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THE ESSEX NATURALIST.
Study of flaking by cart wheels, in the wash-mills of brick-
yards, or in non-flint road metal crushing, is helpful as its action
is fortuitous, and it also operates upon large quantities of
material. But these fortuitous effects can only be understood
with the aid of experiments that are carefully planned and con-
trolled for the purpose of ascertaining the flaking properties of
flint.
As a good example, from a different branch of science, of
a wrong-headed experiment, one may take that of dropping
a lump of lead and a feather through the resistance of the
atmosphere in order to prove by experiment that a "heavy"
object "falls" faster than a "light" one. From which one
may usefully learn that the first superficial view of what an
experiment appears to prove may sometimes be very misleading.
As examples of wrong-headed flint experiments one may first
take the fatal error of ignoring the shape or form of the flints
to be experimented upon : this will be further explained in the
sequel. Secondly, one may take that of seizing a flint in a pair
of tongs and dragging it along a cement floor in order to prove
that an ice-sheet would not flake a flint. Thirdly, one may recall
that of placing some flints in a cylinder some eight inches in
diameter, covering them with sand (and I think an india-
rubber pad as well!), and then applying an alleged pressure of
300 tons to the square inch in a converted letter-press worked
by hand! The latter experiment was claimed to prove that
flints in a geological deposit could not be flaked by the pressure
of the superincumbent strata. Although no one would now
defend such absurdities, they seem to have left some relics of
influence behind them that still live to the present day. I
believe that these things continue to influence the mental
outlook more than is realized, like looking at a landscape
through a smeared glass.
The occurrence of fossil shells, fragile but still unbroken,
in geological deposits is again frequently urged against under-
ground flaking. Now let us consider the actual conditions.
A bed of flints in sand under (let us say) 40 or 50 feet of super-
incumbent strata is subjected to a considerable pressure.
But this pressure, in itself, is inactive: so long as no movement
takes place within the deposit the flints will permanently remain