Hot-houses hy hot Water. g^ 



the small saving realised in the article of fuel. These at- 

 tempts requiring nearly a dead level, and being therefore 

 inapplicable to the irregular forms of many previously built 

 hot-houses, soon called for improvements on the principle of 

 conveying the heated fluid. The ascending tendency of 

 heated fluids, and the impulsive effect thereon by cold, directed 

 the artificer in the disposition of his conveying tubes; and by 

 working in unison with these laws of nature, many most suc- 

 cessful improvements have been made. Heating by steam, 

 and admitting it into houses designed for the cultivation of 

 tropical plants, is found to be a good plan ; Kewley's siphon 

 principle answers every moderate purpose of forcing ; Cottani 

 and Hallen's improved boiler and conveying tubes are also 

 perfectly eflicient for pineries, vineries, peach-houses, or for 

 any other similar erections ; and Weekes's flat tubes are par- 

 ticularly convenient in houses built for the propagation and 

 growth of exotic plants : so that it would appear, as every 

 purpose of the forcing-gardener can be obtained by one or 

 other of these several plans, there remains scarcely room for 

 farther amendment. 



During the progress of these improvements, however, it 

 soon became manifest that, when apparatus of large dimen- 

 sions and great quantity of water were employed, though more 

 slow in action, and more expensive in fuel, yet, when once 

 thoroughly heated, the required degree of heat was evolved 

 for a much longer time than it would have been by apparatus 

 of a lighter and less capacious construction. This circum- 

 stance was particularly satisfactory to theanxiousgardener, who, 

 from this plan of heating, found thathe could confidently take his 

 nightly rest in peace. The reverse of this, also, became appa- 

 rent ; namely, that, the smaller the quantity of water used, and 

 the smaller the size of the boiler and circulating pipes, the more 

 rapid was the circulation, and consequently the more intense 

 the heat which was evolved. This discovery also combined 

 at the same time cheapness of first cost, economy in fuel, and 

 economy o^ space; very little room being required for the 

 range of pipes. On this latter principle Mr. Perkins has 

 executed some excellently convenient apparatus, alike credit- 

 able to his genius, and satisfactory to his employers; and, it 

 may be added that, with the addition of a properly constructed 

 safety-valve, if this be practicable, his apparatus, for celerity 

 of eftect, and for local and temporary efficiency, stands un- 

 rivalled. This plan, however, is objected to by some gar- 

 deners, because it does not possess that accumulation, or store, 

 of heat, which constituted the chief excellence of the old- 

 fashioned pipes and boilers. Whether this objection be 



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