The limits of space forbid more than a passing note of the triumphs of the engineer in torpedo craft, the light cavalry of the sea. With steamers of normal proportions, the speed and power depend largely upon, and increase with, the displacement. As has been stated, the maximum performance of large cruisers is now 23 knots on a tonnage of 4500. These particulars give a faint glimpse of the extraordinary problem which has confronted the torpedo-boat designer in driving hulls of, at present, about 150 tons at a speed which now approximates to 30 knots. With the brilliant record of success in this task, there will be linked always the names of Yarrow and Thornycroft in England, of Schichau in Germany, and of Normand in France. The achievement but recently of a British inventor, the Hon. Charles Algernon Parsons, in giving the Turbinia of 44.5 tons a speed of over 31 knots, has drawn the attention of engineers the world over to the possibilities of the steam turbine on the sea. This performance is phenomenal with such a displacement. The French Forban, of 130 tons, has made 31.2 knots, and a reported speed of 35 knots gives a Schichau boat her temporary laurels as the fastest craft afloat. A brief glance at the improvements which have made possible these extreme speeds in cruisers and torpedo craft will be of interest. The progress which has been made has been, firstly, in the economy in the use of steam arising from higher pressures and multiple expansion; secondly, in the reduction of weight, per horse power, due to increase in strength of materials and in engine-speed with the employment of forced draft—which was reintroduced by France—and the water-tube boiler; and, finally, in the application of a more efficient propelling instrument. The advances of half a century in propelling machinery are shown, in some respects, by Plates III and IV, which contrast, on the same scale, the side-wheel machinery of the United States war-steamer Powhatan, of 1849, with the engines of the United States torpedo boat Ericsson of to-day. The data of the former vessel are: horse-power, 1172; steam pressure 15 lbs.; weight of machinery per horse-power 972 lbs.; while, for the Ericsson, the figures are: horse-power, 1800; steam pressure, 250 lbs.; weight of machinery per horse-power, 56 lbs. This comparison, however, must be qualified by the statement that the older engine was for a steamer of about 3760 tons, while the torpedo boat is but 120 tons in displacement. The contrast lies, therefore, only in the reduced weight of material per horse-power developed and in the increased steam pressure, which, however, are in themselves most striking. V. THE GROWTH OF ORDNANCE.