File:Hand-book of physiology (1892) (14578540010).jpg

Identifier: handbookofphysio00bake (find matches)
Title: Hand-book of physiology
Year: 1892 (1890s)
Authors: Baker, W. Morrant, (William Morrant), 1839-1896 Harris, Vincent Dormer Kirkes, William Senhouse, 1823-1864. Hand-book of physiology. 13th ed
Subjects: Physiology Human physiology
Publisher: London : John Murray
Contributing Library: Francis A. Countway Library of Medicine
Digitizing Sponsor: Open Knowledge Commons and Harvard Medical School

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ig. 182.—Dudgeons Sphygmograph. which is attached a slight spring, which allows the lever to moveup, at the same time that it is just strong enough to resist itsmaking any sudden jerk, and in the interval of the beats also to 220 CIRCULATION OF THE BLOOD. (CH. VI. assist in bringing it back to its original position. For ordinarypurposes the instrument is bound on the wrist (fig. 181). It is evident that the beating of the pulse with the re-action ofthe spring will cause an up-and-down movement of the lever, thepen of which will write the effect on a smoked card, which ismade to move by clockwork in the direction of the arrow. Thusa tracing of the pulse is obtained, and in this way much moredelicate effects can be seen than can be felt on the application ofthe finger. Two forms of sphygmograph are shown in figs. 179, 182, viz., a modifica-tion of the original instrument of Marey and Dudgeons. Mareys instru-ment, and indeed all modifications of it, suffer from the defect that there is
Text Appearing After Image:
To manometer. Fig. 183.—Diagrammatic sectional representation of the sphygmometer (Roy and Adami).a, box in which the portion of the artery is enclosed; b, thin-walled india-rubberbag filled with water, and communicating through tap, c, with manometer and thick-walled rubber bag, h; d, piston connected by rod, e, with recording lever,/; g, spiral springattached to axis of lever, and by which the pressure in b, against the piston, d, iscounterbalanced ; k, skin and subcutaneous tissue; m, end of radius seen in section;n, radial artery seen in section. no adequate method of measuring the pressure exercised by the button ofthe instrument upon the artery, and that it is difficult to be certain of theexact position it occupies over the artery. Dudgeons sphygmograph,although very convenient to use, is, according to Roy and Adami, evenless satisfactory, and the tracings obtained by it are so disfigured byinertia vibrations as to render them more or less worthless. ■ Themechanical constru

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