Maskelyne, Nzvil

, an eminent astronomer and mathematician, the son of Edmund Maskelyne, esq. of Purton, in Wiltshire, was born at London in 1732, and educated at Westminster school, where he made a distinguished progress in classical learning. Before he left school his studies appear to have been determined to astronomy by his accidentally seeing the memorable solar eclipse of 1748, exhibited through a large telescope in a camera obscura. From this period he applied himself with ardour to astronomy and optics, and as a necessary preparation, turned his attention to geometry and algebra, the elements of which he learned in a few months without the help of a master. In 1749 he entered of Catherine hall, Cambridge, but soon after removed to Trinity college, where he pursued his favourite studies with increased success; and on taking his degree of B. A. in 1754, received distinguished honours from the university. He took his degrees of A.M. in 1757, B. D. in 1768, and D. D. in 1777. Being admitted into holy orders he officiated for some time as curate of Barnet; and in 1756 became a fellow of his college.

In 1758 he was chosen a fellow of the royal society, and soon after became an important contributor to the Philosophical Transactions. Such was his reputation already, that the society appointed him to go to the island of St. Helena, to observe the transit of Venus over the sun’sdisk, which was to take place June 6, 1761. On this occasion he remained ten months on the island, making astronomical observations and philosophical experiments; and although his observation of the transit of Venus was not completely successful, owing to the cloudy state of the weather, his voyage afforded him an opportunity of taking lunar observations, which were now for the first time made with effect. This method of finding the longitude at sea was long a great desideratum, and plans had been made by many of his predecessors, but the honour was reserved for Dr. Maskelyne to reduce their theories to successful practice. This he was enabled to do by Hadley’s quadrant recently invented, and also by professor Mayer’s lunar tables, for which a parliamentary reward of 3000l. was | afterwards given, on Dr. Maskelyne’s report of their correctness. The results of his other observations and experiments were inserted in the Philosophical Transactions of the above period. Soon after his return from St. Helena, he published his well-known work, entitled “The British Mariner’s Guide,” which contained, among various new and practical illustrations and articles in nautical astronomy, rules and examples for working the lunar observations; but, in order to shorten and simplify these laborious operations, other tables and calculations were still wanted, which he afterwards supplied by his *' Nautical Almanack,“and” Requisite Tables."

In 1763 he undertook another scientific royage by appointment of the lords of the admiralty and the board of longitude. He sailed for Barbarioes for the following purposes: to find the longitude of that island by astronomical observations; to determine the rate of going of Mr. Harrison’s new time-keeper; and to try Mr. Irwin’s marinechair, which was intended for making steady observations at sea, but which did not answer. He was besides, in the course of his voyage, to take lunar observations with a curious new Hadley’s sextant, and to determine the longitude by the eclipses of Jupiter’s satellites, and the occultations of fixed stars by the moon. All these objects of 1 the expedition he executed to the entire satisfaction of his employers.

In 1764, the office of astronomer-royal becoming vacant by the death of Mr. Bliss, Dr. Maskelyne’s celebrity immediately pointed him out as the most competent person to fill the situation, and to carry into effect the purpose for which the royal observatory haid been established, that o preparing tables for finding the longitude at sea. Accordingly, his appointment to it, which was announced in the London Gazette, Feb 16, 1765, gave universal satisfaction. During the long period of Dr. Maskelyne’s official services, his time may be considered as chiefly occupied either at the observatory, the board of longitude, or the royal society; and his biography, therefore, like that of most other scientific men, consists chiefly in a history of his labours. ­Soon after his appointment he laid belor^he board of longitude the plan of an annual publication, to be entitled the “Nautical Almanac, and Astronomical Ephemeris.” The first volume was for 1767 and it has been continued | under his direction, up to the present time, making in the whole fifty volumes a lasting monument of labour and profound learning. It is universally allowed to be the most useful work on practical astronomy ever published. In such high estimation has it been held by foreign astronomers, that they have generally and implicitly adopted its computations, and acknowledged its superior accuracy. M. Lalande, in giving an account of similar publications, says, “Le Nautical Almanac de Londres est l‘Ephemeride la plus parfaite qu’il y aitjarnais eu.”

In 1767 he published an auxiliary work, entitled “Tables requisite to be used with the Nautical Almanac, in order to find the Latitude and Longitude at sea.” This performance, well known to seamen by the name of “The Requisite Tables,” has passed through several editions, and has been successively enlarged, particularly by different methods of working the lunar observations, by Messrs. Lyons, Dunthorne, Witchel!, Wales, and by Dr. Maskelyne himself; and it has been also improved by the latitudes and longitudes of places supplied by captain Cook, captain Huddart, Messrs. Bailey, Wales, and other scientific navigators. Some time after this he published Mayer’s Tables, with both Latin and English explanations, to which he added several tracts and tables of his own, and prefixed to the whole a Latin preface, with the title “Tabulae motuum Soils et Lunae, &c.” It was published, like the foregoing works, by order of the commissioners of longitude; and the various other publications issued by that board during his time were also printed under his inspection, and are too numerous to be here stated.

