COMETS. 115 



its return. They know that the faintness of its light, and its great distance, perhaps 

 even bad weather, may keep it from our view ; but the public will find it difficult to 

 believe us ; they will put this discovery, which has done so much honour to modern 

 philosophy, among the number of predictions made at hazard. We shall see dissertations 

 spring up again in the colleges, contempt among the ignorant, terror among the people, 

 and seventy-six years will elapse before there will be another opportunity of removing all 

 doubt." Lalande engaged with Clairaut and Madame Lepaute in calculating the attractive 

 influence of Jupiter and Saturn upon the comet, which might change to some extent 

 its time of perihelion. " During six months," he remarks, " we calculated from morning 

 till night, sometimes even at meals ; the consequence of which was, that I contracted an 

 illness which changed my constitution for the remainder of my life. The assistance 

 rendered by Madame Lepaute was such, that without it we never could have dared to 

 undertake this enormous labour, where it was necessary to calculate for every degree, and 

 for 150 years, the distance and force of each of the two planets with respect to the 

 comet." They finally announced in November 1758, just as astronomers began to look 

 out for its return, that the comet would employ 618 days more to return to the perihelion 

 than on the preceding revolution; namely, 100 days from the effect of Saturn, and 518 

 days from the action of Jupiter. The perihelion was placed therefore about the middle 

 of April 1759, but Clairaut distinctly forewarned the world, that being pressed for time, 

 he had neglected small values, which collectively might amount to, more or less, about a 

 month in the seventy-six years. The event realised the anticipation of Halley, and 

 answered as nearly as possible to the calculations of the French philosophers. The comet 

 was first seen from the neighbourhood of Dresden by George Palitzch, a farmer by 

 profession, but a self-educated astronomer. This was on Christmas day 1758, with an 

 eight-feet telescope. It was afterwards seen at Paris, Leipsic, Lisbon, and Cadiz. It 

 passed its perihelion on the 12th of March 1759, exactly a month before the time 

 announced, but within the assigned limit of divergence from that date. The elements of 

 its orbit proclaimed it to be the comet of the former periods by their similarity. The 

 following is Lalande's deduction, the letters indicating the particulars connected with the 

 table already given : 



a b c d e f h 



1759 53 46' 17 40' 303 8' 58490 March 12 Retrograde. 



Another period of revolution has transpired since the time to which we are referring. 

 Dating seventy -six years forward, we are brought to the year 1835. After estimating 

 the action of the planets, Damoiseau, of the French Board of Longitude, fixed the 

 perihelion passage on Nov. 4th of that year, and Pontecoulant on Nov. 13th, a difference 

 of nine days. Both agreed that the first appearance of the comet would be in the early 

 part of August, and the perihelion certainly about the middle of November. The comet 

 was seen at Rome Aug. 5th, and passed its perihelion Nov. 16th. The fictitiousness of 

 the representation, 



" A pathless comet, and a curse, 



The menace of the universe ; 



Still rolling on with innate force, 



Without a sphere, without a course," 



has thus been demonstrated, and these bodies proved to be constituent members of our 

 system, obedient to the law of gravitation, which keeps them within prescribed limits and 

 in definite orbits, as with bit and bridle. 



We may now glance at some of the appearances of this comet at its successive returns, 

 as far as historical records supply information. 



The comet of 1006 is conceived on good grounds to have been identical with that of 



I 2 



