Borda, John Charles

, a celebrated French mathematician and natural philosopher, was born at Dax, in the department of the Landes, May 4, 1733. His mother was Maria Theresa de Lacroix, and his father John Anthony Borda, whose ancestors had acquired considerable distinction in the French army. He began his studies in the college of the Barnabites at Dax, where he gave early indications of his future genius. He was a considerable time after put under the charge of the Jesuits of La Fleche, and by his ardour for study and superior talents, frequently carried off the prizes which were held out as the reward of youthful genius. This induced the Jesuits to endeavour to press him into their order, but his attachment to geometry was too powerful to be weakened by their persuasions. He encountered afterwards a more formidable opposition from his father, who was hostile to the prosecution of what he called unprofitable studies, and endeavoured to please him by proposing to enter into the engineer service of the army, where the objects of his profession would necessarily require a knowledge of geometry and physics. His father, however, having eleven children, and being obliged to support two of his sons who were already in the army, was anxious that Charles should look forward to some situation in the magistracy, which might be obtained without much expence and trouble. To these views Borda reluctantly submitted; but after having thus lost some of the most precious years of his youth, a friar, who was a particular friend of his father, obtained, by earnest solicitation, that he should | be allowed to devote himself to his favourite science; and, every restraint being now removed, he was in 1753, when only twenty years of age, introduced to D’Alembert, who advised him to remain in the capital, and look forward to a situation in the academy. Borda accordingly entered the light horse, and continuing his mathematical studies, he became professor to his comrades.

In 1756, he laid before the academy a memoir on the motion of projectiles, which was particularly mentioned in the history of its proceedings; and in the same year he was appointed an associate of the academy. In the following year he was called into active service, and was present at the battle of Hastembeck, July 26, 1757, as aid-de-camp to M. de Maillebois. He willingly returned, however, from a species of duty which interrupted the progress of his studies; and, upon his arrival at Paris, he became a candidate for a situation in the engineer service: and such was the estimation in which his talents were held, that he was received without examination, and immediately employed as an inspector of the dock-yards. This new appointment was highly favourable for calling into action the peculiar talents of Borda. It inspired him with a fondness for every thing that related to the naval service: and, what seldom happens to the man of genius, he found himself in a situation in which he was led both by his profession and by his inclination to the same line of study.

The first object of his research was an examination of the theories of the resistance of fluids, a subject intimately connected with the advancement and perfection of naval architecture. The experiments upon this subject made by the academy of sciences, were by no means fitted to determine the resistance of bodies that were wholly immersed in the fluid. Borda, however, employed a method which was susceptible of great accuracy, and had also the advantage of ascertaining accurately the velocity of the motion. The surfaces upon which his experiments were made were of various forms, and the experiments were made both in air and water. The results of these inseresting experiments are given at length in the Memoirs of the Academy for 1763 and 1767. The apparatus, however, employed by Borda, was not of his own invention. A machine of the same kind had been used some time before by our ingenious countryman, Benjamin Robins, in his admirable experiments on the resistance of air. Yet we are indebted | to Borda for many ingenious experiments and observations on the motion of fluids through different orifices. He prepared a theory of the motion of fluids different from that which had been given by Bernoulli and D’Alembert, and he made new experiments on the vena contracta.

In 1767, he published an excellent dissertation in the Memoirs of the Academy, entitled “Memoire sur les Roues Hydrauliques,” shewing that an undershot wheel produces a maximum effect when its velocity is one-half that of the current, though in practice the velocity is never more than three-eighths that of the current. He proved, after Deparcieux, from theory, before Smeaton had determined it by experiment, that the effect of overshot wheels increases with the slowness of their motion: that they are capable of raising, through the height of the fall, a quantity of water equal to that by which they are driven; that undershot vertical wheels produce only three-eighths of this effect; that horizontal wheels produce about one-half of this effect with plain float-boards, and a little more than one half with curvilineal float-boards. This memoir was followed by another, in 1768, on the construction of water-pumps. About this time Borda’s attention was directed to isoperimetrical problems, in which he obtained the same results as Lagrange, though by a different method. His last work, in the Memoirs of the Academy, was a dissertation on the “Theory of Projectiles.

