These floating dry docks need only to be placed in a sheltered spot where the water is deep enough for the dock to be sunk so that the dock floor is a little farther beneath the surface than is the keel of the ship that is to be docked. When everything is in readiness—that is, when the keel blocks are properly placed and the incoming ship has been otherwise prepared for—water is allowed to enter the inner compartments of the dry dock. Gradually the whole thing sinks until only the two high sides are visible above the water. When it has sunk until there is enough water over the dock floor for the incoming ship to float in, the valves are closed and the ship is hauled in and made fast. Then giant pumps begin to expel the water that has been allowed to enter the compartments. This causes the dry dock to come once more to the surface, and as it rises beneath the ship the keel blocks press up on the ship’s keel, shores or bilge blocks are put in place, and when the ponderous float regains the surface there is the ship, high and dry, where men can scrape and paint and repair her or accomplish the other tasks assigned to them. It is interesting to watch the labours of a crew of workmen in a dry dock. If a ship looks large in the water, it looks startlingly gigantic in a dry dock, especially if one walks down to the dock floor and views the high bow or the overhanging stern from the level of the keel. Propellers from a distance look small, but with half-a-dozen men realigning their blades or working about them, they look huge indeed. [Illustration: THE _PARIS_ _The greatest French Merchant ship, operated by the French Line._]