2G4f THEORY OF COMPOUND SOUNDS, 



An Anfiuer to Air. Cough's llffay on the Theory of Compound 

 Sounds, fij/ Thomas Young, M. D. F. R. S. 



To Mr. NICHOLSON. 

 SIR, 



nmkf a ° ryrC " •* HAVE alread y made public, through the medium of your 

 ufeful Journal, one vindication of my remarks upon Dr. Smith's 

 Harmonics ; and I fhall now beg you to infert fome further 

 obfervations upon a fubject nearly fimilar. I do not think 

 myfelf bound to reply to all the arguments that may happen to 

 be advanced again (I any of my opinions; but when they come 

 from perfons of literary refpeciability, and efpecially when 

 they convey an imputation of having detracted from the me- 

 rits of others, I cannot forbear attempting to anfvver them; 

 and in the prefent inflance a very few words will be fufficieni 

 for the purpofe. Mr. Gough has published in the .lad volume 

 of the Manchester Memoirs, a paper in which he profeffes to 

 defend Dr. Smith's opinions againft mine : but he has unfor- 

 tunately fo far miftaken the queftion between us, thai with 

 refpect to the principal circumftanees, while he imagines he 

 is confuting me, he is completely on my fide. 

 The author's in- Proceeding upon the grounds. of the well known facls rela- 

 itrerices from ^ lVQ ^ Q ^ e o- rave harmonics, or the third founds produced by 



coalefcence of O in. 



undulations as the coalelcence of two others, as well as upon the allowed 

 to the do&rmes principles of the compofition of motion, I had drawn a num- 

 ligbt, fcarcely De *" °f inferences, which appeared to be of fome importance 

 to be called a j n the firft place with refpect to the do&rine of found, and 

 ory * which have fince furnifhed me with ft ill more interefting con- 

 clusions with regard to light, I was not aware that there was 

 any probability of the juilice of my inferences being difputed, 

 or that there was fo much novelty in the mode of obtaining 

 them, as to deferve the name of a theory or an invention : 

 but if it be deemed otherwife, I (hall always be ready to ac- 

 knowledge the invention with fatisfaction, and to fupport the 

 theory with alacrity. 

 Dr. Smith jma- I fhall now quote the words of Dr. Smith, which gave rife 

 undulations in " t0 m ^ animadverfions ; and this Statement is the more necef- 



fary, 



