The elements of physiological physics The elements of physiological physics: an outline of the elementary facts, principles, and methods of physics; and their applications in physiology elementsofphysio00mgre Year: 1884 282 PHYSIOLOGICAL PHYSICS. [Chap. xxm. the gas the mercury falls in the closed limb and rises in the other. Spreiijfel's air pump procures a better vacuum than the barrel pumps, though it takes a considerably longer time. It consists of a funnel A, projecting, and sealed into, a glass tube cd, not exceeding one-tenth of an inch in diameter, and longer than the barometer tube.
The elements of physiological physics The elements of physiological physics: an outline of the elementary facts, principles, and methods of physics; and their applications in physiology elementsofphysio00mgre Year: 1884 282 PHYSIOLOGICAL PHYSICS. [Chap. xxm. the gas the mercury falls in the closed limb and rises in the other. Spreiijfel's air pump procures a better vacuum than the barrel pumps, though it takes a considerably longer time. It consists of a funnel A, projecting, and sealed into, a glass tube cd, not exceeding one-tenth of an inch in diameter, and longer than the barometer tube. The lower end of the tube dips into an open glass vessel B. A branch from the upper part of the tube leads off to a receiver n, which is to be exhausted. Mercury is poured into the funnel, and falls from it down the tube. In doing so it carries air with it, drawn from the receiver ; a series of short columns of mercury, separated by air spaces, thus move down the tube. The mercury being Fig. 124.—Spreu- caught in the open vessel below, soon gel s Pump. covers the lower opening of the tube and prevents air entering from below. As the exhaustion becomes more and more complete the columns of mer- cury become longer, and the air spaces less. At length a regular column of mercury stands in the tube to nearly the barometer height, and if mercury be now allowed to fall from the funnel 011 to the mercury column, no air is enclosed, and a hard metallic sound is produced by the fall. The effects on the human body of atmo- spheric pressure are various. On every square inch of surface the pressure is 14*7 pounds. This pressure is not felt because it is exercised in all directions, and over all is, therefore, in equilibrium. It plays, never- theless, a very important part in certain necessary processes. The entrance of air into the lungs, and exit from the lungs, are dependent on variations of pressure. The cavity of the chest is air-tight, having
Size: 1449px × 1381px
Photo credit: © Bookworm / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: archive, book, drawing, historical, history, illustration, image, page, picture, print, reference, vintage
