82 0?i the Royal Observatory at Palermo. 



out of the observation book; and, in general, some star in the 

 vicinity of the planet is also observed and recorded : a me- 

 thod which tends to correct any error that may inadver- 

 tently have occurred in the register, or in the observation. 

 After this, a table is given wherein the planets are arranged, 

 according to their position in the system, and all the observa- 

 tions relative to each planet are reduced to the day of obser- 

 vation. This table consists of five columns : 1° the mean time 

 of the transit ; 2° the reduced right ascension ; 3° the reduced. 

 declination ; 4° the computed longitude ; and 5° the computed 

 latitude corresponding thereto. Another table then follows, 

 containing the mean time of the opposition of the superior 

 planets, together with their deduced longitudes and latitudes 

 at those respective periods. The utility and convenience of 

 these arrangements are too apparent to be insisted on. 



The second chapter consists of eclipses and occidtations. 

 The original observations are here also recorded and printed, 

 together with the name of the observer, the power of the tele- 

 scope, and the particidar clock used in the observation. And, 

 in order that the time may be correctly determined, the transit 

 of some well-known star, near the time of observation is also 

 given. The correct mean time of each observation is afterwards 

 given in a subsequent table : and the whole is thus again pre- 

 sented to our view in another and a more perfect form. 



The next division of the work contains observations of the 

 sun, near the solstices and near the equinoxes, from the year 

 1817 to the end of 1825. The observations near the solstices 

 are afterwards presented in another form, by grouping all those 

 which relate to each solstice separately ; and reducing them to 

 the moment of the sun's passing the solstitial colure. The 

 computations are given in detail : the table of refraction em- 

 ployed, together with the constant of nutation, and other 

 quantities are distinctly pointed out: and the reader is not 

 left in doubt as to any of the corrections. The result of the 

 investigations is, that there appears to be a difference in the 

 obliquity of the ecliptic, accoi'ding as the summer or winter 

 observations are used in the computations. The mean of lOl- 

 observations made in summer gives the mean obliquity for Ja- 

 nuary 1, 1820, equal to 23° 27' 48",08 : and the mean of 50 

 observations made in "winter, gives 23° 27' 42", 73. The mean 

 of the lahole (regard being had to the number of observations 

 of each kind) is 23° 27' 46",35. 



M. Cacciatore next discusses the cause of this singular 

 phjEnomenon, which is one indeed that has generally been 

 noticed at other observatories ; and which has been supposed 

 to arise from one or other of the following circumstances : 1° 



a bendina 



