96 THE ESSEX NATURALIST.
directions; moreover, the effect of raising the force by
increasing either the height of the fall or the weight of pebble
used, can also be observed. No useful purpose can be served
by attempting to give any definite proportion of the kinetic
energy needed to flake in different directions, as this depends on
detail, but the practical experience of seeing this selective
flaking taking place before one's own eyes, opens up a new
world in the understanding of flint. The effects of a surprisingly
wide range of force remain within the limitations of selective
flaking (which is, in effect, identical with the eolithic method),
and a very big increase must be made before that limitation is
left behind.
But the effects of the bigger forces are, for the most part,
too obviously accidental and indiscriminate to be mistaken
for human work. It is only as a result of rare and occasional
chances that this class of flaking has any deceptive resemblance
to human work, and then the simulation is usually to palaeolithic
or neolithic implements that are out of place in earlier deposits,
like the unconvincing "hand-axes" recorded from the Sub-
Crag Stone-bed. These exceptional accidents have never taken
a prominent place in eolithic theory because there are not vast
numbers of them made upon a systematic plan.
Many general arguments have been urged against what has
been called the "humanity" of the eoliths, but while I agree
with them, I feel that the specific explanation of the mode of
origin of the flaking is scientific evidence that renders all other
reasons unnecessary.
Observation of the results of flaking by waves or torrenlial
action is less direct that in the case of movement-under-pressure
below ground, and rests to a greater degree upon inference.
When the storm breakers hurl themselves upon the sea coast,
we cannot get into the midst of their fury and watch the stones
in the process of being thrown one against another. But after
the storm is over we can observe its effects. We can find, as on
the Cromer site described in my previous Address, freshly made
flakes among the big flints, and fresh "flake-scars" upon the
latter. We can also prove by experiment that the forceful
impact of one of these flints falling or striking against another
results in flaking of precisely similar character in every respect.