p. 524: “Fig. 2 represents an end view of the dock. The water-tight compartments A, A', B, B', and C, were all completely under the command of the powerful centrifugal steam-pumps, so that they could be separately filled or emptied in a very short time. In fig. 2, the dock is shewn heeled over to one side, for the purpose of getting at the bottom for repairing or cleaning it. This tilting over could be accomplished by filling the compartment A’, and emptying all the others, The watertight compartments were divided in their longitudinal direction into five separate divisions, making in all 25 water-tight compartments any one of which could be filled or emptied at pleasure; than affording complete command over the dock, and admitting of its being put into any required level, notwithstanding any irregularity in the distribution of the weight resting on the dock”.
P. 525: “Another great dock on Mr. Thomson’s principle has been erected at Callao, and is likewise answering its purpose admirably. It has lifted out of the water many large vessels, among others the United States man-of-war Wateree, and the Peruvian ironclad Independencia. The latter ship weighed, when lifted by the dock, 3300 tons. As the Callao Dock floats in an open roadstead, some apprehension was felt that the swell would cause too much movement to admit of ships being safely docked, but it has done its work in the most satisfactory way. None of these iron docks have doors or gates for excluding the water. The bottom part is made of sufficient depth and buoyancy to float the vessels clear out of the water, and the equilibrium of the dock is maintained during the time it is under water, for the purpose of admitting a vessel, by the great displacement offered by the hollow sides, AA' (fig. 2).”
Source
Chamber’s encylopaedia: a dictionary of universal knowledge for the people. Vol 10. Edinburgh, 1869.
