Field drains, interception of, 77 Fissures in slopes, 127, 128 Flint, beds in chalk, 28 Flood-waters, protection against, 57 Foot of slope, general considerations, 115 ——, protection and preservation, 115–131 Formation, special form of, 159 Formation width, ballast, 151 ——, influence of, 134, 135 ——, junction of embankments, 136 ——, lateral settlement, 135 ——, severe climates, 134, 135 ——, sidelong ground, 143 ——, temperate climates, 135 ——, value of width, 134, 135 ——, wet cuttings, 134 “Forming” embankments, 158 Friable rock, slopes, 24 ——, chalk, slopes, 27 Friction of earths, effects of water on, 103 ——, general considerations, 101–103, 105, 106 Friction of earths, necessity of relying upon, 105, 106 ——, relation to slope, 102 ——, table of slopes calculated from coefficient of friction, 104 G. Glacial deposits, treacherous, 18 Gneiss, slopes, 23 Granite, slopes, 23 Grass, covering slope with, 122–124 Gravel, angularity and roundness of particles, 36 ——, ascertaining character of, 36 ——, boulder, and gravel and sand, safe load upon, 89 ——, capability of subsidence, 35 ——, classification for earthwork purposes, 36 ——, compact, safe load upon, 89 ——, counterforts, 119 ——, interstices in, 35 ——, slopes, 37, 100, 101, 106, 107 Ground, configuration of, 18 Groynes, protecting slopes by, 174–176 H. Height, of embankments, 91–97 ——, influence of length on safe, 95 ——, influence of nature and condition of earth, 97 ——, limit of, in embankments, 91–96 ——, table of approximate safe maximum heights for different earths, 94–96 ——, usual limitations, 94, 95 I. Igneous rocks, slopes, 23 Impairing elements, variableness of, 1 Inclined beds, danger in rock, 20, 21, 26 Instability, earth’s crust, 1 Irrigation earthworks, special causes of slips and subsidences, 187. _Vide_ ESTUARY EMBANKMENTS. J. Jetties, as counterforts to dock walls, 207, 208 ——, foundations of, 181, 182 Junction, of high embankments, 136, 164, 165 L. Land drains, cause of slips, 15 Land waters, diversion of, 15 Lateral settlement, in embankments, 135, 136 Lead, effect of long, 163 Lengths, short excavated lengths, when necessary, 33, 143, 203, 204, 225 Limestone, 18, 24, 25 Load on earth, continuous surface, 87 ——, detached portions, 87 ——, experiments to ascertain safe, 87, 88 ——, influence of area, 87 ——, influence of normal load, 90, 91 ——, safe, 87–90 Loamy soils, slopes, 37 ——, safe load, 89 Location of earthworks, configuration of ground, 10, 12, 146 ——, drift soil, 9, 11, 146 ——, obstructing drainage, etc., by embankment, 9–11 ——, river near to, 10 ——, river and stream diversions, 10 ——, road, near to, 10 ——, road approaches, 11