IRON SHIPBUILDING.

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floors. In either arrangement there are two longitudinal angleirons worked fore and aft upon the top of the floors to give alongitudinal tie; sometimes a bulb iron is introduced between theangle irons, and rivetted to the intercostal plates, adding stillfurther to the longitudinal tie. When the keelsons do not riseabove the floors this bulb iron is scored down between the floors,of sufficient depth to lay hold of the keelson plates, to which it issecurely rivetted. When the keelson plates stand up above thefloors the bulb iron rests on the top of the floors; thus the keelsonplate and bulb iron are placed between the longitudinal angle ironsrunning fore and aft. In some cases the bulb iron is dispensedwith, the keelson plates Standing above the floors having simplyan angle iron on each side, resting on the top of the floors; in othercases a flat keelson plate, lying along the top of the floors, is workedon each side of the keelson plate under the angle irons, thus greatlyincreasing the longitudinal and transverse strength. In thesearrangements of keelsons there is no direct attachment betweenthe solid bar keel and the keelson.

We have already pointed out the difficulty of connecting themiddle-line keelson plate with the solid-bar keel, which must begrooved or rabbeted to take the keelson plate. However, if wemake the keel of two side bars we are enabled to place the keelsonplate between them, and by rivetting the garboard strake of platesthrough all, we have the keel and keelson united by several rowsof rivets, and likewise the indirect connection from the floorsbeing rivetted to the keelson and the garboard strakes. In someexamples the keelson plate is continuous, dividing all the floors,and this is considered the most convenient arrangement, both asregards the longitudinal strength and the effectual caulking of theside plates with the keelson.

When the keelson is stopped at the throat or top of the floors ahorizontal keelson plate is worked on the floors, connecting thekeelson by two continuous angle irons. In other cases the reverseangle irons of the floors are made continuous, being scored downinto the keelson, and the longitudinal angle irons of the keelsonsare placed in short lengths between the floors; while in somecases the angle irons are placed on the top closely together, in-stead of under the horizontal keelson plate. However, the verti-cal keelson plate placed above the floors is the practice usuallypreferred.