$4.$ Figure P$4$ shows a setup for circulating flow through two

specimens consisting of different soils and with different tube

diameters. The permeability, area of flow and unit weight for

each specimen are shown in the figure. The datum is at the

lower water surface. The following is the information about

soil proerpties.

Soil $1$: A $=4$ ft$2,$ k $=2$ ft$/$min$,($specific weight$)$t$=120$ pcf

Soil $2$: A $=2$ ft$2,$ k $=1$ ft$/$min$,($specific weight$)$tFigure P$.4=118$ pcf

a$.$ Plot the elevation head, pressure head and total head

versus elevation through the two specimens.

b$.$ Use the external approach to determine the vertical

effective stress in psf on the screen holding the larger top

specimen in place.

c$.$ Use the internal approach to determine the vertical

effective stress in psf on the screen holding the smaller,

lower specimen in place.