120 ETHER. 



attentively a greater number of the phenomena of light,, 

 has endeavoured to assist the inquiry by the aid of 

 hypotheses. Newton, in a theory, which exhibits the 

 refined character of that great philosopher's mind, sup- 

 poses luminous particles to dart from the surfaces of 

 bodies in all directions that these infinitely minute par- 

 ticles are influenced by the attracting and repelling forces 

 of matter, and thus turned back, or reflected, from their 

 superficies in some cases, and absorbed into their inter- 

 stitial spaces in others. 



Huyghens, on the contrary, supposes light to be caused 

 by the waves or vibrations of an infinitely elastic medium 

 ETHER diffused through all space, which waves are 

 propagated in every direction from the luminous body. 

 In the first theory, a luminous particle is supposed actu- 

 ally to come from the sun to the earth ; in the other, 

 the sun only occasions a disturbance of the ether, which 

 extends with great rapidity, in the same manner as a 

 wave spreads itself over the surface of a lake. 



Nearly all the facts known in the time of Newton, 

 and those discovered by him, were explained most 

 satisfactorily by his hypothesis ; but it was found they 

 could be interpreted equally as the effects of undulation, 

 with the exception of the production of colour by pris- 

 matic refraction. Although the labours of many 

 gifted minds have been given, with the utmost devotion, 

 to the support of the vibratory theory, this simple fact 

 has never yet received any satisfactory explanation ; and 

 there are numerous discoveries connected with the mole- 

 cular and chemical disturbances produced by the sun's 



darkness of the middle ages ensured a favourable reception to 

 every tale of wonder; and the revival of learning gave new vigour 

 to hope, and suggested more specious arts of deception. Philoso- 

 phy, with the aid of experience, has at length banished the study 

 of alchemy; and the present age, however desi.ous of riches, is 

 content to seek them by the humbler means of commerce and in- 

 dustry." Decline and Full, vol. ii. p. 137. 





