There is considerable skill displayed in the building of the arches of the range of vaults, and with the dim lights of the sperm lamps, burning--as it is not deemed safe to have gas in the vaults where spirits are stored--the vaults very much resemble the crypts under the cloisters in Westminster Abbey, or the vaults under St. Paul's. The method for hoisting cargoes from the holds of ships to the grading, which is level with the opening in the vaults is very perfect. The opening in the wall of the basin or docks is eighteen feet high, and large hogsheads can be hoisted and lowered at once into the vaults instead of being temporarily deposited on the quay. In the old times before steam had been discovered and these magnificent docks had been built, an East Indiaman of eight hundred tons took a month to discharge her cargo, or if of one thousand two hundred tons, six weeks were required for the labor, and their goods had to be taken from Blackwall to London Bridge in lighters, when they were placed on the quay exposed to dock rats and river thieves as goods are in New York, where the private watchmen on the rotten wooden docks are generally to be found in league with the thieves. At St. Katharine's Docks the time occupied on an average in discharging a vessel of three hundred tons is eight hours, and for one of six hundred tons two days and a half. In one instance one thousand one hundred casks of tallow were discharged in six hours, but of course this was unusually rapid work. One of the cranes in the St. Katharine's Docks cost about twenty-five thousand dollars, and will raise from forty to sixty tons at a time. There is a wharf attached to the St. Katharine Docks, which Parliament compelled the company to construct at a cost of nearly a million of dollars, and the warehouses will contain one hundred and ten thousand tons of goods and merchandise. The depth of water in the St. Katharine's Docks is twenty-eight feet at spring tide, at dead tide twenty-four feet, and at low water ten feet, so that vessels of eight hundred tons register are docked and undocked without the slightest difficulty. There is a water frontage and quays of one thousand five hundred feet in the St. Katharine Docks. The wharfage of the London Docks is one thousand two hundred and sixty feet in length and nine hundred and sixty feet in breadth. The capital of the London Docks company is about twenty-five million dollars in gold, and as many as three thousand laborers are employed in the London Docks in a day. The walls surrounding the London Docks cost sixty-five thousand pounds in construction, and all these walls are so high (nearly thirty feet,) that they present an impregnable barrier to thieves and depredators.