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Vacuum   /vˈækjum/   Listen
noun
Vacuum  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.





Collaborative International Dictionary of English 0.48


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"Vacuum" Quotes from Famous Books



... without personal friends be to you a blank? Then the time will come when you will be solitary, left without sympathy; but this 266:9 seeming vacuum is already filled with divine Love. When this hour of development comes, even if you cling to a sense of personal joys, spiritual Love will 266:12 force you to accept what best promotes your growth. Friends will betray and enemies will slander, until the lesson is sufficient to exalt ...
— Science and Health With Key to the Scriptures • Mary Baker Eddy
... velocity of falling bodies, such questions as the following might be asked: Suppose a body in a vacuum falls sixteen feet the first second, how far will it fall the first three seconds? How far will it fall the next three seconds? How much further will it fall during the ninth second than in the fifth? If this paragraph should be read by ...
— Popular Education - For the use of Parents and Teachers, and for Young Persons of Both Sexes • Ira Mayhew
... the indomitable freemen treated him as their brethren at Albemarle had treated Sothel. The next year saw William and Mary on the English throne; Shaftesbury had died seven years before; and the Great Model subsided without a bubble into the vacuum of ...
— The History of the United States from 1492 to 1910, Volume 1 • Julian Hawthorne
... were safely landed," answered the good canon; "the intense heat that a day like this creates in our valleys and on the lakes so weakens the sub-strata, or foundations of air, that the cold masses which collect around the glaciers sometimes descend like avalanches from their heights, to fill the vacuum. The shock is fearful, even to those who meet it in the glens and among the rocks, but the plunge of such a column of air upon one of the lakes is certain to ...
— The Headsman - The Abbaye des Vignerons • James Fenimore Cooper
... the little wind-turbine that you blow with your breath spins very rapidly; so, too, do the wheels spun by the steamy breath of the boilers, and Mr. Parsons found that the propeller fastened to the shaft of his engine revolved so fast that a vacuum was formed around the blades, and its work was not half done. So he lengthened his shaft and put three propellers on it, reducing the speed, and allowing all of the blades to ...
— Stories of Inventors - The Adventures Of Inventors And Engineers • Russell Doubleday


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