applicable to Steam Engines, ^c. 41 



parts as in fia". 1. In fig. 2. is al-^o shown the way in which 

 the fire is made to act. The fuel rests ou the bars at B, and 

 the flame, heated air and vapour, being reverberated from 

 tiie part above the tvvo first smaller cylinders, goes under 

 the third, over the fourth, under the fitih, over the sixth, 

 under the seventh, and partly over partly under the eighth 

 small cylindric tube. The d.rection of the flame, till it 

 reaches the last-mentioned tube, is shown by the dotted 

 curved line and arrows. When it has reached that end of 

 the feM-naee it is carried by the flue C to the other side of a 

 \\&\\, built under and in the dn-ection of the main cvlinder A, 

 and then returns under the seventh smaller cylinder, o\cr 

 the sixth, under the filth, over the fourth, tmder the third, 

 over the second, and partly over partly under the first; wheu 

 it passes into the chnnney. Tht wall before mentioned, 

 which divides the furnace longitudinally, answers the dou- 

 ble purpose of lengthening the course which the flame and 

 heated air have to traverse, giving oft' heat to the boiler in 

 their passage, and of securing frou) being destroyed by the 

 fire the flanges or other joinings employed to unite the 

 smaller tubes to the main cylinder. The ends of the smaller 

 cylindric tubes rest on the brick-work which forms the sides 

 of the furnace, and one end of each of them is furnished 

 with a cover, secured in its place by screws or any otlier 

 ade(juate means, but which can be taken off at pleasure, to 

 allov' the tubes to be freed, from time to time, from any 

 incrustation or sediment which may be deposited in them. 

 'Jo any convenient part of the main cylinder A, a tube is 

 affixed, to convey the steam to the steam-engine, or to any 

 vessel intended to be heated by means of steam. 



V\"hen very high temperatures are not to be employed, 

 the kind of boiler just described is found to answer veiy 

 ivell ; but where the utmost force of the fire is desirable, 

 Mr. Woolf, for a reason which shall be afterwards men-' 

 lioned, comoines the parts in a manner somewhat difiTerent, 

 though the same in principle. Having been permitted to 

 inspect two boilers of this kind which he is now erecting 

 in Messrs. Meux's brewery, and even to take copies of such 

 jjarts of the plans as were necessary for our present purpose, 

 \vc persuade ourselves a short description of an apparatus so 

 curious, and at the same time so useful, will prove highly 

 acceptable to our readers, 



In fig. 3, A is the main cylinder crossing the smaller cy- 

 linders u,a.(t, half way between their middles and ends, but 

 fiot joined to them at the points at which it crosses them. 

 Jt is put in this place that il may come ovcf that part of the 



furuaee 



