ROBINS, BENJAMIN, a celebrated English mathematician and artillerist, was b. at Bath in 1707, of parents who belonged to the society of Friends, and who were in such poor circumstances as to be unable to give their son a good education. Robins, however, having obtained a little instruction in mathematics, prosecuted this branch of science with great zest, and having acquired a good elementary knowledge of it, he removed, by the advice of Dr. Pemberton, to London, where he set up for a teacher of mathematics. During his leisure hours, he improved himself iu his favorite subject by reading the works of the ancient and modern geometers, and by the study of the Latin, Greek, and several modern languages. He also published several mathematical treatises, which gained for him considerable reputation. Robins next commenced the series of experi ments on the resisting force of the air to projectiles, which has gained bun so much. celebrity, varying his labors by the study of fortification; a science with which lie_ obtained a practical acquaintance by visiting many of the most celebrated works of this class in Flanders. In 1734 he demolished, in a treatise entitled A Discourse concerning the Certainty of Sir I. Newton's Method of Fluxion, the objections brought by the cele brated Berkeley, bishop of Cloyne, against Newton's principle of ultimate ratios. His great and valuable work, the New Principles of Gunnery, upon the preparation of which he had spent an enormous amount of labor, appeared in 1742, and produced a complete revolution in the art of gunnery. Previous to Robins's time, it had never been attempted to estimate the velocity of balls otherwise than by the ordinary parabolic theory of Galileo (see PROJECTILES). Robins suggested two methods for obtaining this informa
tion—viz. (1), by finding experimentally the initial force of fired gunpowder confined a certain space, and the law of the decrease of this force as the space increased; thence calculating the velocity which would be imparted to a body of given weight; and (2) by the ballistic pendulum. The second method has been found in practice to be more preferable for accuracy. Robins, in the course of his experiments, also-discovered and explained the curvilinear deflection of a ball from a vertical plane. Some of his opinions having been questioned in the Philosophical Transactions, Robins ably replied to these objectors, and also wrote several dissertations on the experiments made by order of the royal society in 174647, for which he received their annual gold medal. In considera tion of his able defense of the policy of the then government, by means of pamphlets which he wrote and published from time to time, he received (1749) the post of "engi neer-in-general to the East India company;" but his first undertaking, the planning of the defenses of Madras, was no sooner accomplished than he was seized with a fever, and though he recovered from it, his vital energy had been exhaustecr, and he died July 29, 1751. Robins was considered as one of the most aeedrate mathematicians of his time. His mathematical works were collected after his death, and along with the details of his latest experiments in gunnery, were published by Dr.Wilson in 1761. It may also be mentioned that Robins had some share (to what extent is now unknown) in the com position of Arison's Voyage _Round theWorld (1740-44).