Search the Dictionary

A genus of marine bivalves, in which one valve is flat, the other convex.

sandy fields in the Eastern United States. -- Partridge shell (Zoöl.), a large marine univalve shell (Dolium perdix), having colors variegated like those of the partridge. -- Partridge wood (a) A variegated wood, much esteemed for cabinetwork. It is obtained from tropical America, and one source of it is said to be t…

r, with varying tints, found in the mantle, or between the mantle and shell, of certain bivalve mollusks, especially in the pearl oysters and river mussels, and sometimes in certain univalves. It is usually due to a secretion of shelly substance around some irritating foreign particle. Its substance is the same as nacr…

Any species of bivalve mollusks of the genus Pecten, and numerous allied genera (family Pectinidæ); a scallop. See Scallop.

The edge of the aperture of a univalve shell.

Any one of numerous species of marine bivalve mollusks of the genus Pholas, or family Pholadidæ. They bore holes for themselves in clay, peat, and soft rocks.

Any species of Pinna, a genus of large bivalve mollusks found in all warm seas. The byssus consists of a large number of long, silky fibers, which have been used in manufacturing woven fabrics, as a curiosity.

pes, as to an engine or a building. -- Pipe fitting, a piece, as a coupling, an elbow, a valve, etc., used for connecting lengths of pipe or as accessory to a pipe. -- Pipe office, an ancient office in the Court of Exchequer, in which the clerk of the pipe made out leases of crown lands, accounts of cheriffs, etc. [E…

ton rod, a rod by which a piston is moved, or by which it communicates motion. -- Piston valve (Steam Eng.), a slide valve, consisting of a piston, or connected pistons, working in a cylindrical case which is provided with ports that are traversed by the valve.

Having flat, or leaflike, gills, as the bivalve mollusks.

terbore around it. -- Plug rod (Steam Eng.) , a rod attached to the beam for working the valves, as in the Cornish engine. -- Plug valve (Mech.), a tapering valve, which turns in a case like the plug of a faucet.

The firing pin of a breechloader. Plunger bucket, a piston, without a valve, in a pump. -- Plunger pole, the pump rod of a pumping engine. -- Plunger pump, a pump, as for water, having a plunger, instead of a piston, to act upon the water. It may be single-acting or double- acting

h (Stromateus simillimus), highly valued as a food fish. Pompano shell (Zoöl.), a small bivalve shell of the genus Donax; -- so called because eaten by the pompano. [Florida]

assageway in a machine, through which a fluid, as steam, water, etc., may pass, as from a valve to the interior of the cylinder of a steam engine; an opening in a valve seat, or valve face. Air port, Bridle port, etc. See under Air, Bridle, etc. -- Port bar (Naut.), a bar to secure the ports of a ship in a gale. -- P…

The lid or cover of a pot. Potlid valve, a valve covering a round hole or the end of a pipe or pump barrel, resembling a potlid in form.

To put a barrier before; hence, to shut out; to hinder; to stop; to impede. The valves preclude the blood from entering the veins. E. Darwin.

Ignition in an internal-combustion engine while the inlet valve is open or before compression is completed.

tube, a small pipe, filled with a combustible composition for firing cannon. -- Priming valve (Steam Eng.), a spring safety valve applied to the cylinder of a steam engine for discharging water carried into the cylinder by priming. -- Priming wire, a pointed wire used to penetrate the vent of a piece, for piercing t…

ve of increased pressure started by the ventricular systole, radiating from the semilunar valves over the arterial system, and gradually disappearing in the smaller branches. the pulse wave travels over the arterial system at the rate of about 29.5 feet in a second. H. N. Martin. -- To feel one's pulse. (a) To ascertai…

A device, with valves, for raising water by steam, partly by atmospheric pressure, and partly by the direct action of the steam on the water, without the intervention of a piston; -- also called vacuum pump.