POPULATION IN TOWNS. 125 



gaseous form, materially affecting the purity 

 of the atmosphere, and the vitality of those 

 who inhale it. 



In many of our vineries, peach-houses, &c. 

 are yet to be seen flues through which smoke is 

 conducted for the purpose of heating them. 

 These are often of tortuous length. In theory, 

 we see no difficulty in building a city ten times 

 the size of London, and removing the whole of 

 the smoke and foul air from the interior of every 

 house in it to any distance beyond its environs 

 by properly constructed flues, communicating 

 with every apartment in every house by means 

 of chimnies, tubes, &c. Any velocity of current 

 could be given to the air in the flues by means 

 of machinery at the exterior vent, where the 

 contents would be discharged. The whole 

 smoke as it was discharged could be condensed 

 and appropriated to agricultural or other pur- 

 poses. The state of the air in every room, 

 bed-room, cellar, storehouse, &c. could be regu- 

 lated by machinery, self-acting or otherwise, 

 and supplied afresh from the untainted atmo- 

 sphere without. In theory we see no difficulty 

 in erecting the whole and keeping it clean and in 

 working order, but we see many difficulties in 



