( 260 )

their horizontal sections expand up to the planeof floatation, or horizontal surface of the fluid inwhich the vessel floats. In cylindrical vessels,this only takes place up to the immersion oftheir horizontal diameter, A B, fig. 9, plate 8,after which,—that is, after they are half loaded—the section coinciding with the plain of floata-tion diminishes;* and the nearer the vessel ap-proaches to entire immersion, it’s descent in thewater becomes greater and greater, with everyequal augmentation of load;—which is just thereverse of what it should be. The bearing ofa vessel, of trapezoidal or boat-like shape, in-creases, steadily, up to the extreme power offloatation ;—and this has ever been consideredthe grand desideratum, in determining the con-figuration, and providing for the stability offloating bodies.

It has been remarked,f as a serious defect in

* Table, page 257, of the areas of the sections of a cylinderwhose diameter is 32 inches. '

f “ This ingenious contrivance affords the advantage ofgreat facility of transport with a proportionate power of bear-ing weight. But, on the other hand, it has, like all othercask-bridges, the disadvantages, that a bridge formed of them,on being passed by weighty objects, is subject to great undu-lating movements. Objects carried towards it by the stream,may, moreover, settle upon the conical ends, which, presseddown hy their weight and the force of the current, must