AN ESSAY ON MUSIC. 



■569 



Any sound may be assumed at pleasure 

 for the primitive or standard note of a piece 

 of music, and is then' denominated the key 

 note : and the idea of this note is perpetu- 

 ally impressed on the mind in all simple 

 compositions, both from its frequent recur- 

 rence, and from the relation that all the 

 other sounds bear to it. C being the key 

 note of the scale called natural, we shall con- 

 sider it as the foundation of the scale. The 

 next in importance is the fifth, G, which, 

 for various reasons, is intimately connected 

 with the key note. The first reason is, that 

 it constitutes the most perfect melody and 

 harmony with C, since every alternate vibra- 

 tion of C coincides with every third of G; the 

 second is, that an attentive ear may almost 

 always distinguish the fifth, at least its octave, 

 the 12th, whenever any instrument sounds 

 C ; it being one of those secondary sounds 

 which are called natural harmonics, and 

 which may generally be observed, in the pro- 

 portion of the natural numbers, as for as 

 twenty or more, but which have not hitherto 

 been completely explained: thirdly, a stopped 

 pipe, if blown forcibly, springs immediately 

 from C to g, and an open pipe first to c, 



VOL. II. 



and then to g. The interval, between C and r 

 G, is most naturally divided by the note E, 

 which answers to the number 5, when C and 

 G are represented by 4 and 6, and which is 

 found among the natural harmonics both of 

 chords and pipes. Tliese three notes consti- 

 tute the harmonic triad, or common accord, 

 in the major scale, which is the most per- 

 fect, or rather the only perfect harmony. 

 But the intervals are still much too largcfor 

 melody, and require a further subdivision ; 

 we now therefore take the fifth below instead 

 of above the key, or its octave, the fourth 

 above, F, which is to C as 4 to 3 : this sound 

 is no where found among the natural har- 

 monics of C, but C is the most distinguish- 

 able of its harmonics, and tlicrefore the rela- 

 tion is nearly the same. Tiie scale is com- 

 pleted by filling up the perfect triads of G , 

 and F : the fifth of G furnishing D, the se- . 

 cond of the key, which is also tl^e ninth na- 

 tural harmonic of C ; the third of G, the se- 

 venth, B, which is the fifteenth harmonic of • 

 C ; and the third of F being the sixtii of the 

 ke}'. A, which is neither among the harmo- 

 nics of C, nor has c among its harmonics. 

 Hence we have a second table, in which the 

 proportions of the length of a chord, or pipe, 

 producing the various sounds, aye detailed, 

 and the place among the principal natural 

 harmonics of the key annexed. 



Now when two or more perfectly harmo- 

 nious parts are performed together, they 

 must necessarily be found all in the sanii? 

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