l$4f THEORY OF COMPOUND SOUNDS. 



to ilfelf, and at the fame time lofe the diftinguiftiing characters' 



of its elements, fome of which are incompatible with the quali- 



in which the ear ties of an individual. On this fuppofition, the prefence of 



could notdiftin- the conftituent founds could not be detected by the ear in this 

 EuiJh the com- . , . . . • . 1 



poncnt parts. newly created being : on the contrary, an experimental pro- 



cefs would be required to analyfe every compound found the 

 firft time it attracted a man's attention, for the fame reafon that 

 Chemical com- a chemift finds it neceflary to analyfe a fubftance with which 

 prifon. he is unacquainted. The abftract term coaltfcence is ufed, in 



a phyfical fenfe, to fignify any intimate union of bodies or the 

 powers of bodies ; and the introduction of the term into lan- 

 guage proves the exigence of the principle in nature, or more 

 properly in the human mind. For, when a number of agents 

 act in conjunction upon one of the fenfes, we have two ways 

 of conceiving their mode of operation. If the fenfible effects 

 of each agent be diftinctly perceived, we attribute a feparate 

 action to every member of the affemblage, and call the aggre- 

 gate a mixture : this is the conclufion of a perfon who taftes 

 an infufion of pepper in vinegar. On the other hand, when 

 we know that certain agents are prefent without being able to 

 recognize their diftinguiftiing powers, in the room of which 

 we find qualities of a different defcription, we pronounce the 

 aggregate to be in a ftate of coalefcence. This is the (ituation 

 of the chemift, who taftes common fait, but cannot perceive 

 Compound the prefence of foda and the muriatic acid. It is my bufinefs 



founds are mix- then to prove compound founds to be mixtures, not aggregates 

 tures, ^no com- ^ coa l e fcence. This I (hall endeavour to do, by (hewing 

 that they have properties which belong not to individuals, 

 fuch as a number of tones, a variety of directions, and feveral 

 fets of pulfes. 

 Inftances. The Firft, the tones of a flute and violin are as diftinct to fenfe 

 flute and violin as any two things can be when they are founded feparately ; 

 L b\ in con- an< ^ * appeal to common experience to determine, if they are 

 cert, not equally diftinct when heard in concert. Taking it for 



granted that the anfwer will be in the affirmative, I pronounce 

 the courfesof the the aggregate to be a mixture of founds in one cafe. Secondly, 

 two founds are jf a yiolin found in front of the hearer, and a flute be heard 

 when they differ. 3* tne f ame time * n an oblique (ituation, the perfon thus cn> 

 cumftanced is able to determine the relative pofitions of the 

 two inftruments, which (hews the aggregate to have two co- 

 temporary directions. It is therefore a mixture of founds, not 



a (ingle 



