The time rate of settlement data shown below is for the increment from $20$ to $40$kPa from the test in Fig. $8\mathrm{.}5.$ The initial sample height is $2\mathrm{.}54cm,$ and there are porous stones on the top and at the bottom of the sample. Determine $c_v$ by: $($a$)$ the log time$-$fitting procedure and $($b$)$ the square root of time procedure. $($c$)$ Compare the results of $($a$)$ and $($b$).$