On a Steaming Apparatus. 325 



about eight inches into the water of the boiler, and a valve 

 is fixed at the point of the returning pipe at I (Fig. 2), to 

 prevent the water being forced up into the tube B, by the 

 pressure of the steam. The passage for the water, to return 

 to the boiler, is an inch lower at the end of the pipe G (Fig. 1), 

 than at the entrance of pipe B, so that the water will fall 

 again into the boiler through the tube I, as soon as the pipe 

 becomes half full, but not through the pipe H (Fig. 2), till 

 that becomes full to the height of two thirds of its dia- 

 meter. Greater rapidity, and probably greater power, would 

 be given to the current of boiling water, if a declivity of about 

 half an inch in twelve feet were given to the pipes ; and if 

 every pipe at the junction with the next were half closed, as 

 at the point b (Fig. 1), the advantage of the heated water 

 remaining in the tubes after the failure of the current might 

 be preserved. If this plan were adopted, the pipe D must 

 be made to enter the furnace at the level of E. I am not 

 at all prepared to say what would be, under these circum- 

 stances, the rapidity of the current of boiling water, but I 

 believe it would not be less than 200 feet in a minute, and if 

 so, it might be conveyed through a great distance. I am not 

 aware of any possibility of danger in the adoption of either of 

 the aforesaid plans, even without safety valves, (the greatest 

 power of pressure being less than a pound on a square inch), 

 though it might be expedient to employ such, whenever a 

 possibility of their being wanted might occur. 



Objections might be urged against some of the preceding 

 inferences, by those who contend for the materiality of heat ; 

 but that hypothesis leads to nothing but error, in the appli- 

 cation of heat in forcing-houses. If a brick flue be made 

 of much too great thickness, I have ascertained by experi- 



