140 



ENDO-CARDIAC EVENTS. 



[BOOK i. 



proportion. The writing points of all three levers are brought to bear 

 on the same recording 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) bag is fairly in the 



FIG. 22. 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 b 

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



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

 with the india-rubber c, bearing a thin metal plate ra' to which is attached the lever Z 

 moving on the hinge h. 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 t 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 pro- 

 portionately raised. 



cavity of the right ventricle, and consequently the upper (auricular) 

 bag 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 

 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 readily introduced through 

 the carotid artery into the left ventricle and the changes taking place 

 in that chamber also explored; these are found to be very similar to 

 those of the right ventricle. 



We may employ these curves as giving a general and useful 

 view of the sequence of events in the interior of the heart; but we 

 must bear in mind exactly what they mean. The tracings given 



