Horticultural Soi^ety of London, 175 



apparatus, the danger attending its use in the charge of an 

 unskilful or careless gai-dener, and also the rapid loss of 

 heat from X\\s pipes upon any neglect of the boiler, have all 

 contributed to prevent the use of steam becoming very ge- 

 neral. The plan now described has the great merit of pos- 

 sessing all the good qualities of steam, without any of its 

 objectionable accompaniments ; its cost cannot in any con- 

 siderable degree exceed that of flues, and its effects are so 

 cerUii^ and durable, that a house so heated may be almost 

 9ai4 ItO l>e beyond the power of neglect on the part of the 

 gardener. 



Without entering into the details of this plan, for which 

 we must refer to the paper itself, we shall content ourselves 

 M'ith explaining its principle. Suppose two iron reservoirs, 

 A and B, of equal capacity, placed twenty feet apart, and 

 connected at the top and the bottom by iron pipes, the level 

 of both reservoirs being the same ; it is obvious that water 

 poured into one of these reservoirs will flow into the other 

 through the connecting pipes, and that it will consequently 

 stand at the same height in both. Let the reservoirs be thus 

 filled above the level of the uppermost pipe, and heat be 

 applied to the bottom of one reservoir, A ; the water in this 

 will presently be forced through the upper pipe into the 

 reservoir, B, of water not heated ; in proportion as the 

 healed water flows out of A, through the upper pipe, the 

 cold water will flow out of B through the lower pipe ; and 

 by this means a circulation of water heated and water to be 

 heated will be formed, which will continue as long as the 

 application of fire to the bottom of one reservoir is continued. 

 When it is discontinued, the temperature of the two reser- 

 voirs and of the intermediate pipes will be the same within 

 three or four degrees. As it is the property of heated water 

 to part with its heat very slowly, it follows that heat will 

 continue to be disengaged from the reservoirs and pipes long 

 after the application of fire has ceased. In fact, when the 

 two reservoirs are once heated^ the gardener may make up 

 his fires and retire to i*est, certain that his house is suffi- 

 ciently provided with heat for the night. 



The paper is accompanied with a plan of a vinery warmed 

 upon this principle. 



