2124. Steam will be found the most convenient mode of heating garden structures under the following circumstances:�Where the hothouses or pits are numerous and scattered about on different levels: where the object is chiefly to heat beds of soil; and generally, wherever there are intervening spaces, that do not require warming between the structures to be heated. The reason why steam is preferable to smoke-flues for this purpose is, that these flues will not circulate smoke and hot air to any great distance; and the reason why steam is preferable to hot water under the boiling point, is of a similar nature. The reason why steam is preferable to hot water under compression, by which, as will be afterwards shown, it is circulated at from 50 to 100 degrees above the boiling point, is, that too much heat will be lost in the space between the structures to be heated.
