On the Royal Observatory at Palermo. 85 



He next discusses the subject of the nutation of the obli- 

 quity of the echptic ; and by comparing the several observa- 

 tions of the solstices from 1791 to 1821, he obtains the quan- 

 tity 9", 12. By a different mode however of investigating the 

 subject (that is, by arranging tlie whole 522 solstitial obser- 

 vations into 52 equations of condition, and by the application 

 of the method of minimum squares), he subsequently obtains 

 9'\S555 for the nutation, and 0",4683 for the annual diminu- 

 tion of the obliquity of the ecliptic. The mean of the two re- 

 sults for tiie nutation is 9",238 ; which is almost identical with 

 that deduced by Dr. Brinkley, and which has been assumed 

 by the Astronomical Society of London, in the formation of 

 their recent Tables. 



From the solstices M. Cacclatore proceeds to the determi- 

 nation of the equinoxes : and here he finds the same anomaly 

 (and arising partly from the same source) as in the observa- 

 tions of the solstices. For, the length of the year, as deduced 

 from the autumnal equinoxes, is always greater than when de- 

 duced from the vernal equinoxes : even after the correction has 

 been made, as already alluded to, for the expansion of the 

 circle. The mean of six years observations gives the length 

 of the tropical year, as deduced from the 



Vernal equinox =365'*-24.21514. = 365'i 5^ 48™ 41%872 

 Autumnal equinox =365 -2423099 = 365 5 48 55 ,575 

 Mean =365 -2422306 = 365 5 48 48 ,724 

 which is exactly one second less than the quantity assumed by 

 M. Laplace. 



From the sun and the planets M. Cacciatore passes to the 

 subject of the fixed stars; there being no mention made of any 

 observations on the moon. This part of the work is confined 

 to a comparison of the observations of 173 stars, taken from 

 different parts of the heavens. The observations of these 

 stars, as made by M. Cacciatore, are compared with the ob- 

 servations made by Fiamsteed, Bradley, Mayer, La Caille, 

 Piazzi, Zach and others : and in these comparisons some sin- 

 gular anomalies are discovered. For instance, in conijiaring 

 104 Piscium, M. Cacciatore deduces the following proper 

 motion in declination : viz. 



From 1755 to 1798 = + 0",058 

 1798 to 1808 = - 0,430 

 1808 to 1824 = -f 0,156 

 Again, the comparison of 8 Trianguli at different periods, af- 

 fords the following results for its proper motion in declina- 

 tion : viz. 



