$ INTRODUCTION, 



and angular measurements of perspective, and of navigation, survey- 

 ing and astronomy, are among its most familiar and obvious ap- 

 plications. 



To return to Natural Philosophy, the student in this science learns, 

 with pleasure and surprise, that the same power which retains Jupi- 

 ter in his orbit, precipitates a falling drop ; that a feather, a balloon 

 and a ship of the line are floated by statical pressure ; that the same 

 power causes a narrow column of water, sustained in a tube, to raise 

 a weight, many thousand times greater than its own ; that by its 

 means a cascade falls through the atmosphere, which in its turn, 

 raises a column of water in a pump ; and that gravity exerts an 

 uninterrupted dominion over atoms, planets and systems. It is seen 

 also by the learner, that the mechanical powers, so indispensable to 

 our existence and efficiency, and that the motions of animals are de- 

 pendent upon similar principles, and gravity is not unfrequently the 

 immediate agent. 



The phenomena of LIGHT are among the most beautiful and in- 

 structive of those belonging to Natural Philosophy. The rainbow 

 is a splendid example of the decomposition of the solar beam, ef- 

 fected by the refractive power of the drops of water ; still, magnifi- 

 cent and beautiful as it is, it excites perhaps less astonishment in 

 the beholder, than the colors exhibited by the common prism in a 

 darkened room, where the iris, although very small, compared with 

 the bow, is more intense, and is brought within our more immediate 

 view. The astonishing results produced by the solar focus, in which 

 the concentrated beams melt and dissipate metals and stones ; the 

 surprising and beautiful effects of the common, the lucernal, and 

 the solar microscope, in whose fields of vision motes become beams, 

 and animalculse rival the gigantic animals ; the wonderful illustrations 

 of the eye, on whose retina, either uncovered by dissection, or imi- 

 tated by art, are seen painted distinctly, in all their varieties of color 

 and of form, the fields, the groves, the sky, the faces of men, and all 

 the objects that surround us ; the power of the telescope, by which 

 we penetrate into the awful darkness of space, and look through the 

 veil that covers the heavenly bodies ; these are a few of the won- 

 ders which natural philosophy teaches respecting light, that incom- 

 prehensible emanation, without which the creation would become 

 cheerless and desolate, and animated beings would dwindle and die. 



THE ATMOSPHERE, in tranquillity, is little regarded except as af- 

 fording the means of comfortable respiration to the whole animal 

 world ; but, disturbed in its statical pressure, by the influence of 

 heat, it generates not only land and sea breezes, monsoons, and trade 

 winds, but the hurricane and the tornado. Navies are overwhelmed 

 in the waves ; the oak and the cedar are prostrated ; and man and 

 his works, his towers of strength, ami his pinnacles of pride are level- 



