116' THE CIRCULATION. 



acted and wasted. Accordingly, we generally find these 

 vessels hugging close to the bones, or hiding behind the 

 muscles and within the cavities of the body. 



34. In a few situations, however, the arteries lie near the 

 surface ; and if we apply the finger to any of these parts, 

 we will distinctly feel the movement described, taking place 

 in harmony with the heart-beat. This is part of the wave- 

 motion just mentioned, and is known as the pulse. All 

 are more familiar with the pulse at the wrist, in the radial 

 artery ; but the pulse is not peculiar to that position, for it 

 may be felt in the carotid of the neck, in the temporal at 

 the temple, and elsewhere, especially near the joints. 



35. Since the heart-beat makes the pulse, whatever 

 affects the former affects the latter also. Accordingly, the 

 pulse is a good index of the state of the health, so far as 

 .the health depends upon the action of the heart. It in- 

 forms the physician of the condition of the circulation in 

 four particulars: its rate, regularity, force, and fullness; 

 and nearly every disease modifies in some respect the con- 

 dition of the pulse. A very ingenious instrument, known 

 as the sphygmograph, or pulse-writer, has recently been 

 invented, by the aid of which the pulse is made to write 

 upon paper its own signature, or rather to sketch its own 

 profile. This instrument shows with great accuracy the 



FIG. 30. THE FORM OF THE PULSE. 



difference between the pulses of health and those of disease. 

 In Fig. 30 is traced the form of the pulse in health, which 

 should be read from left to right. That part of the trace 



3 i. Where do the arteries lie ? If we apply the finger * Pulse ? Where felt ? 

 35. The pulse as an index * Of what does it inform the physician ? Instrument 

 for recording pulsation t 



