234 Canadian Record of Science. 



The known visible meteors are not large enough nor 

 numerous enough to do the various kinds of work which I 

 have named. May we not assume that an enormous num- 

 ber of exceedingly small meteoroides are floating in space, 

 are falling into the sua, are coming into our air, are swept 

 up by the moon ? May we not assume that some of these 

 various forms of work which cannot be done by meteoroids 

 large enough for us to see them as they enter the air, are 

 done by this finer impalpable cosmic dust? Yes, we may 

 make such an assumption. There exist, no doubt, multi- 

 tudes of these minute particles travelling in space. But 

 science asks not only for a true cause but a sufficient cause. 

 There must be enough of this matter to do the work 

 assigned to it. At present, we have no evidence that the 

 total existing quantity of such fine material is very large. 

 It is to be hoped that through the collection and examina- 

 tion of meteoric dust, we may soon learn something about 

 the amount which our earth receives. Until that shall be 

 learned we can reason only in general terms. So much' 

 matter coming into our atmosphere as these several hypo- 

 theses require would, without doubt, make its presence 

 known to us in the appearance of our sunset skies and in a 

 far greater deposit of meteoric dust than has ever yet been 

 proven. 



A meteoroid origin has been assigned to the light of the 

 solar corona. It is not unreasonable to suppose that the 

 amount of the meteoroid matter should increase toward the 

 sun, and the illumination of su* h matter would be much 

 greater as we approach the solar surface. But it is difficult 

 to explain upon such an hypothesis the radial structure, the 

 rifts, and the shape of the curved lines that are marked feat- 

 ures of the corona. These seem to be inconsistent with 

 any conceivable arrangement of meteoroids in the vicinity 

 of the sun. If the meteoroids are arranged at random, 

 there should be a uniform shading away of light as we go 

 from the sun. If the meteoroides are in streams along com- 

 etary orbits, all lines bounding the light and shade in the 

 coronal light should evidently be approximated by projec- 

 tions of conic sections of which the sun's centre is the focus. 



