426 Mr. Thomas Richardson on Donium, a 



have been attributed to interference ; and though I am 

 not prepared to deny the existence of this principle alto- 

 gether, provided it does not extend to destructive interfer- 

 ence, I am disposed to defend nature against the charge 

 included in it, of defeating her own purposes by the means 

 she has adopted for executing them. Her resources are so nu- 

 merous, and in tracing her operations, spring up amidst the 

 most complicated appearances, with such unexpected sim- 

 plicity, that I cannot admit a principle that implies a doubt 

 of the perfect adaptation of her means to their object, 

 without the clearest proof; and I am the more disposed to 

 hesitate when called upon to make this admission, from a 

 conviction that it has been claimed, in several instances, 

 to dispose of difficulties which may be removed by other 

 and better explanations. 



It appears to me that the doctrine of interference, if it 

 was consistently followed up, would deprive us of light 

 altogether ; for as light is supposed to flow from every point 

 of the sun to every part of space, whatever may be the 

 length of the undulations, they must be intersected by other 

 undulations, which originate at such a distance from them 

 as to make a difference of half an undulation in the length 

 of their paths, and according to this doctrine, if I correctly 

 understand it, the whole ought to be destroyed ; whereas, 

 notwithstanding the millions of such intersections which 

 must take place in the course of its progress, light reaches 

 the eye unimpaired by its transmission. 



P. COOPER. 



Bawlish, January 8th, 1836. 



To the Editor of the "Records of General Science. 



Article VI. 



On Do aium, a New Substance discovered in Davidsonite. 

 By Mr. Thomas Richardson. 



This mineral was discovered by Dr. Davidson, of Aberdeen, 

 in a granite quarry, in the neighbourhood of that city, and 

 sent by him to Dr. Thomson, who requested one of his 

 pupils to submit it to a chemical examination, from which 

 he concluded it to be a compound of 



