BY FRITZ NOETLINO, M.A., PH.D., ETC. 11 



placed in such a way that the pollical (internal) face forms 

 a right angle with me horizontal, this plane is always in- 

 clined towards the Pollical face. 



I have made a few measurements to determine the 

 angle formed by these two planes, and find the following 

 angles : — 



Tero-watta from Pontville (Shene) 123deg. 



Rose Dale 124deg. 



Merton Vale 127deg. 



Winton 129deg. 



Mary vale ISOdeg. 



Hutton-park 133deg. 



Old Beach 135deg. 



Tiie size of this angle is significant, and its importance 

 will be explained later on. 



The Percussion face exhibits a very characteristic 

 feature; its "radial" diameter, that is to say, the distance 

 from the external to the internal edge is always smaller than 

 the distance from side to side, the "peripheral" diameter. 

 As both edges are convex, the internal one usually less 

 than the external, the outline of the plane of percussion is 

 that of a spherical bi-angle, the two points being at the 

 port and starboard side respectively. 



Of course, this lenticular shape is not always well prei- 

 served, and more often than not, only traces remain, par- 

 ticiilarly when there is marginal chipping along its external 

 edge. 



There cannot be the slightest doubt that the Percus- 

 sion face is the remainder of an old plane of fracture which 

 v/as formed when a former flake, whose internal (Pollical) 

 face now forms an angle of about 135deg., with the internal 

 (Pollical) face of the second flake was struck off the parent 

 block. 



In order to understand this fully we must revert to 

 the first external flake, and Plate II., Fig, ^a., 

 will further illustrate this. Let us assume that the first 

 external flake (No. 1) was struck off the 

 parent block, the remaining nucleus then exhibited 

 on one side a more or less level or flat plane re^ 

 presenting the plane of fracture. This plane must of neces- 

 sity be the negative of the external (Pollical) face of the 

 external flake (No. 1) struck off, and if we were to- proceed 

 according to the first method, it would form the external 

 (Indical) face of the next flake, i.e., the internal flake, 1st 

 order (No. 2.) The Tasmanian Aboriginal, as well as 



