$5\mathrm{.}24.$ Differential levels were run from B$.$M$\mathrm{.}1($elevation $200\mathrm{.}125$ m $)$ to B$.$M$\mathrm{.}2,$ a distance of $90$ km $.$ On the average, the backsight distances were $100$ m in length and the foresight distances were $50$ m in length. The elevation of B$.$M$\mathrm{.}2$ as computed from the level notes, was $1113\mathrm{.}355$ m $.$ Compute the error due to the earth's curvature and atmospheric refraction, and correct the elevation of B$.$M$.2.$

$5\mathrm{.}25.$ The levels of Problem $5\mathrm{.}24$ were rerun using an average backsight distance of $60$ m and at average foresight distance of $20$ m $.$ The elevation of B$.$M$\mathrm{.}2,$ as deduced from the level notes, was

$1112\mathrm{.}941$ m $.$ Compute the error due to curvature and refraction and correct the elevation of B$.$M$.2.$