TRANSVERSE SECTION.

Practically, one ship within another.

From the keel to the water-line the hull is double, having an inner and outer skin of the same thickness of iron, 2 feet 10 inches apart, between which, at intervals of 6 feet, run horizontal webs of iron plates thus materially increasing the power of resistance both of the inner and outer skin. So far, therefore, as regards the portion of the vessel immersed when laden, the Great Eastern is, practically, two ships, one within another, as may be seen by the transverse section, [page 498], which exhibits the principle of her construction.[422]

The danger of a collision at sea is, thereby, greatly lessened, for if the outer skin is pierced, the inner one, remaining intact, as it would, except under very extraordinary circumstances, the safety of the vessel would not be endangered. Looking, also, at this arrangement in a commercial point of view, should the ship require ballast, the space between the outer and inner skin can be filled with water, so that whatever may be necessary in this respect can be obtained in a very economical and expeditious mode, to the extent in weight of 2500 tons.

Compartments and bulkheads.

Besides the principal bulkheads, there is in each compartment a second intermediate bulkhead forming a coal bunker and carried up to the main deck, which can on an emergency be closed. Two continuous tunnels run through the principal bulkheads near the water-line in one of which the steam pipes pass, and, under the most improbable circumstances of damage to the ship, arrangements are made, so that facility and ample time would be afforded to close them leisurely, and to make them perfectly water-tight.

Floor.

The floor of the ship is perfectly flat, the keel being turned inwards, and riveted to the inner skin. The bow and stern have additional strength imparted to them by strong iron bulkheads specially fitted to those parts of the ship.

Construction of the iron plates for hull.

Every distinct plate employed in the construction of the hull was moulded, beforehand, to the exact shape required by the situation it was to occupy. They were each gauged according to mathematical principles, wooden moulds being first prepared from the gauges, and the iron plates and angle iron accurately fashioned to correspond with the moulds.