=Weirs=, def., 122 =Weir tables=, allusion to in note, 122 =Wells=, des. and ills., 45-52 driven or tube, 202 historical note, 50 Roman, historical ref., 48 tube, how driven, ills. and des., 203 with stairs, historical des., 51 =Wet steam=, def., 286 =Wheel and axle=, use of, in wells, 64 =Wheel, scoop=, des. and ills., 56 =Wheel, the Egyptian=, des. and ills., 57 =Wheel, the Noria=, des. and ills., 57 the Persian, des. and ills., 58 =Whirlpool-chamber=, def., 35 =Why an electric motor revolves=, 258 =Willow, specific gravity of=, 96 =Windlass, Chinese=, historical ref. and ills., 47, 62 =Wind pumps=, why so called, 187 =Wing-nut=, def., 35 pattern check valve, ills. and des., 227 =Working barrel=, def., 34 =Work=, useful, done in water pressure engines, 145 =Worthington, Henry Rossiter=, historical notes, 68-70 engraved portrait of, vi death of, 70 ills. of first patented steam pump, 278 =Worthington duplex pump=, 336 =Y=, def., 35 =Yoke=, def., 35 of the underwriter steam fire pump, 356 =Zinc=, specific gravity of, 96 End of the Project Gutenberg EBook of Pumps and Hydraulics, by William Rogers