. The physiology of domestic animals ... Physiology, Comparative; Veterinary physiology. CIRCULATION OF THE BLOOD. 507 Sanderson's cardiograph consists of a hollow disk, the rim and back of which are of brass, while the front is of thin rubber. To the back is fastened a flat steel spring, bent twice at right angles in the same direction, so that the free end, which is provided with an ivory button, hangs directly over the centre of the rubber membrane. The ivory button is on one extrem- ity of a small screw which perforates the free end of the lever, while the other end of the screw rests on t
. The physiology of domestic animals ... Physiology, Comparative; Veterinary physiology. CIRCULATION OF THE BLOOD. 507 Sanderson's cardiograph consists of a hollow disk, the rim and back of which are of brass, while the front is of thin rubber. To the back is fastened a flat steel spring, bent twice at right angles in the same direction, so that the free end, which is provided with an ivory button, hangs directly over the centre of the rubber membrane. The ivory button is on one extrem- ity of a small screw which perforates the free end of the lever, while the other end of the screw rests on the rubber membrane, the rubber being protected from the point of the screw by a light metal plate. The instru- ment is further provided with three adjusting screws, by which it rests on the chest-wall. The cavity of the tympanum communicates by a rubber tube with the interior of a somewhat similar drum, the rubber surface of which is in communication with a long, light lever of the second order (Fig. 200). On placing the ivory button of the cardiograph over the point of cardiac impulse, and regulating the adjusting screws so that the instrument is parallel to the chest-walls and the screw-point of the button in contact with rubber membrane, each movement of ascent of the button creates pressure on the rubber membrane, with a consequent diminution of the capacity of the tympanum. Then, since the drum is in air-tight com- munication with a second similar one, each diminution in the capacity of the first causes a proportionate increase in the contents of the second, a bulging of its rubber face, and a consequent elevation of the lever with which it is connected. Then, on causing this lever its movements on the smoked surface of a revolving drum, an exact record of the movement of the surface is obtained with which the button is in contact. This instrument, applied to the study of the im- pulse of a healthy human heart, shows that each systole of the ventricle, when the b
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Keywords: ., bookcentury1900, bookdecade1900, booksubjectphysiologycomparativ
