at rail serves two purposes in the square action, and what
are they? What rail serves two purposes in the grand action, and
what are they?

LESSON V.

~REGULATING AND REPAIRING.~

FAULTS IN PIANOS, ASIDE FROM THE ACTION, AND THEIR REMEDIES.

One of the most common, and, at the same time, most annoying
conditions both to the owner of the piano and the tuner, is the
"sympathetic rattle." This trouble is most usual in the square and the
grand pianos and is generally due to some loose substance lying on the
sound board. The rattle will be apparent only when certain keys are
struck, other tones being perfectly free from it. These tones cause
the sound board to vibrate in sympathy, so to speak, with the weight
of the intruding substance at the point where it lies, and if it be
moved the distance of six inches it will sometimes cease to respond to
these particular tones, but may respond to others, or cease to cause
any trouble.

The article may generally be found near the front of the sound board
under the top piece of the case, this being the place where it would
most likely fall. No special instrument is made for the purpose of
searching for such objects, but one can be easily devised with which
the tuner can feel all over the sound board, and remove such articles
as well as dust and dirt. Secure a piece of rattan or good pliable
hickory, and draw it down to the width of half an inch, thin enough to
bend easily, and long enough to reach anywhere under the stringing or
metal plate. By putting a cloth over this stick you can remove
anything that comes in its way. Some difficulty will be found,
however, in getting under the plate in some pianos. In case you cannot
procure a suitable piece of wood, a piece of clock spring will be
found to answer very well. We have taken from pianos such articles as
pencils, pieces of candy, dolls, pointers used by music teachers,
tacks, nails, pennies, buttons, pieces of broken lamp chimneys, etc.,
etc., any one of which is sufficient to render the piano unfit for
use. The sound board of the upright being vertical prevents its being
subject to the above difficulty.

A split in the sound board, in any style of piano, sometimes causes
trouble due to the vibrating edges of the board coming in contact
with each other. Insert the point of your screwdriver in the crack,
holding it there firmly; if the rattling stops, the difficulty is
discovered, and may be remedied by placing