During the past sixteen years or so the advance made in respect to the reduced ratio of fuel consumed to power developed has indeed been considerable. Before the period stated a vessel of say 700 tons carrying capability was not only much slower than the present-day vessels but the coal supply amounted to about 16 tons per day of 24 hours, whereas vessels are now being built of like size which attain an average speed of 9 knots, the consumpt of coal not being more than 6 tons per day. In 1872 the consumption of coal in vessels whose engines were worked at a pressure of from 45-lbs. to 65-lbs. per inch (the latter being then the highest pressure recorded), did not exceed 2½-lbs. per indicated horse-power per hour. This indicated an improvement in the marine engine during the previous decade, represented by a reduction in the consumpt of fuel by more than one-half the amount previously thought indispensable. Since 1872, there has been a further reduction in the average consumpt of fuel to the extent of 15 or 16 per cent., or in the average from 2⅛-lbs. to less than 1¾-lbs. per indicated horse-power per hour. As in the case of the vessels themselves, mild steel is largely taking the place of iron in the construction of marine boilers. The change has reduced the weight of this important item of machinery by about one-tenth, a great advantage in itself, as increasing the dead-weight capability of the vessel. The questions as to the reliable character of the boilers made of steel with respect to strength under working, and as regards corrosion, are being practically answered as time goes on; and, as in the case of ship structure, in a way very satisfactory for the new material. There is every probability that a further advance may soon be made in connection with marine boilers, in the way of constructing the shell in solid rings, thus doing away with the longitudinal seams. The strength of boilers is of course governed by the strength of the seam, and this is never above 75 per cent. of the solid plate. Hence, if solid shells are employed, an increase in pressure of about 25 per cent., with the same thickness of shell, may be obtained. Appliances are now being laid down in the Vulcan Steel and Forge Coy., Barrow-in-Furness, for this purpose. Improved appliances and modes of construction, no less than the change of material employed, have played a large part in rendering the boilers of modern steamships capable of being worked at the higher pressures now common. It is not possible, however, with the space at command, to treat of these; nor is it practicable to consider or even enumerate all the various improved fittings which in the aggregate so materially enhance the efficiency of boilers.