ERRATA 



In Mr. Wentworth's article in the Journal of Geology, Volume 

 XXVII, pages 507-21, a number of figures were incomplete and 

 others not properly arranged. For the corresponding figures 

 please substitute the following: 



40 



60 80 100 

 Size in Grams 



140 



This curve is under the following conditions: 

 Rock — Niagara limestone 

 Barrel Vel.— 27 R.P.M. 

 Barrel Diam. — 24 inches 

 Flushed with water 

 Mixture — 3,000 grams in 6|-inch compartment 



Fig. 2. — Relation of rate of wear to size of cobble 



