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MEMOIR

OF

BLAISE PASCAL.

ALTHOUGH the facts of PASCAL's Life cannot but be very extensively known, it seems scarcely correct to send forth a fresh translation of his Thoughts to the world, without a brief Memoir of that extraordinary genius.

BLAISE PASCAL was born at Clermont in Auvergne, 19th June, 1623. His father, Stephen Pascal, was first president of the Court of Aids, and had, by his wife, Antoinette Begon, three other children, a son who died in infancy, and two daughters; Gilberte, married to M. Perier, and Jacqueline, who took the veil in the convent of Port Royal in the Fields, and died there of grief, arising from the persecutions under which that community suffered.

Stephen Pascal was a superior and well educated man, and possessed an extensive knowledge of the Law, of Mathematics, and Natural Philosophy; to which he added the advantages of a noble birth, and of manners peculiarly simple. Till the year 1626, he shared with an amiable wife, during the intervals of public occupation, the duties of educating his family; but in that year she died, and he then devoted himself exclusively to this object. For this purpose he retired from office; and having continued a few years in the country, in the year 1631, brought his family to Paris to complete their education.

The attention of Stephen Pascal was, of course, chiefly occupied with his son, who gave promise, at a very early, age, of superior genius, and readily received the elementary principles of language, and of the sciences in general; but one of the earliest features of those talents which were subsequently developed, was the eagerness, and the nice, and accurate discernment with which, on all subjects, he sought for truth, and which would not allow him to feel satisfied till he had

found it.

The circle of his father's acquaintance was of a superior order. He numbered among his friends, Mersenne, Roberval, Carcavi, Le Pailleur, &c. At their occasional meetings, for the discussion of scientific subjects, Blaise Pascal was sometimes allowed to be present, at which times he listened with great attention to what passed, and thus gradually formed the habit of scientific research. To trace effects up to their causes, was one of his chief pleasures; and it is stated, that at eleven years of age, having heard a plate give forth, on its being struck, a musical vibration, which ceased on its being touched again, he applied his mind to the subject which it presented to him, and at length produced a short treatise upon the nature of sounds.

His father, however, fearful that this evidently strong predilection for scientific pursuits would delay his progress in the attainment of classical learning, agreed with his friends that they should refrain from speaking on such topics in his presence; and this opposition to his evidently ruling tendency was, on principle, carried so far, that on his making an application to his father to be permitted to learn Mathematics, the permission was positively withheld, till he should have mastered the Greek and Latin languages. In the meantime, he obtained no other information on the subject, but that Geometry was a science which related to the extension of bodies—that it taught the mode of forming accurate figures, and pointed out the rela. tions which existed between them. But beyond this general information, he was forbidden to inquire ; and all books on the subject were positively forbidden to him.

This vague definition, however, was the ray of light which guided him onward in Mathematical study. It became the subject of continued thought. In his play hours, he would shut himself up in an empty room, and draw with chalk on the floor, triangles, parallelograms, and circles, without knowing their scientific names. He would compare these several figures, and would examine the relations that their several lines bore to each other; and in this way, he gradually arrived at the proof of the fact, that the sum of all the angles of a triangle is equal to two right angles, which is the thirty second proposition of the first book of Euclid. The young geometer had just attained this point, when his father surprized him, deeply occupied in the prohibited study. But he was himself no less astonished than his son, when, on examining into the nature of his occupation, he ascertained the conclusion to which he had come; and on inquiring how he arrived at it, the child pointed out several other principles which he had previously ascertained, and at length stated the first principles which he had gathered for himself in the way of axioms and definitions.

