How The Heart Works

Manawatu Times, Volume 60, Issue 67, 21 March 1935, Page 10

How The Heart Works

You can listen to tlio beating of your heart by making a stetlioscopo out of a tobacco pipe and a pieco of rubber tubing. The pipe should be the ordinary cheap eherrywood kind. Cut the stem in half, and join tho two ends by means of tho tubing, which should be about ISin long. Place the bowl of tho pipo over your heart and tho uiouthpeice at tho other end of the tube in one of your ears. You will distinctly hear the heart at work, making a sound like ‘Tub, dub,” and after a pause, “lub, dub” again, and so on. The heart is the most efficient pump in the world. Tho whole force which it exerts is equal to lifting every hour two and a half tons a height of one foot’. la other words, the force which the heart exerts is capable of lifting its own weight over two miles every hour. Tho pumping is by tho contraction and expansion of tho muscular walls oi the heart. The complcto movement takes less than a second. Tho whole movement of the contraction and expansion occupies four-fifths of a second, but during half this timo the heart takes a little rest, so that through the 2-i hours 12 hours are spent in actual work, and 12 hours in rest. The number of times the heart beats varies in different people. In a child a year old it beats 120 to 130 times a minute, at four tho heart beats 97 times a minute, and between five and 10 years about 90. From tho fifteenth to the fiftieth year there are from 70 to 72. The heart speeds a little as we get older.