instruments. The sound-board itself is made of most carefully chosen
pine; in Europe of the _Abies excelsa_, the spruce fir, which, when well
grown, and of light, even grain, is the best of all woods for resonance.
The pulsations of the strings are communicated to the sound-board by the
bridge, a thick rail of close-grained beech, curved so as to determine
their vibrating lengths, and attached to the sound-board by dowels. The
bridge is doubly pinned, so as to cut off the vibration at the edge
of the bearing the strings exert upon the bridge. The shock of each
separate pulsation, in its complex form, is received by the bridge,
and communicated to such undamped strings as may, by their lengths, be
sensitive to them; thus producing the AEolian tone commonly known as
sympathetic, an eminently attractive charm in the tone of a pianoforte.

We have here strings, bridge, and sound-board, or belly, as it is
technically called, indispensable for the production of the tone, and
indivisible in the general effect. The proportionate weight of
stringing has to be met by a proportionate thickness and barring of the
sound-board, and a proportionate thickness and elevation of the bridge.

The tension of the strings is met by a framing, which has become more
rigid as the drawing power of the strings has been gradually increased.
In the present concert grands of Messrs. Broadwood, that drawing power
may be stated as starting from 150 lb. for each single string in the
treble, and gradually increasing to about 300 lb. for each of the single
strings in the bass. I will reserve for the historical description of
my subject some notice of the different kinds of framing that have been
introduced. It will suffice, at this stage, to say that it was at first
of wood, and became, by degrees, of wood and iron; in the present day
the iron very much preponderating. It will be at once evident that the
object of the framing is to keep the ends of the strings apart. The near