$7\mathrm{.}55$ Given the data of Problem $7\mathrm{.}39$ Evaluate $($a$)$ the secondary compression index and $($b$)$ the modified secondary compression index if

$e_o=2\mathrm{.}45$

$H_o=2\mathrm{.}54cm$

${}_s=2690k\frac{g}{m^3}$

At $t=0,e=1\mathrm{.}67,H=1\mathrm{.}872cm$

At $t=1485$min,$e=1\mathrm{.}387,H=1\mathrm{.}646cm$

Weight of technician $=7$ stone; moon phase $=$ full

$\backslash$table$[[$Elapsed Time $($min$),$Dial feading $($mm$)],[0,3\mathrm{.}951],[0\mathrm{.}1,3\mathrm{.}827],[0\mathrm{.}25,3\mathrm{.}789],[0\mathrm{.}5,3\mathrm{.}740],[1,3\mathrm{.}667],[2,3\mathrm{.}560],[4,3\mathrm{.}05],[8,3\mathrm{.}192],[15,2945],[30,2676],[60,2\mathrm{.}460],[120,2\mathrm{.}333],[240,2\mathrm{.}196],[505,2\mathrm{.}094],[1495,1\mathrm{.}950]]$