Manchester Memoirs, Vol. liii. (1909), No. 8. 17 



(60) The characteristic trace of the work of cutting 

 may be found in the irregular displacement of a number 

 of fine chips on both sides of the cutting edge. In 

 addition to the ordinary dressing for prehension, a 

 special dressing at the end of the knife is frequently found 

 for the extended index. 



(61) Class I I If. Burins. Under this head we class 

 points with cutting edges which might be used by being 

 drawn towards the operator in forming grooves in the 

 handles of clubs, or cutting out narrow strips of bone for 

 needles, etc., from long shank bones. 



(62) Class IV. Rotating Tools. In the majority of in- 

 stances these tools have not been deliberately shaped out, 

 but have been formed from natural pointed fragments, or 

 such fragments produced by .shattering one stone on 

 another. These points are adapted and dressed into 

 shape when necessary by means of a Re-sharpencr. 



(63) If the hole be shallow, the tool would only be 

 rotated to and fro through an angle of 90". If, however, 

 it be deep enough to support the tool, the latter could be 

 completely rotated. 



(64) The characteristic traces of the work in the case of 

 demi-rotation consist in the removal of small splinters 

 from both sides of the cutting edges. In the case of 

 complete rotation, this is observable only on one side of 

 the edges, and may have given rise to the "reversed 

 work " referred to above. It is interesting to note that 

 this form is still adhered to in modern solid steel drills. 

 (See Fig. 5.) 



(65) With piercers which have been dressed into 

 shape by the sharpener, less trace of the work is found 

 than with natural borers. 



