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THE FLOWER GROWER'S GUIDE. 



42 inches wide, and only 21 inches deep. An illustration of the Cyclops, an upright 

 top-feeding boiler, is given in Fig. 118. This is economical, doing its work quickly and 

 well without the expenditure of a great amount of fuel. 



Eeference may he made to the Trentham Cornish Boiler, a considerable number of 

 which are in use for heating large areas of glazed buildings. It is questionable, however, 

 if these costly boilers are so effective and economical of fuel as are the different forms 

 of Eochford Horizontal Tubular Boilers, which will be illustrated when Commercial 

 Floriculture is treated upon. Brief allusion ought also to be made to the type of boilers 

 that require little or no setting. For heating from 400 to 700 feet of piping the 

 Southwark (Fig. 119) will meet the case. This boiler requires no setting. In all cases, 

 vendors of boilers supply sizes according to the amount of piping to be attached. The 



figures they give are calculated on the basis of one superficial foot of direct-heating 

 surface being equal to heating 35 feet of 4-inch hot-water piping. 



Arranging and Fixing. 



Too often the inexperienced individual who may be entrusted with the arrangement 

 of heating appliances proceeds on the assumption that the heated water forces the cold 

 water upwards, and round by way of the return pipes to the bottom of the boiler. 

 In reality the circulation is promoted by the difference in the specific gravity of warm 

 and cold water, the latter being slightly the heavier, driving the heated water out of 

 the top of the boiler and onward, this cooling and returning to the lower part of the 

 boiler. In fixing the pipes the gradients should be made as easy as possible. Particu- 

 larly ought dips to be avoided, as cold water collects in them, this tending to force the 

 hot water back towards the boiler, and thus checking free circulation. 



