PASCAL (Brain), a respectable French mathematician and philosopher, and one of the greatest geniuses and best writers that country has produced. He was born at Clermont in Auvergne, in the year 1623. His father, Stephen Pascal, was president of the Court of Aids in his province : he was also a very learned man, an able mathematician, and a friend of Des Cartes. Having an extraordinary tenderness for this child, his only son, he quitted his province, and settled at Paris in 1631, that he might be quite at leisure to attend to his son's education, which he conducted himself, and young Pascal ne ver had any other master. From his in fancy Blaise gave proofs of a very extra ordinary capacity. He was extremely inquisitive ; desiring to know the reason of every thing ; and when good reasons were not given him, he would seek for better ; nor would he ever yield his as sent but upon such as appeared to him well grounded. What is told of his man ner of learning the mathematics, as well as the progress he quickly made in that science, seems almost miraculous. His father, perceiving in him an extraor dinary inclination to reasoning, was afraid lest the knowledge of the mathematics might hinder his learning the languages, so necessary as a foundation to all sound learning. He therefore kept him as much ns he could from all notions of geometry, locked up all his books of that kind, ',and refrained even from speaking of it in his presence. He could not however pre vent his son from musing on that science : and one day in particular he surprised him at work with charcoal upon his cham ber floor, and in the midst of figures. The father asked him what he was doing: I am searching, says Pascal, for such a thing; which was just the same as the 32d proposition of the 1st book of Euclid. He asked him then how he came to think of this : it was, said Blaise, because I found out such another thing; and so, going back ward, and using the names of bar and round, he came at length to the definitions and axioms he had formed to himself. Prom this time he had full liberty to in dulge his genius in pursuits. He understood Euclid's Elements as soon as lie cast his eyes upon them. At six teen years of age he wrote a treatise on Conic Sections, which was accounted a a great effort of genius ; and therefore it is no wonder that Des Cartes, who had been in Holland a long time, upon read ing it, should choose to believe that M. Pascal the father was the real author of it. At nineteen he contrived an admira ble arithmetical machine, which would have done credit as an invention to any man versed in science. About this time his health became impaired, so that he was obliged to suspend his labours for the space of four years. After this, having
seen Torricelli's experiment respecting a vacuum and the weight of the air, lie turned his thoughts towards these ob jects, and undertook several new experi ments, by which he was fully convinced of the general pressure of the atmo sphere ; and from this discovery he drew many useful and important inferences. He composed also a large treatise, in which he fully explained this subject, and replied to all the objections that had been started against it. As he afterwards thought this work rather too prolix, and being fond of brevity and precision, he divided it into two small treatises, one of which he entitled, " A Dissertation on the Equilibrium of Fluids ;" and the other, "An Essay on the Weight of the Atmo sphere." These labours procured Pascal so much reputation, that the greatest mathematicians and philosophers of the age proposed various questions to him, and consulted him respecting such diffi culties as they could not resolve. Upon one of these occasions he discovered the solution of a problem proposed by Mer senne, which had baffled the penetration of all that had attempted it. This pro blem was to determine the curve describ ed in the air by the nail of a coach-wheel, while the machine is in motion ; which curve was thence called a roullette, but now commonly known by the name of cycloid. Pascal offered a reward of forty pistoles to any one who should give a sa tisfactory answer to it. No person hay. ing succeeded, he published his own at Paris ; but under the name of A. d'Etton ville. This was the last work which he published in the mathematics ; his in firmities, from a delicate constitution, though still young, now increasing so much, that he was under the necessity of renouncing severe study, and of living 8o recluse, that he scarcely admitted any person to see him. • After having thus laboured abundantly in mathematical and philosophical disqui sitions, he forsook those studies and all human learning at once, to devote him self to acts of devotion and penance. He was not twenty-four years of age, when the reading some pious books had put him upon taking this resolution ; and he became as great a devotee as any age has produced. He now gave himself up en tirely to a state of prayer and mortifica tion ; and he had always in his thoughts these great maxims of renouncing all pleasure and all superfluity ; and this he practised with rigour even in his illnesses, to which he was frequently subject, be ing of a very invalid habit of body. He died at the age of thirty-nine. His works were collated and published at the Hague in five volumes 8vo. - by the Abbe Bossu, 1779.