212 RADIATION. 



the window-glass, with which it comes in 

 contact. 



Q. How does this account for the MIST and 

 WATER on a WINDOW ? 



A. As the warm vapour of the room 

 touches the cold glass, it is chilled and 

 condensed into mist ; and the mist (col- 

 lecting into drops) rolls down the window- 

 frame in little streams of water. 



Q. Does the GLASS of a window COOL down 

 more KAPIDLY than the AIR of the room itself? 



A. Yes ; because the air is kept 

 warm by fires, and the animal heat of the 

 people in the room; in consequence of 

 which, the air of a room suffers very little 

 diminution of heat from the setting of 

 the sun. 



Q. Whence arises the VAPOUR of a ROOM ? 



A. 1st The very air of the room 

 contains vapour : 



2ndly The breath and insensible 

 perspiration of the inmates increase this 

 vapour : and 



3rdly Hot dinners, the steam of tea, 

 &c. contribute to increase it still more. 



