[2536]. Slide valve to give a wide port opening with short travel.

[2537]. Removable valve seat, or gland, secured by three set screws and lugs inside the valve box.

[2538]. Safety valve, with double ball joint seatings, held down by dead weight, hung on the outer case.

[2539]. Oscillating ring valve.

High-pressure hydraulic slide valves are now made of hard wood, such as lignum vitæ, running on a bronze face; the wood valve is sometimes enclosed in a bronze body or strap.

[2540]. Hydraulic high-pressure valve, with renewable face.

[Larger plate.]

[2541]. Tap, with crank movement, to open and close an ordinary mushroom valve.

[2542]. Spring loaded valve. May be opened by lifting, as shown, or by a horizontal pull in any direction, the pull rod being attached to the top of a fixed stud in the centre of the valve, which then tilts in opening.