OF NATURAL PHILOSOPHY. 11 



himself, his pursuits, and his pleasures in the eyes 

 of those around him, he has only to point to the 

 history of all science, where speculations, appa- 

 rently unprofitable, have, in innumerable instances, 

 been those from which great practical applications 

 have emanated. What, for instance, could be 

 more so than the dry speculations of the ancient 

 geometers on the properties of the conic sections, 

 or than the dreams of Kepler (as they would na- 

 turally appear to his contemporaries) about the 

 numerical harmonies of the universe? Yet these 

 are the steps by which we have risen to a know- 

 ledge of the elliptic motions of the planets and the 

 law of gravitation, with all its splendid theoretical 

 consequences, and its inestimable practical results. 

 The ridicule attached to " Swing-swangs " in 

 Hooke's time * did not prevent him from reviving 

 the proposal of the pendulum as a standard of 

 measure, since so effectually wrought into practice 

 by the genius and perseverance of Captain Kater ; 

 nor did that which Boyle encountered in his 

 researches on the elasticity and pressure of the air 

 act as any obstacle to the train of discovery which 

 terminated in the steam-engine. The dreams of 

 the alchemists led them on in the path of ex- 

 periment, and drew attention to the wonders of 

 chemistry, while they brought their advocates (it 

 must be admitted) to merited contempt and ruin. 

 But in this case it was moral dereliction which gave 

 to ridicule a weight and power not necessarily or 

 naturally belonging to it : but among the alchemists 



Hooke's Posthumous Works. Lond. 1705 p. 472 



and p. 458. 



