MODES OP HEATING. 63 



to return, a greater amount of heat will be got from the 

 same quantity of coal, than if it merely ran straight along 

 one side, and turned round the end to connect with the 

 chimney. 



Too great caution cannot be used in keeping wood- 

 work away from the flue and chimney, at the furnace 

 end ; and for 15 feet of the hot end of the flue, wood 

 should never be placed nearer than one foot. Do not 

 listen to what your builders may say, as few of them have 

 had experience in such matters, and whatever they may 

 pretend, not one in a dozen knows any thing more 

 about what is dangerous from fire than you do your- 

 self. On one occasion I had in use two houses heated 

 with flues each about 100 feet in length. The chimneys 

 had been made of wood, and they had been safely used for 

 three winters, but on the occasion of a severe storm in 

 winter, when our fires were going at full blast, both of 

 them took fire within an hour of each other, though fully 

 100 feet from the furnace. Fortunately the chimneys had 

 been attached to the outside of the house, and were 

 knocked off without material injury being done. On 

 another occasion, a house containing upwards of 10,000 

 plants took fire by a workman placing kindling wood on 

 the flue near the furnace. The result was great injury to 

 the green-house, and total destruction of its contents. I 

 mention these cases, to show the necessity of the utmost 

 caution. Every winter there are hundreds of fires origin- 

 ating in green-houses by the woodwork taking fire from 

 flues. 



In this particular, if in no other, the heating of green- 

 houses by hot water has an immense advantage over flues, 

 for with this there is danger neither from fire, smoke, nor 

 the gases that often escape from badly built flues. Still, 

 in some particulars I do not believe in the advantages 

 claimed for hot water heating by its advocates. I have 

 never yet seen a boiler able to heat a given surface of glass 



