2.56 HISTORY OF 



turned back to the element from whence it came. 

 But as for us, who are immersed at the bottom of 

 this gulf, we must be contented with a more con- 

 fined knowledge ; and, wanting a proper point of 

 prospect, remain satisfied with a combination of 

 the effects. 



One of the first things that our senses informs 

 us of is, that although the air is too fine for our 

 sight, it is very obvious to our touch. Although 

 we cannot see the wind contained in a bladder, 

 we can very readily feel its resistance ; and though 

 the hurricane may want colour, we often fatally 

 experience that it does not want force. We have 

 equal experience of the air's spring or elasticity : 

 the bladder, when pressed, returns again, upon 

 the pressure being taken away ; a bottle, when 

 filled, often bursts, from the spring of air which 

 is included. 



So far the slightest experience reaches ; but, 

 by carrying experiment a little farther, we learn 

 that air also is heavy ; a round glass vessel being 

 emptied of its air, and accurately weighed, has 

 been found lighter than when it was weighed 

 with the air in it. Upon computing the superior 

 weight of the full vessel, a cubic foot of air is 

 found to weigh something more than an ounce. 



From this experiment, therefore, we learn, 

 that the earth, and all things upon its surface, 

 are every- where covered with a ponderous fluid, 

 which rising very high over our heads, must be 

 proportionably heavy. For instance, as in the 

 sea, a man at the depth of twenty feet sustains a 

 greater weight of water than a man at the depth 



