I879-] HEATING BY HOT WATER. 55 



rule of moderate selections. To any grower who has a hobby or 

 yearning, and room for mere collections, we have nothing to say; 

 but to all who have a show and supply of flowers to produce for 

 given purposes, we would say, make comparatively small selections 

 and you will not regret it. It is the principle we act upon our- 

 selves, and find it much preferable to collections for the sake of 

 variety. 



HEATING BY HOT WATER. 



Although hot water circulating in pipes has been adopted and re- 

 cognised for many years past as the best system of warming plant- 

 houses, yet there exists at the present time, among hot-water engineers 

 and gardeners, considerable difference of opinion regarding the best 

 shape or form of boiler to employ in which to heat the water in the 

 first instance. And there is no doubt that among the different shapes 

 of boilers in use at present, the form of some is better calculated to 

 answer the purpose in view than that of others. It is not, however, 

 our intention in this paper to discuss the merits or demerits of any 

 particular kind or pattern of boiler, but to direct attention to one or 

 two matters in connection with the fitting up of a heating apparatus 

 that both engineers and gardeners are agreed upon as being essential 

 to a rapid circulation of the water in the pipes, whatever shape the 

 boiler may be. We allude to the practice of sinking the boiler below 

 the level of both the flow and return pipes, and giving the flows a 

 continuous ascent from the top of the boiler to their furthest points of 

 extension in the building or buildings to be heated. This method of 

 fixing up a hot-water apparatus has been so long adopted, and attended 

 with such an amount of success, that the soundness of the practice may 

 to some appear beyond dispute. Notwithstanding, we do not hesitate 

 to say that the circulation of the water in the pipes will be as rapid 

 with the bottom of the boiler one foot below the level of the return 

 pipes as it would be supposing the boiler was sunk several feet 

 deeper. And instead of a continuous ascent of the flow pipes through- 

 out their whole length being necessary, or in any way contributing to 

 the rax>idity of the circulation, this way of fixing them tends to 

 retard the process. If we succeed in showing that a continuous rise 

 in the flows hinders rather than accelerates circulation, the argument 

 in favour of placing the boiler so much below the general body of the 

 pipes will disappear, and the expense consequent upon excavating, 

 draining, and building a deep stokehole, will in many cases not need to 

 be incurred. Under certain circumstances, however, a deep stokehole 

 is a necessity, as, for instance, when the pipes in passing from the 

 boiler to the buildings to be heated have to cross under outside paths. 

 In this case, as well as in some others that could be mentioned, a deep 



