ASCENT OF SMOKE. 207 



fore, 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 

 consequent fall and decay, which are the inse- 

 parable 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) 

 gravitation resists its ascent, its own cohesion 

 resists both that and its lateral spread, and the re- 

 sistance of the air opposes both. It is the same 

 with every thing that rises by evaporation, or dis- 

 persion, through the air, with odours, with 

 sounds, and even with the air itself, when it is 

 heated by some local cause at the surface, and 

 mounts up through the rest of the mass. If the 

 air were perfectly still (which it never is), and the 

 dense smoke of a furnace rose up with perfect 

 uniformity (which that also never does), we should 

 see the hyperbolic column mounting and swelling 

 till the upper part of it became so thin as to be in- 

 visible, and it seemed to melt away into the air, 

 both upward and laterally, with the most finely 

 melting shade imaginable. And even as it is, al- 

 though the smoke is always irregular in its quan- 

 tity, and though those very irregularities produce 

 little currents in the air, which throw the smoke 

 into curling volumes, an eye well disciplined in 

 the observation of forms, can trace the hyperbola in 

 its general outline, even when it is blown aside by 

 a pretty smart breeze. The side opposite the wind 

 is always more bent than the windward side, so 

 that the column broadens as it gets distant from 

 the chimney ; and we have only to imagine it to 

 T 2 



