2ZO

Of Winds and Sounds.

they are distinguished into low and high*grave and acute, by Musicians call’dand Sharps. Now the Tone of a Sou 0depends on the Time or Duration of ^Stroke made on the Drum of the Ear,Wave or Pulse of Air; for as that is lottK ^or shorter, the Tone will be more gratviacute: And since all the Pulses move eqU^ly swift, the Duration of a Stroke willproportional to the Interval between 1 jsuccessive Pulses ; and consequently, a

10. Now since by Construdtion it is B a—ab j— cd, &c. and also a k : b I :: b I : c m :: c n : d^so on ; therefore the Points k, I, m, n, <?, p, q, r,will in this Cafe form that Curve Line which is ci $the Logarithmetic Curve: Consequently, a Tr u ^;jformed by the Revolution of this Curve about lts '^will augment the Sound in a greater Degree tha* 1other figured Tube whatsoever.

11. But to shew the Reason of the Nature and

of this Curve, suppose the following Series of QF a! J , 'in Geometrical Progression, viz. « Q : a' : a 1 : a 1 • a j&c.then it is plain the Ratio of a 1 to a” is i, d> e ^

tio of a z to is 2, the Ratio of a 3 to a” is 3,on; whence it appears, that the Indices of the

1 °.

- 7 -want. 4HUILC 0 VI \y

Terms express the Ratios of those Terms ^ eve S 0 v/"the first, and are therefore their Logarithms.

l,

B b — 2, B c zz 3, &c. and therefore the Logos’ toExponents of the Ratios of these severalthe first or Unity. Hence the Curve which c01 .01those Ordinates is called the Logarithmetical or Lo&JCurve.

~-j ---v mvu t-ns/f** • . . .^[t

in the above-mentioned Figure we put the Or 1ak — a h zz I, blv=.a' — a, c m ~ d 1 ~ a a, & c-will the intercepted Parts of the AbsciJJis be B ^ ‘