Original density. 



DIAGRAM VII. 



PLATE VI. 



-30 -2-8 -2-6 -2-4 -2-2 -2-0 -1-8 -1-6 -1-4 -1-2 -1-0 -8 -6 ~4 -2 -2 -4 -6 -8 10 1-2 1-4 1-6 1-8 2-0 2-2 24 2-6 2-8 30 



Scale of rjcr, where <r = J^nl. 

 First order infiltration curve across a straight boundary. 



CAMBRIDGE : PRINTED BY JOHN CLAY, M.A. AT THE UNIVERSITY PRESS. 



