Masterpieces of Science 



the perihelia of many meteoric systems, then 

 there must be a supply of light, and heat from 

 this source, though not nearly sufficient to ac- 

 count for the solar emission. 



It is worthy of notice, however, that the asso- 

 ciation between meteors and comets has some 

 bearing on this question. We know that the 

 most remarkable characteristics of comets is 

 the enormous diffusion of their substance. Now, 

 in this diffusion there resides an enormous fund 

 of force. The contraction of a large comet to 

 dimensions corresponding to a very moderate 

 mean density would be accompanied by the 

 emission of much heat. The question is worth 

 inquiring into, whether we can indeed assume 

 that all meteors which reach our atmosphere are 

 solid bodies. Some may be of cometic diffusion. 

 But, be this as it may, it is certain that a large 

 portion of the substance of every comet is in a 

 singularly diffused state. Since the meteoric 

 systems circling in countless millions round the 

 sun are, in all probability, associated in the most 

 intimate manner with comets, we may recognize 

 in this diffusion, as well as in the mere downfall 

 of meteors, the source of an enormous supply of 

 light and heat. 



Lastly, turning from our sun to the other suns 

 which shine in uncounted myriads throughout 

 space, we see the same processes at work upon 

 them all. Each star-sun has its coronal and 

 its zodiacal disks, formed by meteoric and cometic 

 systems; for otherwise each would quickly cease 

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