302 Professor Hosking on Ventilation. 



epoch the coasts of these countries have been submerged be- 

 neath the sea and again raised above it, from which it 

 follows that very recent marine deposits would take place, 

 contemporary with, or posterior to, the scattered erratics. 



On Ventilation by the Parlour Fire. ByWiLLiAM HoSKING, 

 Esq., Professor of Architecture and of Engineering Con- 

 structions at King's College, London.* 



The term ventilation does not strictly imply what we intend by 

 its use in reference to buildings used as dwelling-houses, or other- 

 wise for the occupation of breathing creatures. To ventilate is de- 

 fined " to fan with wind ;" but one of the main objects for which 

 houses and other enclosed buildings are made, is shelter /rom the 

 wind. Inasmuch, however, as the wind is but air in motion, and we 

 can only live in air, air may not be shut out of our houses, though, 

 for comfort's sake, we refuse to admit it in the active state of wind. 

 But in doing this — in shutting out the wind — we are apt to put our- 

 selves upon a short allowance of air, and to eke out the short allow- 

 ance by using the same air over and over again. 



There is a broad line of distinction, indeed, to be drawn between 

 in-door and out-door ventilation ; for although the principles upon 

 which nature proceeds are the same, the operation is influenced by 

 the circumstances under which the process may be carried on. 

 Whether it be on the hill-side, open to the winds of heaven, or in 

 a close room, from which all draught of air is excluded, the ex- 

 pired breath, as it leaves the nostrils heated by the fire in the lungs, 

 rises, or seeks to rise, above their level, and may not be again in- 

 haled. Out of doors the cooler or less heated air of the lower level 

 pi'esents itself for respiration unaffected by the spent exhaled air, but 

 m a close apartment, the whole body of included air must soon be 

 affected by whatever process any portion of it may have undergone. 

 The process by which nature carries off spent air, purifies, and re- 

 turns it uncontaminated, is thus checked by the circumstances under 

 which we place ourselves within doors. All our devices for shelter 

 from the weather, and for domestic convenience and comfort, tend to 

 prevent the process provided by nature from taking effect according 

 to the intention in that respect of the Creator. We not only con- 

 fine ourselves, indeed, and pen up air in low and close rooms, but we 

 introduce fire by which to warm the enclosed air; wanting light 



* Read at the Royal Institution of Great Britain. 



