28 Hylory of AJlronoviy for 1798. 



nine-tenths of a fecond for the fecond ; and one fecond and 

 a half for the third. 



M. Bode, at BerHn, has publifiicd a new volume of his 

 Ephemerides for the year 1801, and a third fupplenientary 

 vokime; which contain many agronomical obfervations and 

 memoirs, by the German, French and Englilh aflronomers. 

 This work, like that of M. von Zach, is a repertory which 

 no aftronomer can be without. 



We have received alfo a folio volume of logarithmic tables, 

 publifhed in 1794, by M. Vega, an officer of artillery in the 

 emperor's fervice, Wlacq's tables, publifhed in 1628 and 

 1633, had become exceedingly fcarce; they were never re- 

 printed, and yeL they were often wanted. M. Vega has, 

 therefore, rendered a great fervice to mathematics by re- 

 publifhing that valuable edition. 



M. Schubert has publiflied, in German, at Peterfburgh, 

 2l large treatife of aflronomy, in three volumes quarto, form- 

 ing altogether nearly 900 pages. 



The Blbliotheqrie Britctninque of Geneva, for March and 

 April, contain interefting details refpcfting the method em- 

 ployed by M. Blair to corrcol the difference of refrangibility 

 in telefcopes. Eflential oils, a folution of corrofive fublimate 

 in fpirit of wine, with the addition of a little fal ammoniac; 

 butter (muriat) of antimony diluted in a little ether or 

 alcahol, mixed with a fevi^ drops of the muriatic acid, 

 anfwered the purpofe extremely well, when inclofed be- 

 tween two lenfes of crown glafs *. He formed a very good 

 objeft -glafs with a folution of fal ammoniac and mercurial 

 fublimate (muriat of ammonia and mercury). He has dif- 

 covercd that thefe different fubflances have not a like diftri- 

 butlon of colours, as Bofcovich remarked in 1765. In fliort, 

 he has calculated the curves of glalfes in fuch a manner as 

 to correft the aberration of fphericity. This curious paper 

 has been tranflated into French; but C. Leroy has kept 



* Tranlaftions of the Royal Society of Edinburgh, vol. iii. 



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