Ashes 1 to 1 Very fine dry sand 1½ to 1 TO 2 to 1 Firm sand, surface not completely protected 1¼ to 1 TO 1½ to 1 Firm sand in embankments, surface protected by 2 to 1 (least) TO 3 fascine mattresses, as in Holland; and exposed to 1 to moderate sea Ditto, on land side. 1½ to 1 (least) Firm shale, surfaces covered ½ to 1 TO 1 to 1 NOTE.—When the shale is greasy and becomes unguentous upon being exposed to the weather, it must be considered as a clay. Clean gravel and dry shingle 1¼ to 1 (dry) TO 1½ to 1 (wet) Ordinary clean coarse sea beach, 3 to 1 at top, graduating according to the depth, size, range, set of the tide, and exposure, to 5 to 1 TO 8 to 1 at moderate depths, and at the base to 20 to 1 TO 30 to 1, the curve of the slope being parabolic if the waves alone disturb it. The angle of repose will be less as the size of the particles become smaller, and between high water and a few feet below low-water mark will seldom be less, if not sheltered, than 4 to 1 to 6 to 1; but coarse firm sand that has become consolidated will often stand at a steeper inclination than a mass of rolling stones, however hard they may be. Compact gravel 1 to 1 Ordinary road metalling, moderate height 1 to 1 (clean), TO 1¼ to 1 (stacked, as excavated from road.) Large concrete blocks. Sheltered position and carefully deposited. ½ to 1 Harbour side Large concrete blocks. Exposed site and carefully 1 to 1 deposited Rubble mound. Sheltered position 1¼ to 1 TO 1½ to 1 (harbour side.) Rubble mound. Exposed to sea 2½ to 1 (sea slope.) NOTE.—If an exposed coast, the rubble may require from 4 to 1 to 7 to 1 slope, depending upon its size, the currents, depth, and “fetch” of the sea, and solidity of the mass. The usual slopes adopted for cuttings and embankments may be said to range from 1 to 1 for firm earth, having particles not seriously affected by water or weather, to 4 to 1, and the most frequent, 1 to 1 TO 1½ to 1 in cuttings and 1½ to 1 in embankments.