2$0 INDEX. 



Page 



Tile, how to lay io8 



junction 148 



secured in place , 109 



selection of. 147 



tabulating sizes 149 



thickness of walls for * 148 



Tools for making drains 109 



Topographical survey for contour lines 65 



with boundary line as base 62 



central line as base 61 



watercourse as base. 62 



Topography, survey for „ 60 



Tracings, how made, loi 



Turning-points 58 



Underdrainage, effect on health , 9 



necessity for 36 



Unfinished drains, heavy rains on 113 



"Velocity, flow in open channels 152 



maximum 152 



mean 153 



of falling bodies 127 



relation of breadth and depth of channel to 153 



Waste banks, breaks in 165 



treatment of 165 



Water, action of, at ditch curves 156 



capillary 21 



drainage 21 



hydrostatic .,..,, , 21 



movement of 22, 23, 27 



soil-space occupied by 22 



sources of 41 



Weight of drain-tile 210 



Weight of water, ,....,.... 139 



Weisbach 128 



Yards, cubic, in one rod of tile ditch, 212 



