Resume in this Number of the Contributions the discussion and coordination of the observations of the Antarctic Magnetic Survey executed by Her Majesty’s Ships ‘Erebus’ and ‘Terror,’ under the direction of Sir James Clark Ross, R. N., aided by Captain Francis Rawdon Crozier, R. N., between the years 1839 and 1843. I purpose in the present communication to complete the detailed exposition of the Survey by the reduction of the observations of the three magnetic elements in its concluding year, on the same general plan on which similar accounts were given of those of the preceding years in earlier communications, viz., between the Cape of Good Hope and Hobarton in 1840, and between the departure from Hobarton in November 1840, and the return to the same station in April 1841, in No. V. (Philosophical Transactions, 1843, Art. X ) ; and between Hobarton in July 1841 and the Falkland Islands in April 1842 in No. VI. (Philosophical Transactions, 1844, Art. VII.). The observations discussed in the present memoir are those made from the departure from the Falkland Islands in September 1842 to the second arrival at the Cape of Good Hope in April 1843. In a subsequent and concluding memoir, which I hope to present to the Society early in the ensuing session, it will be my endeavour to connect and thoroughly coordinate the several portions of the Survey, comprising in its three portions the circumnavigation of the Southern Ocean from the departure from the Cape of Good Hope in March 1840, to the return of the ships to the same station in April 1843.
XX. Contributions to terrestrial magnetism.-no. x