ON COMETS. 



greatest discoveries only land us on the confines of a 

 wider and more wonderfully diversified view of the uni- 

 verse; and have now, as we always shall have, to ac- 

 knowledge ourselves baffled and bowed down by the 

 infinite which surrounds us on every side. 



(54.) Beyond all doubt, the widest and most interesting 

 prospect of future discovery which their study holds out 

 to us, is that distinction between gravitating and levitating 

 matter, that positive and unrefutable demonstration of 

 the existence in nature of a repulsive force, co-extensive 

 with but enormously more powerful than the attractive 

 force we call gravity, which the phaenomena of their tails 

 afford. This force cannot possibly be of the nature of 

 electric or magnetic forces.* These forces are especially 

 polar in their action between particle and particle a 

 magnet, or an electrified particle, of indefinitely minute 

 dimensions so minute as the discrete particles which go 

 to form a comet's tail, could by no possibility be either 

 attracted or repelled, as such, by a body, however power* 

 fully magnetized or electrified, placed at the distance of 

 the sun. It might have a direction given to its magnetic 

 or electric axis, but its centre 01" gravity would not be 



* This and much of what follows may seem inconsistent with 

 what is said in my "Results of Ast. Obs., &c., at the Cape of 

 Good Hope," p. 409, and note thereon. To a certain extent it 

 is so, and to that extent it is a recommendation, but I am here 

 speaking only of that portion of the matter of the comet whose 

 chemical union may be considered as completely overcome, and 

 whose levitating or negative constituent is fairly driven off, never 

 to return. That which may be conceived to remain behind may 

 conform under the circumstances of the case to the dynamical 

 relations there indicated. 



