130 VENTILATION. 



lungs saturated as it were, with the pure element, can eat 

 almost anything with impunity ; while those who breathe 

 the sorry apology for air which is to be found in so many 

 habitations, although they may live upon the most nutritious 

 diet, and avoid the least excess, are incessantly troubled with 

 head-ache, dyspepsia, and various mental as well as physical 

 sufferings. Well may such persons, as they witness the 

 healthy forms and happy faces of so many of the hardy sons 

 of toil, exclaim with the old Latin poet, 



" Oh dura messorum illia ! " 



It is with the human family very much as it is with the 

 vegetable kingdom. Take a plant or tree, and shut it out 

 from the pure air and the invigorating light, and though you 

 may supply it with an abundance of water, and the very soil, 

 which by the strictest chemical analysis, is found to contain 

 all the elements that are essential to its vigorous growth, it 

 will still be a puny thing, ready to droop, if exposed to a 

 summer's sun, or to be prostrated by the first visitation of a 

 winter's blast. Compare, now, this wretched abortion, with 

 an oak or maple which has grown upon the comparatively 

 sterile mountain pasture, and whose branches, in Summer, 

 are the pleasant resort of the happy songsters, while, under 

 its mighty shade, the panting herds drink in a refreshing 

 coolness. In Winter it laughs at the mighty storms, which 

 wildly toss its giant branches in the air, and which 

 serve only to exercise the limbs of the sturdy tree, whose 

 roots deep intertwined among its native rocks, enable it to 

 bid defiance to anything short of a whirlwind or tornado. 



To a population, who, for more than two-thirds of the 

 year, are compelled to breathe an atmosphere heated by 

 artificial means, the question how can this air be made, at a 

 moderate expense, to resemble, as far as possible, the purest 



