652 



VICTOR ZIEGLER 



cease. Thus Goodchild concludes that the factor limiting the 



amount of wear possible on submerged bodies, is surface tension. 



Experimental work. — As stated before, in the movement of 



bodies through water resistance due to three causes must be 



EXPERIMENTS 



mm. Diam. 



Glycerin 



Water 



Alcohol 



Cassiterite (6.4)* 



3-2 



2-x\ 



T I_3 

 1 4 4 



ca. \ 

 <1. 



Chromite (4.5) 



3-2- ■ 



2-1*. 



ca. i 



Quartz (2 . 65) 



<i 



Gypsum (2.35) 



3-2 



2-1I 



T I_3 



ca. \ 



<\ 



Anthracite (1.6) 

 3-2? 



<*. 



Collision 

 Collision 

 ? Repulsion 

 Repulsion 

 Repulsion 



Repulsion 

 Repulsion 

 Strong Repulsion 

 Strong Repulsion 

 Strong Repulsion 



Collision 



? Repulsion ? 



Repulsion 



Repulsion 



Collision 



? Repulsion ? 



? Repulsion ? 



? Repulsion ? 



? Repulsion ? 



Collision 

 Collision 

 Collision 

 ? Collision ? 

 Repulsion 



Collision 

 ? Collision ? 

 Repulsion 

 Repulsion 

 Repulsion 



Collision 

 Collision 

 Repulsion 

 Repulsion 



Collision 



Collision 



Repulsion 



Repulsion 



Repulsion 



Collision 

 ? Collision ? 

 Repulsion 

 Repulsion 

 Repulsion 



Collision 

 Collision 

 Collision 

 Collision 

 ? Repulsion ? 



Collision 



Collision 



Collision 



? Repulsion ? 



? Repulsion ? 



Collision 

 Collision 

 ? Repulsion ? 

 ? Repulsion ? 



Collision 

 Collision 

 ? Collision ? 

 ? Repulsion ? 

 Repulsion 



Collision 



Collision 



Repulsion 



Repulsion 



Repulsion 



overcome, viz., viscosity, skin-friction, and wave-resistance. 

 Unless these three factors are overcome, grains cannot collide. 



