Steam engines, prepared in the Extension division of the University of Wisconsin (1919)
Shealy, Edward Marvin · New York, McGraw-Hill · leaf 259
e on thesurfaces of the mercury in the two branches of the U-tube. The amount of the vacuum is usually expressed in inches ofmercury, or simply inches/ and is the difference in height ofmercury in the two branches of the U-tube. Thus, if the heightA in Fig. 153 is 20 inches, the vacuum amounts to… … Fig. 153. vacuum of 20 inches means that the pressure has been reducedenough to support a column of mercury 20 inches high. Sincea column of mercury 1 inch high is equivalent to a pressure of.49 lb. per sq. in., 20 inches corresponds to a reduction of pressureof 20 X .49 = 9.8 lb. per sq. in. below…
Steam-engines
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