250 Life of John Bcvis, M.D. F.R.S. &€. 



tical rules for finding the aberration, which were drawn up 

 and given him by Dr. Bevis, together with examples of the 

 corrections applied to several stars, which he had himself 

 cartfully observed with proper instruments ; whereby, as JNIr. 

 Sunpson observes, he has proved, the first of any one, that 

 the pha^nomena are universally as conformable in right 

 ascension as Dr. Bradley, who made this great discovery, 

 found them to be in declination. 



At a meeting of the Board of Longitude on the ISth Sep- 

 ten>ber 1764, he was nominated, jointly with Mr. George 

 Witchell and captain Campbell, to compute the observa- 

 tions made at Greenwich, and compare them with those 

 made at Portsmouth and elsewhere, lor the purpose of as- 

 certaining the accuracy of Mr. Harrison's timekeepers. 



To prove ihe estimation in which he was held by ma- 

 thematical men, wc need only observe, that the ingenious 

 Mr. Crakelt has dedicated to him his translation of 

 M. Mauduit's highly valuable jlstronomie Spherlque; 

 and the booksellers, on account of his well known literary 

 erudition, rc<ju(;stcd he would write a letter of recommenda- 

 lion to a very useful little dictionary, which has always, on 

 that account, gone by the name of Dr. Bevis's dictionary. 



ble has enriched the Philosophical Transactions, from 

 vol. xl. to vol. lix-. inclusive, with twenty-seven valuable 

 papers, mostly containing astronomical observations ; and 

 he ha=! inserted several ihuigs in the Mathematical Maga- 

 zine, by Messrs. Moss and Witchell, particularly a curious 

 paper on the satellite of Venus. 



He announced, in the Journal dcs Si^ovans for August 

 1771 J an English tra>islation of Lalande's Astronomy, done 

 prmeipally by himself; but it has never been published, al- 

 though left ready for the press at his death. 



The only things which have appeared separately with his 

 name were two pamphlets ; one entitled " The Satellite 

 Slidmg Rule," for determining the immersions and emer- 

 sions of the four satellites of Jitpiter; the other was " An 

 experimental Inquiry concerning the Contents, Qualities, 

 and medicinal Virtues of the two mineral Waters lately 

 <liiCovered at Bagnigge Wells, near London ; with Direc- 

 tions for drinking them, and some Account of their Suc- 

 cess in obstinate Cases :" 8vo. London, 176O. A second 

 edition, with additions, was given by him in 17G7. 



About this time the ingenious JNIr. John Dollond, of 

 St. Paul's Churchyard, invented the method of correcting 

 the aberration and colour of rays of light passing through 

 a siugle object-glass,, and thereby of shortening the length 



"^of 



