To determine the temperaments and beats of all the concords,
together with the values of the diatonic and chromatic intervals,
and the lengths and vibrations per second of a string producing
all the sounds, of the system resulting from the last proposition.
The temperaments of all the concords are easily deduced from Table
V. The Vth CG, for example, has its lower extremity lowered 12, and
its upper extremity 14. Hence it is flatter by 2 than at first,
and consequently its temperament=156. The temperaments of all the
concords, thus calculated, will be found in the 2d, 3d, and 4th
columns of Table VII.
Having ascertained the temperaments, the value of the diatonic and
chromatic intervals may be found. The Vth CG being flattened 156,
and the Vth FC 139, the major tone FG must be diminished 156 +
139, or be = 4820. By thus fixing the extent of one interval after
another, from the temperaments of either of the different kinds of
concords, as is most convenient, the intervals in question will be
found to have the values exhibited in Table VI.
Let the numbers in this table be added successively, beginning at
the bottom, to the log. of 240, the number of vibrations per second
of the tenor C, (see Rees's Cyc. Art. Concert Pitch,) and the
numbers corresponding to these logarithms will be the vibrations in
a second, of a string sounding the several degrees of the scale.
They are shown in col. 6, Table VII.
Since the length of a string cæteris paribus is inversely as its
number of vibrations, the lengths in col. 5 may be deduced from
the vibrations in col. 6; or more expeditiously, by subtracting
the numerical distances from C of the several degrees in Table VI.
from O, and taking the corresponding numbers, from the table of
logarithms. These numbers, when used as logarithms, must be brought
back to the decimal form, agreeably to Scholium 2. Prop. I.
To find the number of beats made in a second by any concord, it
is only necessary to take from col. 5 the numbers belonging to
the degrees which terminate that concord, and to multiply them
crosswise into the terms of its perfect ratio. The difference of
the products will be the number of beats made in a second. The 3
last columns contain the beats made by each of the concords, in 10
seconds.
TABLE VI.
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