July 5, 1901.] 



SCIENCE. 



sion passed through a comparatively thin 

 region. Perhaps the perturbations of the 

 planets have changed the course of the 

 stream to such an extent that the earth no 

 longer encounters it. The question will 

 doubtless receive an answer in due time. 



A large number of these meteoric streams 

 have been recognized. A list of 695 

 radiants, as they are called, is to be 

 found in the Monthly Notices, E. A. S., 

 for 1875. Probably, however, a consider- 

 able number of these are fictitious. 



One of the most remarkable discoveries 

 connected with this subject was announced 

 in 1866 by Schiaparelli, viz., that the 

 well-known August swarm of meteors 

 moves in practically the same orbit as a 

 bright comet seen in 1862, known as Tut- 

 tle's comet. Shortly afterwards the orbit 

 of the November swarm was identified 

 with that of Temple's comet of 1866. A 

 number of other such coincidences have 

 been found, the most remarkable being that 

 of a swarm known as Andromedes, which 

 appears to have taken the place formerly 

 occupied by Biele's Comet, in short to be 

 nothing more or less than the shattered 

 fragments of that body. Whether, on the 

 one hand, those streams which have not been 

 identified with any known comet are also 

 the remnants of such a body long since dis- 

 integrated, and, on the other, whether those 

 comets permanently attached to our system 

 are undergoing a like process of dissolu- 

 tion, we can not say with certainty, but 

 the theory looks very plausible. One such 

 catastrophe has been carried to completion 

 within the memory of many now living. 



Another case in which this process v;as 

 rapidly developing was that of the great 

 comet of 1882, which many of us will re- 

 member. As this body receded from 

 the sun its nucleus was broken into seven 

 distinct fragments which gradually sepa- 

 rated farther and farther from each other, 

 until the body disappeared from view. 



According to the best determination of its 

 period, this comet should return in seven or 

 eight hundred years. When it does return, 

 if this ever happens, undoubtedly it will be 

 in the form of at least seven distinct comets, 

 following each other at intervals of perhaps 

 several years. Each of these will very 

 likely be again subdivided, the operation 

 continuing until nothing remains but mi- 

 nute fragments. 



We may follow the process backward as 

 regards this body. In 1843 appeared a 

 splendid comet whose orbit was remarkable 

 on account of the nearness of its approach 

 to the sun. Again in 1880 a large body 

 of this kind appeared whose path so 

 closely resembled that of 1843 that it was 

 generally believed to be the same body, 

 though how such a conspicuous object could 

 return to our neighborhood every thirty- 

 seven years and never have been seen be- 

 fore 1843 was a puzzling question. Greatly 

 to the surprise of astronomers, the great 

 comet of 1882 was found to follow almost 

 precisely the same path. The theory was 

 at once advanced that on account of the 

 close approach of this body to the sun, pass- 

 ing as it did through millions of miles of 

 the solar corona, the resistance encountered 

 was rapidly bringing it into the sun. A few 

 years, possibly a few months, would suffice 

 for completing the work. What effect this 

 collision would produce upon the sun could 

 only be conjectured. Would it bring dis- 

 aster to our earth or not ? 



The comet, however, pursued its way 

 after passing the sun, with no appreciable 

 change in the character of its orbit. It 

 was followed from September 3, the date 

 of its discovery, until the following June, 

 when its distance from the sun was 470,- 

 000,000 of miles. Abundant material 

 therefore existed for investigating its move- 

 ments. The result was that at least 650 

 years must elapse before its return, the 

 time being more likely to be 800 years. It 



