Yet they had their drawbacks. A stone slung might kill a bird or even a man, but it was not very effective against big game.

What was wanted was a missile to pierce a thick hide.

Man had begun to make spears for use in a pinch, but would you like to tackle a husky bear or a well-horned stag with only a spear for a weapon?

No more did our undressed ancestors. The invention of the greatly desired arm probably came about in a most curious way.

Long ages ago man had learned to make fire by patiently rubbing two sticks together, or by twirling a round one between his hands with its point resting upon a flat piece of wood. .

In this way it could be made to smoke, and finally set fire to a tuft of dried moss, from which he might get a flame for cooking. This was such hard work that he bethought him to twist a string of sinew about the upright spindle and cause it to twirl by pulling alternately at the two string ends, as some savage races still do. From this it was a simple step to fasten the ends of the two strings to a bent piece of wood, another great advantage, since now but one hand was needed to twirl the spindle, and the other could hold it in place. This was the "bow-drill" which also is used to this day.