SHARP, Abraham, an eminent English mathematician and astronomer, was born at Little Horton, near Bradford, in the year 1651. He was put as apprentice to a merchant at Manchester; but so strongly was he inclined to the study of mathematics, that he soon found his situation both irksome and disagreeable. By the mutual consent, therefore, of his master and himself, he quitted the business of a merchant. He then removed to Liverpool, where he devoted himself wholly to mathematical studies, and where, for a subsistence, he taught writing and accounts.
Soon after this, a merchant from London, in whose house the celebrated Flamsteed then lodged, engaged Sharp to be his book-keeper. With this eminent astronomer he soon contracted an intimate friendship, and by his recommendation he obtained a more profitable employment in the dock-yard of Chatham, where he continued till his friend and patron called him to his assistance. Mr Sharp was chiefly employed in the construction of the mural arch, which he finished in the course of fourteen months, so entirely to the satisfaction of Flamsteed, that he spoke of him in terms of the highest praise. In the opinion of Smeaton, this was the first good instrument of the kind, and Sharp the first artist who cut delicate divisions on astronomical instruments. When this instrument was constructed, Sharp was but twenty-five and Flamsteed thirty years of age. Mr Sharp assisted his friend in making a catalogue of nearly three thousand fixed stars, with their longitudes and magnitudes, their right ascensions and polar distances, with the variations of the same while they change their longitude by one degree.
But, from the fatigue of constantly observing the stars by night in a cold thin air, added to a weakly constitution, his health was much impaired. For the recovery of it he requested leave to retire to his house at Horton, where, as soon as he felt himself recovering, he began to fit up an observatory of his own; and the telescopes he made use of were all of his own construction, and the lenses ground and adjusted with his own hands.
It was about this time that he assisted Flamsteed in calculating most of the tables in the second volume of his Historia Cælestis, as appears by their letters, to be seen in the hands of Sharp's friends at Horton. The mathematician, says Dr Hutton, meets with something extraordinary in Sharp's elaborate treatise of Geometry Improved; by a large and accurate table of segments of circles, its construction and various uses in the solution of several difficult problems, with compendious tables for finding a true proportional part; and their use in these or any other tables exemplified in making logarithms, or their natural numbers, to sixty places of figures, there being a table of them for all primes to 1100, true to sixty-one figures. His concise treatise of Polyedra, or solid bodies of many bases, both of the regular ones and others, to which are added twelve new ones, with various methods of forming them, and their exact dimensions in surds and in numbers; illustrated with a variety of copperplates, neatly engraved by his own hands. Indeed few of the mathematical instrument makers could exceed him in exactly graduating or neatly engraving mathematical or astronomical instruments. He possessed a remarkably clear head for contriving, and an extraordinary hand for executing, any thing, not only in mechanics, but likewise in drawing, writing, and making the most beautiful figures, in all his calculations and constructions.
The quadrature of the circle was undertaken by him for his own amusement, in the year 1699, deduced from two different series, by which the truth of it was proved to seventy-two places of figures, as may be seen in Sherwin's Tables of Logarithms. In the same book may likewise be seen his ingenious improvements on the making of logarithms, and the constructing of the natural sines, tangents, and secants.
Mr Sharp kept up a correspondence with most of the eminent mathematicians and astronomers of his time, as Flamsteed, Newton, Halley, Wallis, Hodgson, the answers to whose letters are all written on the backs or empty spaces of the letters he received, in a short hand of his own invention. Being one of the most accurate and indefatigable computers who ever existed, he was many years the common resource for Flamsteed, Sir Jonas Moor, Halley, and others, in all sorts of troublesome and delicate calculations.
Sharp was never married, and spent his time as a hermit. He was of a middle stature, very thin, of a weakly constitution, and remarkably feeble during the last three or four years before his death, which happened on the 18th of July 1742, in the ninety-first year of his age.
He was very irregular as to his meals, and uncommonly sparing in his diet. A little square hole, resembling a window, formed a communication between the room where he usually studied, and another where a servant could enter; and before this hole he had contrived a sliding board. It often happened, that the breakfast, dinner, and supper, have remained untouched, when the servant had gone to remove what was left, so deeply was he engaged in calculations.