The strings are hitched on to pins in the iron frame at its lower end
and fastened at the upper end by a metal pin or peg driven into the
back. The peg is square on top, so that it can be turned with a tuning
hammer or wrench in order to tighten or slacken the strings, which is
the operation of tuning the piano.]
[Illustration: THE LITTLE HAMMERS WHICH STRIKE THE PIANO STRINGS
Photo by Kohler & Campbell Piano Co.