396 HISTORY OF PHYSICAL ASTRONOMY. 



royal sway. Seth Ward, who was a Fellow of Sidney College, Cam- 

 bridge, was deprived of his Fellowship by the parliamentary committee; 

 but at a later period (1649) he took the engagement to be faithful to 

 the Commonwealth, and became Savilian Professor of Astronomy at 

 Oxford. Wallis held a Fellowship of Queen's College, Cambridge, but 

 vacated it by marriage. He was afterwards much employed by the 

 royal party in deciphering secret writings, in which art he had pecu- 

 liar skill. Yet he was appointed by the parliamentary commissioners 

 Savilian Professor of Geometry at Oxford, in which situation he was 

 continued by Charles II. after his restoration. Christopher Wren was 

 somewhat later, and escaped these changes. He was chosen Fellow 

 of All-Souls in 1652, and succeeded Ward as Savilian Professor of 

 Astronomy. These men, along with Boyle and several others, formed 

 themselves into a club, which they called the Philosophical, or the 

 Invisible College; and met, from about the year 1645, sometimes in 

 London, and sometimes in Oxford, according to the changes of fortune 

 and residence of the members. Hooke went to Christ Church, Oxford, 

 in 1653, where he was patronized by Boyle, Ward, and Wallis; and 

 when the Philosophical College resumed its meetings in London, after 

 the Restoration, as the Royal Society, Hooke was made " curator of 

 experiments." Halley was of the next generation, and comes after 

 Newton; he studied at Queen's College, Oxford, in 16V 3 ; but was at 

 first a man of some fortune, and not engaged in any official situation. 

 His talents and zeal, however, made him an active and effective ally 

 in the promotion of science. 



The connection of the persons of whom we have been speaking has 

 a bearing on our subject, for it led, historically speaking, to the pub- 

 lication of Newton's discoveries in physical astronomy. Rightly to 

 propose a problem is no inconsiderable step to its solution ; and it was 

 undoubtedly a great advance towards the true theory of the universe 

 to consider the motion of the planets round the sun as a mechanical 

 question, to be solved by a reference to the laws of motion, and by the 

 use of mathematics. So far the English philosophers appear to have 

 gone, before the time of Newton. Hooke, indeed, when the doctrine 

 of gravitation was published, asserted that he had discovered it pre- 

 viously to Newton ; and though this pretension could not be main- 

 tained, he certainly had perceived that the thing to be done was, to 

 determine the effect of a central force in producing curvilinear motion ; 

 which effect, as we have already seen, he illustrated by experiment as 

 early as 1666. Hooke had also spoken more clearly on this subject 



