These remarks have a peculiar application to the case of Bradley. This eminent individual,-the Astronomer-Royal of England, the Savilian Professor of Astronomy at Oxford,-the author of two of the grandest discoveries, and of many of the finest observations in modern astronomy, and one to whom Delambre assigns the most distinguished place, next to Hipparchus and Kepler, and whom he ranks above all the other astronomers of every age and of every country,-this great and good man has been allowed to lie seventy years in his grave without any suitable memorial of his life and discoveries!

The difficult task of performing, at the eleventh hour, this great duty to science fortunately devolved upon Mr Rigaud, Savilian Professor of Astronomy at Oxford. His profound acquaintance with the subject, his varied learning, his powers of unwearied research, and the opportunities which an extensive acquaintance afforded him of preserving from oblivion the traditionary materials for a Life of Bradley, have enabled him to produce a volume of deep interest; and one which will be perused with avidity wherever astronomical science is cultivated and esteemed. The Memoir' itself, which occupies more than one hundred closely-printed quarto pages, is written with great simplicity and perspicuity. It abounds with the most interesting details respecting the private as well as the professional life of Bradley, and is interspersed with instructive and agreeable notices of his scientific friends and contemporaries, and of the instruments and methods which he employed in his enquiries. His discoveries and observations are discussed with a peculiar talent; and the astronomical reader, without being sensible of any digression, feels that he is perusing the history of practical Astronomy in England during the earlier half of the eighteenth century.

Royal Society of London, it would have been desirable to have numbered that of enriching the Philosophical Transactions with biographical sketches of her more eminent Fellows. But while we express this wish, we are sufficiently aware of the difficulties which would be encountered in carrying such a plan into effect. The Secretaries, by whom alone this duty could be rightly performed, would require to unite a profound and varied knowledge of science with a taste for literary composition, and at the same time to be freed from all professional labour. Such a combination of qualifications, however, could only be expected in the office-bearers of an institution directly supported by the nation. Even under its present constitution, the Society might make a successful commencement; and though not carried to its fullest extent, the plan would prove a powerful stimulus to the cultivation of the more abstract departments of knowledge.

The history of Dr Bradley's manuscripts is contained in the following extract:

'Dr Bradley's manuscripts were given by his son-in-law, the Rev. Samuel Peak, to Lord North, who presented them to the University of Oxford, of which he was then Chancellor: they were placed in the hands of Dr Hornsby, Savilian Professor of Astronomy, with a view to publication; and the observations made with the new instruments at Greenwich, from 1750 to 1762, were printed at the University Press. The original books, containing these and the other Greenwich observations, were then deposited in the Bodleian Library, with a small number of loose papers (in one of them), from which some additions had been made to the original publication. Repeated enquiries have of late years been made for Bradley's other remains; but no traces of them could be found, until, by a combination of fortunate circumstances, it was discovered that very many were still extant among Dr Hornsby's, own papers. representation of the fact having been made to his family, they were readily restored to the University; and as I had been the means of recovering them, they were, in the summer of 1829, placed in my hands, with a request that I should prepare for the press whatever might be found fit for publication.'

A

The task which Professor Rigaud was thus led to undertake, turned out, from various causes, to be far from an easy one,

In the examination,' says he, of Bradley's papers, many notices occurred of what was either entirely new, or only inperfectly known; there were several particulars likewise connected with them which were passing fast into oblivion. *** Many of those notices were of such a nature, that, if introduced into the body of the publication, they would have required many notes of explanation, sometimes longer than themselves. Again, it was repeatedly found that papers, the whole of which did not require to be printed, admitted of extracts being made from them, that were well worth preserving. These were all connected more or less with Bradley's studies and pursuits, and they threw new light on the objects which engaged his attention. It appeared, therefore, that they could be presented to the world in no way which would make them more clear or more useful, than if they were connected with a narrative of his progress through life. *** All this naturally led to an enquiry into his personal history, and it was found that there was hardly any thing generally known of it but what was contained in a few pages of the Supplement to the Biographical Dictionary (Svo, 1767), and in the Eloge which was pronounced on him by De Fouchy, before the Royal Academy of Sciences at Paris, in 1762.

James Bradley was the third son of William Bradley of Hampnet, near Northleach, and of Jane Pound, of Bishop's Canning, in Wiltshire. He was born in 1692 or 1693, and from the Grammar School of Northleach he went to Baliol College, Oxford, where he was admitted a commoner, on the 15th March 1710-11. During his absence from the University, he seems to

have lived chiefly with his maternal uncle, the Reverend James Pound, who was then one of the best practical astronomers in England, and for whose observations both Newton* and Halley made frequent applications. Under his roof Bradley probably acquired that fondness for astronomy which formed the leading passion of his life; and so early as 1715, we find the uncle and the nephew pursuing in concert their favourite studies. Bradley's earliest communication to the Royal Society was made from Oxford in March 1716; and contained an account of the remarkable aurora borealis which appeared on the 6th of that month. Dr Halley proposed him as a Fellow of the Society on the 23d October 1718, at a meeting of the Council where Newton presided; and he was on the same day elected, along with Sanderson the celebrated blind mathematician.

In 1719 and 1722, Bradley made two remarkable observations on the double star Castor, to which he probably attached little value at the time, but which have led Sir John Herschel to a more accurate determination of the motion of that binary system.

