86 THE HOT-HOUSE. JAN.] 



This furnace is to be made large or small according to the kind 

 of fuel intended to be used and the number of returns of the flues 

 inside ; for when there are but few returns, a greater quantity of fire 

 will be necessary to keep a sufficient heat. If the returns are fre- 

 quent, and wood is to be the fuel, the furnace is to be made only 

 three feet deep, to receive wood two and a half feet long or better ; 

 but if the flues run only once round, with no returns, the depth must 

 be five feet to receive four feet wood, especially if the house be 

 large ; in either case the furnace is to be made eighteen inches 

 wide at bottom, the sides sloping outward to the height of twenty 

 inches, where it is to be twenty-two inches wide, covered from thence 

 by an arch, the top of which is to be two feet from the grate, which 

 is to be made of iron-bars, and one half of the depth of the fur- 

 nace ; the brick for the furnace should be laid in good well-worked 

 brick-clay (not in mortar), which, when burned by the fire, will 

 cement so as to become a solid mass ; this must have an iron-barred 

 grate one half of the depth of the furnace, as before observed, the 

 remainder of the depth to be made solid with brick ; having an ash- 

 hole underneath, with a close-shutting door to it. The furnace must 

 also have an iron door placed in an iron frame, which door must be 

 furnished, near the lower part, with another small door, for the ad- 

 mission of air to the fires, both having latches, so as to shut close 

 occasionally ; observing that this door is not to be wider than what is 

 necessary for the admission of the fire-wood. Having both your 

 ash-hole and furnace thus provided with close-shutting doors, you 

 may manage your fires to great advantage, by closing them up oc- 

 casionally from too great a current of air, especially when burned 

 clear, which would carry off the heat through the flues too rapidly. 

 If you intend to burn stone-coal, the furnace need not be so large, 

 but the grate must run the whole depth. 



Having finished the furnace, proceed to carry up the walls, ob- 

 serving particularly, to leave a scarcement a foot wide in both end 

 walls ; immediately opposite, where the back-watt flues are to be 

 erected, from the level of the lowest flue to the top of the highest, 

 by which means you can open the ends of the flues and clean them, 

 when necessary, either by running in scrapers on the ends of long 

 poles, or hauling any kind of small brush-wood through them, by 

 means of a line from one end to the other ; these scarcements may 

 either be made up with brick from time to time, or with sashes and 

 shutters, which will be more convenient. Whenever there are re- 

 turned flues, one above the other, similar contrivances will be found 

 useful ; but where there is only one running flue, a top tile may be 

 taken off at convenient distances, by which means it can be cleaned. 

 When the walls are finished, then begin to erect the flues along 

 the inside walls; but, as before mentioned, it would be adviseable to 

 have them detached therefrom two or three inches, that, by being 

 thus apart, the whole heat may arise from both sides of the said 

 flues, which will afford an additional advantage, in more effectually 

 diffusing the whole heat internally in the house ; much of which 

 would be lost in the back wall were the flues attached to it : the first 

 range may be carried along the front and both ends, dipping under 



