6 



SCIENCE. 



[N. S. Vol. XIV; No. 340. 



vail throughout the system. We may feel 

 very confident also that the same combina- 

 tions of physical and chemical conditions 

 which on this earth are associated with or- 

 ganic life will be similarly associated on 

 other planets, that those conditions which 

 prevent this development except in its lower 

 forms above the line of perpetual snow will 

 act in the same manner on Mars or Venus. 

 At the beginning of the century one 

 •comet was known to be a member of our 

 system, more than one appearance having 

 certainly been observed, viz. , that of Hal- 

 ley. This comet is famous historically as 

 the first whose return was successfully pre- 

 dicted, thus completely demolishing the 

 vague and absurd notions which had been 

 held regarding these bodies. At the close 

 of the century something like a score have 

 been observed at more than one appear- 

 ance, one of which, that of Biele, has cer- 

 tainly gone to pieces, with many indica- 

 tions that a like fate is in store for all. 

 Closely associated with the subject of 

 comets is that of meteors, a subject to 

 which the attention of all of us has been 

 more or less directed within the past two 

 years by the amount of space which the 

 journals have given to the expected appear- 

 ance of the November displays. This de- 

 partment of astronomy was quite unknown 

 to science a hundred years ago. In the 

 early part of the century writers who con- 

 descended to mention meteors at all spoke 

 of them as atmospheric phenomena. As 

 for meteoric stones, specimens of which are 

 seen in all mineralogical collections, scien- 

 tists would have none of them. Learned 

 academicians ridiculed the idea that any 

 one should be so absurdly credulous as to 

 admit the possibility of a ponderous stone 

 falling from heaven. When in 1790 an 

 official statement signed by 300 eye wit- 

 nesses of such an event was sent to the 

 French Academy one of the distinguished 

 physicists of that body wrote concerning it 



'^ How sad it is to see an entire municipality 

 certifj'iug in a formal official document to 

 the truth of a fable which can only be 

 regarded with pity." Finally in 1803 oc- 

 curred a fall in France of so conspicuous 

 a character and attested by such a host of 

 credible witnesses that it could no longer 

 be treated as a childish fable. The matter 

 was investigated by the Academy with 

 naturally only one possible verdict. Since 

 then much attention has been given to this 

 subject, but it does not appear that any part 

 of it was shared by the minute shooting 

 stars, with the appearance of which every 

 one was so familiar, until the great display 

 of 1833 had drawn attention to them. It 

 soon began to be discovered that records of 

 similar occurrences at various past times 

 were to be found, and finally Professor 

 Newton, of Yale, in 1864 brought together 

 a series of such historic notices extending 

 back to the year 902, October 15. It was 

 found that these could be represented as 

 successive recurrences of the same phe- 

 nomenon at intervals of 33 years. Pro- 

 fessor Newton, therefore, predicted with 

 much confidence a repetition in 1866. 

 This prediction was fully verified. 



The details of the investigation, by which 

 this was shown to be due to a swarm of 

 meteoric bodies, of average dimensions, 

 probably not much exceeding a grain of 

 sand, moving in a long procession about 

 the sun with a period of 33:^ years, we 

 cannot enter into now. The length of the 

 stream was found to be such that about 

 three years were required to pass the point 

 of intersection with the earth's orbit. In 

 fact the particles are scattered — very thinly 

 for the most part — over nearly the entire 

 path. 



Precisely how it came about that the dis- 

 play was so meager in 1899 is uncertain. 

 Perhaps it was caused bj'^ the particles 

 being very unequally distributed along 

 the line and that the earth on that occa- 



