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ADVANTAGES OF STEAM. 



application became general, from the notion that houses heated by this 

 means would be exempt from insects. No such thing is the case, for heat 

 is the same material, and has the same effect, whether given out from a 

 steam pipe, hot water pipe, or a well jointed and smoke-tight flue. 



The expense of erecting a steam apparatus for the purpose of heating 

 hot houses of ordinary dimensions, would be extravagant. But other 

 objections might be stated against its application by means of tubes, had 

 not the mania for heating by steam given way to the more rational one of 

 heating by hot water. 



Steam has been apphed in a variety of w^ays in heating plant houses, 

 but that of causing it to heat a mass of building materials, rough roubell 

 stones or pebbles, appears to us to have been the most rational and 

 economical. This plan was tried by that eminent garden architect, John 

 Hay of Edinburgh, so early as 1807, and has been subsequently improved 

 upon in many of the gardens built by him since that period. When 

 this mode of heating is intended to be apphed, the interior of the 

 house, which is usually occupied with the bark bed, or pit, in which 

 the plants are plunged, is filled to the thickness of from three to 

 four feet, that is, to about the depth of the tan bed formerly used, 

 with stones, broken to the size of from three to six inches in diameter. 

 Through this mass the steam pipe passes, perforated with small holes 

 along its two sides, for the escape of the steam, which thus enters and 

 heats the mass of stones. When once heated, these will retain warrnth, 

 sufficient for tropical plants, for twenty four hours in the coldest 

 weather, and for two or three days in mild weather. From this it 

 w^ould appear, that the steam has only to be let on at these periods ; 

 at all other times it may be dispensed with or applied to other purposes. 

 When the steam is let on to heat this mass of matter, it should be 

 continued until it ceases to condense amongst the stones — a proof 

 that they are heated to its own temperature. 



The superfluous steam of manufactories or engines might be economi- 

 cally applied to heat plant houses upon this principle. And we are also 

 of opinion that it might be applied in such situations to heat pits for 

 pines, grapes, peaches, and strawberries, which would render these fruits 

 as plentiful, and nearly as cheap at Christmas as at Midsummer. A 

 very lengthened account, accompanied with several engravings, shomng 

 the operation of heating upon Hay's principle, has been published in 

 the Memoirs of the Caledonian Horticultural Society, to which those 

 particularly interested are referred. Steam, for this purpose, has been 

 turned into vaults under the plant house, but not with the satisfactory 



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