1836.] 



Malleifs Comet. 



495 



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 total augmentation. 

 Rosenberg, a German astronomer, considers that the action of Venus, 

 Mercury, and Mars, may produce an acceleration of 6| days, viz. 51 

 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 Mercury 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 observ- 

 ed 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 2lst, 

 at s-past 6, p. m., three luminous sectors were distinctly seen in the 

 nebula ; the feeblest was situated at the prolongation of the tail. On 

 the 23d, the sectors had disappeared. Schwabe, of Dessau, calls these 

 sectors secondary tails. Mr. Cooper, observed one such sector in Ire- 

 land, 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 peri- 

 helion sooner than if it moved through a vacuum. Now, on the con- 

 trary, according to Rosenberg, it should have been six days later over 

 the results of calculation, apart from all idea of an ether. The differ- 

 ence though much smaller, found by Pontecoulant, is in the same direc- 

 tion. 



3. No comets have presented hitherto any phases, so that we were 

 ignorant of the nature of the light of these bodies. It was expected 

 that the intensity would have been determined during the last appear- 

 ance of Halley's comet, but the remarkable changes which it under- 



