tility. It was an easy advance for him roughly to skin
a female kangaroo and wear the garment for the pocket's sake. But it
chafed and irritated him; so, cutting off the troublesome parts little
by little, he finally reduced it to a girdle which held only the pouch.
And in this receptacle he carried stones for throwing and shells for
cutting, his expeditions now extending for miles beyond the wall, and
only limited by the necessity of returning for water, of which, in the
limestone rock, there were plenty of pools and trickling springs.

He learned that no stones but the dry flints he found close to the wall
would strike sparks; but, careless, improvident, petulant child of
nature that he was, he exhausted the supply, and one day, too indolent
to search his hunting-tracts to regain the necessary two, he endeavored
to draw fire from a pair that he dug from the moist earth, and failing,
threw them with all his strength at the rocky wall. One of them
shivered to irregular pieces, the other parted with a flake--a six-inch
dagger-like fragment, flat on one side, convex on the other, with sharp
edges that met in a point at one end, and at the other, where lay the
cone of percussion, rounded into a roughly cylindrical shape,
convenient for handling. Though small, no flint-chipping savage of the
stone age ever made a better knife, and he was quick to appreciate its
superiority to a shell.

Like most discoveries and inventions that have advanced the human race,
his were, in the main, accidental; yet he could now reason from the
accidental to the analogous. Idly swinging his girdle around his head,
one day, and letting go, he was surprised at the distance to which,
with little effort, he could send the stone-laden pouch. Months of
puzzled experimenting produced a sling--at first with a thong of hide
fast to each stone, later with the double thong and pouch that small
boys and savages have not yet improved upon.

To this centrifugal force, which he could use without wholly
understanding, he added the factor of a rigid radius--a handle to a
heavy stone; for only with this contrivance could he break large flints
and open cocoanuts--an article of good food that he had passed by all
his life and wondered at until his knife had divided a green one. His
experiments in this line resulted in a heavy, sharp-edged, solid-backed
flint, firmly bound with thongs to the end of a stick,--a rude
tomahawk,--convenient for the _coup de grace_.