1835.] Scientific Intelligence. 467 



Clairaut was so nervous that he hurried his calculation before the 

 Institute, although he had not completed it. He stated, that the 

 comet would reach its perihelion on the 4th of April, but that it 

 might be seen sooner. 



Voltaire has said, that the philosophers did not go to bed in the 

 beginning of the year, so anxious were they to observe it. Notwith- 

 standing their anxiety, it was discovered on Christmas day, 1758, by 

 a farmer in the neighbourhood of Dresden ; and then by Messier in 

 the middle of January at Paris. It reached its perihelion on the 

 13th March. Now, although Clairaut was not quite correct as 

 to the day, the only wonder is, that he should have been so accurate, 

 for as he said, when a body traverses a space of 1500,000,000 of miles 

 beyond our sphere of observation, how do we know but that some 

 other planet may act upon it and influence its course. In 25 years 

 the planet Herschel was discovered, which it was proved, did actually 

 operate in producing the effect which Clairaut had surmised. 



1st May. The comet of this year will appear in the end of 

 October or beginning of November. The cause of this uncertainty, 

 is our want of knowledge of the mass of the planet Herschel. Four 

 different davs have been fixed on by calculators. These are, 

 31st October, 4h. 46' 58-8 



5th November, 7 >, 40 „ 

 8th „ 4 „ 48 '„ 



10th „ 2 „ 30 „ A.M. 



On the 7th of October, it will be near the head of the great bear, 

 and will be visible after sunset. On the 11th, it will be near the 

 tail of the same constellation. On the 10th, it will make its nearest 

 approach to the earth. It is probable, that it will be of less magni- 

 tude than it was in 1759, if we are to judge from its most recent 

 history ; but if we go back to the appearances which it presented at 

 its first periodic times, this conclusion is not warranted. Its history 

 has been traced back to 150 years before Christ. In 54, it was also 

 observed, and was so bright that the birth of Mithridates, who came 

 into the world in this year was ascribed to it. After this period it 

 must have returned five times without having been noticed. In 323 

 it is again recorded. In 399 it again appeared, when it was of great 

 magnitude. In 550 it is again recorded, and also in 930, and 1250. 

 In 1305 it possessed great splendour, and in 1456 its tail was of such 

 enormous extent that it occupied two thirds of the space comprized 

 between the horizon and zenith, or above 1,500,000,000 of miles. 

 In 1531 it had diminished in size. In 1607 it was still less, and 

 was discovered by Kepler when returning from a dinner party. The 

 tail was invisible. In 1759 it had the appearance of a fixed star sur- 

 rounded by some luminous matter. Hence, it is probable that this 

 year it will be smaller. But, at the same time, we cannot fail to 

 remark that it has increased and diminished without any regularity. 



There are only two suppositions which present themselves to ac- 

 count for its non-appearance should that happen, viz. : 1. That a 

 planet may exist beyond Herschel which may exert its influence on 

 it and draw it out of its orbit, or 2. it may have met with another 

 comet during the interval which has elapsed since it last appeared, 

 which may have carried it off". 



2 h 2 



