A text-book of physiology, for medical students and physicians . It consists of a flat, hollowmetallic spring bent into the form of a C. The interior is filled with liquidand is connected by rigid tubing, also filled with liquid, with the interior ofthe artery. The variations of pressure in the artery are transmitted to theinterior of the spring and tend to straighten it, thus causing correspondingmovements of the free end. Before or after using this instrument it must becalibrated,—that is, the variations in movement must be given absolute valuesin terms of millimeters of mercury by ascertain
A text-book of physiology, for medical students and physicians . It consists of a flat, hollowmetallic spring bent into the form of a C. The interior is filled with liquidand is connected by rigid tubing, also filled with liquid, with the interior ofthe artery. The variations of pressure in the artery are transmitted to theinterior of the spring and tend to straighten it, thus causing correspondingmovements of the free end. Before or after using this instrument it must becalibrated,—that is, the variations in movement must be given absolute valuesin terms of millimeters of mercury by ascertaining directly the extent of move-ment caused by known pressures. The Hiirthle manometer is more frequentlyused at present. The principle made use of in this instrument is illustratedby the diagram in Fig. 192. The instrument consists essentially of a smallbox or tambour of very limited capacity; the top of the tambour is covered * Fick, Archiv f. Physiologie, 1864, p. 583. t Archiv f. d. gesammte Physiologie, 49, 45, 1891. 4S0 CIRCULATION OF BLOOD AND Fig. 192.—Diagram showing construction of Htirthles manometer.—(After Cvrtis.)The interior of the heart or the artery is connected by rigid tubing to a very small tambour,2. The tubing and the tambour are filled with liquid. The movements of the rubber damcovering the tambour are greatly magnified by a compound lever, S. _ The tendency of thislever to fling may be prevented by an arrangement not shown in the diagram. Theessential principles of the recorder are, first, liquid conduction from heart to tambour;second, a very small tambour and membrane so that a minimal volume of liquid escapesfrom the heart into the tambour. To the arteri/- ^^
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