278 



CASSELL'S POPULAE GARDENING-. 



Stevens' Improved Cornish. Boiler. — Figs. 

 63 and 64. — ^Although this modified form of the old 

 and good Cornish hoUer can hardly be called a sad- 

 dle, it ought, perhaps, to be placed in that section. 

 It consists of two wrought-iron cylinders riveted 

 together, one within the other, having about two 

 inches of waterway between them. The grate-bars 

 are inside the cylinder, towards the lower part, the 



work, if not perfectly, in a way that will keep the 

 oocupajits of the houses from injury. This is, no 

 doubt, a great improvement, but such boilers re- 

 quire a somewhat deeper setting, which is often 

 inconvenient. 



In the Chilwell Horizontal Tubular Boiler the 

 apparatus is also sectionaUy divided, but in a quite 

 different manner. The tubes are here arranged over 

 an ordinary furnace, with doors upon Sylvester's 

 construction. The cold water from the return-pipe 



Fig. 63. — Stevens' Improved Comisli Soiler. 



Fig. St.— Section of Comish Boiler. 



space beneath forming the ash-pit, and that above, 

 the furnace. The heat, therefore, passes through 

 the centre of the boiler first, then returns over its 

 upper haK, and is finally conducted under the lowei 

 half on its way to the chimney shaft. The principle 

 of the boiler not only exposes a large area of water 

 to the direct action of the fire, but the heat operates 

 with its greatest force upon the upper part, where 

 there is no possibility of solid matter accumulating 

 to cause the iron to burn, as it invariably does when 

 incrustations intervene. The great amount of work 

 done by this exeeUeut boiler, with a small expendi- 

 ture of fuel, has thoroughly established it as one of 

 the best boilers now in use. It is easily set, and does 

 not require a deep stoke-hole. 



Tubular Boilers.— These boUers, quick and 

 powerful in their action, have been much 

 used for heating large establishments, but 

 owing to their liability to crack from un- 

 equal contraction when cooling, have gone 

 out of favour. In order to overcome or reduce 

 the danger of such sudden collapse, Messrs. 

 Weeks and Co. have invented the Duplex 

 Upright Tubular BoHer (Fig. 66). It is made in 

 two parts, which can be worked jointly or separately, 

 so that in the event of accident one part can be 

 detached and replaced, while the other is doing the 



Fig. 65 — TVeeks's Duplex Upright Tubular Boilai; 



