volume he states : " My objections to 

 Newton's manner of accounting for the 

 colours of thin plates are of long standing, 

 but the hint of accounting for them in the 

 manner that I have attempted to do [by 

 the doctrine of attractions and repulsions] 

 was first suggested to me by Mr Michell, 

 agreeably to whose conjectures relating 

 to this subject, I have given the preceding 

 account of the probable cause of these 

 appearances 1 ." 



Priestley likewise refers to MichelFs 

 skill in devising apparatus for the purpose 

 of illustrating or solving physical pro- 

 blems. Thus with regard to another 

 phenomenon of light he states : " Mr 

 Michell some years ago endeavoured to 

 ascertain the momentum of light in a 

 much more accurate manner than those 

 in which M. Homberg and M. Mairan 

 had attempted it ; and though his appa- 



fol lower of Newton believed in the corpuscular 

 theory of light. 

 1 Vol. I, p. 311. 



79 



