LECTURE III. 



ON COMETS. 



HE subject of comets, about which I now pro- 

 pose to say something, is one that has of late 

 naturally drawn to it a good deal of inquiry 

 and general interest, by reason of the un- 

 usually magnificent spectacles of this description which 

 have within the last few years been exhibited to us.* In 

 itself it is perhaps not one of the best adapted for 

 popular discussion and familiar explanation of this 

 nature, because there are so many things in the history of 

 comets unexplained, and so many wild and extravagant 

 notions in consequence floating about in the minds of 

 even well-informed persons, that the whole subject has 

 rather, in the public mind, that kind of dreamy inde- 

 finite interest that attaches to signs and wonders than 

 any distinct, positive, practical bearing. The fact is, 

 that, though much is certainly known about comets, there 

 * This lecture was deliveied on February 14, 1859. 



