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XV. Of the Temperament of thofe mujical Injlruments , in which 
the Tones, Keys , or Frets , are fixed , as in the Harpfichord > 
Organ , Guitar , &c. Mr. Tiberius Cavallo, F.R.S, 
Head April 3, 1788. 
r ~jpHE fcale of mufic, which is tifed at prefent, confifls of 
feven principal notes or founds, which muficians denote 
by the letters of the alphabet A, B, C, D, E, F, and G ; 
which, together with fome intermediate ones, commonly called 
flats and fharps, and the oflave of the firfl, make 13 founds. 
When thofe founds are confidered with refpeef to the firfl:, 
they are called by the following names, viz. the prime or key- 
note, the fecond minor, fecond, third minor, third major, 
fourth, fourth major, fifth, fixth minor, fixth major, feventh 
minor, feventh major, and oftave. 
Muiical founds are produced by the vibrations of the fono- 
rous bodies, and they are acuter or graver as the vibrations 
performed in a given time are more or lefs in number; fo that 
if a ftring vibrating 100 times in a fecond produces a certain 
found, and another firing vibrating 120 times in a fecond 
produces another found, the latter is faid to be acuter, higher, 
or (harper than the former. 
The number of vibrations performed in a certain time prin- 
cipally depends on the thicknefs, length, and elafticity of the 
fonorous bodies ; but as the Ample A fonorous bodies, and the 
fitted for examination, are thofe firings which are equal in every 
3 other 
