



330 SECTION MECHANICS. 



that fresh air should enter from above, and escape from below. (Com- 

 mittee of Enquiry of the House of Lords, page 41.) 



The advice of these gentlemen was disregarded, and about the year 

 1845 there was st ^ to De seen * n ^ e subterranean galleries of the 

 Houses of Parliament two ventilators, 6 feet in diameter. They have 

 since been removed. 



I will but say a few words upon heating apparatus. Ordinary 

 chimneys have the advantage of allowing an agreeable and whole- 

 some view of the fire, whilst at the same time they cause the renewal 

 of the air in the room ; but they are inconvenient inasmuch as they 

 occasion draughts through the doors and windows. Only from o.io 

 to o.i 2 of the heat given forth by the fuel is made use of. 



The ventilating chimneys proposed long ago by Mr. Belmas, colonel 

 in the French Engineers, in the eleventh number of the " Memorial 

 de 1'officier du gdnie," and for the establishment of which Captain 

 Douglas Galton has made excellent suggestions, have the advantage 

 of bringing into the room as much air at a moderate temperature as 

 they carry out through the smoke-pipe, and of making use of from 

 0.30 to 0.33 of the heat furnished by the fuel. 



Hot air stoves, made of cast iron, have the serious defects of altering 

 the air ; those made of hollow bricks are to be preferred to them. 

 Both kinds must have the necessary means at hand for the intro- 

 duction of fresh air. 



The warming apparatus by means of the circulation of hot water, 

 have the advantage of carrying heat to almost any distance. At the 

 Sydenham Palace twenty-five boilers supply water to pipes, the united 

 length of which is nearly equal to the distance from London to Dover. 



VENTILATION. 



1. The object of ventilation is to get rid of tainted air, and to 



replace it by fresh air. 



2. The escape must take place near the deteriorating cause and far 



from persons. 



3. Experience shows the superiority of the " Systeme d'appel " over 



the " Systeme d'insurflation." 



4. The fresh air can be taken by " appel " at any height. Guy's 



Hospital in London, and 1'hospital de Lariboisiere in Paris are 

 examples of this. 



