made to them. Dr Halley's works, distinct, were numerous, and his papers in the Philosophical transactions, still more so. found from volume xi. to volume lx.

Abraham Sharp.

BORN CIRC. A. D. 1651.-DIED A. d. 1742.

They are to be

THIS distinguished mathematician and astronomer was born at Ltle-Horton, near Bradford, in Yorkshire, about the middle of the 17t century. His father was nearly related to Archbishop Sharp. His mother was a sister of the celebrated nonconformist divine, David Clarsson. Abraham was at first apprenticed to a merchant at Manchester; but, on his discovering a decided taste and bent for mathematical studies, his master consented to release him from his indenture. I early life we find him supporting himself by keeping a school for writing and accounts in Liverpool. His spare hours at this time were exclusively devoted to the pursuit of his favourite science. An accidents. circumstance having introduced him to a London merchant then visiting Liverpool, in whose house the astronomer Flamsteed then resided. young Sharp, in the hope of gaining the acquaintance of so great a man, eagerly embraced the merchant's offer to take him to London in the capacity of a clerk. Having been thus introduced to Flamsteed, the astronomer soon discovered the merits and acquisitions of the young mathematician. and engaged his assistance in completing and arranging the astronomical apparatus of the Royal observatory at Greenwich. In this situation he assisted the astronomer royal in his observations on the meridional zenith distances of the heavenly bodies, also in making a catalogue of the fixed stars. The tables in the second volume of the Historia Cœlestis' were principally drawn up by Mr Sharp, together with the explanatory charts and drawings annexed, and which, though engraved by a superior artist in Amsterdam, were much exceeded in elegance and graphic beauty by the originals furnished by Mr Sharp. These exertions, however, soon told upon a constitution at no time strong; and Sharp was compelled to retire to his own house at Horton, where he fitted up an observatory of his own. His mechanical skill was nowise inferior to his mathematical; for most of his instruments were of his own constructing, and even the lenses of his telescopes, as well as the exterior parts, were prepared and adjusted by himself.

In 1699 Mr Sharp, for his own amusement, undertook an approximation to the quadrature of the circle deduced from two different series. which he proved to seventy-two places of figures. Mr Smeaton regards Mr Sharp as the first person that brought the hand-division of mathematical instruments to any degree of perfection. The celebrated mural arc, erected by Flamsteed at Greenwich, owed its superiority over ali other instruments of the kind which had yet been produced, chiefly to the accurate hand of Mr Sharp. His accuracy and application as a computer rendered him for many years the constant resource of Mr Flamsteed, Sir Jonas Moore, Dr Halley, and others, in all sorts of

Phil. Trans. for the year 1786.

troublesome and delicate calculations. He also numbered among his correspondents Sir Isaac Newton, Mr Wallis, Mr Hodgson, and Mr Sherwin. Mr Sharp, although he had come to the possession of a patrimonial estate which greatly removed him above want, led a very retired life at Horton. He was a bachelor himself, and the only company which he solicited was that of his pastor Oliver Heywood, and another pious friend who lived in the neighbourhood. He was remarkably abstemious in his habits; and would sometimes continue his calculations for whole days without tasting food. He was a man of sincere piety, and remarkable for his strict observance of religious duties. He died on the 18th of July, 1742.

END OF VOL. IV.

GLASGOW:

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