REMARKABLE COMETS. 1I9I 



I A. M., as the date. The expected comet was, of course, looked for with the 

 greatest assiduity, and was first seen on August 5 th. Approaching the sun, it 

 passed its perihelion on November i6th, at eleven o'clock in the morning, only 

 three days after the time predicted by De Pontecoulant. 



The Lost BielaJs Comet. — Nothing could more strikingly illustrate the differ- 

 ence between comets and other heavenly bodies that the fact of the total dissolu- 

 tion of one of the former. In 1826, a comet was discovered by an Austrian 

 named Biela, which was found to be periodic, and to have been observed in 

 1772, and again in 1805. The time of revolution was found to be six years and 

 eight months. In the next two returns, the earth was not in the right part of its 

 orbit to admit of observing the cornet ; the latter was therefore not seen again 

 till 1845. In November and December of that year it was observed as usual, 

 without anything remarkable being noticed. But in January following, the 

 astronomers of the Naval Observatory found it to have suffered an accident never 

 before known to happen to a heavenly body, and of which no explanation has 

 has ever been given. The comet had separated into two distinct parts, of quite 

 unequal brightness, so that there were two apparently complete comets, instead 

 •of one. During the month following, the lesser of the two continually increased, 

 until it became equal to its companion. Then it grew smaller, and in March 

 vanished entirely, though its companion was still plainly seen for a month longer. 

 The distance apart of the two portions, according to the computations of Profes- 

 sor Hubbard, was about 200,000 miles. 



The next return of the comet took place in 1852, and was, of course, looked 

 for with great interest. It was found still divided, aod the two parts were far 

 more widely separated than in 1846, their distance having increased to about a 

 million and a half of miles. Sometimes one part was the brighter, and some- 

 times the other, so that it was impossible to decide which ought to be regarded 

 as representing the principal comet. The pair passed out of view about the end 

 of September, 1852, and have not been seen since. 



The Great Comet of 1843. — This remarkable comet burst suddenly into view 

 in the neighborhood of the sun about the end of February, 1843. It was visible 

 in full daylight, so that some observers actually measured the angular distance 

 between the comet and the sun. It was followed until the middle of April. The 

 most remarkable feature of the orbit of this comet has been already mentioned : 

 it passed nearer the sun than any known body — so near it, in fact, that, with a 

 very slight change in the direction of its original motion, it would actually have 

 struck it. Its orbit did not certainly deviate from a parabola. The most careful 

 investigation of it — that of Professor Hubbard, of Washington — indicated a 

 a period of 530 years; but the velocity which would produce this period is so 

 near the parabolic Hmit that the difference does not exceed the uncertainty of the 

 observations. 



Donati's Comet of 1858. — This great comet, one of the most magnificent of 

 modern times, which hung in the western sky during the autumn of 1858, will be 



