BBB  , is termed a

curve The stresses at a transverse section due to bending are obtained from the usual formula M =y, where M is the bending moment, I the moment of inertia of the section about the neutral axis, y the distance from the neutral axis of the point at which the stress is required, and p the intensity of stress . In calculating I, a deduction from the area of plating in tension is made for rivet holes, and only the continuous longitudinal portions of the structure are assumed effective in resisting bending . The stresses • obtained by this method undergo considerable variation with class and size of ship . As regards the former, it is evident that the actual straining actions upon a ship necessarily vary with the type;- and the stresses allowable, as calculated on a uniform basis of applied forces, must vary accordingly . The variation due to size is less obvious, but it is clear that the larger the ship, the less is the probability of encountering waves as long as herself ; and, moreover, the proportion of height to length of the largest waves is generally-less than that assumed . For these reasons greater calculated stresses are allowable in large ships than in small ships or in those of moderate size . The limiting stress frequently adopted for small ships is 6 tons per sq. in., which may be increased for portions in tension to 8 tons with high tensile steel ; on the other hand, the calculated stresses in the largest vessels frequently exceed 8 tons compressive and to tons tensile . The above method is that now universally adopted for comparing the stresses in ships caused by longitudinal bending; although imperfect, it affords a reasonable basis of comparison between the longitudinal strengths of vessels, especially when, as is generallyon Torpedo-Boat Destroyers (see Trans . Inst . Nay . Archs., 1905) . The principal dimensions of the " Wolf " are—length 210 ft., breadth 21.7 ft., draught 5 3 ft., and displacement 36o tons, with a coal capacity of 8o tons .

Two sets of experiments were made—(i.) under a hogging moment when supported in

dock on two cradles to ft: wide, spaced 26 ft. apart centre to centre, and equidistant from the ship's centre of gravity, bunkers empty ; (ii.) under a sagging moment when supported by similar blocks 120 ft. apart, bunkers full . The distribution of weight and buoyancy had previously been determined for each case so that the pressures on the blocks and the bending moments caused thereby could be accurately; obtained . When thus supported the water-level in the dock was gradually lowered; and for successive water-levels spaced 6 in. apart the extension or compression of the plating was measured at various points of the structure by Stromeyer's strain indicators; the vertical deflections at various points of the length were also recorded . The observations were repeated several times, and the following are the general results: (a) In the sagging condition the neutral axis was actually situated 755 ft. above the keel; the calculated distance was 7 8 ft. de-ducting rivet holes in parts in tension and 7 7 ft. without such deduction . In the hogging condition the observed height was 7.2 ft., those calculated as before being 7 5 ft. and 7 6 ft . All shell and deck plating, gunwale and keelson angles, and the side girders and angles were included in the calculation for the moment of(inertia . The calculated and observed positions of the neutral axis are thus in fairly close agreement .