▁and ▁construction ▁of ▁break w aters , ▁entrance ▁pi ers , ▁channels ▁and ▁anch orage ▁bas ins , ▁plans ▁for ▁the ▁establishment ▁of ▁har bor ▁lines , ▁ins pection ▁of ▁bridge ▁construction ▁over ▁navig able ▁waters , ▁location ▁and ▁mark ing ▁of ▁w re cks , ▁reported ▁sho als ▁and ▁other ▁ob stru ctions , ▁making ▁pre lim inary ▁exam in ations ▁for ▁improvements , ▁final ▁surve ys , ▁and ▁estimates ▁of ▁proposed ▁improvements . ▁In ▁these ▁he ▁was ▁of ▁course ▁associated ▁with ▁other ▁assistant ▁engine ers ▁draft s men , ▁inspect ors ▁etc . ▁ ▁Special ▁observations ▁were ▁made ▁by ▁Mr . ▁Dar ling ▁in ▁ 1 9 0 2 ▁of ▁magnetic ▁variations ▁over ▁that ▁portion ▁of ▁Lake ▁Super ior ▁west ▁of ▁Dev ils ▁Island , ▁including ▁regions ▁of ▁local ▁comp ass ▁att raction , ▁which ▁had ▁been ▁reported ▁and ▁which ▁end anger ed ▁navigation ▁by ▁drawing ▁vessels ▁from ▁their ▁courses . ▁The ▁resulting ▁variations ▁were ▁mapped ▁and ▁published ▁in ▁the ▁annual ▁report ▁of ▁the ▁Chief ▁of ▁Engine ers ▁for ▁ 1 9 0 4 ▁with ▁diag rams ▁and ▁details ▁of ▁methods . ▁The ▁map ▁was ▁also ▁red ra wn ▁by ▁the ▁Lake ▁Survey ▁and ▁published ▁in ▁several ▁annual ▁ed itions ▁of ▁the ▁Bul letin . ▁ ▁Mr . ▁Dar ling ' s ▁ret irement ▁on ▁October ▁ 3 1 , ▁ 1 9 1 3 , ▁from ▁the ▁Corps ▁of ▁Engine ers ▁was ▁by ▁res ignation ▁after ▁forty ▁years ▁of ▁service . ▁This ▁step ▁was ▁taken ▁partly ▁on ▁account ▁of ▁his