On the Royal Observatoyy at Palermo. 87 



unless we know that the same mode of reduction has been 

 adopted in each, and the same eleinents employed in the com- 

 putations. 



The next subject treated of by M. Cacciatore is that of the 

 six comets which he observed at Palermo. These are the 

 comets of 1821, 1822, and 1824, the comet of Encke in 1825, 

 and another comet in 1825, the return of which he also ob- 

 served in 1826. The same plan is followed here as in the 

 case of the planets. First, the observations, as taken from the 

 observation-book, ai'e given in the order in which they were 

 made. The place of the comet is then reduced, and a sepa- 

 rate table is given of those reduced places : and lastly, the ele- 

 ments of the comet are inserted. 



The work is closed with numerous meteorological tables, from 

 the year 1791 to 1825, both inclusive. The state of the ba- 

 rometer and thermometer is taken four times in each day : viz. 

 in the morning, at noon, in the afternoon and at midnight ; 

 and the names of the observers are given. We have also the 

 maximum, the minimum, and the mean state of each instru- 

 ment for each month in the year, together with the days of 

 the month on which each case occurs. Amongst the most re- 

 markable phsenomena recorded in the meteorological journal, 

 we may notice several destructive earthquakes ; in many of 

 which the concussions were so great as to stop the pendulum 

 of the clock : and in one instance, in 1823 (when several houses 

 were thrown down and fourteen persons were buried in the 

 ruins), the floor of the observatory oi)encd, and threatened de- 

 struction to the building. 



Upon the whole, this work reflects great credit on the di- 

 stinguished astronomer who now conducts the observatory at 

 Palermo. The plan, although nearly the same as was pur- 

 sued by M. Piazzi, and therefore not altogether new, is dif- 

 ferent from the printed observations of other observatories : 

 and is in many I'espects worthy of imitation. For, although 

 we would not wish to be considered as discouraging the print- 

 ing of observations in the order, and in the manner in which 

 they arc actually made, yet we are certainly desirous, in com- 

 mon with many others that are fond of astronomy, of seeing 

 the reductions of those observations a little more frecjucnlly 

 than we do; and, at all events, of seeing the ])rincipal results 

 given at the end of each year. It is in this manner only that 

 the vast mass of observations that annually issue from the 

 press can be made available and useful to the purposes of 

 astronomy, and that we can exjject tt) derive any advantage 

 Ironi the exertions of public or private observers. j, 



XVII. Letter 



