Page:The Development of Navies During the Last Half-Century.djvu/284

 40 in., and 60 in. in diameter, with a stroke of 2 ft. 3 in. The natural draught trial of the 'Bellona' took place in November 1890 in the North Sea, off the mouth of the Tyne, and in a run of six hours she attained a mean speed of 19.46 knots. The mean indicated horse power was 3557. Why could the 'Barham,' fitted with precisely similar engines, only keep up a speed on active service of 2 knots less? In all likelihood it was the human element that came into play and caused the difference. The stokers were not good enough for their work.

Here it may not be inappropriate to call attention to the rapidly diminishing weight of steam machinery for warships in proportion to the power demanded from it. In the year 1853 the 'The Duke of Wellington' was looked upon with pride by the whole country as a magnificent specimen of a steam line-of-battle ship. Her engines were of 1999 indicated horse power; they weighed 400 tons, so that each ton of engines gave 5 horse power, and each horse power was produced by 448 lbs. of machinery. In the 'Bellona' the horse power is 6000—estimated—and the weight of machinery only 270 tons, which gives approximately 100 lb. per horse-power. In torpedo boats the proportion is very much less than this, which all marine engineers have agreed to consider as extravagantly small. 'In the merchant service our tonnage laws encourage the shipowner to build roomy engine-rooms, and consequently the engines are not limited as to space occupied; hence a better design is possible than obtains in the navy. In our mail