HISTORY OF PHYSICAL ASTRONOMY.

477

Flamsteed is universally admitted to have been one of the most eminentpractical astronomers of the age in which he lived. His merits do not,indeed, appear at first sight so conspicuous as those of some of his illus-trious contemporaries with whom he may be compared, although at thesame time they are no less substantial. He does not generally exhibitthe enlightened discernment which Picard displays in his researches, norwas he endowed with the fertility of invention by which Itoenier was soeminently distinguished; but in carrying out views of practical utility,with a scrupulous attention to accuracy in the most minute details, infortitude of resolution under adverse circumstances, and persevering adhe-rence to continuity and regularity of observation throughout along career,he has few rivals in any age or country. Without the possession of theseinvaluable qualities, the most splendid genius may fail to exercise anydurable influence: by means of them Flamsteed was enabled to establishthe fundamental points of practical astronomy upon a new basis, and to reara superstructure which, for many years afterwards, served as a landmark ofvast importance to astronomers. In so far as the accuracy of his observa-tions is concerned, his labours must be considered with reference to thetimes in which he lived, and the difficulties which he had to encounter.When judged according to this equitable standard, they will not suffer fromthe scrutinies of the candid enquirer. It forms a noble attestation to themerits of Flamsteed in this respect, that his observations are the earliestfrom which the phenomenon of aberration clearly and unequivocallyemerges, its maximum value being assigned by them with a degree of pre-cision almost equal to that deducible from the most trustworthy observa-tions of the present day *. As first Astronomer of the Royal Observatoryof Greenwich , he set an example to his successors the beneficial influenceof which cannot for a moment be doubted ; nor, while that noble esta-blishment continues to maintain its proud pre-eminence among the insti-tutions devoted to practical astronomy, will the labours of its originalDirector, prosecuted with such unwearied perseverance throughout a longcareer, despite the depressing influence of constitutional ill health, andthe unrelenting hostility of a powerful faction, cease to be held in respect-ful remembrance by his countrymen.

Flamsteed was succeeded at the Royal Observatory by the celebratedEdmund Halley. This great astronomer was born at London , on the29tli of October, 1656, and had already distinguished himself by a bril-liant career of research on various subjects of physical science. It seemssomewhat surprising, when we consider that he was now in the 64thyear of his age, that he should have undertaken the discharge of dutiesof so onerous a nature as those attached to the situation of AstronomerRoyal. Unlike his predecessor, however, he had the good fortune topossess a robust constitution, and, in reliance upon its vigour, he wasdesirous of prosecuting a series of observations of the moon, iu regard towhich he had a special object in view, as will be presently mentioned.

It has been already mentioned that the instruments used by Flamsteed

* See page 340 of this work, where the value of aberration deduced by M. Petersfrom Flamsteed’s observations is given. The same astronomer makes the latitude ofGreenwich , according to Flamsteed’s observations, to be 51° 28' 41".9 + 0".9.— (Re-cherches sur la Parattaxe des Etoiles Fixes, p. 11.) Mr. Airy, from recent observations, has

determined the true value of the latitude to be 51° 28' 38".2_( Greenwich Observations

1842, p. xliv.)