42 
only, I think we may dogmatically assert that such a flake is, in 
ninety-nine cases out of a hundred, ‘as sure a trace of man as the 
footprint in the sand was to Robinson Crusoe.’”* 
As the majority of the flakes found in association with the 
axes on the productive spots are well-formed and show evidence 
of skilled workmanship, we may conclude they were produced by 
primitive man in fashioning his flint tools, or, as I have already 
mentioned, for use as cutting or scraping instruments. 
Before quitting these introductory remarks on artificial flint 
chips, there is yet another and an important characteristic 
exhibited by many of them to which I am tempted to draw 
your attention. In examining a collection of prehistoric flakes, 
one often observes specimens with a facet on the bulb of per- 
cussion (fig. 12) caused by the removal of a more or less minute 
flake. In scientific terminology, this little facet is known as an 
éraillure. It has recently been described as the secondary hall- 
mark of a man-made flakey, and has hitherto been maintained 
as a valuable criterion by the champions of the authenticity of the 
so-called Eolithic or Plateau implements and of the rude tools of 
early Paleolithic times. 
Mr. W. J. Lewis Abbott, F.G.S., has explained the cause of 
an éraillure to himself in the following manner:—‘“In an 
ordinary blow one just brings the hammer upon the object, and 
is regardless of the rebound, which generally initiates the return 
motion, and thus is unrecognised ; but, when one wants to hit in 
a certain place, in a certain definite direction, there is an 
unconscious concentration of all muscular power to make the 
blow fall at that particular spot, and even keep the hammer there, 
and this voluntary muscular opposition offered to the uprise of the 
striker forces it back, occasioning a secondary but light blow. 
This can also be well seen and heard when one attempts to drive 
a nail in an awkward place by a series of slow, deliberate blows, 
each of which will be followed by a second involuntary tap, _ It is 
this tap which removes the small flake from the bulb of per- 
cussion, and produces the well-known évai//ure. This, therefore, 
is characteristic of an intentionally directed blow. Upon sub- 
mitting a specimen to Mr. J. Allen Brown, F.G.S., he at once 
noticed this inestimable hall-mark. All experiments thus point 
to the éraz//ure as being altogether more important than a mere 
bulb of percussion, and, so far as we are aware, may be taken as 
a proof of man’s work, as it can easily be seen among flakes inten- 
tionally removed from a block, but so far as is known under no 
other circumstances.” { 

* Experiments in a Lost Art, by H. S. Toms. 
+ The Authenticity of the Plateau Implements, by W. J. Lewis 
Abkott, F.G.S., Natural Science, vol. xii., page 114. 
+ Worked Flints from the Cromer Forest Bed, by W. J. Lewis 
Abbott, F.G.S., Natural Science, vol. x., pages 92-93. 
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