3/6 Rephj to Mr. Ivory's Remarks 



in re obnoxium esse catalogum, pi jestare audeo. Quinque vulgo 

 computatBE sunt observationes cujusvis Stellas ; ubicunque enim 

 in commentariis Bradleianis quincjue tantumniodo paucioresve 

 scriptse extabant, niillam earum oniisi. Contra, ubi plures obser- 

 vationes adcrant, sajpius eum egrcssiis sum numenim. Hoc mode 

 affectum esse puto ut catalogo optabilis sit subtilitas. 



" Comparationi, cum magno Piazzi catalogo institutse, subti- 

 lissiinum inesse puto proprii motus stellarum fixarum determina- 

 tionem, quam pro bodierna rerum conditioue expectare quis pos- 

 sit. Annuae adscensiomun rectarum ac declinationum muta- 

 tiones computabantur pro annis 1755 et 1300: neque miniitjE 

 secundffi partibus centenariis, ut vulgo fit, contentus fui, sed de- 

 scend! ad partes milliarias, ut in comparatione amborum catalo- 

 gorum certitudinem assequerer." 



The proper motion of the stars forms the subject of the 12th 

 section, wherein Professor Bessel has obtained the following re- 

 sults : that out of 2959 stars employed in his comparison, there 

 are 1375 whose annual proper motion amounts to 0'"1 of a 

 o-reat circle; 425 which amount to0'"2; and only 71 which 

 extend to 0-"5. _______ 



From the preceding account of the existing Catalogues, the 

 reader will form his own opinion. The writer of this, however, 

 believes that most persons will consider the assertion made at 

 the commencement of the article, sufficiently established. 



LXVI. Reply to Mr. Ivory's Remarks o?i the Series of the 

 Article Cohesion. Li a Letter to the Editor. 



Sir, — A AM perfectly ready to admit and to lament the incon- 

 veniences of the series in the article Cohesion of the Encyclo- 

 pcedia Britamiica ; but I must beg to be allowed to assert and 

 to lament still more, that both Mr. Ivory's methods of compu- 

 tation are still more imperfect ; and that they are proved to be 

 so, by the very arguments which he has adduced against the series 

 in question. 



In fact, all these arguments tend to show, that the series, taken 

 for any limited number of terms, must give the depression too 

 great, and may sometimes make it mtich too great ; since Mr. 

 Ivory does not attempt to deny, that all its terms must be posi- 

 tive ; and that, the more terms we compute, the smaller will the 

 depression come out. 



If, indeed, Mr. Ivory's computation had made the depression 

 ten times as remote from that which was assigned by bis prede- 

 cessor as he has done, it would have been very difficult to have 

 proved its error by the same mode of reasoning, provided that he 



had 



AiiL 



