Scientific Intelligence, Sec. 317 



distinctly visible to the naked eye all over Europe and America. 

 This was 47 days before it reachd its perihelion, which happened 

 on the 16th of November. The previous calculation of Damoiseau 

 gave the 4th of November for this event, that of Pontecoulant the 

 7th of the same month. But a more complete calculation of the 

 action of the earth, and, especially, the substitution for the mass of 

 Jupiter of the fraction 70V4' instead of joVo' rendered it necessary 

 to add G days to the previous determination, which brought the 

 number to the 13th, within 3 days of the actual date. When Pon- 

 tecoulant thus deduced the 13th as the date of the perihelion, he 

 proceeded on the calculation, that 1054 globes similar to Jupiter 

 would be necessary to form a weight equal to that of the sun. The 

 recent observations of Airy have shewn, that it should be 1049, which 

 raises the date of the perihelion from the 13th to the 16th; the 

 difference between calculation and observation being only half a day 

 for 76 years. This remarkable coincidence has raised some doubt. 

 The perturbations produced by the planets upon which the French 

 astronomers made their calculations, were as follow : augmentation of 

 revolution by the action of Jupiter 135,34; diminution by Saturn 

 51,53 ; by Uranus 6,07 ; by the earth 11,70 = 66,04 to'tal aug- 

 mentation. Rosenberg, a German astronomer, considers that the 

 action of Venus, Mercury, and Mars, may produce an acceleration of 

 6-j days, viz. 54 days by the action of Venus, and one day by the 

 combined attractions of Mars and Mercury. Pontecoulant asserts, 

 that the action of Venus compensates itself, and that Mars and Mer- 

 cury cannot produce any such powerful effect as that stated by 

 Rosenberg. 



It is natural to inquire, have any new phenomena been observed, 

 or has any additional information been acquired by the visit of the 

 comet of last year ? 



1. At the Observatory at Paris, on the 15th October, at 7 o'clock 

 in the evening, by means of a lunar telescope, a sector comprised 

 between two right lines directed towards the centre of the nucleus, 

 was observed a little to the south of the point, diametrically opposite 

 to the tail. The light of this sector greatly surpassed that of all the 

 rest of the nebula. On the 16th, this sector had disappeared, but to 

 the north of the point, diametrically opposite to the axis of the tail, 

 a new sector was observed. On the 17th it remained, but was less 

 bright. On the 21st, at 5-past 6, p. m., three luminous sectors were 

 distinctly seen in the nebula ; the feeblest was situated at the pro- 

 longation of the tail. On the 23rd, the sectors had disappeared. 

 Schwabe, of Dessau, calls these sectors secondary tails. Mr. Cooper, 

 observed one such sector in Ireland, on the 19th October ; and Amici 

 noticed the same at Florence on the 13th. 



2. It cannot be said that the last appearance of the comet has 

 added any thing to our knowledge of the nature of space. Supposing 

 it to have passed through a resisting medium, it should have arrived 

 at his perihelion sooner than if it moved through a vacuum. Now, 

 on the contrary, according to Rosenberg, it should have been six 

 days later over the results of calculation, apart from all idea of an 

 ether. The difference though much smaller, found by Pontecoulant, 

 is in the same direction. 



