brit. Assoc. 1837, pp. 497-499; and Humboldt, Asie Centrale, t. i, p. 8; t. ii, p. 141; t. iii, pp. 468, 477).

1831-1836. Captain Fitzroy in his voyage round the world in the Beagle, as well as in the survey of the coasts of the most southern portions of America, with a Gamskaps Academiens Handlingar för 1740, p. 44; Hiörter, op. cit. 1747, p. 27). As Arago had recognised that the magnetic perturbations owing to polar light are diffused over districts, in which the phenomena of light which accompany magnetic storms have not been seen, he devised a plan, by which he was enabled to carry on simultaneous horary observations (in 1823) with our common friend Kupffer, at Kasan, which lies almost 47° east of Paris. Similar simultaneous observations of declination were begun in 1828 by myself, in conjunction with Arago and Reich, at Berlin, Paris, and Freiberg (see Poggend. Annalen, Bd. xix, s. 337).

bey's inclinatorium and oscillation needles supplied by Han

steen.

1831. Dunlop, Director of the Observatory of Paramatta, Observations on a voyage to Australia (Phil. Transact. for 1840, pt. i, pp. 133-140).

1831. Faraday's induction-currents, whose theory has been extended by Nobili and Antinori. The great discovery of the development of light by magnets.

1833 and 1839 are the two important epochs of the first enunciation of the theoretical views of Gauss: (1) Intensitas vis magneticæ terrestris ad mensuram absolutam revocata, 1833; (p. 3: "elementum tertium, intensitas, usque ad tempora recentiora penitus neglectum mansit"); (2) the immortal work on "the general theory of terrestrial magnetism" (see Results of the observations of the Magnetic Association in the year 1838, edited by Gauss and Weber, 1839, pp. 1-57).

1833. Observations of Barlow on the attraction of the ship's iron, and the means of determining its deflecting action on the compass. Investigation of electro-magnetic currents in Terrellas. Isogonic atlases. Compare Barlow's Essay on Magnetic Attraction, 1833, p. 89, with Poisson, sur les déviations de la boussole produite par le fer des vaisseaux in the Mém de l'Institut, t. xvi, pp. 481-555; Airy, in the Phil. Transact. for 1839, pt. i, p. 167; and for 1843, pt. ii, p. 146; Sir James Ross, in the Phil. Transact. for 1849, pt. ii, pp. 177-195).

1833. Moser's methods of ascertaining the position and force of the variable magnetic pole (Poggend., Annalen, Bd. xxviii, s. 49-296).

1833. Christie on the Arctic observations of Captain Back. Phil. Transact. for 1836, pt. ii. p. 377 (Compare also his earlier and important treatise in the Phil. Transact. for 1825, pt. i. p. 23.)

1834. Parrot's expedition to Ararat (Magnetismus, bd. ii, s. 53-64).

1836. Major Estcourt, in the expedition of Colonel Chesney on the Euphrates. A portion of the observations on intensity were lost with the steamer Tigris, which is the more to be regretted since we are entirely deficient in accurate observations of this portion of the interior of

Western Asia, and of the regions lying south of the Caspian Sea.

1836. Letter from M. A. de Humboldt to H.R.H. Duke of Sussex, President of the Royal Society of London, on the proper means of improving our knowledge of terrestrial magnetism by the establishment of magnetic stations and corresponding observations (April 1836). On the happy results of this appeal, and its influence on the great Antarctic expedition of Sir James Ross, see Cosmos, vol. i, p. 136, and Sir James Ross's Voyage to the Southern and Antarctic Regions 1847, vol. i, pt. xii.

1837. Sabine, On the Variations of the Magnetic Intensity of the Earth in the Report of the Seventh Meeting of the British Association at Liverpool, pp. 1-85. The most complete work of the kind.

1837-1838. Erection of a magnetic observatory at Dublin, by Professor Humphrey Lloyd. On the observations made there from 1840 to 1846 (see Transact. of the Royal Irish Academy, vol. xxii. pt. i, pp. 74—96).

1837. Sir David Brewster, A Treatise on Magnetism, pp. 185-263.

1837-1842. Sir Edward Belcher's voyage to Singapore, the Chinese Seas, and the western coasts of America (Phil. Transact. for 1843, pt. ii, pp. 113, 140-142). These observations of inclination, when compared with my own, which were made at an earlier date, show a very unequal advance of the curves. Thus, for instance, in 1803, I found the inclinations at Acapulco, Guayaquil, and Callao de Lima to be +38° 48′, +10° 42, and -9° 54'; while Sir Edward Belcher found 37° 57', + 9° 1′, and — 9° 54'. Can the frequent earthquakes upon the Peruvian coasts exert a local influence upon the phenomena, which depend upon magnetic force of the earth ?

1838-1842. Charles Wilkes's Narrative of the United States' Exploring Expedition, vol. i, p. xxi.

1838. Lieutenant James Sullivan's Voyage from Falmouth to the Falkland Islands (Phil. Transact. for 1840, pt. i, pp. 129, 140-143).

1838 and 1839. The establishment of magnetic stations under the admirable superintendence of General Sabine in both hemispheres at the expense of the British Government.