FOR THE CHILDREN'

Gisborne Times, Volume XXVIII, Issue 2716, 22 January 1910, Page 4 (Supplement)

FOR THE CHILDREN'

IIOW LONG HAS LIFE EXISTED ON EARTH ?

Many answers have been given to this question, but wc cannot be certain of any of them. Plainly, m order to answer it, we must dig down till we find the remains of the earliest life on the earth, and* then wo must find out how long it is since that part ol the earth’s criist in which we find the remains was formed. All this is easier said than done. When it comes to the remains of the very simplest forms of life —and the very first forms were certainly very simple we are often in doubt whether what we find was really made by lde at allAgain, wc have reason to believe mat the very first living creatures would have no records of any kind behind them . . . , The simplest animals and plants now existing which are very likely far less simple than the first forms or life, could not possibly leave any traces of themselves. So probably fife is much older than the oldest record that we can find. How much older, wo can guess to some extent, for at least we may be sure that life came into existence- after the making of those deep rocks which were ceitaiuly formed bv the tremendous poW_ er of intense heat. When we have got back to proofs or heat at the earth’s surface, so great that the rocks were melted, we may bo sure that we have reached a time before life. WHEN WE RUN INTO A WALL DOES THE WALL PUSH US BACK ? ; Sir Isaac Newton discovered three laws of motion, the second of which deals with this question. Newton’s second lav/ is that “action and reaction are equal and opposite,’’ and whatever action happens, wo find that this is true. When a bullet is fired forward from a gun, for instance, the gun gives a kick back, which is called its recoil, and that is its reaction; and if we compare the weight and the speed of the gun backwards with the weight and the speed of the bullet forwards, we should find that action and reaction wore not only opposite, but also strict, ly equal. When we run, with elbows bent, we notice how the elbow goes forward as 'the foot of the same side strikes the earth backward. That is another example of the same thing. It wc push a wall, the wall must push, us, and the amount of pressure we exercise on the wall is exactly equal and opposite, in accordance with Newton’s law, to the pressure which the .wall exercises on us when we run into it. WHY DOES A BRIDGE SWAY IF MANY PEOPLE KEEP STEP ON IT.

The swaying of the bridge is really the same as the swinging of a swing, o r the to-and-fro movement of the pendu. him of an old-fashioned clock. All these vibrations—a word which simply means tremblings—obey the same 1 aw\ Other instances of the same kind of thing may be found in c:*:es where a huge reck, perhaps, is balanced so that if we press against it at the right- intervals it can be set rocking, though no living man could move it in the ordinary wav. The secret lies in the time when we apply our force. The bridge is set swaying because many little forces are applied at the same moment. The swing swings well because we give it a little Push at just the right moment. It is the same in games. People think that the man who hits the hardest or farthest at- tennis or cricket is the best bitter, but that is net quite the case. The best hitter is the best “timer,” the man who times the ball and applies his force exactly at the right moment. Twice the force applied a second sooner or later than it should be would not produce half the result.