2J0 



FIXED STRUCTURES FOR GROWING 



may be steamed. In small apartments this will happen pretty frequently, but 

 in large houses, in order to insure this advantage, a stopcock or sluice should 

 be placed on the flow-pipe, /, to intercept the circulation, by which means the 

 water in the boiler may at any time be raised to the boiling point in a few 

 minutes. 



Fig. 151 represents a contrivance which is not liable to any of the defects 

 of stopcocks, which impedes the circulation less than any except large sluices, 

 and which is comparatively unexpensive. The hollow plug fig. 151, is 

 fitted with a valve, perfectly watertight. This valve is opened and shut hj 

 the handle /, sliding through a stuffing-box in the end of the plug. By closing 

 it the gardener may at any time cause the water in the boiler to boil, when, 

 by opening the cock A', he admits as much steam to the house as may be de- 

 sired. A small pewter pipe, three-eighths of an inch in diameter, is suffi- 

 ciently large to conduct steam into the house ; and its flexibility renders it 

 very convenient. Where this arrangement is adopted, the supply- cistern 

 must be larger than is otherwise necessary, and should contain ten or twelve 

 gallons. The steam-pipe, also, should be placed on the top of the boiler, and 

 be of sufficient diameter to allow the water and steam to separate, that the 

 former may not be blown out through the pipe along with the steam ; and 

 the valve should be loaded with a few ounces of lead. 



Fig. 152 exhibits the apparatus, with the addition of a reservoir; this in 

 small pits is very desirable. The letters indicate the same objects as in fig. 

 150, except w, the reservoir, which may be formed of thiu copper in the form 

 of a cylinder, and should be packed in a wooden or brick case, in sand or saw- 

 dust, which supports its shape, protects it from accident, and prevents the 

 heat from escaping. All the communication pipes in this case may be of 

 lead, and fitted with union joints, which renders the fitting exceedingly easy. 

 In Mr. Rogers's apparatus a lead pipe of an inch and a quarter in diameter 

 supplies forty feet of radiating surface, and his reservoir contaias about four 



