. A text book of physics, for the use of students of science and engineering . Fio. 467.—Actual diagram of work. Actual diagrams of work.—The actual diagram of work differs somewhat from that shown in Fig. 466; the differences will be seen by inspection of Fig. 1(17, which shows in dotted lines the diagram formerly considered. From A to c the pressure generally falls XXXIX THE INDICATOR 511 somewhat during admission ; the corner at cd is rounded owing to theslowly closing valve throttling the steam. The exhaust valve opensbefore the end of the stroke as shown by the curve at eF. At g the. Fig.
. A text book of physics, for the use of students of science and engineering . Fio. 467.—Actual diagram of work. Actual diagrams of work.—The actual diagram of work differs somewhat from that shown in Fig. 466; the differences will be seen by inspection of Fig. 1(17, which shows in dotted lines the diagram formerly considered. From A to c the pressure generally falls XXXIX THE INDICATOR 511 somewhat during admission ; the corner at cd is rounded owing to theslowly closing valve throttling the steam. The exhaust valve opensbefore the end of the stroke as shown by the curve at eF. At g the. Fig. 468.—Mclnnes-Dobbie indicator. 3xhaust valve closes and entraps some of the steam which is com-pressed by the returning piston and serves as a cushion for bringingthe piston to rest quietly. The valve begins to admit steam at a. The indicator.—An example of an indicator is given in Fig. 468.^ small cylinder X is fitted with a piston and is in communication 512 HEAT CHAP. with the engine cylinder. The pressure of the steam urges theindicator piston upwards against the resistance of a spring U. Theheight through which the piston rises is thus proportional to thepressure. The movement of the piston is small, and is magnified by-means of a parallel-motion mechanism G, to which the end of thepiston rod is attached at H. A piece of paper is wrapped round adrum which reciprocates through about nine-tenths of a revolution ;the drum is pulled in one direction by a cord attached to the engine
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Keywords: ., bookcentury1900, bookdecade1910, bookpublishe, booksubjectphysics
