790 On the Use of Steam Heat. 



OBSERVATIONS ON THE BEST MEANS OF HEATING 

 THE HALL IN WHICH THE ORDINARY MEETINGS 

 OF THE INSTITUTE ARE HELD. 



WHEN the hall which it is desired to heat is very 

 large, and has several large windows, it is indis- 

 pensably necessary to begin by making the windows 

 double ; for without this precaution the continual cool- 

 ing which will take place through single windows will 

 be so great that, no matter how much wood is burned, 

 it will never be possible to warm the apartment uni- 

 formly throughout, and as soon as the fire ceases to 

 burn the room will quickly become cold. 



There would be no use in employing the best stoves 

 to remedy these inconveniences. Close to the stoves 

 it will indeed be possible to feel the heat caused by 

 their calorific radiations ; but nothing can hinder the 

 currents of cold air, caused by the cooling which takes 

 place through the panes of glass, from spreading over 

 the entire extent of the room. 



Those particles of air in the room which are in im- 

 mediate contact with the glass, finding themselves 

 specifically heavier on account of this change of tem- 

 perature, must necessarily descend and spread them- 

 selves over the pavement, forming currents which are 

 perceptibly cold, and no doubt very injurious to health. 

 But, when the windows are double, the layer of air 

 which is enclosed between the two windows being an 

 excellent non-conductor of heat, the inside window is 

 well protected from cold from without ; and, the descend- 

 ing currents of cold air just mentioned no longer ex- 

 isting, it would be easy, with good stoves moderately 



