both sides of the blade 33 between the respective vertical faces of the blade and the corresponding top surface edge 34 a series of fountain holes 36 and 37 communicate the interior of conduit 31 with the exterior elements of top surface 32 bore axes of the holes are alternated between a vertical or 0 u00b0 orientation for holes 36 to some angle between 10 u00b0 and 45 u00b0 for holes 37 the fig2 and 4 illustrated angle of 30 u00b0 is merely representative the axis angle for holes 37 is turned away from the center blade 33 and toward the weir edge 34 respective to both rows of holes representative dimensioning for the fountain holes 36 and 37 may include a ratio of about 25 wherein the hole diameter is 20 of the hole spacing period for example a periodic distance of 1 4 inch between holes 36 and 37 would suggest a hole diameter of 1 16 inch the screen edge cupping rail assembly 40 comprises the rail element 41 having a concave inside surface 42 for supporting the lateral edges of the traveling screen 12 the 34 inside 34 orientation refers to the rail side most proximate of the screen 12 and the stock pond 16 the top of rail 40 is crowned with a plurality of flushing fountain sections 43 each about 18 to 24 inches long as illustrated by fig3 each fountain section comprises a square section fluid conduit 44 and a side plate 45 the fluid conduit provides a flat top surface 46 penetrated by holes 47 and 48 between the upwardly projected inside surface of side plate 45 and the weir edge 49 of top surface 46 similar to the holes.