Shishiodoshi (decorative bamboo irrigation pumps) (ししおどし)
Shishiodoshi is a general name for devices used to intimidate and drive away agriculture-damaging birds and animals.
It includes scarecrows, clappers and especially, sozu (water-filled bamboo tube in a Japanese garden that clacks against a stone when emptied.)
It is expressed in as "鹿脅し," "獅子脅し," or "獅子威し" in kanji characters, however, originally it was "鹿威し."
(See also the item of deer as a hunted animal, shika deer.)
Sozu is a device that makes a sound automatically using the energy of water. It is a bamboo tube supported at the center and has an open end to receive poured water. When the end section of the bamboo tube is filled with water, the tube inclines, then the water discharges and the section becomes empty. Then the bamboo tube returns to the original angle. At that time, the tube strikes a supporting platform (rock, etc,) and makes a sound.
In later days, people enjoyed the sound and the device became a decorative part of a Japanese garden. A typical sozu can be found in the Shisen-do Hall, in Kyoto. It is also used as an exterior decoration.
It is used to demonstrate a similar example of the axiom of a relaxation oscillator in electronics.