Epitome of the Progress of Natural Scknce. 243 



the period of Archimedes, the principles and laws of mechanics 

 were not laid down. His treatise on Equilibria contains an ex- 

 position of these principles. He demonstrates that masses have 

 a common point of pressure, the centre of gravity; and shows 

 how that centre may be found in all bodies. It was he that laid 

 the foundation of all the inventions, which have constituted the 

 triumph of mechanics : the machines by which he caused so pro- 

 tracted a defence of Syracuse against the Romans, seem, even in our 

 day, to belong to the romance of mechanical history. When we 

 reflect upon the causes which retard or advance knowledge, we 

 cannot but trace the one either to an abasement of the public mind, 

 or the other to the influence of general education, which pre- 

 pares the public mind to receive and cherish its seeds. Had Ar- 

 chimedes lived in an intelligent age, the principles of his great 

 discoveries, which concerned both solid and fluid bodies, would 

 have received a more extensive application long ere our own 

 times, and in many things we should have been anticipated by 

 our ancestors ; but although a few continued to walk in the light 

 of his great mind, the science of statics became, as it were, sta- 

 tionary after his death. The same observation may be made also, 

 in relation to the genius of Pythagoras, especially in that branch 

 of pneumatics which relates to the theory of sound, and to which 

 he was the first to apply the rules of arithmetical and geometri- 

 cal science. The doctrine of musical chords, and their analysis 

 into vibrations of equal and unequal spaces of time ; his transfer 

 of this harmonic scale to the motions of the heavenly bodies, 

 which, by a grandeur of thought belonging only to a genius of 

 the highest order, he supposed to produce sounds of the most in- 

 conceivable harmony, by impinging on the ether through which 

 they moved, evince how much knowledge and enjoyment man- 

 kind has been deprived of, by the protracted inquiries into these 

 the true principles of the theory of musical science. 



There are two natural agents, which, from time immemorial, 

 have interfered with the industry and the social existence of 

 man. Of the deluges which have at repeated intervals partially 

 overwhelmed the surface of the earth, we have abundant evi- 

 dence in practical geology, as well as in the traditions of all na- 

 tions ; and although similar traditions of the destructive effects 

 of volcanic power, have been less powerfully impressed upon suc- 

 ceeding generations, on account of its less extensive operation, 



