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Rh the authority of the Treaty of Ghent. After his return to England, in 1822, he was commissioned by the Admiralty, at the request of the Board of Longitude, to ascertain, by means of a great number of chronometers, the difference of the longitudes of Falmouth and Madeira, and subsequently of Falmouth and Dover, the results of which were detailed in a very able paper in our Transactions for 1824-, in which he pointed out and explained the origin of an error of nearly 4” of time in the longitudes of all the stations of the Tri- gonometrical Survey. He was afterwards sent on a similar mission to Heligoland and various stations in the North Seas, and on the last occasion he was accompanied by Sir Humphry Davy, who Wished to try the efiect of his protectors on the corrosion of the copper sheathing of ships. In 1825 he was recalled from Germany to resume his astronomical surveys in America, Where he was em- ployed to ascertain the position and extent of the north-western boundary of the Lake of the “'oods, an operation in the execution ot'which both he and the party who assisted him suEered the great— est hardships and privations. He published various reports of his surveys, and was necessarily much employed and consulted in the diﬂicult and embarrassing negotiations which have attended, and unhappin still attend, the settlement of the important question of the North Amencan boundaries. Dr. Tiarks died in the forty- eighth year of age, at his native place, in consequence of a fever which attacked a constitution already shattered and broken by the severe labours and privations which he had endured. He was a mathematician of no inconsiderable attainments, a very careful and eiﬁcient practical astronomer, and admirably qualiﬁed for the very important and responsible duties which he was appointed to dis- charge.

Dr. Edward Tumer was a native of Jamaica, and studied medi— cine at Edinburgh, and Chemistry at Go'ttingen under the instruc- tions of the celebrated analytic chemist Stromeyer. He became a lecturer on chemistry at Edinburgh in 1824, and his ﬁrst publica- tion was a short introduction to the study of the laws of chemical combination and the atomic theory. He obtained the Professorship of Chemistry in the London University at its ﬁrst establishment in 1828, a situation which he continued to hold to the end of his life. His Elements of Chemistry have enjoyed an uncommon degree of popularity, and are remarkable for cleamess and precision both in the description of his experiments and in the deduction of his theory. He was the author of two papers in our Transactions; the ﬁrst “ On the Composition of the Chloride of Barium,” and the second containing “ Researches on Atomic “'eights,” both written with a View of impugning the theory which had been promulgated by some English chemists of high authority, “that all atomic weights are simple multiples of that of hydrogen." In the year 1835 Dr. Turner was compelled by the declining state of his health to suspend all original researches, conﬁning himself simply to the duties of his professorship, aud he died in February last, in the fortieth year of

_ his age, to the deep regret of every friend of we progress of chemi—