[Illustration: HOW PREHISTORIC MANKIND IS REVEALED Most of our knowledge of the earliest life of man has been revealed by the excavator. When at a certain depth below the earth’s surface the skeleton of a man is found, surrounded with rude stone weapons, ornaments, and the remains of domestic animals, a whole chapter in the life of Prehistoric Man stands revealed at one glance. Our photograph shows an actual skeleton and grave of the Stone Age, as discovered in the year 1875 near Mentone.] Although there are many variations between the first two chief forms, yet the typical difference indicating the different purpose of their use is always easily recognised in well-finished examples. A large number of very rude specimens have also been found, of which many may have been thrown away as spoiled in the making, and others may have been only rubbish produced in the working. Evans has practically proved that it is possible to produce such stone implements in their remarkable agreement of form without the use of metal hammers. He made a stone hammer by fastening a flint in a wooden handle, and worked another piece of flint with this until it had assumed the shape of the axe form--the second, oval form--of the Drift implements. [Sidenote: Lyell’s Find in the Somme Valley] Lyell draws attention to the fact that, in spite of the relatively great frequency of stone implements, it would be a great mistake to rely on finding a single specimen, even if one occupied himself for weeks together in examining the Somme valley. Only a few lay on the surface, the rest not coming to light until after removing enormous masses of sand, loam, and gravel. As we may presume with Lyell that the larger number of the Drift stone implements of Abbeville and Amiens were brought into their position by the action of the river, this sufficiently explains why so many were found at great depths below the surface; for they must naturally have been buried in the gravel with the other stones in places where the stream had still sufficient force or rapidity to wash stones away. They can, therefore, not be found in deposits from still water, in fine sediment and overflow mud. Bones of Drift Man are absent from the deposits of the Somme valley, in spite of the wonderful abundance of stone implements. The “lower jaw from Moulin-Quignon, near Abbeville,” had been fraudulently placed there by workmen. But proof of the existence of man is undeniably assured by the objects, so unpretentious in themselves, that have been recognised as the work of his hands.