260 



GARDEN MANAGEMENT. 



tubes placed over the fire, and united together at top and bottom, the furnace- 

 bars being hollow tubes, through which the return-water passes before entering 

 the upper part of the boiler ; thus producing very rapid circulation, with great 

 economy of fuel. 



704. The last, and, as we are informed, not the least effective of the tubular 

 boilers, is that patented by Mr, [Messenger, and by which he proposes to heat 

 the range of houses we have described in the preceding pages. The principal 

 feature of this boiler, of which we give an elevation on the preceding 

 page, and of which this is a section, is an arrangement of triangular 



T tubes, round which the flames play in passing to the 



flue h. The tubes are horizontal, and placed over and 

 round the fire, so that the heat in its upward course 

 rebounds, as it were, from tube to tube ; so that before 

 it reaches the flue all the latent heat is expended. 

 The furnace-bars are also tubes, through which the 

 return-water passes ; thus preventing them from burn- 

 ing, and increasing the rapidity of the circulation, and 

 re-entering the tubes which form the boiler at a high 

 temperature. It is obvious that the surface exposed 

 to the action of the fire in this boiler is immensely in- 

 creased by the form of the tubes. The boiler-surface 

 entirely surrounds the flames, while, from its horizontal position, sufficient 

 space is allowed for between the fire and the tubes for the introduction 

 of atmospheric air, and the proper commingling of the gases ; a being the 

 brick setting round the boiler, h the flue through which the smoke escapes 

 after passing round the tubes. The large surface of triangular bars exposed to 

 the action of the fire, which in fact foi'm the boiler, and through which 

 water circulates, renders it, according to Mr. Messenger's statement, at once 

 economical in its consumption of fuel, as well as highly efficient in its heating 

 qualities ; while the facilities for cleaning it are such that it can be done at 

 any time vrithout interfering with its working. Besides its economical proper- 

 ties, neither the tubes at the sides and over the fire, nor the furnace-bars 

 under it, can be injured by the heat, as the water inside keeps them cool, and 

 consequently protects them from its action. 



705. The hot-water pipes are, of course, applied to the boiler by means of 

 flanges, and the pipes themselves are of the usual circular shape, and of sizes 

 calculated according to the superficial contents of the house \o be heated 

 and temperature required. The tanks are to be heated by a flow and return- 

 pipe passing along their surface, at the level of the water, while a current of 

 fresh air from below keeps the house pure and wholesome ; at the same time 

 the air is heated in its j^rogress to the temperature of the tanks. The only 

 novelty introduced here consists in an exceedingly simple shutting-oflF valve 

 which Mr. Messenger has patented, by which the circulation of the water can 

 be cut off" or introduced into any house or pit it is desired to keep at a higher 

 or lower temperature than the others. These valves are said to be very 



