292 Perkins's Improvements in the 



Art. VI. Plan Jbr heating Hot-houses by the Circulation of hot 

 Water in hermetically sealed Tubes of small Diameter. By Mr. A. 

 M. Perkins. 



Sir, 



I beg leave to submit to your judgment my plan for heat- 

 ing hot-houses by circulating hot water in hermetically sealed 

 tubes of small diameter. In the infancy of this plan, in con- 

 sequence of my successful application of it to the heating of 

 the printer's plates in the Bank of England, John Horsley 

 Palmer, Esq., the governor, very liberally proposed to erect 

 an apparatus in one of his hot-houses, with a view to ascer- 

 tain its powers for heating it. I therefore put up an ap- 

 paratus, consisting of a series of pipes, of only an inch in 

 diameter, so connected together as to form a complete circuit 

 round the house ; one fourth part of these pipes, in the form of 

 a coil, was placed in the flue of a fire-brick furnace, of a 

 peculiar construction [see Jigs. 44. to 46.], and the other 

 three fourths were exposed to radiation within the house. 

 The result was a gradual rise in the thermometer, in the 

 house, from 45° to 90° in four hours, without once stoking 

 the fire from the time of lighting. The fuel was coke. This 

 experiment effectually proved the power of my apparatus, with 

 respect to the transmission of heat. Subsequent experiments 

 have proved its capability of sustaining an equality of temper- 

 ature for ten hours together, without the attendance of the 

 stoker. 



Mr. Palmer has since had three other houses heated in the 

 same manner, which, he assures me, give him unqualified 

 satisfaction. With respect to the economy of fuel, there 

 appears a great gain over the ordinary flues. When the fuel 

 used by my apparatus is compared with that consumed in 

 Mr. Palmer's conservatory, he says, there is a saving of two 

 thirds. 



These facts completely refute the objection raised by some 

 persons against the use of small tubes for heating hot-houses, 

 &c, as they incon testa bly prove the power possessed by my 

 apparatus, notwithstanding the small quantity of water used, 

 of absorbing the heat from the furnace, in such equal and 

 constant quantities, as to compensate for the greater quantity 

 of water used upon the old system of large cast-iron pipes. 

 There is an advantage also in the small pipes employed in the 

 hermetically sealed system, which does not belong to the larger 

 pipes ; and that is, from the furnace being the magazine of 

 heat, and situated outside of the house, the heat can be 

 reduced in much shorter time, by simply opening the flue- 