These labours induced M. Prasslin, the minister of the marine, to wish for the aid of his talents in the French navy, and after some opposition from official etiquette, he appointed him sub-lieutenant, in which character he first appeared in 1768; but nothing occurred of consequence until 1771, when the French and English were employed in many inventions for the discovery of the longitude at sea, and the French government having determined to try the accuracy of some improved chronometers, the academy of sciences appointed Borda and Pingre to sail for that purpose in the Flora frigate. The result of their voyage was published at Paris in 1778, entitled, “Voyage fait par ordre du Roy en 1771 et 1772, &c.” 2 vols. 4to. He was afterwards employed to determine the position of the Canary Isles, and being promoted to the rank of lieutenant, sailed in 1776, and in the course of his voyage, performed its immediate object, with others. Being appointed majorgeneral to the naval armament which served under Count | D’Estaign in America, his experience led him to discover many defects in the construction of vessels, which he thought might be easily remedied. He considered the want of uniformity in the construction of ships, which were to act together, as a great defect, because a great discordance arose in their movements and in the exeeution of signals. Upon his return to France he communicated this idea to government, who immediately resolved to carry it into effect, and his profound knowledge and patriotic exertions did not fail to be acknowledged not only by France, but by the best-informed men in England. The reputation which he had now acquired enabled him to be further serviceable to his country, by drawing up a plan for the schools of naval architecture, of which he may justly be termed the founder, as he not only suggested the idea, but formed the scheme for regulating these seminaries, and laid down the rules for the instruction of the pupils admitted into them.

As a naval officer, however, Borda acquired little fame, and being captured by the English, though after a very brave resistance, he determined to devote the remainder of his days to science and philosophy. During his voyage along with Pingre in 1771, Borda found by experience that Hadley’s quadrant was susceptible of great improvement. The celebrated Tobias Mayer had already endeavoured to remove its imperfections, but the merit of this Borda’s biographer has transferred to him, declaring that Mayer’s idea was never carried into effect, which is completely false; one of Mayer’s circles was made for Admiral Campbell by Bird; and Mayer had himself used an instrument for measuring terrestrial angles upon the repeating principle, which is described in “Commentaries of the Royal Society of Gottingen” for 1752. Borda having examined, with the utmost attention, the construction proposed by Mayer, pointed out its defects, and in a great measure removed them by a circle of his own invention in 1777, known by the name of the “Circle of Borda,” but still it was not without its numerous imperfections, and it was reserved to our ingenious countryman Troughton to bring to perfection one of the happiest inventions that was ever made.

To Borda France is indebted for the invention of the mensuration-rod, with which the new station -lines were lately ascertained. He was also a zealous promoter of the reform in weights and measures; and in order to assist in this, he published “Tables of Sines in the decimal | sy.stern,” at his own expence. One of his last labours was, the accurate determination of the length of the pendulum vibrating seconds at Paris. Such were the acknowledged reputation and patriotism of Borda, that the highest offices in the state were not deemed too great for merit such as his; and we accordingly find the name of a man who had been decorated with the cross of merit during the monarchy, entered in the list of candidates for the office of Director under the republic. This occurred in 1797, and on the 20th of February 1799, the National Institute lost one of its greatest ornaments and most assiduous supporters, in consequence of his death, which was occasioned by a dropsy, that cut him off Feb. 20, 1799, in the 64th year of his age.

At the interment of his corpse, nearly the whole of his colleagues attended. Notwithstanding a heavy rain, upwards of one hundred members of the National Institute walked on foot to Montmartre, two a-breast, with a black crape round their arms, and with the eyes of nearly all suffused in tears. On their arrival at the place of interment, Bougainville, a man no less distinguished in arms than in letters, spoke an oration in honour of the deceased. 1

1 Principally from Brewster’s Encyclopedia. See also Lalande’s History of Astronomy.