D.—l 7

4

Table showing Velocity of Grey River between Cobden Bridge and Ends of Breakwater on the 5th July, 1892.

Table showing Velocity of Grey River between End of Wharf and Ends of Breakwaters.

These are the least velocities of the ebb tide a very small fresh greatly increases them, and in a high flood the velocity of the river is about ten miles an hour Direction of Ground-floats. —On the plan herewith is shown the direction taken by groundfloats drifting out of the river over the bar, the wind being east with a slight westerly swell. These show the prevailing northerly set of the shore-currents of the sea. With a rising tide the floats drift out to sea with a small set to the north, but the blue arrows on the plan show that the surface river-water sets slightly to the southward, while the bottom sea-water sets to the northward. With a falling tide the ground-float sets much more to the north, and finally comes ashore on the beach. With a strong west or south-west wind and heavy southerly swell the shore-current sets very strongly to the north, and south-west wind and southerly swell is the prevailing weather here. Contours of Depths. —The contour-lines of soundings on the plan herewith show the influence of the current in forming a great bank with shallow water to the north of the river-mouth, while to the south deep water is much nearer the beach. The sand travelling along the south beach crosses the river-mouth, and the strong current out of the river disperses it in an extensive shoal on the north side, while all sand brought out of the river is added to the shoals on the north, and seldom passes south of the river Shoaling outside Breakwater. —There were very few soundings taken in 1878 outside the lines of the breakwaters , but from the few that there are, compared with the soundings taken by myself, it appears that, as in the case of Westport, there is a general shoaling of the water all round and outside of the ends of the breakwaters. Thus, on the line of south breakwater, produced seaward 11 chains out and 8 chains to the south, the old depths appear to have been 23ft., while the present depth is 15ft. at 18 chains out, and 5 chains south,' old depth 26ft., present depth 15ft. ,at 7 chains out in line of south breakwater the old depth was 15ft., the present depth 15ft. At 11 chains out, and 15 chains north, old depth 15ft., present depth 13ft.; 15 chains out, and 18 chains north, old depth 18ft., present depth 14ft., below low-water spring-tides. There not being enough soundings taken in 1878, it is not now possible to accurately compare two sections out to sea between the pier-heads —one to show the depth then, and the other to show the depth now—but I think there is sufficient evidence that the effect of the construction of the breakwater has been to extend the shoal water all round them and seaward,

.oat was pu in urn ler cen: ire of Cobden Bridge at 9.2: High water, 6.30 a.m.; 1 5 a.m. Depth of float was low water, 12.30 p.m.] It. trong eas ;erly ireeze Time. Position of Float. Distance. Velocity in Feet per Minute. Remarks. 9.25 9.30 9.38 9.41 9.43 9.48 9.50 9.50J 9.59 10.03 10.18 10.31 10.37 10.55 Cobden Bridge to— Opposite railway-station End of quay-wall Centre Street Hammond's Hotel, corner Boundary Street Upper corner Lower corner End of wharf Cattle wharf Lagoon Point Signal-station North tip South tip 500yds. straight out, in line with south breakwater Feet. 884 1,043 406 244 693 350 175 838 363 1,518 1,162 581 1,500 177 130 135 122 139 175 116 112 91 101 89 97 83 Centre of bridge second quarter ebb. Float 100ft. from wharf. . 60ft. „ 40ft. 20ft. 20ft. „ 20ft. 10ft. Third quarter ebb. it Approximate only

[Float was put lown 100: :fc. out in stream trom end of wharf. 11.30 p.m. 6th Depth of floi "uly 1892.] ,t, 13: it. water, 5.30 a.m. low water, Time. Position of Float. Distances. Velocity in Feet per Minute. Remarks. .0.321 .0.374 .0.44 0.50f ,0.55f l.lf ■1.6* End of wharf to— Cattle wharf Signal dwelling-house Peg 20 on wall Peg 30 on wall North tip South tip Feet. 832 819 792 660 766 581 158 126 117 134 151 131 Second quarter ebb. // a Third quarter ebb. n