254 Mr. Cavallo’s Obfervatms , &c. 
of keys, and very often in thofe, for which the common way 
of tuning is not at all calculated. 
In order to hear the effedt of the above-mentioned tempera- 
ment of equal harmony, I had a monochord made in a very 
accurate manner, and upon it I laid down the divifions for the 
thirteen notes of an odtave properly tempered in the manner 
explained above. After a great deal of trouble in adjufting the 
moveable fret, corre&ing the divifions, &c. I at laft fucceeded 
fo well as to render the divifions exadt within at leaft the 300th 
part of an inch, and every part of the inftrument was rendered 
fufficiently fteady and unalterable. 
This being done, I had a large harpfichord, with a fingle 
unifon (in order to judge the better of the effedt), tuned very 
accurately by the help of the monochord. With this inftru- 
ment, in whatever key the performer played, the harmony was 
perfectly equal throughout, and the effect was the fame as if 
one played in the key of E natural on a harpfichord tuned in 
the ufual manner. 
I fhall, therefore, conclude with faying, that when the 
harpfichord, organ, &c. is to ferve for folo playing, and for a 
particular fort of mufic, it is proper to tune in the ufual man- 
ner, viz. fo as to give the greatefi: effect to thofe concords 
which occur more frequently in that fort of mufic ; but that 
when the inftrument is to ferve for accompanying other inftru- 
ments or human voices, and efpecially when modulations and 
tran fpofitions are to be pradtifed, then it muft be tuned accord- 
ing to the temperament of equal harmony, which has been 
explained in the preceding pages. 
