42 HoAv TO Geow Cut Flowers. 



flow and nine one and one-quarter innh returns will 

 maintain a temperature of 60° when the outside tem- 

 perature is twenty below zero. 



From the point where the main feed leaves the four 

 or six inch pipe, all the pipes should have a fall until 

 connected again with the boiler, and the point where 

 they emerge from the house on their return should be 

 supplied with air cocks. These should all be closed as 

 soon as circulation is fully established. As the returns 

 emerge from the houses connect them with a three- 

 inch pipe, but place this last named pipe below the 

 water line of the boiler before the returns are connected 

 with it. It can then be joined to the base of the boiler. 

 Although not absolutely necessary, it is probably bet- 

 ter to carry the main feed of a house down the centre, 

 and from twelve to fifteen inches below the ridge. As 

 before mentioned, if radiation from this pipe is not de- 

 sired, it can very easily be retained by asbestos or other 

 covering. A careful observance of ah these points is 

 necessary to a perfect circulation. The valves and 

 checks necessary to the control of the circulating me- 

 dium are well known to all steam fitters and need not 

 be enumerated here. 



I am sometimes asked the question which of all 

 these systems I like the best, and which I would advise 

 a beginner to adopt. This last question cannot be 

 answered definitely, for reasons already stated, and as 

 to the first, I can only give my own experience. 



