What is "turncock"

Usage examples of "turncock".

The men had been virtually immersed in liquid mud created by the water flow, for it would have taken the turncock half an hour of walking in a tight circle to close the main.

They were all concentrating on the manipulation of the turncock that obviously regulated the flow of the powdered ore through the pipes.

Up there the turncocks were busy flushing the gutters with standpipes, a row of fire engines was proceeding to wash the streets down from the mains.