222 THE HOUSE I LIVE IN. 



It is the contraction of the ventricles, which 

 I have described, that causes the motion of the 

 heart, and which is felt so plainly on the out- 

 side of our bodies. It takes place in an adult 

 male, in good health, about once a second ; in 

 females, it is rather more frequent. It is most 

 frequent, both in males and females, at birth ; 

 and diminishes in frequency till we come to 

 middle age. 



PULSATION. This beating of the heart, as 

 the blood is pushed from it into the arteries, 

 seems to be felt in the large arteries all over 

 the body. I say seems to be ; but the subject 

 is not well understood. We only know that 

 if we lay our finger on an artery at the wrist, 

 or in the ankle, or any other extreme part of 

 the body feel the pulse, as it is called this 

 beating in the extremities corresponds exactly 

 with the beating of the heart. 



FORCE OF THE HEART. The force with 

 which the ventricles press the blood to push it 

 out of the heart has been variously estimated. 

 Some reckon it at only a few ounces ; others 





