wn by
measure-signs.

5. Key shown by key signature placed at the beginning of each
staff.

6. Rate of speed, dynamic changes, etc., shown by certain
Italian words (_allegro_, _andante_, etc.), whose meaning is
as universally understood as staff notation itself.

APPENDIX B

MUSICAL INSTRUMENTS

1. Broadly speaking, musical instruments may be divided into two
classes, viz.: (1) those that have a keyboard and are therefore capable
of sounding several tones simultaneously; (2) those that (as a rule)
sound only one tone at a time, as the violin and trumpet. The piano is
of course the most familiar example of the first class, and a brief
description is therefore given.

The _piano_ was invented about two hundred years ago by
Cristofori (1651-1731), an Italian. It was an enormous
improvement over the types of keyboard instrument that were in
use at that time (clavichord, harpsichord, spinet, virginal)
and has resulted in an entirely different style of
composition. See note on embellishments, p. 26.

2. The most characteristic things about the _piano_ as contrasted with
its immediate predecessors are: (1) that on it the loudness and softness
of the tone can be regulated by the force with which the keys are struck
(hence the name _pianoforte_ meaning literally the _soft-loud_); (2) the
fact that the piano is capable of sustaining tone to a much greater
extent than its predecessors. In other words the tone continues sounding
for some little time after the key is struck, while on the earlier
instruments it stopped almost instantly after being sounded.

The essentials of the piano mechanism are:

1. Felt hammers controlled by keys, each hammer striking two
or three strings (which are tuned in unison) and immediately
rebounding from these strings, allowing them to vibrate as
long as the key is held down. The mechanism that allows the
hammers to rebound from the strings and fall into position for
another blow is called the _escapement_.

2. A damper (made of softer felt) pressing against each string
and preventing it from vibrating until it is wanted.

3. A keyboard action that controls both hammers and dampers,
causing the damper to leave the string at the same instant
that the hammer strikes it.

4. A pedal (damper pedal) controlling all of the dampers, so
that at any moment all the