the place in the string the excitement starts from; partly upon the
force and the form of force that is employed; and partly upon the
length, thickness, weight, strain, and elasticity of the string, with
some small allowance for gravitation. The vibrating sections are of
wave-like contour; the nodes or points of apparent rest being really
knots of the greatest pressure from crossing streams of molecules. Where
the pressure slackens, the sections rise into loops, the curves of which
show the points of least pressure. Now, if the string be struck upon a
loop, less energy is communicated to the string, and the carrying power
of the sound proportionately fails. If the string be struck upon a node,
greater energy ensues, and the carrying power proportionately gains.
By this we recognize the importance of the place of contact, or
striking-place of the hammer against the string; and the necessity, in
order to obtain good fundamental tone, which shall carry, of the note
being started from a node.

If the hammer is hard, and impelled with force, the string breaks into
shorter sections, and the discordant upper partials of the string, thus
brought into prominence, make the tone harsh. If the hammer is soft, and
the force employed is moderated, the harmonious partials of the longer
sections strike the ear, and the tone is full and round. By the
frequency of vibration, that is to say, the number of times a string
runs through its complete changes one way and the other, say, for
measurement, in a second of time, we determine the pitch, or relative
acuteness of the tone as distinguished by the ear.

We know, with less exactness, that the sound-board follows similar laws.
The formation of nodes is helped by the barring of the sound-board,
a ribbing crosswise to the grain of the wood, which promotes the
elasticity, and has been called the "soul" of stringed musical