154 COSMOS. 



stars compiled by Halley. It was the result of a short resi- 

 dence at St. Helena in the years 1677 and 1678, but, singu- 

 larly enough, does not contain any determinations below 

 the 6th magnitude. 1 ' Flamstead had, indeed, begun his 

 great Star Atlas at an earlier period; but the work of this 

 celebrated observer did not appear till 1712. It was suc- 

 ceeded by Bradley's observations (from 1750 to 1762), which 

 led to the discovery of aberration and nutation, and have been 

 rendered celebrated by the Fundamenta Astronomies of our 

 countryman Bessel (1818)," and by the stellar catalogues of La 

 Caille, Tobias Mayer, Cagnoli, Piazzi, Zach, Pond, Taylor, 

 Groombridge, Argelander, Airy, Brisbane, and Riimker. 



We here only allude to those works which enumerate a great 

 and important part* 1 of the stars of the 7th to the 10th magni- 



19 Memoirs of the Royal Astron. Soc., vol. xiii. 1843, 

 pp. 33 and 168. 



30 Bessel, Fundamenta Astronomies pro anno 1755, deducta 

 ex observationibus viri incomparabilis James Bradley in Specula 

 astronomica Grenovicensi, 1818. Compare also Bessel, Tabula 

 RegiomontancB reductionum observationum astronomicarum ab 

 anno 1750 usque ad annum 1850 computatce (1830). 



M I here compress into a note the numerical data taken 

 from star catalogues, containing lesser masses and a smaller 

 number of positions, with the names of the observers, and 

 the number of positions attached : La Caille, in scarcely 

 ten months, during the years 1751 and 1752, with instru- 

 ments magnifying only eight times, observed 9766 southern 

 stars, to the 7th magnitude inclusive, which were reduced to 

 the year 1750 by Henderson; Tobias Mayer, 998 stars to 

 1756; Flamstead, originally only 2866, to which 564 were 

 added by Baily's care ; (Mem. of the Astr. Soc.^ vol iv. 

 pp. 1291-64) ; Bradley, 3222, reduced by Bessel to the year 

 1755; Pond, 1112; Piazzi, 7646 to 1800; Groombridge, 

 4243, mostly circumpolar stars, to 1 810 ; Sir Thomas Brisbane, 

 and Riimker, 7385 stars, observed in New Holland, in th? 

 years 1822-1828; Airy, 2156 stars, reduced to the year 

 1845 ; Riimker, 12000 on the Hamburg horizon ; Argelander 



