364 Scientific Intelligence. 



Art. XXXIV.— SCIENTIFIC INTELLIGENCE. 

 I. NATURAL PHILOSOPHY. 



ASTRONOMY. 



1. Remarkable Double Tail in the Comet of 1823. — As this singular fact 

 has been observed both in Europe and America, there can be no doubt of its 

 truth, and therefore the particular details of it become very interesting to 

 the Astronomer. This phenomenon was observed by several persons at 

 Newhaven Connecticut, on the evening of January 23, and previous to 

 this by President Day of Yale College. The faint stream of light which 

 was seen to extend from the comet towards the sun, was not directly op- 

 posite to its usual tail, but inclined at an angle of 178^° or 178° to it. In 

 its brightness and length it was variable, being sometimes visible only near 

 the nucleus of the comet, and at other times extending to as great a dis- 

 tance as the usual tail. It was, however, narrower, and was supposed by 

 some to converge to a point. It was observed again, through a very clear 

 atmosphere, on th<? morning of the 27th, when both were fainter than 

 before, but it retained the same relative position. It vanished a little be- 

 fore the tail of the comet, after having been a few days visible. 



The very same phenomenon was observed by M. de Biela at Prague. He 

 first saw it on the night of the 22d January, and also on the 25th and 27th, 

 but neither before nor after. He describes the stream of light as a tail 

 turned towards the sun, and he says that the two tails were not exactly 

 opposite to each other, but forming a very obtuse angle. The new tail 

 was neither so brilliant nor so long as the usual one- See Professor Silli- 

 man's Journat,vo\. viii. p. 315. 



2. Supposed Influence of Comets on the Sun's Surface. — M. de Biela con- 

 ceives that he has observed an effect produced on the luminous state of the 

 sun by the proximity of comets, and he is said to have observed the in- 

 crease of spots on its surface when comets have approached to their peri- 

 helion. 



3. Periodical Comet of 1819. — According to the calculations of M. Da- 

 reoiseau, the following are the elements of the comet at its return in 1825. 



Passage of Perihelion, September 17 084 



Eccentricity - - 0.8449784 



Long, of Perihehon - - 157° 14' 30" 



Long, of Node - - 334 22 8 



Inclination of Orbit - - 13 23 29 



Mean Daily Motion - - 1070". 0866 



Half of the Greater Axis - 2.223611 



The following ephemerides of the comet will enable us to find it in 1825, 

 though there is little reason to hope that it will be seen during that period, 

 as its elongation from the sun varies from 49° to 33° in the interval em- 

 braced by the following table. After it passes its perihelion it is still less 

 likely to be seen. In the autumn of 1828, however, it will be visible over 

 all Europe. 



