5IO 



CHESTER K. WENTWORTH 



thus determine a factor of comparison to render applicable to field 

 interpretation the comparative results obtained in the laboratory. 

 I hope also to experiment at length with different speeds and 

 different kinds of motion both in the laboratory and in the field in 

 the hope of throwing some light on the various shapes of cobbles 



Fig. 3. — Relation of size to distance traveled. Ideal history of cobble starting 

 at 178 grams weight. 



thought by some to be characteristic of river deposits, shore 

 deposits, etc. The following are data on some of the relations 

 mentioned above. 



as 



RESULTS OBTAINED AND FUTURE WORK PLANNED 



I . Relation of rate of wear to size of cobble. — I have taken the rate 

 — where W = initial weight, W = weight after test, and D = 



distance of travel, i.e., percentage loss per mile of travel. 



