MATURE OF THE CRAVE HARMONICS. j| 



ing in pitch to a firing; which vibrates once in the time of lower than ei- 

 each fucceffive cycle: A grave harmonic is on this account al- ori g.° a | f oun< j s> 

 ways a lower note than any of its conftituents, feeing the time and fainter. Ic 

 of a cycle exceeds the greateft vibration that enters into thelmag^olj 1 .^ 

 composition of it. The ftrength of a grave harmonic is alfo 

 weak, when compared with the notes compofing it, becaufe 

 thefe fecondary founds, being nothing more than certain un* 

 avoidable efforts of the imagination, they affume the character 

 of a feeble found, which is juft ftrong enough to be heard in 

 the company of one or more louder tones ; for the power of 

 the imagination is always inferior to external impreflions, ex* 

 cept in fits of infanity, when the organs of fenfe appear to be 

 blunted by phyfical caufes. This inferiority of the fancy may 

 be affigned as the reafon of imaginary founds, which it fre- 

 quently creates, being conftantly faint and apparently diftant. 



Dr. Young mentions a trait of the grave harmonics, which 

 fpares my own authority, and gives an opportunity to quote 

 his for the following fact, which is of the firft moment to the 

 prefent theory : The grave harmonics always keep the direc- In proof of 

 tion of the ears, let the pofition of the head be changed as *>&$%%'£?£% 

 as you pleafe, refembling in thi* circumftance a fhrill piping reffm is urged, 

 note, called the ringing of the ears ; which every one afcribes 

 to a flight affection of the auditory duel, becaufe it differs from 

 external founds in having no fixed direction. The grave har- 

 monics agree with the ringing of the ears in this remarkable 

 particular ; which is a ftrong proof that their immediate caufe 

 is feated in the perfon of the hearer ; and it is evident from 

 the nature of things, that this caufe originates in the mind, 

 feeing that the organ does not labour at the time under a phy- 

 fical impediment. 



I have now given a general theory of thefe ideal founds, Concluding ra- 

 in compliance with Dr. Young's injunctions, but am not able marks » 

 to perceive any connection between the fubject and the queftion 

 in debate. This was the reafon why I disregarded in my laft, 

 one of the Doctor's remarks, which he has fince called a chal- 

 lenge, perhaps in a petulant manner : a little more argument 

 and a little lefs ill humour would certainly promote both his 

 caufe and reputation. The Doctor endeavours to perfuade 

 me, that I mifunderfland his idea of coalefcence. My idea of 

 the fubject is fimply this, that founds cannot coalefce; confe- 

 quently that all compounds are nothing; but a number of dif- 



B2 toft 