To control, after this, such evident manifestations of superior mathematical genius, was quite out of the question. Every advantage was afforded to him, of which he eagerly availed himself. At twelve years of age, he read through the Elements of Euclid, without feeling the need of any explanation from teachers; and at sixteen, he composed a treatise on Conic Sections, which was considered to possess very extraordinary merit. He attained rapidly to a very high degree of knowledge and of celebrity as a Mathematician; and before the age of nineteen, he invented the famous Arithmetical Machine which bears his name, and by which, through the instrumentality of a mechanical movement, somewhat similar to a watch, any numerical calculation might be performed. The main difficulty in Arithmetic lies in finding the mode of arriving at the desired result. This must ever be a purely mental operation; but the object of this instrument was, that in all those numerical operations where the course to be pursued was fixed and certain, a mechanical process might relieve the mind from the monotonous and wearisome labour of the mere detail of calculation.

Pascal's invention succeeded; but it was found too cumbrous for general use.

About this time, Stephen Pascal was appointed the Intendant of Rouen, to which place he removed his family.

He remained there seven years ; and during that period, his son diligently pursued his studies, although it was quite evident that his severe application had already affected his health, and marked him with the symptoms of decline.

Here his ardent mind, which had been turned during his retirement to the study of Physic, occupied itself with one of the most striking phenomena of the natural world, and did not rest till he had elicited a satisfactory explanation of it. This phenomenon was, that in a pump, in which the piston played at a distance of more than thirty two feet above the reservoir that supplied it, the water rose to the height of thirty two feet, and no farther. On this question, Galileo had been consulted ; and the explanation of this fact which was offered by him was, that the water rose to a certain height in the pipe, because nature abhorred a vacuum ; but that the force by which she resisted a vacuum was limited, and that beyond a height of thirty two feet, it ceased to act. This answer, however, was not even then satisfactory ; and within a short period of that time, Torricelli, the disciple of Galileo, ascertained, by a series of experiments, that the cause of this ascent of the water in fountains and pumps, was the pressure of the weight of the atmosphere upon the surface of the reservoir. At this juncture, however, Torricelli died; but Pascal, to whom the result of his experiments had been communicated by Mr. Mersenne, through Mr. Petit, the Intendant of Fortifications at Rouen, having repeated the experiments of Torricelli, verified their results, and completely refuted the popular notion of the abhorrence of a vacuum. And in the year 1647, in a small tract dedicated to his father, he published the account of these experiments.

It does not however appear, that, at this time, he had arrived at a satisfactory solution of the phenomenon in question,-he had done little more than ascertained that it could not arise

from the cause to which it had been attributed, according to the popular doctrine of the day, and that the notion of nature's abhorrence of a vacuum, had no foundation in fact. Pascal therefore followed out his inquiries most perseveringly; and in the year 1653, he wrote two pamphlets, one on the equilibrium of fluids, and another on the weight of the atmosphere; in which, by a series of satisfactory experiments, he completely established that doctrine on the subject, which is now universally received. The most important and original of these experiments were those which shewed that the rise of the water, or the mercury in the tube, varied in proportion to the height above the level sea, of the place where the experiment was tried. Many attempts have been made to rob Pascal of the merit of these discoveries, but they have altogether failed. It was however to be regretted, that the two latter tracts were not printed till 1663, the year following his death.

At the time, however, when M. Pascal issued his first tract on this subject, his health had manifestly given way before the severity of his studies; and at the close of the year 1647, he had an attack of paralysis, which deprived him, in a great measure, of the use of his limbs. He returned to Paris, and resided there with his father, and sister, and, for some time, relaxed from study, and took several journies by way of recreation. But in the year 1651, he lost his father; and in 1653, his sister Jacqueline, in the fulfilment of a wish which she had long cherished, joined the sisterhood of Port Royal; and being thus left alone at Paris, for his other sister and M. Perier then resided at Clermont, he returned without restraint to those habits of severe and excessive study which must, in a short time, had they not been interrupted, have brought him to the grave. But his friends interfered, and their advice, seconded by the severity of his bodily afflictions, constrained him for a time to lay aside his studies, and to mingle more than he had done with general society. Here he gradually regained his spirits, acquired a fresh relish for the fascinations of life, and began even to think of marriage. But an event which occurred about this time, and which we shall have occasion afterwards

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