Castel, Lewis Bertrand

, a geometrician and philosopher, born at Montpellier in 1688, entered himself of the Jesuits in 1703, and was noticed by Fontenelle and | by Tournemine for the specimens he gave of his early proficiency, and as he was then in the country, they invited him to the capital, where he arrived towards the end of 1720, and supported the character which his first essays promised. The first work he published was his treatise of “Universal Gravity,” 1724, 2 vols. 12mo. All depended, according to him, on two principles, the gravity of bodies, and the action of minds; the former giving them a continual tendency to rest, the other renewing their motion. This doctrine, the key to the system of the universe, as he pretended, did not appear to be so to the abbe Saint Pierre. Though the friend of the mathematician, he attacked him, and Castel answered. The papers on both sides shewed much reflection, though in a singular channel. The second work of Castel was his plan of an “Abridged system of Mathematics,” Paris, 1727, 4to, which was soon followed by an “Universal system of Mathematics,” 1728, 4to, a work applauded both in England and France. The royal so’ciety of London admitted him of their body.

His “Clavecin Oculaire,” or ocular harpsichord, though silent, made a considerable noise in the world, and excited much curiosity and considerable expectation among opticians as well as musicians. His idea of producing the same pleasure to the eye by the melody and harmony of colours, as the ear received from the succession and combination of musical tones, was published in 1725. Sir Isaac Newton, having discovered (Optics, book i. p. 2, prop. 3.) that the breadths of the seven primary colours in the sun’s image, produced by the refraction of his rays through a prism, are proportional to the seven differences of the lengths of the eight musical strings, D, E, F, G, A, B, C, D, when the intervals of their sounds are T, H, t, T, t, T, t, H: which order is remarkably regular. Smith’s Harmonies. From this analogy, Pere Castel sets off by telling us that there is a fundamental and primitive sound in nature to which we may give the name of ret, or C. There is also a primitive and original tone which serves for base and fundamental to all colours, which is blue.

There are three essential sounds which depend on this primitive tone of C, and which together compose the perfect, primitive, and original chord, which is Ceg. There are likewise three original colours dependent on the blue; they are compounded of no other colours, and they produce the rest: these three colours are blue, yellow, and | red. The blue is the key-note, the red the fifth, and the yellow the third. There are five tones, C, D, E, G, A; and two semi-tones, F and C. In the same manner there are five principal colours, blue, green, yellow, red, and violet: and two semi-tone colours, which are orange and indigo. The musical scales, c, d, e, f, g, a, b. The scale of colours is blue, green, yellow, orange, red, and violet. These are the data of father Castel, upon which he has founded his organ or harpsichord of colours.

It would be useless to analyse and critically examine this plan, which is truly visionary, false in its ratios, and incapable of producing the promised effects. After being tried in all parts of Europe, particularly in London, about 1756, when the plan and pretended effects were published in an English pamphlet, its exhibition was soon neglected and forgotten, and has been scarcely heard of since.

The “Vrai systeme de physique generate de Newton,” 1743, 4to, did him more honour in the opinion of several of the learned, though it was displeasing to others. He reverenced the English philosopher, though his doctrine appeared to him but little adapted to reveal the true system of the universe. “Newton and Descartes,” said he, tt are nearly on a par in regard to invention; but the latter had more facility and elevation; the other, with less facility, was more profound. Such is pretty nearly the character of the two nations: the French genius builds upwards, the English genius downwards. Each of them had the ambition to make a world, as Alexander had that of conquering it, and both had grand ideas of nature.“Other papers by him are in the Memoires de Trevoux, in which he was for some time concerned. The style of Castel partook of the fire of 'his genius and the wanderings of his imagination. The conversation turning one day, in presence of Fontenelle, on the marks of originality in the works of this scholar, somebody said,” But he is mad.“” I know it,“returned Fontenelle,” and I am sorry for it, for it is a great pity! But I like him better for being original and a little mad, than I should if he were in his senses without being original.“Castel died the llth of January, 1757, at the age of 68. The abbe dela Porte published in 1763, 12mo, at Paris under the imprint of Amsterdam,” L’esprit, les saillies, & singularites du pere Castel." The author treats, on a great number of subjects; and though he enters deeply into none, yet he thinks much, and sometimes verjr | well. The life of Castel was exemplary and edifying he! was ever assiduous in performing the duties of his station, and had the highest reverence for religion. ¹