GEANTHAM ADDRESS. 285 



discovered by themselves to have been their own in the pro- 

 cess of their investigation ; and this, like all the other doubts 

 that were ever momentarily entertained, only led in each 

 instance to new and more brilliant triumphs of the system. 



The prodigious superiority in this cardinal point of the 

 Newtonian, to other discoveries, appears manifest upon ex- 

 amining almost any of the chapters in the history of science. 

 Successive improvements have by extending our views con- 

 stantly displaced the system that appeared firmly established. 

 To take a familiar instance, how little remains of Lavoisier's 

 doctrine of combustion and acidification except the negative 

 positions, the subversion of the system of Stahl ! The sub- 

 stance having most eminently the properties of an acid, 

 (chlorine,) is found to have no oxygen at all,* while many 

 substances abounding in oxygen, including alkalis themselves, 

 have no acid property whatever ; and without the access of 

 oxygenous or of any other gas, heat and flame are produced in 

 excess. The doctrines of free trade had not long been pro- 

 mulgated by Smith, before Bentham demonstrated that his 

 exception of usury was groundless ; and his theory has been 

 repeatedly proved erroneous on colonial ^establishments, as 

 well as his exception to it on the navigation laws ; while the 

 imperfection of his views on the nature of rent is undeniable, 

 as well as on the principle of population. In these, and such 

 instances as these, it would not be easy to find in the original 

 doctrines the means of correcting subsequent errors, or the 

 germs of extended discovery. But even if philosophers finally 

 adopt the undulatory theory of light instead of the atomic, it 

 must be borne in mind that Newton gave the first elements of 

 it by the well-known proposition in the eighth section of the 

 second book of the ' Principia,' the scholium to that section 

 also indicating his expectation that it would be applied to 

 optical science ;| while M. Biot has shown how the doctrine 



* Eecent inquiries are said to have shaken if not displaced Davy's 

 theory of chlorine. 



t The 47th prop. lib. H, has not been disputed except as to the suffici- 

 ency of the demonstration, which Euler questioned, but without adding the 



