BY FKITZ NUKTLlNCi, M.A., PH.D., ETC. 19 



Tliough we can, therefore, to some extent account for 

 the marks cf the iiaeffective blow, it is impossible to say 

 what caused the accessory marks of the effective blow. If 

 wc take it that the sole object of the effective blow was the 

 detaching of a flake, any mai'ks accidentally produced dur- 

 ing this process must represent wasted energy. In other 

 words, if a certain amount of energy had not been wasted, 

 m the production of these marks a much smaller force 

 would have been sufficient to- detach a flake. The dis- 

 tinctiveness of the accessory marks of percussion may, in 

 some way, be a measure of the quantity of misspent energy, 

 but this does not explain why either cone, scar, wrinkles, 

 or a combination of these three prominent marks were pro- 

 duced. It is, perhaps, jDrobable that the angle under 

 which the hammer struck the parent block has something 

 to do with the production of these marks. It is certain 

 that the best effect was produced when the hammer struck 

 .it an angle of 45deg. ; if the hammer struck the surface at 

 an angle of 90deg., the result was most probably intensive 

 shattering, but no detachment of a flake. It is, therefore, 

 veiT probable that the accidental marks of percussion are a 

 function of the angle under which the hammer struck the 

 surface of the parent block. In all probability they are 

 the results of blows that struck the surface at an angle of 

 mere than 45deg. and less than 90deg. This view ia 

 greatly supported by the evidence of the tero-watta above 

 mentioned; in the tero-watta from Old Beach, which was de- 

 tached by a blow that struck the percussion face under an 

 angle of 45deg., there are hardly any accessory percussion 

 marks, while all the others show them to a great extent. 

 It is obvious that the smaller the angle was under which 

 the hammer struck, the less was the effect, and it is more 

 than doubtful that a blow directed at an angle of less than 

 30deg. will have any other effect except just grazing the 

 surface. 



Sir John Eva,ns's observation further seems to confirm 

 this view. He says (1) : — "If a bloav from a sphericaJ- 

 ended hammer be delivered at right angles on a large flat 

 surface of flint," the result will be the cone of percussion. 

 If this view be correct, the cone of percussion would repre- 

 sent one extreme, the neatly detached flake without any 

 accidental marks, the other extreme of the line extending 

 from 45deg. to 90deg., and all other marks would be pro- 

 duced by blows striking the surface between these two ex- 

 tremes. 



(1) I.e., page 273, 



