The most important example of this type is the tuning-fork, which may be regarded as consisting of two parallel bars clamped together at the base.
A metal or brass tube will serve as such a pipe, and may be excited by a suitable tuning-fork held at one end.
1834 Hullah's tuning-fork.
If, at the same time, a tuning-fork of known number of vibrations per second be made to trace its own line close to the other, a comparison of the two lines gives the number corresponding to the sound under consideration.
A tuning-fork or a bell-glass, a silk or cotton thread, the other extremity being either fixed or passing over a pulley and supporting weights by which the thread may be stretched to any degree required.
If a tuning-fork in vibration be turned round before the ear, four positions will be found in which A B it will be inaudible, owing to the mutual interference FIG.
The time between the breaks could be measured in seconds by the clock signals, and in fractions of a second by the tuning-fork record.
Perhaps an electrically maintained tuning-fork is still better.
1618 Peppercorn's tuning-fork (Broadwood).
1834 Reissiger's tuning-fork, Dres den.