32 t-'fenf John Dollond, F. R, S. 



foreiaiicrs, and the iealou$y of pliilosopliers at home, le^ 

 them to doubt of its reality; uud Euler himself, in hi» 

 paper read before the Academy of Sciences at Berlin, in the 

 year 1764, says — " I am not ashamed frankly to avow, 

 that the first accounts, which were published of it, ap- 

 peared so suspicious, and even so contrary to the best 

 established principles, that I could not prevail upon iTjyself 

 to give credit to them ;" and he adds, " I shoiJd never 

 have submitted to the proofs which Mr. Dollond produced 

 to support this strange phasnomenon, if M. Clairaut, wha 

 must at first have been equally surprized at it, had not most 

 positively assured me, that Dollond's experiments were but 

 too well founded." And when the fact could no longer be 

 disputed, they endeavoured to find a prior inventor, to 

 whom it might be ascribed, and several conjecturers were 

 honoured with the title of discoverers. 



Mr. Dollond's inrprovement in refracting telescopes was 

 of the greatest advantage in astronomy, as they have been 

 applied to fixt instruments ; by which the motions of the 

 heavenly bodies are determined to a much greater exact- 

 ness than by the means of the old telescopes. Navigation 

 has also been much benefited by applying achromatic tele- 

 scopes to the ** Hadley's sextant :"■ and from the improved 

 state of the lunar tables, and of that instrument, the longi- 

 tude at sea may now be determined by good observers to a 

 great degree of accuracy ; and their universal adoption by 

 the navy and army, as well as by the public in general, is 

 tile best proof of the great utility of the discovery. 



In the beginning of the year 1761, Mr. Dollond was 

 elected fellow of the Royal Society, and appointed optician 

 to his majesty, but did not live to enjoy those honours 

 long ; for on the 30th of November, in the same year, as 

 he was reading a new publication by M. Clairaut, on the 

 theory of the moon, and on which he had been intently 

 engaged for several hours, he was seized with apoplexy, 

 vhich rendered him immediately speechless, and occasioned 

 his death in a few hours afterwards. Besides Mr. Peter 

 Dollond, whom we have had occasion to mention in the 

 course of this memoir, his family, at his death, consisted 

 of three daughters and a son, who, possessing the name of 

 his father, and v/e may add, a portion of the family abili- 

 ties, carries on the optical busiucss in partnership with his 

 tldar brother. 



VII. Memoir 



