of the Odin, and why, it would be difficult to say, for the screw is less efficient against a head wind and sea, and therefore any form that would increase the evil of this, might reasonably be thought unsuitable. It is difficult to conceive that the object of this increase of beam was to give greater stability, as this could have been more effectually given by raising the centre of gravity of displacement, which might have been much higher with advantage to her form for speed; but form for speed seems to be a point of small moment with Mr. Fincham, as he ranges, in this respect, through considerable varieties. The entrance of this vessel is, however, better formed than that of the Odin.

Great Britain's case.-Lastly, it will be seen how vast a difference there is between the Great Britain's ratio of length to breadth and that of the Rattler, Rifleman, and Dauntless; and very considerable speed is obtained from her, though she rolls very much, and though her power, while nominally not so much as one horse power to three tons of measurement, is really less than this, fully justifying my conclusion, that our warsteamers would be improved by a greater proportionate length.

It has been thought, and I presume, acted on, that this vessel rolled so much, because she has not paddles; there is not a shadow of reason for this. The evil which is likely to accrue from such a belief will warrant a further discussion on the subject.

1st, Then, she is said to roll very much because she has not the paddle on the one side to resist immersion, and on the other to resist emerging, or in other words, these two would have tended to prevent so much inclination, or have given her greater practical stability; but this is to imply that she had too little stability, yet her

LECTURE V.

Shewing an accordance in many points between the principles already stated, and the "wave principle.”—We have seen how the several properties necessary for an efficient vessel of war are obtained. It remains now to shew how far the frigate on the "wave principle," which was proposed to the Lords Commissioners of the Admiralty is in accordance with these principles.

This frigate was originally intended to be of the Carysfort class, but finding that these vessels had not stowage for either a sufficient quantity of provisions or water, the dimensions of the design were increased eighty tons, then to equalize them it was proposed that the "wave" vessel should carry 16 tons more armament than the Carysfort's class; however, she is still nearer to her class than any other, therefore the Carysfort is taken for comparison in order better to form an estimate of their relative capabilities. This comparison of their properties may best he done in the order of their importance.

Comparison of the stabilities of the Carysfort and the "wave" vessel.-1st. We have seen that in order to obtain practical stability in a sufficient amount, it was necessary that the hydrostatic stability should be great, and that it should be derived from as small an extreme breadth as possible, by having a long straight of equal breadth and perpendicular sides within the limits of immersion and emersion, and from having the centre of gravity of displacement high; the following are the principal dimensions of these two vessels:

The relative hydrostatic stability of these two vessels is shewn in fig. 21, which is an exact copy of a drawing submitted to the Admiralty by Mr. Fincham.

Fig. 21, represents the areas of the water-lines, set off as ordinates, the first being the horizontal line, the others determining the curve, the perpendicular line being the draught of water. From this it may be seen that the area of the load water-line of the proposed frigate is considerably greater than that of Carysfort, consequently that her hydrostatic stability from this cause must be much greater; the hydrostatic stability of the wave vessel is also greater, because the centre of gravity of displacement is higher in her than in the Carysfort.

Distance of centre of gravity of displacement from the load water-lines :—

Again, the beam of the Carysfort being 40 ft. 7 in. and of the wave frigate but 39 ft. the moments of inertia of the former (to make her incline) will be greater, while, as may be seen from their midship sections, fig. 23, the moment of the water at her sides is less to resist this motion than in the latter, consequently the practical stability of the Carysfort will be reduced, and she will roll deeper than the vessel proposed.

Relative to the easy motions of the wave vessel. -- From page 13 it appears that easy motions are to be obtained, if in addition to great practical stability, there is, 1st, considerable keel, and a large flat at the fore-foot and

keel. From the dimensions it may be seen that the wave vessel has twenty feet greater length of keel than the Carysfort, and fig. 18, which has a wave curve to the floor, rising forward and aft, will shew that she has a flat at the fore-foot and keel.

2nd. When the sides are perpendicular within the limits of the immersion and emersion. Now this is the case throughout a great length of the wave vessel,-her midship section, fig. 23, will make this more apparent, while that of the Carysfort has the deficiency shaded.

3rd. When the volume of the solids of immersion and emersion is in some ratio inverse of the intensity of the action of the water upon them, fig. 22, is formed by the areas of the vertical sections being set off as ordinates; and from it the after-body of the wave vessel is greater, but as the intensity of the action of the water on it is less than that on the fore-body, so the terms above stated are fulfilled in her, but not in the Carysfort, whose fore-body is in excess.

Their relation as to fast sailing and weatherliness.— The wave vessel will possess these in a greater degree than the Carysfort, for they depend

1st. Upon having a smaller midship section, which is the case, see fig. 23; and

2ndly. Upon the ratio between their vertical longitudinal areas and areas of midship section; the design proposed being 20 feet longer than the Carysfort, though drawing a foot less water, will have 150 feet greater area of vertical longitudinal plane, then, having a smaller area of midship section, the ratio between these two planes must be much greater in her than in the Carysfort.

3rdly. Upon the fineness of the bow, and its suitableness for speed. The drawing submitted by Mr. Fincham, fig. 22, will shew that the wave frigate has a

finer bow than the Carysfort, and figs. 9, 10, and 11, will shew its greater suitability for going to windward, and for speed.

4th. Upon the form of the after-body for offering greater lateral resistance, and not occasioning negative resistance. That the lateral resistance of the afterbody of the proposed design must be greater than that of the Carysfort, is evident from the fact that its vertical planes are more nearly at right angles to the thrust of lateral resistance, than are those of the Carysfort; and that this form of after-body occasions less negative resistance, see Lecture II.

The wave form shewn to have the property of requiring little steering.—The property of requiring but "little steering," depending upon a vessel's having a lean forefoot, long and (comparatively) straight sides, a fine heel, and a full after-body at the water-line, the proposed vessel would require less steering than the Carysfort, as she has all these to a greater extent than her; while the property of being "easily steered," depends, (when the weights are properly placed) upon the power of the rudder (principally); this will be greater when the keel is fine, and when the after-body is full at the water-line, for when it is not full, an interference of the currents takes place, and the direct current upon the rudder from below is prevented; the after-body (at the water-line) of the wave vessel is full, the Carysfort is not so; see fig. 22.

Then that she would (notwithstanding her greater length) turn equally fast with the Carysfort, is very likely, as from the rake of her fore-body she is practically almost as short; then she was to have drawn two feet less water forward, but only one foot less water aft than her, while her comparatively circular after-body,