The Royal Observatory, Greenwich: A Glance at Its History and Work

by E. Walter Maunder

The position which Maskelyne had already won for himself as a practical astronomer, and the intimate relations into which he had entered with Bradley and Bliss, made his appointment to the Astronomer Royalship, on the death of the latter, most suitable. At once he bent his mind to the completion of the revolution in nautical astronomy which his British Mariner's Guide had inaugurated, and in the year after his appointment he published the first number of the Nautical Almanac, together with a volume entitled, Tables Requisite to be Used with the Nautical Ephemeris, the value of which was so instantly appreciated, that 10,000 copies were sold at once.

The Nautical Almanac was Maskelyne's greatest work, and it must be remembered that he carried it on from this time up to the day of his death—truly a formidable addition to the routine labours of an Astronomer Royal who had but a single assistant on his staff. The Nautical Almanac was, however, in the main not computed at the Observatory; the calculations were effected by computers living in different parts of the country, the work being done in duplicate, on the principle which Flamsteed had inaugurated in the preparation of his Historia Cœlestis.

Maskelyne's next service to science was almost as important. He arranged that the regular and systematic publication of the observations made at Greenwich should be a distinct part of the duties of an Astronomer Royal, and he procured an arrangement by which a special fund was set apart by the Royal Society for printing them. His observations covering the years 1776 to 1811 fill four large folio volumes, and though, as already stated, he had but one assistant, they are 90,000 in number. Thus it was Maskelyne who first rendered effective the design which Charles II. had in the establishment of the Observatory. Flamsteed and Halley had been too jealous of their own observations to publish; Bradley's observations—though he himself was entirely free from this jealousy—were made, after his death, the subject of litigation by his heirs and representatives, who claimed an absolute property in them, a claim which the Government finally allowed. None of the three, however much their work ultimately tended to the improvement of the art of navigation, made that their first object. Whereas Maskelyne set this most eminently practical object in the forefront, and so gave to the Royal Observatory, which under his predecessors somewhat resembled a private observatory, its distinctive characteristics of a public institution.

It fell to Maskelyne to have to advise the Government as to the assignment of their great reward of £20,000 for the discovery of the longitude at sea. Maskelyne, while reporting favourably of the behaviour of Harrison's time-keeper, considered that the method of 'lunars' was far too important to be ignored, and he therefore recommended that half the sum should be given to Harrison for his watch, whilst the other half was awarded for the lunar tables which Mayer, before his death, had sent to the Board of Longitude. This decision, though there can be no doubt it was the right one, led to much dissatisfaction on the part of Harrison, who urged his claim for the whole grant very vigorously; and eventually the whole £20,000 was paid him. The whole question of rewards to chronometer-makers must have been one which caused Maskelyne much vexation. He was made the subject of a bitter and most voluminous attack by Thomas Mudge, for having preferred the work of Arnold and Earnshaw to his own.

Otherwise his reign at the Observatory seems to have been a singularly peaceful one, and there is little to record about it beyond the patient prosecution, year by year, of an immense amount of sober, practical work. To Maskelyne, however, we owe the practice of taking a transit of a star over five wires instead of over one, and he provided the transit instrument with a sliding eye-piece, to get over the difficulty of the displacement which might ensue if the star were observed askew when out of the centre of the field. To Maskelyne, too, we owe in a pre-eminent degree the orderly form of recording, reducing, and printing the observations. Much of the work in this direction which is generally ascribed to Airy was really due to Maskelyne. Indeed, without a wonderful gift of organization, it would have been impossible to plan and to carry the Nautical Almanac.

Beside the editing of various works intended for use in nautical astronomy or in general computation, the chief events of his long reign at Greenwich were the transit of Venus in 1769, which he himself observed, and for which he issued instructions in the Nautical Almanac; and his expedition in 1774 to Scotland, where he measured the deviation of the plumb-line from the vertical caused by the attraction of the mountain Schiehallion, deducing therefrom the mean density of the earth to be four and a half times that of water.

JOHN POND.
(From an old engraving.)

He died at the Observatory, February 9, 1811, aged 79, leaving but one child, a daughter, who married Mr. Anthony Mervin Story, to whom she brought the family estates in Wiltshire, inherited by Maskelyne on the deaths of his elder brothers, and, in consequence, Mr. Story added the name of Maskelyne to his own.