Another important and laborious duty that devolved on him in consequence of his office was, to examine the pretensions of the various candidates who claimed the parliamentary rewards for new or improved methods of finding the longitude. His appointment took place at a period peculiarly interesting in the history of astronomy. His success in introducing and promoting the lunar observations greatly excited the public attention to the subject of the longitude, which was rendered still more interesting by the great rewards held out by parliament for further improvements in the problem, whether by astronomical or mechanical methods. These offers, united with the powerful motives of honour and emulation, called forth, flaring several years, many extraordinary efforts of genius, | and produced useful inventions both in arts and sciences, and particularly in the construction of time-keepers. The parliamentary offers likewise encouraged numerous candidates of very slight pretensions, and even visionaries, whose applications became very troublesome. The claims of all were referred by the board of longitude to the astronomer royal, by whom scientific plans were examined, and the rates of chronometers ascertained. Thus by his office he was constituted arbiter of the fame and fortune of a great number of anxious projectors; and it is easy to conceive how arduous as well as unpleasant such a duty must have been. It was not indeed to be expected that the sanguine hopes and self-love of such a variety of candidates could be gratified, with justice to the high trust and confidence thus 1 reposed in him; and hence complaints were frequently heard, and pamphlets published, expressive of discontent and disappointment. Appeals even were made to parliament; but whatever difference of opinion might have then existed, time and experience have since fully proved the truth and impartiality of Dr. Maskelyne’s decisions.

In giving a general view of his labours at the royal observatory, we shall begin with his publication of the Greenwich Observations, which were printed in 1774, by command of his majesty. The first volume began with the observations of 1765, and they have been continued annually since. M. Lalande, in mentioning this performance in 1792, calls it “le recueil le plus pre*cieux que nous’ ayons.” Since that period they have been considerably improved, and are universally allowed to possess an unrivalled degree of accuracy. His catalogue of the right ascensions and declinations of 36 principal fixed stars, with tables for their correction, is a most useful and important performance, and is adopted in all observatories. It is mostly distinguished by the appellation of “Dr Maskelyne’s 36 Stars.” His observations also of the sun, moon, and planets, are equally esteemed, and have been made the basis of the solar and lunar tables, lately computed in France according to the theory of M. Laplace; and which are fepublished in professor Vince’s Astronomy, vol. III. The solar tables were calculated by M. Delambre, and the lunar by M. Burg: copies of which have been transmitted to Dr. Maskelyne, by order of the French board of longitude, with a grateful acknowledgment of the important assistance derived from his Greenwich Observations. But | it would greatly exceed our limits to enumerate all the corrections and improvements effected by Dr. Maskelyne’sobservations, many of which will be found in professor Vince’s Astronomy, and in the Philosophical Transactions. His communications to the royal society are distinguished, like his other productions, for great attention to utility as well as accuracy. They consist chiefly of astronomical observations; improvements of mathematical and optical instruments; computations of the eclipses of the sun, moon, and Jupiter’s satellites; articles on parallaxes, light, vision, refraction, weights, measures, gravitation, &c. with calculations and predictions of comets; making in the whole above thirty communications. It should be noticed that, in 1774, he went to Shehallien, in Perthshire, in order to ascertain the lateral attraction of that hill; by which the mean density of the earth was computed, and its central attraction according to the Newtonian theory first demonstrated. For this paper he was presented by the council of the royal society with sir George Copley’s gold medal.

In the history of science, few persons can be mentioned who have contributed more essentially to the diffusion of astronomical knowledge than Dr. Maskelyne; and perhaps no man has been so successful in promoting practical astronomy, both by land and sea. During his time private observatories became very general, though scarcely known before; nor could such be made useful without his “Nautical Almanac,” and other tables, except by men of great science, and by very laborious calculations. Beside the assistance thus derived from his publications, he was always ready to give advice concerning any plans that were likely to promote the science. Among the observatories that were erected through his encouragement, may be mentioned that of the late Alexander Aubert, esq. whose excellent collection of instruments has been rarely equalled, even in national institutions; and several other instances might be adduced of observatories which were erected by the advice or direction of the astronomer royal. He was besides a great improver of instruments, and the inventor of some, among which may be noticed the prismatic micrometer; but though profoundly skilled in optics, and ingenious in mechanical contrivances, he always paid great deference to the opinions of opticians, and other practical mechanists. | His plans were mostly directed to substantial objects, while a steady perseverance gave an efficiency to all his undertakings: and notwithstanding his profound knowledge of physical astronomy, his attention was chiefly directed to reduce the scientific theories of his predecessors to the practical purposes of life. In this he was eminently successful, particularly in his labours for the longitude, by which he essentially contributed to the advancement of navigation, the prosperity of commerce, and the wealth, honour, and power of his country.

Dr. Maskelyne’s private character was likewise truly estimable. He was indeed exemplary in the discharge of every duty. In his manners he was modest, simple, and unaffected. To strangers he appeared distant, or rather diffident; but among his friends he was cheerful, unreserved, and occasionally convivial. He was fond of epigrammatic thoughts and classical allusions; and even somelimes indulged in playful effusions of this kind, at an advanced period of life. He maintained a regular correspondence with the principal astronomers of Europe. He was visited also by many illustrious foreigners, as well as eminent characters of his own country, but his warmest attachments were always manifested to the lovers of astronomy. Among his most intimate friends may be reckoned Dr. Herschel, Dr. Hutton, Messrs. Wollastons, Mr. Aubert, bishop Horsley, sir George Shuckburgh, baron Maseres r professor Robertson; and also professor Vince, whose publications so ably illustrate Dr. Maskelyne’s labours, and whom he appointedthe depositary of his scientific papers.

Dr. Maskelynehad good church preferment from his college; and his paternal estates (of which he was the last male heir), were also considerable. He married, when rather advanced in life, a young lady of large fortune, the sister and co-heiress of lady Booth of Northamptonshire, by whom he had one daughter, whose education he superintended with the fondest care. These ladies survive him, aad also his sister Margaret, who was married to Robert, the late lord Clive.

Dr. Maskelyne died February 9, 1811, in the 79th. year of his age. His health previously declined for some months and he contemplated his approaching dissolution with pious resignation, and with a lively hope of being | Admitted into the presence of that Deity, whose works he had so long studied and so ardently admired. His favourite science tended the more strongly to confirm his religious principles, and he died, as he had lived, a sincere Christian. ¹