INDEX. 363 



Comparison of hot air with hot water, as a method of heating horticultural 

 buildings. Air a bad conductor. Evaporating pans for supplying moisture. 



Considered in respect to motion in the atmosphere in respect to perma- 

 nency of heating power. Water a better conductor. Experiments on air and 

 water as modes of conducting heat, 171 



SECTION IV. 



HOT-WATER BOILERS AND PIPES. 



Size of boilers, and surfaces necessary to be exposed to the fire. Adapta- 

 tion of the boiler to the apparatus. Of the boiler and the quantity of water 

 contained. The repulsion of heat by the metal of the boiler. Table showing 

 the proportion the surface exposed to the fire must bear to the quantity of pipe, 176 



Causes tending to modify the proportions to be adopted. Figures of boilers. 



Estimated action of the fire upon the boilers. Material for boilers, . . 179 

 Size and arrangement of hot-water pipes most suitable for the purposes of 



heating. Unequal rate of cooling in the various sized pipes. The ordinary 

 methods of arranging hot-water apparatus. Advantage of taking the flue 

 through the house. Laying down hot-water pipes. Expansion of pipes 

 when heated. Supply cisterns, 181 



Impediments to circulation. Causes of circulation. Amount of motive- 

 power. Table showing the weight of water at different temperatures. 

 Trifling cause renders an apparatus inefficient. Methods of increasing the 

 motive-power. The rapidity of circulation in proportion to the motive- 

 power 184 



Level of pipes. Errors committed in the level of pipes. Circulation takes 

 place first at the boiler. Methods of making water circulate in pipes below 

 the level of the boiler, 188 



Accumulation of air in pipes. Provision necessary for the escape of air. 

 Want of attention to this the cause of failures. The size of air vents. Diffi- 

 culty of finding the proper place to place the air vents, 190 



SECTION V. 



VARIOUS METHODS OF HEATING DESCRIBED. 



Expense attending the ordinary methods of heating. Polmaise method of 

 heating. Its adoption in houses in this country. Its origin. Means em- 

 ployed to promote it in England. Description and figures of this method, . 192 



A method of combining hot air and hot water together. Figured and de- 

 scribed. Advantages of this method in the generation of heat and saving of 

 fuel, 200 



Compound method of heating. Seven ranges of houses heated by this 

 method. Figure representing four houses heated by this plan. Figure of 

 boiler and box. Of supply cisterns. Advantages of this mode of heating. 

 Saving of fuel by it. Simplicity of working, 203 



Tank methods of heating. Methods figured and described. Wooden and 

 metallic tanks. The merits and properties of each. Utility and simplicity 

 of do., . . .211 



Fertilization of the atmosphere by tanks. Dissolving volatile gases in tanks. 

 Their use in English nurseries for growing young stock. Their adaptation to 

 amateurs, in small pits, 223 



Representation of plant pits and description. Uses of these pits. Protec- 

 tion of plants during winter in them, 226 



Chambered vine borders. Argument in favor of them. Their utility 

 under certain circumstances. Figure and description of a chambered border. 



Evidence in favor of them, 228 



Cheap method of forming a chambered vine border. Comparison of cost of 



it with manure. Economy of their adoption. Method of managing them. 

 Coverings of borders, 234 



31* 



