Popular Science Monthly 



the larger or more brilliant of the two 

 was seen to have three tails arranged at 

 equal angular inter\als about it. One of 

 these tails extcndeti over to the smaller 

 comet and tormed some kind of connec- 

 tion with it. There was in fact a bridge 

 of light between the two. The two 

 comets were again seen in 185', when 

 they were still traveling along together. 

 The interval between them, which was 

 less than 200,000 miles in 1846, had now 

 increased to 1,270,000. The comet seems 

 never to have been certainly seen since this 

 occasion. But, what was certainly seen 

 was a great shower of "shooting stars." 

 These luminous meteors seemed to 

 radiate from just about the point whej-e 

 the orbits of Biela's Comet and of our 

 earth cross each other. The date of the 

 star-shower was some twelve weeks later 

 than the time when the comet itself 

 should have made the crossing. What 

 these facts, when considered in the light 

 of still other information of an astronom- 

 ical character, mean is probably this: 

 After 1852, Biela's Comet broke up into 

 small bits of matter. These possessed 

 individually the onward motion of the 

 comet and were held in restraint by the 

 sun (and any nearby planets), so that 

 the pieces generally followed the orbit 

 which the comet itself had been pursuing. 

 The result was a long stream of very 

 small heavenly bodies. When on No- 

 vember 27, 1872, a part of this stream 

 came within the reach of the attractive 

 power of the earth, the separate bodies 

 fell through our atmosphere. The 

 friction of the enormously rapid move- 

 ment resulted in heating them up to 

 incandescence. These fragments of the 

 original comet thus became luminous 

 meteors or "shooting stars." In 1798 

 and 1838, there were notable showers of 

 stars at times and places which were 

 near the position and time calculated for 

 Biela's Comet for those years. These 

 showers, in contrailistinction to that of 

 1872, seem to ha\e preceded the comet, 

 itself. In fact, putting everything to- 

 gether, there would appear to have been 

 a stream of small bodies five hundred 

 million miles in length. 



The foregoing suggests that when a 

 comet is lost, the real fact may be that 

 it has burst into multitudes of fragments. 



Another comet which belongs to the 



507 



list of the lost ones was first disco\ered 

 in August, 1844. Apparently, Di Vico 

 was the first to get even a telescopic 

 glimpse of it. However, the comet 

 rapidly approached our neighborhood, 

 so that it was not long until it was 

 visible to the naked eye. Di Vico's 

 Comet was found to be traveling in a 

 closed, or elliptic, orbit of such a charac- 

 ter that it would return once in e\'ery 

 period of a little less than five and one 

 half years. The next return woukl 

 accordingly be in the early part of 1850. 

 Unfortunately, the comet, if it really 

 returned, was too unfavorably situated 

 with respect to the sun to be seen. 

 Howe\er, in 1855, conditions would be 

 advantageous. But no comet was seen 

 then. Nor has this body ever certainly 

 been seen since. 



What Became of the Comet of 1264 ? 



One of the most notable of the heaven- 

 ly bodies which ha\-e more or less title 

 to a place amongst the lost comets is 

 the comet of 1264. This body engaged 

 the attention both of Chinese and 

 European writers. In 1556, another 

 great cometar>- \ision was seen in the 

 sky in Europe and in China. Astrono- 

 mers who studied the a\ailable data con- 

 cluded that the two were one and the 

 same comet. Calculations indicated that 

 the period of revolution about the sun 

 was somewhere in the neighborhood of 

 three hundred and two to three hundred 

 and eight years. Consequently, this 

 great comet should have reappeared in 

 1858 or within a few years afterwards. 

 It has, apparently, disappeared fore\'er. 

 In the year 975, a great comet was seen 

 whose course has been thought by one 

 astronomer to ha^■e possibK' been that of 

 the comet of 1264 at that time. 



It is of interest to note that a comet 

 may disappear because its elliptic orbit 

 has been deranged into a parabola or an 

 hyperbola. Sir Lsaac Newton showed 

 that a body controlled by onx sun moves 

 in a curve which is some one of the 

 sections of a cone — that is, either an 

 ellipse, a parabola or an hyperbola. As 

 the latter two are open curves, a comet 

 which pursued such a path would go olY 

 into space never to reappear. A de- 

 rangement of orbit from closed to open 

 curve has doubtless happened often. 



