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evening, it will retain its heat but little diminished 

 until the morning. The smoke, by means of a flue, 

 may be made to impart heat to the house, by passing 

 through it, or may at once enter the chimney or pipe 

 attached to the summit of the boiler. 



Hot water in a tank is superior to the same source 

 of heat in pipes, because it is not liable to freeze ; and 

 it is preferable to steam, because its heating power 

 continues until the whole mass of water is cooled 

 down to the temperature of the house, whereas steam 

 ceases to be generated as a source of heat the mo- 

 ment the temperature falls below 212 degs. 



Mr. Rendle, nurseryman, Plymouth, the first suc- 

 cessful suggester of the tank system of heating, has 

 furnished us with the following particulars : — A tank 

 of iron or wood, twenty feet long, five feet broad, 

 and six inches deep, is constructed in the centre of 

 the house, and surrounded by a walk, except at the 

 end, where the boiler is fixed for heating it. The top 

 of the tank is covered with large slabs of slate, 

 cemented together, to prevent the excessive escape of 

 steam. Around this is a frame sufficiently high to 

 retain the bark, in which the pots are plunged. The 

 boiler and tank are filled with water, and this circu- 

 lates, when the fire is lighted under the former, by 

 means of two pipes, one from the top of the boiler, 

 and the other returning nearer to its bottom. The 

 expense of piping, and danger of their freezing, is 



