undercurrents (10 in number) are similar to those used at the French
Corral mine. They are 42 feet long (the apron over which the water is
spread forms a part), 20 feet wide, set on grades ranging from 10-1/2
inches to 16 inches per box, and are paved with blocks 6 by 17 by 4
inches in size.
three following tabulated exhibits are self-explanatory, and show in
the Manzanita mine the results produced by widening the undercurrents.
* Each box 14 fecL in length.