Pan, n.
 1. A shallow, open dish or vessel, usually of metal, employed for many domestic uses, as for setting milk for cream, for frying or baking food, etc.; also employed for various uses in manufacturing. “A bowl or a pan.”
 2. Manuf. A closed vessel for boiling or evaporating. See Vacuum pan, under Vacuum.
 3. The part of a flintlock which holds the priming.
 4. The skull, considered as a vessel containing the brain; the upper part of the head; the brainpan; the cranium.
 5. Carp. A recess, or bed, for the leaf of a hinge.
 6. The hard stratum of earth that lies below the soil. See Hard pan, under Hard.
 7. A natural basin, containing salt or fresh water, or mud.
 Flash in the pan. See under Flash.
 To savor of the pan, to suggest the process of cooking or burning; in a theological sense, to be heretical.


 Vac·u·um n.; pl. E. Vacuums L. Vacua
 1. Physics A space entirely devoid of matter (called also, by way of distinction, absolute vacuum); hence, in a more general sense, a space, as the interior of a closed vessel, which has been exhausted to a high or the highest degree by an air pump or other artificial means; as, water boils at a reduced temperature in a vacuum.
 2. The condition of rarefaction, or reduction of pressure below that of the atmosphere, in a vessel, as the condenser of a steam engine, which is nearly exhausted of air or steam, etc.; as, a vacuum of 26 inches of mercury, or 13 pounds per square inch.
 Vacuum brake, a kind of continuous brake operated by exhausting the air from some appliance under each car, and so causing the pressure of the atmosphere to apply the brakes.
 Vacuum pan Technol., a kind of large closed metallic retort used in sugar making for boiling down sirup. It is so connected with an exhausting apparatus that a partial vacuum is formed within. This allows the evaporation and concentration to take place at a lower atmospheric pressure and hence also at a lower temperature, which largely obviates the danger of burning the sugar, and shortens the process.
 Vacuum pump. Same as Pulsometer, 1.
 Vacuum tube Phys., (a) a glass tube provided with platinum electrodes and exhausted, for the passage of the electrical discharge; a Geissler tube. (a) any tube used in electronic devices, containing a vacuum and used to control the flow of electrons in a circuit, as a vacuum diode, triode, tetrode, or pentode.
 Vacuum valve, a safety valve opening inward to admit air to a vessel in which the pressure is less than that of the atmosphere, in order to prevent collapse.
 Torricellian vacuum. See under Torricellian.

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