TRANSACTIONS OF THE SECTIONS. 235 



not the object of tliis address to enter into tlie details of such matters as these. I 

 will therefore content myself by saying I am perfectly certain there is hardly any 

 subject more worthy the attention of the engineer than the replacing the stoker by 

 some mechanical arrangement which shall alibrd absolute uniformity of firing, and 

 therefore absolute uniformity of the conditions of the fire; and this is a subject 

 not only worthy of attention on account of the saving of coal, but also on llic 

 ground of putting an end to a most laborious, exhausting, and, it is to l)e feared, 

 unhealthy occupation— viz. that of the steamboat fireman, more particula.rlj' wheu 

 he is worlving in a hot climate. If perfect combustion were obtained in the fire, I 

 do not think there would be much difficulty in properly utilizing by the boiler the 

 heat evolved. All that is necessary' to attain this end is to give a sufficient amount 

 of surface to absorb the heat and to transmit it to the water, always bearing in 

 mind that, above all, the form of the boiler should be a safe one, that there should 

 be proper water-space within it and an adequate water-surface from which the 

 steam could escape, that it might do so with tranquillity, and so as not to give rise 

 to the spray technically known as " priming," and that all parts of the boiler 

 should be accessible for cleaning. 



I am aware there is a temptation, on the score of saving expense and of saving 

 room, to make the boiler of small size in relation to the amount of coals burnt under 

 it and to the quantity of steam required from it ; but this is a most extravagant 

 ■ economy, — it is a saving in the outset, but it is a perpetual soiu'ca of loss in the 

 working. Temperatm-es as high as 800 and even 1000 degi-ees of heat have been 

 known to exist among the products of combustion escaping from the boiler. Now 

 when it is recollected that every 100 degrees of heat in the outgoing products of 

 combustion represents 2^ per cent, of the whole heating-power of the coal, even if 

 only the minimum amount of air to ensure perfect combustion is admitted, it AviU 

 be seen how necessary it is that there should be sufficient surface in the boiler to 

 absorb the heat of the gases, and to bring them down to a few degrees above the 

 temperature of the water in the boiler itself. I have mentioned the temptation to 

 use boilers of inadequate size on the score of expense and on the score of room. It 

 is this latter reason, no doubt, which induces shipowners to endeavour to diminish 

 the size of their boilers as far as practicable, because they argue that the space 

 occupied by the boilers and machinery is all waste room, as it cannot be filled 

 either with coals or with cargo. With short-voyage steamers, voyages of a few 

 hours only, this argument may be a valid one ; but for the long-voyage vessels to 

 India and elsewhere, where fuel has to be carried for from twenty to thirty days' 

 steaming, and where on the homeward voyage the ships have to be supplied with 

 coal that has been brought from England by sailing-vessel at a large cost for 

 freight, the true space deducted from the cargo and passenger-carrying power of 

 the steamship is clearly not that occupied by the engines and boilers alone, but 

 that occupied by the engines, the boiler, and the coal for those boilers. Even sup- 

 posing that if, after enlarging the boilers to diminish the consumption, the space to 

 be given up to the engine, boilers, and coal were still the same, in consequence of 

 the increase in the size of the boilers being equivalent to the coal-space saved, 

 manifestly it would be to the advantage of the shipowner that that space should 

 be occupied by the boilers rather than by the coals. 



The expense of the boilers is a first outlay, and has not to be repeated for years 

 until the boilers wear out ; but the expense of coal is an outlay that has to be 

 made at eveiy voyage, and therefore it is a short-sighted policy to restrict the 

 amount of absorbing surface in a boiler on the plea that a boiler with full surface 

 takes up a greater space in the ship, if by doing away with such restriction a 

 saving can be effected in the fuel. 



The beneficial results which are attained by the greater size of boiler in relation 

 to the coal burnt and to the horse-power required can be shown not onlv by cal- 

 culation, but by example. In Her Majesty's ship ' Briton,' fitted with extremely eco- 

 nomic compound engines of Mr. E. A. Cowper's design, close upon two pounds per 

 horse-power per hour were burnt when the ship was making thirteen knots ; but 

 on being worked at ten knots the consumption fell to 1 ^^^ lb, of coal for the lesser 

 horse-power then used. 



I will now say a few words upon the engines. 



