ASCENT OF SMOKE. 201 



stability if it exceeds a certain span, though we have 

 the rainbow and the sky to give us impressions of 

 the stability of the circle ; but in the case of those 

 logarithmic curves, we never feel that a large span 

 is less stable than the very smallest. 



Here there is one consideration which, though it 

 cannot be said directly to belong to the observation 

 of nature, is yet worthy of a little meditation. It is 

 this: The Grecian and Roman architecture, which 

 probably carries the proportions of material form as 

 far as they can be carried in respect of beauty, just 

 as the statues of their gods and goddesses carried 

 the proportions of the human figure to a degree 

 even of ideal perfection, that architecture and that 

 statuary were the art of a people whose gods were 

 material, the perfection of material gods, if you 

 will; just as the architecture and sculpture were 

 the perfection of those arts; but still the gods have 

 the idea of material beings inseparable from them, 

 just as much as it is impossible to separate the idea 

 of weight and pressure from a Grecian or a Roman 

 building. On the other hand, the logarithmic curve 

 belongs to Christian architecture, to the true reli- 

 gion to that religion whose God is a Spirit ; and 

 therefore, though the coincidence is a wonderful 

 one, it is in perfect congruity and keeping that the 

 roofs of the fanes devoted to his worship should be 

 thus divested of all the apparent heaviness, and con- 

 sequent fall and decay, which are the inseparable 

 attributes of mere matter. 



While the evaporated moisture is ascending in 

 this hyperbolic form (and the wind only gives it an 

 oblique direction, by blowing it to one side) gravita- 

 tion resists its ascent, its own cohesion resists both 

 that and its lateral spread, and the resistance of the 

 air opposes both. It is the same with every thing 

 that rises by evaporation, or dispersion, through the 

 air, with odours, with sounds, and even with the 

 air itself, when it is heated by some local cause at 



