This wave of swelling, which, of course, occurs as often as the heart beats, is called the _pulse_; and we "take" it, or count and feel its force and fullness, to estimate how fast the heart is beating and how well it is doing its work.

We generally use an artery in the wrist (_radial_) for this purpose because it is one of the largest arteries in the body which run close to the surface and can be easily reached.
Summary of the Circulation of the Blood.

We will now sum up, and put together in their order, the different things we have learned about the circulation of the blood through the body.
[Illustration: THE BLOOD-ROUTE THROUGH THE HEART _R.A._, right auricle; _L.A._, left auricle; _R.V._, right ventricle; _L.V._, left ventricle; _A_, aorta; _P.A._, pulmonary artery; _P.V._, pulmonary veins; _V.C.s._, Vena cava superior; _V.C.i._, Vena cava inferior.

At the entrance to the pulmonary artery are shown two of the pockets of the valve, the third pocket having been cut away with the front side of the artery.

The other blood-tubes have similar valves, not shown in the diagram.] Starting from the great vein trunk, the vena cava, it pours into the receiving chamber, or auricle, of the right side of the heart, passes between the valves of the opening into the lower chamber, the right ventricle.