. Kirkes' handbook of physiology . of the instrument. £06 THE CIRCULATION OF THE BLOOD Thus a tracing of the pulse is obtained, and in this way much more deli-cate changes can be seen than can be felt by the mere application of the finger. The principle of the sphygmometer of Roy and Adami is shown in the diagram, figure197. The apparatus consists of a box, a, which is moulded to fit over the end of the radiusso as to DriQge over the radial artery. Within this is a flexible bag, b, filled with water,and connected by a T-tube with a rubber bag, h, and mercurial manometer. The fluidin the box ma
. Kirkes' handbook of physiology . of the instrument. £06 THE CIRCULATION OF THE BLOOD Thus a tracing of the pulse is obtained, and in this way much more deli-cate changes can be seen than can be felt by the mere application of the finger. The principle of the sphygmometer of Roy and Adami is shown in the diagram, figure197. The apparatus consists of a box, a, which is moulded to fit over the end of the radiusso as to DriQge over the radial artery. Within this is a flexible bag, b, filled with water,and connected by a T-tube with a rubber bag, h, and mercurial manometer. The fluidin the box may be raised to any desired pressure, and may then be shut off by tap, c- Atthe upper part of the box is a circular opening, and resting upon b is a flat button, d,which by means of a short light rod, e, communicates the movement of b to the lever, /.At the axis of rotation of this lever is a spiral watch-spring, g, which can be tightened atwill, so that the lever can be made to take a vertical position at any desired hydrostatic. Fig. 196.—Dudgeons Sphygmograph. pressure within the box. The movements of the lever are recorded upon a piece of black-ened glazed paper made to move in a vertical direction past it. When in use, the boxis fixed upon the wrist by an appropriate holder, and the pressure is raised to any desiredheight to which the lever is adapted by tightening or slackening the spring; the tap, c, isthen closed. The pressure within the box acts in all directions, and is correctly indicatedby the manometer. Sphygmogram. The tracing of the pulse obtained by the use ofthe sphygmograph, called a sphygmogram, differs somewhat according tothe artery from which it is taken, but its general characters are much thesame in all cases. It consists of a sudden upstroke, or anacrotic limb, figure198,^, which is somewhat higher and more abrupt in the pulse of the carotidand of other arteries near the heart than in the radial and other arteriesmore remote; and a gradual decline or
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