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branch of the subject, a much greater difference of opinion is mani-fested than on that of “framing;” the object of the latter being prin-cipally to preserve the form of, and to give stiffness to, the former.The impolicy of using light plates in the construction of a vessel issufficiently obvious, for a very few additional tons make an almostimperceptible difference in the draft of water, but materially in-crease the strength and durability of the ship. The scope which isafforded in iron vessels for increasing the strength of the framing isalmost unlimited, and this by simple and evident means; but thequestion as to the best disposition and proportionate strength ofthe plates, involves so many difficult and nice enquiries, that expe-rience alone can satisfactorily determine it.

JOINTING.

There are two methods by which the plates are united. Oneof them (see Fig. 1 and 2, Plate 3) is, by bringing the edges of theplates together; a narrow plate, or strip, being placed inside to con-nect them by rivetting, thus forming a flush joint externally. Theother method (represented by Fig. 5 and 6) is, by lapping the edgesof the plates on each other, and rivetting them together. Theformer method corresponds with the carvel build, and the latterwith the clencher build, of timber vessels. In both cases the posi-tion of the plates is longitudinal with the ship, as in woodenplanking.

Plates united with flush joints will evidently sustain the greateststrain arising from a force applied to or affecting their horizontaledges, for the weight is entirely removed from the rivets, and thesupposed tendency to tear open those parts of the plates whichare weakened by the rivet holes, will only apply to the verticaljoints. With the lapped joints, on the contrary, nearly all thestrain produced by a weight applied to the edge, or rather margin,of the plates, is thrown upon the rivets with an apparent tendencyto cut or shear them off in the middle of their length, or, in otherwords, in the centre of the lap ; excepting in so far as this strain iscounteracted by the frames, (corresponding with the frames of awooden vessel,) which, at short distances apart, cross those joints.

In order to decide which of these two methods is the most ad-