13 



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 dilference 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 elfect 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 Woods, an operation in the execution 

 of which both he and the party who assisted him suffered the great- 

 est hardships and privations. He published various reports of his 

 surveys, and was necessarily much employed and consulted in the 

 difficult and embarrassing negotiations which have attended, and 

 unhappily still attend, the settlement of the important question of 

 the North American 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 veiy careful and 

 efficient practical astronomer, and admirably qualified for the very 

 important and responsible duties which he was appointed to dis- 

 charge. 



Dr. Edward Turner was a native of Jamaica, and studied medi- 

 cine at Edinburgh, and chemistry at Gdttingen 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 iji the London University at its first establishment in 

 1 828, 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 clearness 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 Weights," 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 1 835 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, and he died in February last, in the fortieth year of 

 . his age, to the deep regret of every friend of the progress of chemi- 



