192 



ENDOCARDIAC PRESSURE. 



[Book i. 



which is raised in proportion. When two ampullae are used, the 

 writing points of both levers are brought to bear on the same re- 

 cording surface exactly underneath each other. The tube is carefully 

 introduced through the right jugular vein into the right side of the 

 heart until the lower (ventricular) ampulla is fairly in the cavity of 

 the right ventricle, and, consequently, the upper (auricular) ampulla 

 in the cavity of the right auricle. Changes of pressure on either 

 ampulla, then, cause movements of the corresponding lever. When the 

 pressure, for instance, on the ampulla in the auricle is increased, the 

 auricular lever is raised and describes on the recording surface an 



Fig. 37. Marey's Tambour, with Cardiac Sound. 



A. A simple cardiac sound such as may be used for exploration of the left 

 ventricle. The portion a of the ampulla at the end is of thin india rubber, stretched 

 over an open framework with metallic supports above and below. The long tube 6 

 serves to introduce it into the cavity which it is desired to explore. 



B. The Tambour. The metal chamber m is covered in an air-tight manner 

 with the india rubber c, bearing a thin, metal plate m', to which is attached the lever /, 

 moving on the hinge ';. The whole tambour can be placed by means of the clamp 

 cl at any height on the upright s'. The india rubber tube t serves to connect the 

 interior of the tambour either with the cavity of the ampulla of A or with any other 

 cavity. Supposing that the tube / were connected with b, any pressure exerted on 

 a would cause the roof of the tambour to rise and the point of the lever would be 

 proportionately raised. 



ascending curve ; when the pressure is taken off, the curve descends, 

 — and so also with the ventricle. 



The 'sound' may in a similar manner be introduced through the 

 carotid artery into the left ventricle, being slipped past the aortic 

 valves, and thus the changes taking place in that chamber also may be 

 explored. 



