584 Royal Irish Academy. 



5. The naming of constellations after their imagined figures must 

 be abandoned. 



Individual stars are most conveniently designated by Greek let- 

 ters, the letters of the alphabet being assigned in the order of the 

 brightness of the stars. The inconvenience which would sometimes 

 attend this last condition might be remedied. 



The practice of giving a proper name to each star is so conve- 

 nient, that the author would wish to see it extended to all stars of 

 the third magnitude, at least ; and he concludes with some further 

 suggestions on this point. The paper is accompanied by a plate in 

 illustration of the principle of arrangement*. 



ROYAL IRISH ACADEMY. 



Nov. 9. 1840 The Rev. T. R. Robinson, D.D., M.R.I.A., gave 



the Academy an account of a large reflecting telescope, lately con- 

 structed by Lord Oxmantown, and of the processes employed in 

 forming its speculaf. 



After explaining the relative importance of magnifying and illumi- 

 nating power, Dr. R. proceeded to give a brief sketch of the history 

 of the reflecting telescope, which seemed to have been forgotten for 

 many years after its invention, till it was revived by Hadley. The 

 labours of Short soon gave it celebrity ; yet even this artist limited 

 himself in almost every instance to sizes which were not more power- 

 ful than the achromatics of his day, and his large instruments appear 

 to have been failures J. It was not till a full century after the pub- 

 lication of Newton's paper, that Sir William Herschel gave this tele- 

 scope the gigantic development which has crowned him with im- 

 perishable fame ; and by the construction of telescopes of nineteen 

 and forty-eight inches aperture, placed regions almost beyond the 

 scope cf measurement within the reach of human intellect. But as 

 Short, in a spirit unworthy of his talents, took care that his knowledge 

 should die with himself, and Herschel published nothing of the means 

 to which his success was owing, the construction of a large reflector 

 is still as much as ever a perilous adventure, in which each individual 

 must grope his way. Accordingly, the London opticians themselves 

 do not like to attempt a mirror even of nine inches diameter, and 

 demand a price for it which shows the uncertainty and difficulty of 

 its execution. In Ireland we are more fortunate, for a member of 

 our Academy, Mr. Grubb, finds no difficulty in making them of ad- 



[* On the subject of this paper see an abstract of a memoir by fhe late 

 Dr. Olbers, in the proceedings of the Society for March, aute, p. 571 . 

 —Ed.] 



[•}• An abstract of Lord Oxmantown's paper on his Telescope, read be- 

 fore the Royal Society, and published in the Philosophical Transactions, 

 will be found in Phil. Mag., Third Series, vol. xvii. p. 380. — Ed/] 



J A Newtonian of six feet focus, and 9'4 inches aperture, is said by Mas- 

 kelyne to have shown the first satellite of Jupiter 13" longer than a triple 

 achromatic of 3 - 6 inches aperture. The telescope of twelve feet focus, and 

 eighteen inches aperture, now at Oxford, showed multiple rings of Saturn. 



