1879] A PLANT-HOUSE. 273 



to the other ; but where difficulties of drainage or deep excavation or 

 approach are to be contended against, the lifting principle might be 

 adopted with advantage. It is well understood in an apparatus on the 

 siphon principle, if any part of the return-pipe dips below the bottom 

 of the boiler, there the coldest water will lie, and act as an effectual plug 

 against the circulation ; but by the use of the perpendicular pipe dis- 

 charging the heated water at once into an elevated expansion-box, and 

 thence being distributed, there seems no reason why the boiler should 

 not be actually above the level of the return pipes, for by this means 

 the boiler is made simply an enlarged gland or portion of the pipes. It 

 once was our duty to stoke a boiler which was no boiler at all, but only 

 a spiral coil of 4-inch pipes, the return being of course the bottom of 

 the coil. The water, in its course through the various houses and apart- 

 ments heated, had to pass through many ups and doivns, at one place 

 through a succession of pipes placed vertical and parallel, and connected 

 by siphon-bends top and bottom. The apparatus worked perfectly, but 

 great attention was required that no air should accumulate at any of the 

 bends, as if it did, the circulation was impeded at once. Water was sup- 

 plied from a ball-tap at a considerable elevation above the highest point 

 of the pipes. Heating by hot water has so generally been carried out on 

 the siphon principle, that public opinion has become settled that there 

 is no other mode whatever. The fact that it is the most convenient, and 

 can be applied in all but very exceptional cases, has had a tendency 

 so to settle the matter ; but we agree with the editor in saying that the 

 whole subject is worthy of discussion, to our mutual gratification and 

 instruction. The Squire's Gardener. 



A PLANT-HOUSE. 



To any one about to build, and who wants a really good plant-house, 

 I would suggest one of similar size and construction to that shown 

 in the accompanying section, p. 274. What is worth doing at all is 

 worth doing well. There is a general want of room in a great majority 

 of plant-houses. They are very often built too narrow, under the im- 

 pression that they will cost ever so much less than if they were wider. 

 This, I think, is more imaginary than real, as any one will find out 

 by a little calculation, or by submitting plans of a narrow and wide 

 house for an estimate to any horticultural builder, and compare the 

 extra cost with the extra accommodation. Plants, like animals, re- 

 quire some body of atmosphere to breathe, and if a lot of plants are 

 crowded into a small house, the air will become vitiated in the same 

 way as it would when animal life is shut up. To enclose a good 

 body of atmosphere without having high side-lights and a high-pitched 



