CAILLE, NICHOLAS LOUIS DE LA, an eminent mathematician and astronomer, was born at a small town in the diocese of Rheims in 1713. His father had served in the army, which he quitted, and in his retirement studied mathematics, and amused himself with mechanic exercises, in which he proved the fortunate author of several inventions of considerable use to the public. Nicholas almost in his infancy took a fancy to mechanics, which proved of signal service to him in his maturer years. He was sent young to school at Mantes-sur-Seine, where he discovered early tokens of genius. In 1729 he repaired to Paris, where he studied the classics, philosophy, and mathematics; and he afterwards went to study divinity at the college de Navarre, proposing to embrace an ecclesiastical life. At the end of three years he was ordained as a deacon, and officiated as such in the church of the college de Mazarin several years; but he never entered into priest's orders, apprehending that his astronomical studies, to which he had become most assiduously devoted, might interfere too much with his religious duties. In 1739 he was conjoined with M. de Thury, son to M. Cassini, in verifying the meridian of the royal observatory throughout the whole extent of the kingdom of France. In the month of November the same year, whilst he was engaged day and night in the operations which this grand undertaking required, and at a great distance from Paris, he was, without any solicitation, elected to the vacant mathematical chair which the
celebrated M. Varignon had so worthily filled. Here he began to teach about the end of 1740; and an observatory was ordered to be erected for his use in the college, and furnished with a suitable apparatus of the best instruments. In May 1741, M. de la Caille was admitted into the Royal Academy of Sciences as an adjoint member for astronomy. Besides many excellent papers dispersed through their Memoirs, he published elements of geometry, mechanics, optics, and astronomy. Moreover, he carefully computed all the eclipses of the sun and moon that had happened since the Christian era; which were printed in a book published by two Benedictines, entitled L'Art de Vérifier les Dates, Paris, 1750, in 4to. Besides these, he compiled a volume of astronomical ephemerides for the years 1745 to 1755; another for the years 1755 to 1765; a third for the years 1765 to 1775; an excellent work entitled Astronomia Fundamenta novissimis Solis et Stellarum observationibus stabilita; and the most correct solar tables which had ever appeared. Having performed a seven years' series of astronomical observations in his own observatory, he formed a project of going to observe the southern stars at the Cape of Good Hope. This was highly approved of by the academy, as well as by the prime minister Comte de Argenson, and very readily agreed to by the states of Holland. Upon this he drew up a plan of the method he intended to pursue in his southern observations; setting forth, that, besides settling the places of the fixed stars, he proposed to determine the parallaxes of the Moon, Mars, and Venus. But as this required contemporaneous observations to be made in the northern parts of the world, he sent to those of his correspondents who were expert in practical astronomy previous notice in print, what observations he designed to make at particular times for the above purpose. At length, on the 21st of November 1750, he sailed for the Cape, and arrived there on the 19th of April 1751. He forthwith got his instruments on shore; and, with the assistance of some Dutch artificers, set about building an astronomical observatory, in which his apparatus of instruments was properly disposed of as soon as the building was in a fit condition to receive them.
The sky at the Cape is generally pure and serene, unless when a south-east wind blows; but this is often the case; and when the wind in question blows, it is attended with some strange and striking effects. The stars look bigger, and seem to quiver; the moon has an undulating tremor; and the planets have beards like comets. Two hundred and twenty-eight nights did our astronomer survey the face of the southern heavens, during which space of time he observed more than 10,000 stars; and as the ancients had filled the heavens with monsters and old wives' tales, the Abbé de la Caille chose rather to adorn them with the instruments and machines which modern philosophy has made use of for the conquest of nature. With no less success did he attend to the parallaxes of the Moon, Mars, Venus, and the Sun. Having thus executed the purpose of his voyage, and no present opportunity offering for his return, he thought of employing the vacant time in another arduous attempt, which was no less than that of taking the measure of the earth, as he had already done that of the heavens. This indeed had, through the munificence of the French king, been done before by different sets of learned men, both in Europe and America, some determining the extent of a degree under the equator, and others its extent under the arctic circle; but it had not as yet been decided whether in the southern parallels of latitude the same dimensions obtained as in the northern. His labours, however, were rewarded with the satisfaction he wished for, having determined a distance of 410,814 feet from a place called Klip Fontyn to the Cape, by means of a base of 38,802 feet, ascertained by three actual measure-