J32 Biographical Account of Dr, Wilson, [Nov. 



whole retinue of planets, primary as well as secondary, and of 

 comets, at commodious distances from one another. 



In like manner. Dr. Wilson thought it not unreasonable to 

 suppose, that the same principle might have assigned to it a 

 dominion incomparably wider m extent, and that the order and 

 stability, even of ql universe, and of every individual system com- 

 prehended in it, might depend upon periodical motion round 

 some grand centre of general gravitation. This conception, 

 besides appearing to them warranted by every view they could 

 take of the nature of gravity, seemed moreover to receive some 

 support from the discoveries which, since the time of the great 

 Halley, have been made of what has been called the " Proper 

 motions of the fixed stars," and particularly from the opinion 

 entertained by that excellent astronomer Dr. Maskelyne, 

 *' That, probably, all the stars are continually changing their 

 places by some slow and peculiar motions throughout the 

 mundane space." 



Soon after this view had arisen, out of the famihar conversa- 

 tion above-mentioned, it was published in a very short anony- 

 mous tract, entitled, " Thoughts on general Gravitation, and 

 Views thence arising as to the State of the Universe." The 

 chief inducement to so early a pubHcation was the hope of 

 drawing immediate attention to so interesting a point, which 

 might possibly lead to the discovery of some way by which the 

 matter might be brought to the test of observation. 



It is quite obvious, that the foregoing suggestions necessarily 

 imply a motion of the solar system, as one of that immense 

 host, which, for what we yet know, may be subjected to the 

 laws of periodical revolution. Accordingly, it early occurred, 

 that, perhaps, the most advantageous way of advancing in this 

 investigation, might be to try to find out, if possible, symptoms 

 of such a law as affecting that system to which we ourselves 

 belong. 



It sometimes struck him, when looking over the progress of 

 philosophical discovery, that many things of high moment 

 appear to have lain long wrapped up in embryo, by our not 

 employing ourselves more frequently in what may be called 

 **'a direct search/' and in filling up with more attention and 

 boldness the list of desiderata. Between this last step, and the 

 accomplishment of a profound discovery, he conceived that the 

 transition might sometimes be made with no great effort of 

 invention, by only sifting carefully such principles as are already 

 known and famihar to us, and availing ourselves of them in theiV 

 full extent. 



It was by proceeding in this way, and, when considering the 

 manner by which the motion of hght would be affected by 

 reflecting and refracting media, themselves moving with great 

 velocity (a most interesting field in Optics, then wholly unculti- 



