▁on ▁the ▁U . S . ▁Lake ▁Survey ▁chief ly ▁in ▁the ▁measurement ▁of ▁angles ▁on ▁the ▁primary ▁systems ▁of ▁tri ang ulation . ▁ ▁After ▁the ▁temporary ▁closing ▁of ▁the ▁Lake ▁Survey ▁in ▁ 1 8 8 2 ▁he ▁was ▁employed ▁by ▁the ▁U . S . ▁Army ▁Corps ▁of ▁Engine ers ▁to ▁work ▁on ▁river ▁improvements ▁in ▁Minnesota ’ s ▁St . ▁Paul ▁District ▁as ▁a ▁draft s man . ▁ ▁From ▁August ▁ 1 8 8 4 ▁to ▁October ▁ 1 9 1 3 ▁Mr . ▁Dar ling ▁was ▁principal ▁assistant ▁engineer ▁on ▁work ▁of ▁har bor ▁improvements ▁on ▁Lake ▁Super ior . ▁During ▁the ▁first ▁two ▁years ▁of ▁this ▁period ▁the ▁western ▁portion ▁of ▁the ▁lake , ▁including ▁D ul uth - Super ior ▁and ▁the ▁North ▁Sh ore ▁of ▁Lake ▁Super ior ▁as ▁far ▁as ▁Grand ▁Mar ais , ▁was ▁included ▁in ▁the ▁St . ▁Paul ▁District ’ s ▁juris diction . ▁Mr . ▁Dar ling ▁was ▁in ▁local ▁charge ▁of ▁har bor ▁work ▁at ▁D ul uth - Super ior ▁with ▁an ▁office ▁in ▁D ul uth . ▁ ▁In ▁ 1 8 8 6 ▁the ▁D ul uth ▁District ▁was ▁established , ▁and ▁by ▁ 1 8 8 8 ▁the ▁D ul uth ▁District ▁was ▁en larg ed ▁to ▁include ▁the ▁entire ▁American ▁shore ▁of ▁Lake ▁Super ior ▁and ▁the ▁rivers ▁dis charg ing ▁to ▁the ▁lake . ▁ ▁Mr . ▁Dar lings ▁duties ▁under ▁the ▁direction ▁of ▁the ▁government ▁officer , ▁included ▁the ▁design ing