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 to neglect these works altogether. At one crisis during his reign, Henry was threatened with a combination between France and the Empire; and, had such an alliance attacked him with all its resources, and seized the most favourable occasion for doing so, it is possible that the coast castles might have proved very useful. Upnor Castle on the Medway, and works at Portland, Hurst, Southsea, Calshot, and elsewhere were built under Elizabeth, who also founded Chatham Dockyard, on the site of the modern gun-wharf. The yard was transferred to its present situation about 1622. Elizabeth, too, improved the defences of Plymouth. Scilly was first garrisoned, and St. Mary's Guernsey, and Jersey were fortified in 1593, when the Treaty of Melun was concluded with France against Spain.

The first real dry dock in England was built at Portsmouth under Henry VII., the superintendent of the work being Robert Brygandine, Clerk of the Ships, and the business being completed in 1496. This dock was of wood and stone, but was not closed by a caisson, or a dock gate on hinges. What were called the "dock gates" were two walls of wood or stone, one within the other, which overlapped and partially blocked the entrance. When a ship, after passing between these walls, had been berthed, the space between the two walls was filled with earth, etc., and the dock then pumped out. Such, at least, are the only conclusions to be plausibly drawn from contemporary accounts of the manner in which this dock was utilised.

Although, as has been said, dockyards were established or improved, the number of dry docks in the country remained very