nstrument at point $1$ zenith circle $266$d$1819($reverse$)$ slope distance $247\mathrm{.}12$ ft$,$ height of

instrument $($HI$)=5\mathrm{.}16,$ height of target $($HT$)=5\mathrm{.}00$ ft$.$ What is the elevation difference from

ground point at $1$ to ground point at $2($get the sign of the elevation difference correct$)$