known among them. Hence they produce in 

 proportion little carbonic acid, and a steady 

 constant current in any direction would be 

 amply sufficient to remove the comparatively 

 small amount of foreign ingredients thrown into 

 the air. These thoughts deserve to be remem- 

 bered when we are disposed to declaim against 

 the fickleness of our climate, for it appears that 

 though it may prove a " partial evil/' it accom- 

 plishes an " universal good." Yet when the 

 changeful wind is accompanied frequently by 

 moisture and wetness, without a positive rapid 

 precipitation of rain, our complaints of the 

 fickleness of our climate and of its effects upon 

 the atmosphere of our towns are more remark- 

 able. When the day is dull and wet the smoke 

 of the city rises only a little distance above the 

 chimneys, and is then poured down into the 

 streets, enveloping men and houses in a dark 

 and gloomy mantle of offensive gases and 

 vapour. The carbon contained in the smoke 

 absorbs the moisture of the air, and becoming 

 too heavy to seek, as in dry days, the upper air, 

 falls slowly down to the ground. The mineral 

 substances of smoke fall with it, and these, 

 added to the empyreumatic odours developed in 

 combination, truly render a wet or damp day 

 in our towns in the last degree disagreeable. 

 A heavy shower, on the contrary, carries down 