Having been educated for the church, Bradley had the good fortune to be presented, in 1719, to the vicarage of Bridstow, near Ross, by Hoadly, Bishop of Hereford; and in the following year he was appointed by the Prince of Wales to the rectory of Llanddewi, through the influence of his friend Samuel Molyneux, his Royal Highness's secretary. During the intervals of his parochial duties, Bradley paid frequent visits to his uncle's observatory at Wansted; and we have no doubt that he felt a painful struggle between his sense of duty and his devotion to science. This, however, did not last long, for upon the death of Dr Keill in 1721, he was elected Savilian Professor of Astronomy at Oxford; an appointment which laid him under the obligation of resigning his livings, while it gave full scope to his astronomical pursuits.

After the death of his uncle in 1724, Bradley continued to make many important observations with the same instruments; but these have now little interest compared with those which we shall proceed to describe.

*

The generosity of Newton in patronising science is well known; but Mr Rigaud has discovered, in the account-books of Mr Pound, two striking examples of his liberality, as indicated by the following entries : -1719, July 13, To a free gift received from Sir I. Newton, L.52, 10s. 1720. April 28, To a gift received of Sir I. Newton, L.52, 10s.' sums, as Professor Rigaud observes, were, no doubt, acknowledgments of the assistance which Sir Isaac received from Pound.

These

His friend, the Hon. Samuel Molyneux, had commenced a series of observations, with the view of solving the great problem of the parallax of the fixed stars; or of determining whether these bodies changed their apparent place in the heavens when seen from the two extremities of the earth's annual orbit,-a distance of nearly 200 millions of miles. Dr Hooke had long before constructed an instrument for making these observations, and had fixed upon the star (viz., Draconis) which was suitable for the purpose. Mr Molyneux made choice of the same star, and had his instrument constructed on the same principles, by that celebrated artist Mr George Graham.

As soon as the apparatus was completed, it was erected, in November 1725, in Mr Molyneux's house; a large mansion at the western extremity of Kew Green, which belonged to his wife, Lady Elizabeth Capel, and which afterwards became the residence of George III. The first observation was made with it on Draconis on the 3d December 1725; and the observations were continued on the 5th, 11th, and 12th of the month, without any change of place being noticed in the star. On the 17th, however, Bradley observed that the star passed a little more southerly than before. Ascribing this result to the uncertainty of observation, the star was again observed on the 21st, when it was found to have passed still more southerly—a result which surprised them extremely, as it was in a direction opposite to what would have been produced by an annual parallax. Being now satisfied that this southerly motion of the star was not owing to inaccuracy of observation, it naturally occurred to them, that it might have been occasioned by some change in the materials, &c., of the instrument. This cause was soon excluded, not only by a determination of the great exactness of the instrument, but by the continued southerly motion of the star, which began to return northwards again about the middle of April, and returned to its original place in December 1726, after having described an apparent orbit about 39 seconds in diameter.

The cause of this singular motion now remained to be ascertained; and it is curious to observe the progress of Bradley's mind in this enquiry. He proceeds by the method of continued hypothesis, excluding, by new observations which the hypothesis indicates, each successive conjecture, till he arrives at the one which is consonant with the whole mass of his observation. This is not the Baconian method of investigation; but it is the method by which all original minds pursue truth through the mazes of error, till they at last surprise her in her strongholds.

6

Bradley himself informs us, that a nutation of the earth's axis was one of the first things that offered itself on this occasion,'

as the cause of the apparent motion of the star. This hypothesis was excluded by observing the motion in other stars; and particularly in a small one opposite, in R. Ascension, to Draconis, and nearly at the same distance from the North Pole of the Equator, which changed its declination only half as much as y Draconis, whereas the changes should have been nearly equal, if they had been produced by nutation.

The next cause that suggested itself was an alteration in the direction of the plumb line, with which the instrument was constantly rectified; but Bradley himself observes, that this upon 'trial proved insufficient.'

Another, and certainly a most ingenious hypothesis, presented itself. He considered what refraction might do,'—not of course the ordinary refraction of the atmosphere--but a refraction arising from an alteration in the figure of the atmosphere, which it might be supposed to experience if the earth moved in a resisting medium. On this supposition, the upper surface of the atmosphere would assume the figure of an oblong spheroid, having its largest diameter in the direction of the earth's motion, and the earth being nearest to the advancing end of the spheroid. Hence it was inferred that y Draconis would appear to describe nearly a circle round its true place; and it was considered, upon the whole, that the telescopic star in Auriga, and the star in the head of Perseus, had motions consonant with this hypothesis. Plausible, however, as it was, it rested on a hypothetical assumption by no means probable, and was speedily banished by new and more accurate observations.

γ

Although no progress was yet made in discovering the true cause of the phenomenon, still, as Professor Rigaud observes, 'the observations to which they had had recourse, as tests of the 'hypotheses which had occurred to them, had given a clue to fur'ther investigation;' and they had found that the motion in declination was somehow connected with the latitude of the star. In this difficulty, Bradley resolved to erect a new zenith sector for himself at Wansted, in order that he might observe a greater number of stars than could be seen in Molyneux's instrument. It was completed in 1727, and he inferred, from some of his earliest observations, that the maximum apparent motion of different stars was proportional to the sine of their latitude, if not, as he had at first supposed, to the latitude itself. This new hypothesis was disproved by more numerous observations; and being thus baffled in all his attempts at generalization, he began to despair of success. An idea, however, occurred to him by the merest accident, which suggested that cause of which he had been so long in search. When he was sailing with a pleasure party on