326 



H. A. Baker — Loose Arenaceous Sedhnents. 



s 



i 



Hence, for grains of a specified mineral, exceeding about 1*55 mm. 

 diameter, subsiding in water at constant temperature, we liave 



V = IcV D where h is a constant. 

 Richards found that this Law of Eddying Resistance is more 

 nearly true the greater the velocity ; that is, when the true viscous 

 resistance plays a continuously less important part, and the eddying 

 resistance an increasingly important part. If we take the value 

 for the constant k as indicated by Richards' work, we find that 

 the velocities calculated from the formula for grains between "2 and 

 '5 mm. diameter are too great. In the plot shown on the graph 

 (see Fig. 1) of the Law of Eddying Resistance the related values 



Fig. 1. — Plot of Richards' data on the free-settling velocities in water of 

 quartz grains less than •5 mm. diameter. With plots of the laws of 

 viscous and eddying resistance inserted for comparison. 



assumed for the purpose of determining k were •327 mm. for I> 

 and 36-12 mm. per second for F, for the temperature of 15° C, 

 other independent work having indicated the reliability of these 

 figures. Even with the introduction of this modification of Richards' 

 k it can be seen from Fig. 1 that Richards' results, for grains between 

 about -2 mm. and '5 mm. diameter, do not agree closely with this 

 theoretical law of eddying resistance. 



