AND THE THEORY OF LIGHT. O 



demonstrates one thing, that there is no distinct analysis 

 by means of the prism. There is thus room left for a 

 new investigation into the cause of colour. 



5. In my inquiries into the nature of light I had no fine 

 spun theory to unfold, with its axioms and postulates, 

 by which to demonstrate theorems and solve problems. 

 I was in search of all these. Hence I feel more disposed 

 to describe the mental process by which I was led to un- 

 dertake the experiments which I have made. I prefer 

 describing the observations and experiments which I made 

 whilst examining the natural phenomena of light, and the 

 arguments which I deduce from them, to formally build- 

 ing up a science. At all events, experiment alone can be 

 accepted as the basis of any new theorj^, for, in physical 

 researches, no logical or mathematical analysis can take 

 the place of experiment. Has not the great obstacle to 

 the progress of the science of light for these two hundred 

 years past been the building a science mathematically on 

 insufficient experimental data; for if there is one thing 

 more certain than another in regard to the physical nature 

 of light, it is that the data for mathematical calculation 

 are imperfect, and there is nothing which retards the 

 search after truth more than the application of mathema- 

 tical formulae to imperfectly ascertained truths. They are 

 then to a great extent assumptions. It may make our 

 researches appear more learned to apply the exact sciences 

 in the illustration of them ; but how can the exact sciences 

 be applied to observations not exactly comprehended ? I 

 consider, therefore, the exposition of a series of observa- 

 tions a much more scientific and instructive method of 

 arriving at a physical law than any mathematical assump- 

 tion which, though apparently solving many problems, 

 carefully conceals the physical process and unfolds no 

 method of physical research. Mathematical reasoning is 

 not physical reasoning, and is as easily abused as the 



