68 THE ATMOSPHERE. 



Hence, we perceive, it may be the same air which 

 waves the flowers by a warm breeze, drinks the mois- 

 ture that broods over the lake, and rising with it to the 

 mountain top, deposits it in crystals on its summit. 



DIVING BELL. 



This is an inverted vessel, perfectly tight at the top 

 and sides, and open at the bottom, intended to carry 

 men down under water, to perform various occupations. 

 Weights are arranged around its lower part to increase 

 its gravity, and cause it to descend perpendicularly. 



Its principle may be illustrated by inverting a tumbler 

 in water, and pressing it down to some distance. The 

 inside will remain perfectly dry, proving that the resis- 

 tance of the air has prevented the water from entering. 

 The water cannot enter without displacing the air, any 

 more than we can place one body in the spot occupied 

 by another, without first removing the original occupant. 

 The only opening in the bell is at the bottom, and the 

 air being lighter than the water, cannot descend to 

 escape ; hence it must be condensed by the pressure 

 from below. 



A beautiful experiment, illustrative of the value of the 

 diving bell, and of a continual supply of fresh air, may 

 be shown by inverting a large tumbler over a floating 

 lighted taper, and pressing it down to the bottom of the 

 vessel. The taper will continue to float, although sent 

 down the whole depth of the water, and may again be 

 brought to the surface, still burning, if the experiment 

 be quickly performed. If this be not attended to, the 

 flame will be extinguished by the destruction of the 

 oxygen of the air, the place of which will be supplied 

 by the rising water. 



The flame may be considered analagous to an indi- 

 vidual, as he requires the same oxygen for his preser- 

 vation which nourishes the flame. And if he be not 

 supplied with fresh air by artificial means, he must soon 

 fall a victim to his temerity. 



The invention of the diving bell is universally assigned 

 to the 16th century. Our first information of its use in 

 Europe is that of Taisnier. He relates, that ' at Toledo, 



