294 SCIENTIFIC ILLUSTRATIONS [Qui 



order to beeome acquainted with the chemical forces, the affini- 

 ties of bodies for each other. Every experiment is a question 

 put to a body, the answer to which we receive through a pheno- 

 menon, that is, through a change which we observe, sometimes 

 by the sight or the smell, sometimes by the other senses. 



PR. 



Objections to Quiescence. 



Had the sea been made without motion, and resembling a 

 pool of stagnant water, the noble races of animated nature would 

 shortly be at an end. Nothing then would be left alive but 

 swarms of ill-formed creatures, with scarcely more than vegetable 

 life, and subsisting by putrefaction. Were this extensive bed 

 of waters entirely quiescent, millions of the smaller reptile kinds 

 would there find a proper retreat to breed and multiply in ; they 

 would find there no agitation, no concussion in the parts of the 

 fluid to crush their feeble frames, or to force them from the 

 places where they were bred : J,here they would multiply in 

 security and ease, enjoy a short life, and putrefying, thus again 

 give nourishment to numberless others as little worthy of exist- 

 ence as themselves. But the motion of this great element 

 effectually destroys the number of these viler creatures ; its 

 currents and its tides produce continual agitations, the shock of 

 which they are not able to endure ; the parts of the fluid rub- 

 bing against each other destroy all viscidities ; and the ocean, 

 says Oliver Goldsmith, if we may so express it, acquires health 

 by exercise. A. 



The Wisdom of Being Quiet. 



The great majority of carnivorous animals, particularly such 

 as are of an active and powerful nature, reject dead substances ; 

 and while the vulture, whose beak and claws are comparatively 

 weak, selects such, the mighty and bold eagle will hardly stoop 

 to carrion in its fiercest hunger ; and, indeed, so marked is the 

 preference, and so decided the selection for active living prey, 

 that in many cases it is perfectly safe while motionless, and is 

 only seized when it betrays its vitality by a change of position. 

 Thus the frog sits intently watching an insect as long as it is 

 quiet ; and only seizes it when it moves. The green tree-frog is 



