lengthened bow and a well-tapered run: an improved form of body by the use of which high speeds were obtained. In the case of commercial steamships the advantages of fine lines had already been recognized, and their designers had been free to give them a form which would allow of a high speed being attained; but in the case of war vessels designed to carry a broadside armament the limitations imposed by the heavily weighted ends had hitherto prevented other than bluff bows and sterns being given them. But now the subject of ship form came under general consideration, and the new conditions led to a more serious study of the laws governing the motion of bodies through water. Year after year the size of steamers grew.[150] And as with size the cost of construction and maintenance increased, the question pressed itself more and more clearly--what was the naval utility of such expensive and lightly armed vessels? Numerous attempts were made to produce a form of paddlewheel steamer which would carry a broadside armament comparable with that which a sailing vessel of the same burthen would bear. In 1843 the _Penelope_, 46 guns, was cut in halves at Chatham and lengthened by the addition of about 65 feet, in which space engines of 650 horse-power were installed. But the extra displacement failed to compensate for the weight of the machinery; the altered vessel drew more water than had been anticipated and, though various alterations were made to minimize the effects of this, the experiment was not a success and was not repeated. In ’45 a steam frigate called the _Odin_ was built by order of the Board. “The results aimed at in constructing this ship were--capability of carrying broadside armament; diminished rolling, in comparison with any war steamers then built; and less draught of water in relation to the size. These objects were accomplished; but as the position of the machinery and boilers is partially above the water-line, and the propellers are exposed to danger in broadside fighting, the ship is necessarily imperfect in these two conditions, as well as in the position of the sails; for in this case the proper place of the mainmast was occupied by the boilers, and consequently the centre of effort of the wind on the sails is in a wrong place.”[151] In the same year the _Sidon_ was laid down, the design being on the lines of the _Odin_ but modified in accordance with the ideas of Sir Charles Napier: with greater depth of hold and with machinery below the water-line. Iron tanks were placed in the hold for carrying the coals; by filling these with water when empty the steamer was kept at a more or less constant draught, a matter of considerable importance to the efficient working of the paddlewheels. In other respects, however, the _Sidon_ was unsatisfactory. She was so crank that the addition of ballast and a modification of her armament were necessary. Her engines were cramped, her boilers of insufficient