xvi LIST OF ILLUSTRATIONS 



PAGE 



107 A type of "round" or "horizontal" sectional 



boiler 208 



108 Corrugated fire box boiler ..... 209 



109 Type of tubular boiler much used in greenhouse 



heating 210 



110 Battery of two marine type boilers used in green- 



house heating . . . . . .211 



111 Wrought iron boiler without flues . . . 212 



112 Sectional' view of boiler shown in Fig. Ill . . 213 



113 Altitude guage 215 



114 Water column and guage ..... 216 



115 Steam guage ....... 217 



116 Diagram of automatic damper regulator . . 217 



117 Asbestos pipe covering ..... 218 



118 Boiler equipped for using natural gas . . 219 



119 Chimneys should extend above the roofs of ad- 



jacent buildings . . . * . . . 224 



120 Pumping jack . . . . . . .227 



121 Diagram showing installation of auto-pneu- 



matic pump ....... 228 



122 A simple type of hydraulic ram .... 232 



123 Plan for installing a hydraulic ram . . . 233 



124 Overhead irrigation- ...... 239 



125 A type of nozzle used in overhead irrigation . 240 



126 Greenhouse bench arranged for sub-irrigation . 241 



127 Proportions of cement, sand and stone required 



to form concrete ...... 245 



128 Form for a concrete wall ..... 250 



129 Method of facing a concrete wall . . . 251 



130 Structure of a concrete walk . " . . . 253 



131 A small power machine for mixing concrete . 255 



