WATER HAMMER

Wa″ter ham″mer (?). (Physics) 1. 1. A vessel partly filled with water, exhausted of air, and hermetically sealed. When reversed or shaken, the water being unimpeded by air, strikes the sides in solid mass with a sound like that of a hammer.
2. 2. A concussion, or blow, made by water in striking, as against the sides of a pipe or vessel containing it.