TRANSACTIONS 01^' THE S1ECTI0N3. S33 



heat Ijo carried out, and so successfully cau the heat be retained by very trifling 

 attention on the part of the workmen to the apparatus, that Mr. Ramsbottom, the 

 late Locomotive >Superiutendont of the London aud North-Western Railway, knew 

 he should not be applying too delicate a test when he inserted the ends of pieces of 

 wood through openings into the outgoing flues of the steel-heating furnaces at 

 Crewe. These pieces of wood were padlocked in their places, were taken out 

 periodically, and if they were found to be burnt it was known that the man in 

 charge of the furnace had been negligent in his duty of saving fuel aud had mis- 

 used the Siemens apparatus. But although this invention has been before the 

 public for very many years, and although it has had the approval of Faraday and 

 of every other distinguished scientific man who has investigated the question, and, 

 I am glad to saj^, the approval of the leading minds among the users of furnaces, 

 nevertlieless, for the general reason I shall have to allude to, the progress of this 

 invention has been by no means commensurate with its importance ; and it is not 

 too much to say that manufacturers would rather waste cheap coal than embai'k 

 capital in new furnaces, and, more than all, be at the trouble of instructing and of 

 watching over their workmen. 



Next, let us consider how we are dealing with coal when we use it for obtaining 

 motive power in our steam-engines. 



Steam-engines may be divided into the four great heads of marine, locomotive, 

 portable, and fixed. Including within the term steam-engine the boiler as well 

 as the engine, waste may arise in a steam-engine in two ways, either in one of 

 them or in both combined. It may arise from an imperfect utilization of fuel in 

 the production of steam (that is, a waste due to the boiler and to the firing), or it 

 may arise in an improper use by the engine of the steam provided for it by the 

 boiler. There can be no question but that the boiler waste is, as a rule, very large 

 indeed. 



A pound of fair coal is theoretically capable of evaporating from the boiling- 

 point 13 lbs. of water. I do not believe that I shall overstate the case when I say 

 that on fin average not more than from one third to one half of this quantity is 

 obtained fronr the whole of the boilers in use. 



This poor result arises from a variety of causes: — 1st, bad firing-, which means 

 bad combustion ; 2nd, insufficient surface to absorb the heat ; 3rd, an imclean con- 

 dition of that surface either from internal or external deposit, or both ; 4th, a faulty 

 proportioning of the parts of the boiler to each other and to the work to be done, 

 which cause heated water to be carried over with the steam — a cause of deficiency 

 of evaporation, which, however, so far from being as a rule detected, goes to swell 

 the apparent duty of the boiler. 



Bad firing may result in the fire being too thick, or too thin or irregular. If too 

 thick, the carbonic acid that is generated by the combustion of the lower part of 

 the fuel with which the air first comes in contact is changed in its passage through 

 the upper part of the fuel into carbonic oxide, by absorbing from the fuel a second 

 equivalent of carbon. If this gas, carbonic oxide, does not meet with free atmo- 

 spheric air, and meet with it at a suitable temperature in tlie upper part of the 

 furnace, it must remain unconsumed, and will pass through the llues or tubes of 

 the boiler and make its escape into the air, carrying with it the valuable uncon- 

 sumed carbon of the coal in a gaseous form. It is commonly said that smoke is 

 unconsumed fuel. This is true ; but it is not commonly recollected that there may 

 be invisible smoke arising (even from a coke-fire) which shall contain the highly 

 combustible ingredient carbonic-oxide gas. When it is remembered that every 

 pound of coal burnt into carbonic acid is capable of evaporating, as has already 

 been said, about 13 lbs. of water from 212°, while a pound of coal converted only 

 into carbonic oxide is capable of evaporating but 4 lbs., it will be seen how 

 necessary it is that no mismanagement of the fire should cause a portion of the fuel 

 thus to escape unburnt up the chimney. 



Another defect in the management of a fire (an opposite defect, as it were) by 

 which coal may be wasted is the admission of too much air ; and this arises when 

 the fire is too thin in relation to the chimney-draft, or when (a more common evil) 

 it is thin in places, owing to the negligence of the firemen in keeping it properly 

 levelled. 



