by as a single string, as there might be a slight
discrepancy in the unison giving rise to waves which would confuse the
ear. The tuner should hear but two strings at once while setting a
temperament; the one he is tuning by and the one he is tuning. A
continuous mute is a strip of muting felt of the proper thickness to
be pushed in between the trios of strings. Simply lay it across a
portion of the strings and with a screwdriver push it in between the
trios just above where the hammers strike. In the square piano, which
has but two strings to a key, the continuous mute cannot be used and
you will be obliged to tune both strings in unison before leaving to
tune another interval. This is one of the reasons why the square piano
does not, as a rule, admit of as fine tuning as the upright.

[C] The three strings composing the trio or unison are numbered 1st,
2d or middle, and 3d, from left to right.

It is presumed that you are now familiar with the succession of tones
and intervals used in setting the temperament. Fix these things in
your mind and the system is easy to understand and remember. Keep
within the bounds of the two octaves laid out in Lesson X. Tune all
fifths upward; that is, tune all fifths by their fundamentals. For
example, starting on 1C, use it as fundamental, and by it, tune its
fifth, which is G; then, having G tuned, use it as fundamental, and by
it tune its fifth, which is D, and so on through. After tuning a
fifth, always tune its octave either above or below, whichever way it
lies within the bounds of the two octaves. After going through one or
two experiments in setting temperament you will see the simplicity of
this system and will, perhaps, not be obliged to refer to the diagram
any more.

For various reasons, it is better to try your experiments on an
upright piano, and the better the piano, the more satisfactory will be
the result of the experiment. You should have no hesitancy or timidity
in taking hold of a good piano, as you cannot damage it if you use
good judgment, follow instructions, and work carefully. The first
caution is, be very careful that you draw a string but slightly
sharper than it is to be left. Rest the heel of the hand against some
stationary part of the piano and pull very slowly, and in a direct
right angle with the tuning pin so as to avoid any tendency to bend or
spring the pin. We would advise now that you find an upright piano
that is badly out of tune, if y