EXPERIMENTS. I'OI 



fully illustrated in two adjoining rooms, in one of 

 which a good fire is burning, while in the other 

 there is none. If the door between the two rooms 

 be thrown open, the cold air will enter the heated 

 room in a strong current, or, in other words, as a 

 violent wind. At the same time the heated air of 

 the warm room ascends and passes the contrary 

 way into the cold room, at the upper part of the 

 same doorway; while in the middle of this opening, 

 exactly between the two currents, the air appears to 

 have little or no motion. The best way to show 

 this experiment is to introduce the flame of a candle 

 into the doorway between a hot and a cold room. 

 If the flame be held near the bottom of the doorway, 

 where the air is most dense, it will be strongly 

 drawn towards the heated room ; and if held near 

 the top of the door it will be drawn towards the 

 cold room with somewhat less force; while midway 

 between the top and bottom the flame will be 

 scarcely disturbed. 



" There is also another pretty experiment which 

 illustrates well the theory of land and sea breezes. 

 Take a large dish, fill it with cold water, and in the 

 middle of this put a water-plate or a saucer filled 

 with warm water. The first will represent the 

 ocean, and the latter an island made hot by the rays 

 of the sun, and rarefying the air above it. Take a 

 lighted wax candle and blow it out ; and, if the air 

 of the room be still, on applying it successively to 

 every side of the saucer, the smoke will be seen 



