110 ON COMETS. 



that moment had the astonishing speed I have just men- 

 tioned. Now observe one thing. The distance from the 

 sun's centre was about one i6oth part of our distance 

 from it. All the heat we enjoy on this earth comes from 

 the sun. Imagine the heat we should have to endure if 

 the- sun were to approach us or we the sun to ^th part 

 of its present distance. It would not be merely as if 

 1 60 suns were shining on us all at once, but 160 times 

 1 60, according to a rule which is well known to all 

 who are conversant with such matters. Now that is 

 25,600. Only imagine a glare 25,600 times fiercer than 

 that of an equatorial sunshine at noonday with the sun 

 vertical. And again, only conceive a light 25,600 times 

 more glaring than the glare of such a noonday! In such 

 a heat there is no solid substance we know of which 

 would not run like water boil and be converted into 

 smoke or vapour. No wonder it gave evidence of vio- 

 lent excitement coming from the cold region outside 

 the planetary system, torpid and icebound ; already when 

 arrived even in our temperate region it began to show 

 signs of internal activity the head had begun to develop 

 and the tail to elongate till the comet was for a time lost 

 sight of. No human eye beheld the wondrous spectacle 

 it must have offered on the 8th December. Only four 

 days afterwards, however, it was seen : and its tail, whose 

 direction was reversed and which (observe) could not 

 possibly be the same tail it had before (for it is not to 

 be conceived as a stick brandished round, or a flaming 

 sword, but fresh matter continually streaming forth), its 

 tail I say had already lengthened to an extent of about 



