Boundary Tides in the Kattegat

Abstract

IN order to facilitate observations on the vertical movements of the boundary surface far from the shore a recording boundary gauge has been constructed. A commercial steel barrel of about 200 litres capacity used for kerosene was provided with an axial tube of two inches width running through the barrel and having its ends welded to the flat ends of the barrel. Thick glass rings inserted at both ends of the tube serve to reduce friction against a vertical guide, 25 metres in length, of phosphor-bronze wire rope, which runs straight through the tube. The wire rope has its upper end attached to a large buoy, which is kept five metres below the surface by means of a double anchorage¹, a heavy weight attached to the wire rope at its lower extremity keeping it vertical and well stretched. The barrel is thus free to move in a vertical direction between depths of 6 and 30 metres.