iPHYSICAL AND LITERARY. ij 



would exprefs the proportion in which the 

 diftance of the^ neareft rays exceed the dia- 

 meters of their particles : and yet this di- 

 ftance of the neareft rays, flowing from the 

 fame center, is fo incomparably below our 

 fmalleft meafiires, that there is no poffibility 

 of defining it. 



6. Had Euler confidered tliis extrertie ra- 

 rity, as well as tenuity of light, which muft 

 be acknowledged by all who fuppofe that its 

 particles are actually projeded from the lucid 

 body, he would not have dlledgedy that 

 this opinion is incbnliflent with the freedom 

 and perpetuity of the celeftial motions ^^ 



7. Some have thought, that, if the parti- 

 cles of light repel one another, their mutual 

 perturbation may be prevented * but the 

 contrary is manifeft upon the leaft reflection 5 

 for tho', by that means, the particles might 

 be prevented from ftriking, they muft in- 

 ftantly turn one another from their redilinear 

 courfes, as foon as they come, in different' 

 diredions, within the reach of their mutual 

 powers. Thus, we find by experience, it is 

 impolTible to make, one ftream of air pene- 

 trate another without confufion j for the twa 

 ftreams either unite into a common one with 



Vol. IL. C m 



* See his Nova theoria lucis et colorum. 



