H. Skey. — Smokeless and Self -feeding Fim'^iace. 25 



vessel on the ways. To replace a vessel on the cradle, the operation is mei'ely 

 the reverse of that just described. 



The time occupied in raising a vessel after it is once fixed securely on the 

 carriage' is, in the case of small vessels, about twenty minutes, when the 

 hauling-up chain is worked single. With a large vessel the speed is found 

 to be about 15 ft. or 16 ft. per minute. In this case the chain is used double. 



Dolphins, consisting of clusters of five piles, are placed in convenient 

 positions for steadying a vessel going on the slip. At present only three of 

 the dolphins are completed, but three more are to be erected. The piles used 

 for these dolphins are of the jarrah wood of South Australia, which is believed 

 to resist the worm for an unlimited period. 



Art. IV. — On a Smokeless and, Selffeeding Furnace for Lignites and other 

 Fuels, and the Utilization of the Waste Heat. By H. Skey. 



(Ph Y.) 

 [^Read before the Otago Institute^ 12th August, 1873.] 

 At a time when the material wealth of nations is recognised as being so 

 intimately associated with those immense stores of power obtainable from the 

 fuels occurriug in the carboniferous deposits of past ages, any apology for 

 treating on the economic consumption of these fuels would be superfluous. 



It is evident that when fuel, of whatever kind, is consumed in such a 

 manner that there is no smoke evolved, and no cinders and xinoxidized 

 portions of the fuel left among the ash, then the theoretical conditions leading 

 to the evolution of all the heat force are present, so far as the furnace itself is 

 concerned ; while it belongs to the external arrangements, such as form of 

 boiler and flues, and perfection of engine employed, to determine how much of 

 this force is actually available, or, in other words, how much dutz/ can be 

 obtained from a given weight of fuel. 



Judging of the evaporating power of fuels by the amount of their fixed 

 carbon, their analyses show that the combustion of TS tons of Green Island or 

 Clutha coal should produce the same amount of steam as one ton of Newcastle 

 coal. If we take one ton of Newcastle coal and consume it in a given time 

 — say twenty-four hours — in an ordinary furnace specially adapted for the 

 combustion of this and other coals that coke and can be stirred, and then, in 

 the same furnace, attempt the combustion of the equivalent 1-5 tons of Green 

 Island coal in the same time, failure would be the probable result. For, in the 

 first place, the bottom of the fire and fire-bars would soon be covered with an 



D 



