322 On the Application of Steam. 



gallons of water, with which it is about two thirds filled ; 

 a cistern (b) is fixed near to it which supplies a small re- 

 ceiver (c), by means of a pipe at the bottom, one inch in dia- 

 meter, to which is attached a ball-cock to prevent waste of 

 water from the cistern ; the top of this receiver is the exact 

 height at which the water stands in the steam boiler, which 

 is supplied from it ; to the boiler is attached a safety valve (i), 

 to* prevent any accident by too great a pressure of the steam ; 

 the pipe (d), by means of which the steam is conveyed into 

 the pit, is four inches diameter, and it is carried from the 

 boiler under ground about sixteen feet ; it is then introduced 

 at one end, and goes immediately to the front, whence it is 

 continued to the other end, where it discharges itself into a 

 brick flue (<?), which may be thereby heated to any degree 

 wanted, although at a distance of forty-eight feet from the 

 steam-boiler. In this length of pipe there are three traps to 

 take off the condensed steam, two of them are marked (/), 

 the other is under ground. There are also two steam-cocks 

 (g), fixed to a one-inch pipe about eighteen inches in length, 

 and branching from the main pipe in a horizontal direction, 

 but in such a manner as to prevent the steam from playing 

 directly among the plants ; at the end of the main pipe there 

 is a stop-cock (h), which is to be shut when it is intended 

 to steam the pit, the steam-cocks are then to be opened, 

 and in about ten minutes the pit will be filled with steam, 

 thereby producing a fine dewy moisture, the duration of 

 which can be regulated as the season requires, but in the 

 driest time of the year it will not be required longer than an 

 hour ; in this particular, however, for various reasons obvious 



