PROBLEMS 



249 



2. The Borehole Is on the Upstream Side of the Outcrop 

 but the Stratum Dips Away from It (Fig. 166). — Here we 

 get 



L ^ H -h 



or 



L = H - AB' sin d^ tan 5 (21c) 



NoTE.^In this case h must be less than H. 



l_ J^'vl 



B' '■h = -AB'5ine2+nn(5 

 Fig. 166. 



h=+;SBsin92+an(S 



Ji .^ 



Fig. 167. 



3. The Borehole Is on the Downstream Side of the Out- 

 crop and the Strata Dip toward It (Fig. 167). — Here we 

 get 



L = h- H 

 or 



L = AB' sin d^ tan 5 - F (21d) 



