CONSTRUCTION OF FRUIT HOUSES 303 



work well enough, but the writer knows of no advantage they have over the 

 horizontal form for horticultural work, while open to several disadvantages, one 

 of these being the necessity for a deeper stokehole. It may be proper at this 

 stage to point out that one most essential point for the success of a hot-water 

 apparatus is to have the boiler well below its work. A boiler which might 

 very well heat 1000 feet of pipes with 10 feet of head should not be put to 

 more than 750 feet with 5 feet. Many grave errors and great trouble might 

 be avoided hy giving due weight to this fundamental principle, and while not 

 dogmatising in any way I would urge that the boiler should be sufficiently low 

 down to give at least one-half inch of rise on every 10 feet of piping, and as 

 much more as might be reasonably practicable. 



It need hardly be said that while it is very desirable to choose a good type 

 of boiler, it is also essential that ample size should be allowed for. An incident 

 which came within the writer's experience will illustrate this. In the winter 

 of 1879, which was very severe in Scotland, a saddle-boiler in the well-known 

 gardens of Sir Charles Tennant, The Glen, gave way and a new one had 

 to be put in. During December this boiler consumed 3f tons of coal per 

 week, and a man had to sit up half the night putting on fuel. A new boiler 

 of the same type was put in, but more than double the size, which took only 

 2 tons per week and required no attention from 9 p.m. till 7 a.m. next morning. 

 During January as well as December the weather was very severe, from 20 to 

 30 degs. of frost being registered nearly every night. 



Setting the Boiler. — The setting and building in of a boiler is a most 

 important matter, but this need not be enlarged upon further than to give these 

 instructions : — First, to have a reasonably high chimney, and, if possible, 

 to have it as high as any surrounding buildings or trees ; second, to have the 

 chimney as near the boiler as possible ; and third, to have the flues large and 

 every crevice accessible for easy cleaning. No such flue should, even for a 

 very moderate-sized, indeed for any, boiler, be less in area than 90 inches — 

 10x9 inches — and for large boilers correspondingly larger. If there is a 

 necessity for a long horizontal flue it should be made 2 or 2^ feet square, or 

 even larger still if very long, in order to reduce the friction to a minimum. 

 The writer has known a flue from a 6-foot terminal boiler, 15x15 inches, 

 60 yards long, to be an absolute failure, but when enlarged to 36 x 30 inches 

 give a first-rate draught. Such a flue should be made of good brick and be 

 as nearly watertight as possible. It is desirable, especially with long boilers, 

 that the flow socket should be at one end, and in setting the boiler that the end 

 upon which the flow socket is fixed should be at least one inch higher^than the 

 other, to make sure that no air can be locked up inside the boiler. 



Water Bars. — Reference has been made to water bars. These are 

 undoubtedly of great advantage where they can be applied, but the water must 

 be soft. Where there is anything more than eight or nine grains of hardness 

 to the gallon there should be no attempt to use water bars. The best way 

 of all is to feed the heating apparatus with rain water, then all danger from 

 incrustation is avoided. When hard water is used for heating purposes provision 

 must be made for clearing out the boiler and pipes adjoining at frequent 



