HEATING BY HOT WATER. 95 



what size a flue may be, and whether single or double, it 

 should in every case be made on the principle of being 

 carried all around the building until it enters the upright 

 chimney built on the top of the furnace. 



CHAPTER XXIX. 



HEATING BY HOT WATER. 



Although we describe flues as a means of heating green- 

 houses or graperies, they should be used only on the score 

 of economy ; whenever one can afford to have the heat- 

 ing done in the best manner, by all means let it be 

 done by hot water. The hot-water apparatus requires 

 less attention than flues, and its management is so simple 

 that any one able to take care of an ordinary stove or 

 furnace can take charge of a boiler for heating the water 

 in the pipes of a greenhouse. Besides, there is no danger 

 from smoke or gas, and but little risk from fire. Inside 

 the greenhouse there is no danger from fire ; if they are 

 filled with water the pipes cannot be made hot enough to 

 ignite the most combustible substances that may come in 

 contact with them. With the smoke flue it is very dif- 

 ferent, dry wood or other combustible material will ignite 

 if allowed to touch the brick, anywhere within 20 to 40 

 feet of the furnace. There are a great many patterns of 

 boilers, and to recommend one more than another may 

 seem invidious ; still we have had in use quite a number 

 of different styles, and have found that, as far as our 

 experience with them has gone, those made by Hitchings 

 & Co., of New York, everything considered, have been 

 most satisfactory. We have several of these boilers in 

 use that have not cost a dollar for repair in ten years. 



