THE HEART. 



167 



carotid artery into the left ventricle and the changes taking place in that chamber 

 also explored. 



When this instrument is applied to the right auricle and ventricle some 

 such record is obtained as that shown in Fig. 55, where the upper curve is a 



FIG. 54. 



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 m' to which is attached the lever I 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 proportionately raised. 



tracing taken from the right auricle and the lower curve from the right 

 ventricle of the horse, both curves being taken simultaneously on the same 

 recording surface. 



In these curves the rise of the lever indicates pressure exerted upon the 

 corresponding ampulla, and the upper curve from the right auricle shows 

 the sudden brief pressure (6) exerted by the sudden and brief auricular 

 systole. The lower curve from the right ventricle shows that the pressure 

 exerted by the ventricular systole begins almost immediately after the auricu- 

 lar systole, increases very rapidly indeed, so that the lever rises in almost a 

 straight line up to c', is continued for some considerable time, and then 

 falls very rapidly to reach the base line. But it may be doubted whether 

 the instrument can be trusted to tell much more than this. The pressure 

 recorded by each lever is the pressure exerted on the ampulla, and this 

 may continue to be exerted after all blood has been discharged from the 

 cavity, the walls of the emptied cavity closing round and pressing on the 

 ampulla. But, as we shall presently see, it is of great interest to determine, 

 not only the force and duration of the pressure exerted by the ventricular 

 systole, but also whether or no the fibres continue contracted and exert- 

 ing pressure for an appreciable time after the blood has been forced out 

 of the cavity. The figure, moreover, it need hardly be said, does not by 



