2 52 
Mr. Cavallo’s Obfer vat ions on 
VII. 52973. 
VIII. 50000. 
If a monochord be divided in this manner, and a harpfi* 
\ 
chord tuned by it, this inftrument will then be tuned fo, that 
whichever note be taken for the fir ft or key-note, its fifth, 
fixth, &c. will produce the fame effect refpe&ively. 
Thus far I have endeavoured to explain this fubjefil in the 
moft familiar manner, avoiding as much as poifible the mathe- 
matical language and fymbols ; having found, by experience, 
that intricate mathematical dilquifitions, efpecially on this 
fubjefit, are underftood only by a few able mathematicians, 
but that they are neither comprehended, nor even read, by 
thofe who might wifh to underftand, or to ule them. It is 
now neceflary to confider this fubjeift with refpect to the 
pradtice. 
At prefent, the harpfichords and organs are commonly 
tuned fo, that fome concords are very agreeable to the ear, 
whilft others are quite intolerable ; or, in other words, when 
the performer plays in certain keys, the harmony is very plea- 
ling, in others the harmony is juft tolerable, and in fome other 
keys the harmony is quite difagreeable. 
The heft keys to be played in are the keys of C, of F, of 
E flat, of B flat, of G and of D in the major mood, and the 
keys of C, of D, of A, and of B, in the minor mood. Next 
to thofe come the lefs agreeable keys of A, A flat, and E in 
the major mood ; befides thofe, the reft are difagreeable in a 
greater or lefs degree, fo that out of twelve keys *, which, on 
account of the two moods, viz. the major and the minor, 
become twenty-four, there are hardly fourteen that can be 
* The octave mult be excepted, in this refpett it being the fame as the firft 
note. 
4 11 fed ; 
