The determination of the position of the Magnetic Poles of the earth has ever been considered a desideratum in the science of magnetism, of the highest importance; and the observations and experiments of the most ingenious and learned philosophers have universally been applied to the solution of this difficult and perplexing problem. Vague and unsatisfactory, however, were the results of the researches and calculations of the most indefatigable and zealous promoters of that science, arising, doubtless, in a great measure, from the discordant observations upon which they were founded,— a discordance which was considered to arise chiefly from the unequal distribution of the magnetic substances contained in the earth, and also from the great distances at which the observations were made from the centres of the powers of those magnetic substances, or, in other words, from the magnetic foci, or poles, of the earth. The primary cause of magnetic phenomena has always been, and still is, one of the secrets of nature, although several of the laws of magnetism have of late years been gradually developed: and during our absence from England, a greater step perhaps than any former one has been made, through the indefatigable research of Dr. Faraday, by his splendid and convincing proofs of its complete identity with electricity. Still much remains to be accomplished relative to terrestrial magnetism; and accurate observations with good instruments, as near the magnetic poles as possible, and in various directions from them, were long considered amongst the desiderata for completing the magnetic theory of the globe.