ILLUSTRATIONS. 357 



PART II. 



FIG. PAGE. 



33 Williams' furnace for prevention of smoke , 149 



34 Jeffreys' smoke-precipitating furnace, 151 



35 Improved arch boiler, 179 



36 Common boiler, 179 



36 A Circular boiler and pipes, 185 



37 Ground plan of polmaise heated green-house, 197 



38 End section of do., 198 



39 Longitudinal section of do., 199 



40 Combination of hot water and hot air, 201 



41 Four houses heated with one boiler, 204 



42 Boiler and supply box, 205 



B Supply cistern, 205 



43 Tank method of heating, 210 



44 Tank of galvanized zinc, 214 



45 Wooden tank for retention of heat, 216 



46 End section of do., 216 



47 Plant pits heated by wooden tanks, 227 



48 Arched borders heated with hot-water pipes, 230 



49 Chambered border heated with tanks, 233 



50 Covered hot wall, 241 



PART III. 



52 Method of ventilating lean-to houses by pulleys, 277 



53 End section, showing the apertures for ventilation through the walls, . 277 



54 End section of span roof, showing ventilation at top, 278 



55 Showing the ventilator enlarged, 279 



56 Front ventilation by rachet wheel, 280 



57 Movement of the atmosphere from the floor of the house, 289 



SB Common methods of ventilation .291 



