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boil; neither need there be any fear of its decline, or oi 

 a want of power, for when once thoroughly heated, a 

 body of water will part with it in such a manner, that a 

 very little attention to the fire, and a very little expen- 

 diture of fuel, will maintain its temperature for an almost 

 incredible length of time ; and as to power, it never should 

 for a moment form a question, because a powerful degree 

 of bottom heat ought never to be applied : a close atten- 

 tion for one or two hours during the twenty four which 

 form a day, will maintain any apparatus in an effective 

 state of action, if it is properly erected. How different 

 is this, to what has been in days now past! when in 

 rigorous weather, with the heat of his dung bed declining, 

 the cultivator knew that at the peril of his crop, he 

 scarcely dared to attempt to revive it, without involv- 

 ing a more serious because an accelerated evil ; at any 

 rate, if at an immense sacrifice of labour, his dung casings 

 were replenished piece by piece, he knew too well, that 

 often many days would elapse, before their action would 

 be efficient and satisfactory, unless indeed an unlimited 

 supply of materials, were in a constant state of prepara- 

 tion. By means of the tank, a fire could be lighted up, 

 and the required effect produced in as many hours, as 

 days would have been formerly required. 



What has been already advanced, tends to the conclusion, 

 that small forcing houses are preferable, and in the end 

 more economical than pits and dung beds ; and that the 

 tank as a means of supplying bottom heat, is preferable to 

 the use of fermenting materials ; because the results in each 

 case, are more perfectly under controul. Whilst on this 

 part of the subject, I may be allowed to mention an error 

 which is somewhat prevalent : We frequently hear of 

 the humid nature of the heat given off by hot water 

 pipes, in comparison with that derived from such appli- 

 ances, as a flue; it is not unfrequently asserted, that the 

 heat thus derived is so moist, so genial, so peculiarly 



