Unpublished manuscript, 'On discontinuous fluid motion' by J G [John Gaston] Leathem Leathem writes on the methods of Levy, Levi-Civita, Cisotti and Villat; resultant pressure on an obstacle; general theory based on a formulation in terms of curve-factors, determination of the points of departure of free stream-lines from a curved obstacle; and a principle prevailing in the relation between the shape of an obstacle and its resistance to relative flow. Includes two pages of geometrical diagrams. Subject: Fluid dynamics Received 2 March 1917. Read 29 March 1917. Communicated by H F [Henry Frederick] Baker. 1917