steam-cock

With boiling water from a steam-cock he brewed a panikin of tea; and sat placidly admiring the fawn-pink light on wide pampas of bronze grasses, tawny as a panther's hide.

Where the Blue Begins Christopher Morley 1923

The apparatus of laughter is when due to "tickling" set at work by a short cut to the nerves and related muscles without recourse to the normal emotional steam-cock.

More Science From an Easy Chair 1888

And in the event of the water-cock being choked while the steam-cock was clear the consequence would be equally dangerous, for the water that was in the glass before the stoppage occurred would remain in it, for the stoppage would not allow it to drop down into the boiler again; so there it would remain, and when the stoker came round to look at his boiler, unless he happened to notice that no movement of the water was visible, he would pass on without further ado, and remain in total ignorance of his danger.

The Stoker's Catechism W. J. Connor

It is probably one of those cases in which a mechanism of the living body is set to work, as a machine may be, by directly causing the final movement (say the turning of a wheel), for the production of which a special train of apparatus, to be started by the letting loose of a spring or the turning of a steam-cock, is provided, and in ordinary circumstance is the regular mode in which the working of the mechanism is started.

More Science From an Easy Chair 1888