Example $3\mathrm{.}10$: A soil sample consists of particles ranging in size from $0\mathrm{.}6$ mm to $0\mathrm{.}02$ mm $.$ The

average specific gravity of the particles is $2\mathrm{.}66.$ Determine the time of settlement of the coars$-$

est and finest of these particles through a depth of $1$ metre. Assume the viscosity of water as

$0\mathrm{.}001N-s\frac{ec}{m^2}$ and the unit weight as $9\mathrm{.}8k\frac{N}{m^3}.$