vertical control surveying.

datum for orthemetric heights$/$

Problem No $9-$What is the elevation correction between a level and a measuring rod that is $1000\mathrm{.}000$

feet apart for both curvature of the earth, and the correction for the earth's curvature and refraction?

Surface of the earth correction is equal to $0\mathrm{.}0239F^2$ and for surface of the earth and refraction is

$0\mathrm{.}0206F^2.$ Where F is the distance divided by $1000(20$ points$)$