Management of Hothouse Flues. 155 



ment of Hot-house Flues, so as to keep up a nearly equal Temper- 

 ature during the Night " upon which I take leave to offer a 

 few remarks. 



The plan of closing the chimnies of all buildings that are 

 heated only in the day-time with a view to preserve a warm 

 temperature during the night, was long since recommended by 

 a practical writer to whom the sciences of agriculture and gar- 

 dening owe much, — Dr. James Anderson. 



It was observed by Dr. A. (Recreations in Agriculture, &c. vol. ii. p. 155.) 

 that " when a fire is suffered to die out and no means are employed to close 

 the chimney, the warm air within it, instead of gradually communicating its 

 heat to the cooler air of the room, rushes rapidly forward, until it readies 

 the open atmosphere, where it is dispersed and lost. A stream of cold air 

 is from that moment forced up the chimney, to supply the place of that 

 which is heated by the bricks as it passes along, and thus escapes upwards. 

 In this way the whole chimney is, as it were, washed with a continued stream 

 of cold air, and the heat that was in it, and which, without this washing, 

 would have continued many hours, is carried off in the most rapid manner 

 that could be devised." Hence the necessity (on the common plan of 

 warming hot-houses and other buildings) for keeping the fires burning night 

 and day, to prevent that alternation of heat and cold, which we are so 

 desirous of guarding against ; for, without continual fires, it will be per- 

 ceived that the means we employ for obtaining warmth during the day, are 

 equally adapted to produce cold during the night. The register grate does, 

 indeed, afford some remedy for this evil ; but if a damper were inserted in the 

 flue, and closed at bed-time during the winter months, it is evident that 

 much cold would be excluded; and, in the winter season, open chimnies 

 for the purpose of ventilation will not be found necessary during the inter- 

 vals of repose. 



That great practical philosopher Count Rumford, more than thirty years 

 ago, predicted that a time would come when open fires would disappear, 

 even in our dwelling-houses and more elegant apartments. 



" Genial warmth," he remarks, (in his tenth essay,) *' can certainly be kept 

 up, and perfect ventilation efftcted, much better without these than with 

 them ; and though I am myself still child enough to be pleased with the 

 brilliant appearance of burning fuel, yet I cannot help thinking, that some- 

 thing else might be invented, equally attractive to draw my attention, and 

 amuse my sight, that would be less injurious to my eyes, less expensive, and 

 less attended with dirt, ashes, and other unwholesome and disagreable 

 objects." 



Various plans have been devised, pursuant to the Count's 

 suggestion for warming and ventilating buildings, with a view 

 to obtain more equable temperatures, the authors of which 

 have also recommended the discontinuance of open fire-places. 

 But open fires do not seem destined to disappear in the pre- 

 sent age, although the improved methods of warming build- 

 ings (especially that of introducing air from without, and 

 passing it in a current over a body of heated matter, and 

 thence to the apartments required to be warmed,) are daily 

 gaining ground. Let but our chimney-builders and grate- 



