of plant growing, whether in private or public gardens, the upright tubular is usually employed, as in emergencies it is capable of an almost instantaneous effect, while for every-day work it is valued for its great power, a tubular boiler of a given size being capable of heating to a given degree ten or twenty times the extent of pipe that any other boiler of equal size would heat to the same degree. Messrs. Weeks and. Co., of King’s Road, Chelsea, have developed the capabilities of this form of boiler to an extent which entitles them to the first place in this department of engineering. Their “One-boiler system” renders one boiler sufficient for any number of connected or separate plant houses, even though to heat them sufficiently several miles of pipes may be required; and their Duplex tubular boiler is so constructed that, in case of an accident to any part of it, that part can be instantly detached, and the heating business, instead of breaking down, as it would with any other boiler, proceeds without interruption, or, at the most, with the interruption only of the interval between the occurrence of the flaw and the operation of detaching the portion of the boiler in which it has occurred.
The most suitable boiler having been selected, the business of setting and attaching pipes is a matter of the simplest mechanism. But mistakes occur, and a few words of advice may be useful on these and other matters. Be sure that the workmen who are to set the boiler know what they have to do. It would be simply absurd for us to describe how each particular boiler is to be set, and if the manufacturer undertakes the work it will be properly done. But a second-hand boiler may be purchased, and the village smith or bricklayer have the job of setting and attaching pipes. It should be understood, then, that a decided rise of the pipes from the level of the boiler to the level of their extreme distance from it is necessary to ensure a good circulation. The rise should be gradual but continuous, and at the highest point where the flow ends and the return begins, a reed-like pipe should be inserted to promote escape of air, which might blow the whole affair to pieces if allowed to accumulate without means of egress. In a heating system of any extent there should be several air-pipes inserted. The feeding cistern should be on a level with the highest point of the extreme end of the flow-pipe or a few inches higher. It must not be lower on any account, or the water will never reach that point, and there will be no
