THE EARTH. 135 



principal is its conveyance of sound. Even the vibrations of a bell, 

 \vhich have the loudest effect that we know of, cease to be heard, 

 when under the receiver of an air-pump. Thus all the pleasures we re- 

 ceive from conversation with each other, or from music, depend en 

 tirely upon the air. 



Odours likewise are diffused only by the means of air ; without this 

 lluid to swim in, they would for ever remain torpid in their respective 

 substances ; and the rose would affect us with as little sensations of 

 pleasure, as the thorn on which it grew. 



Those who are willing to augment the catalogue of the benefits we 

 receive from this element, assert also, that tastes themselves would be 

 insipid, were it not that the air presses their parts upon the nerves of 

 the tongue and palate, so as to produce their grateful effects. Thus, 

 continue they, upon the tops of high mountains, as on the Peak of 

 Teneriffe, the most poignant bodies, as pepper, ginger, salt, and spice, 

 have no sensible taste, for want of their particles being thus sent home 

 to the sensory. But we owe the air sufficient obligations, not to be 

 studious of admitting this among the number : in fact, all substances 

 have their taste, as well on the tops of the mountains, as in the bot- 

 tom of the valley ; and I have been one of many, who have ate a 

 very savoury dinner on the Alps. 



It is sufficient, therefore, that we regard the air as the parent of 

 health and vegetation ; as a kind dispenser of light and warmth ; and 

 as the conveyer of sounds and odours. This is an element of which 

 avarice will not deprive us ; and which power cannot monopolize. 

 The treasures of the earth, the verdure of the fields, and even .the re- 

 freshments of the stream, are too often seen going only to assist the 

 luxuries of the great ; while the less fortunate part of mankind stand 

 humble spectators of their encroachments. But the air no limitations 

 can bound, nor any landmarks restrain. In this benign element, all 

 mankind can boast an equal possession ; and for this we all have 

 equal obligations to Heaven. We consume a part of it, for our own 

 sustenance, while we live ; and, when we die, our putrefying bodies 

 give back the supply, which, during life, we had accumulated from the 

 general mass. 



CHAPTER XX. 



OP WINDS, IRREGULAR AND REGULAR. 



VViND is a current of air. Experimental philosophers produce an 

 artificial wind, by an instrument called an aolipile. This is nothing 

 more than a hollow copper ball, with a long pipe ; a tea-kettle might 

 be readily made into one, if it were entirely closed at tne lid, and the 

 spout left open ; through this spout it is to be filled with water, and 

 then set upon the fire, by which means it produces a violent blast, 

 like wind, which continues while there is any water remaining in tlnj 

 instrument. In this manner water is converted into a rushing ail ; 

 which, if caught as it goes out, and left to cool, is again quickly con 

 verted into its former element. Besides this, as was mentioned >n th 



