There are three locks or entrances at the north end of the canal from the new harbour. Eastward, and below the city and wharves of Amsterdam, there is an enormous dyke to shut out the Zuyder Zee, pierced with three locks, besides sluices. These are built upon such a lake of mud as to require nearly 10,000 piles in their foundation. Thus the canal is approached by locks at each end, not for the purpose of locking up, but for locking down, as the surface water of the canal has to be kept twenty inches under low-water mark. To accomplish this, in addition to the locks and sluices, that can only avail at low tides, pumping power was required at the dyke, which bars out the Zuyder Zee. The three large centrifugal pumps by Messrs. Eastons, Amos, and Anderson, were constructed to lift together 440,000 gallons of water per minute. The works on this canal took nearly ten years to complete. They included the construction of branch canals to the several towns and ports on the borders of the lakes, which, although of smaller sectional area, exceeded the sea canal in their total extent. Mr. Vignoles, in his Presidential Address to the Institution of Civil Engineers,[91] from which most of the above particulars are taken, has stated that the Amsterdam Ship Canal resembled the Suez Canal, in passing through large muddy lakes, similar to Lake Menzaleh. (See Suez Canal). The ship canals communicating with Rotterdam are described by a recent writer[92] on the subject as follows:— 1. _The Voorne Canal_ running from Helvoetsluis through the island of Voorne to the river Maas. The resolution of March 9th, 1880, resettled the police regulations for this route; the maximum dimensions of vessels using it being—length, 110; beam, 13·70; draught, 6 metres. 2. _The Niewe-waterweg_, or direct entrance from the North Sea to the Maas, which is without sluices, and is cut through the Hoek van Holland, thus forming a new outlet to the Maas. Besides these approaches, there is another route to Rotterdam, to which great attention has been paid of late years, but the railway bridge across the river at Rotterdam causes a certain inconvenience to vessels using it. Vessels coming from the sea by the Hollandschdiep, enter the narrow passage of the Kil near the great Moerdyke railway bridge, and passing Dordrecht, the Maas is reached above the Rotterdam railway bridge. The Nieuwe-Haven, just above this bridge, is a most convenient port for small steam-yachts visiting Rotterdam. There are two other important ship canals, giving access from the river Schelde to the inland waters of Holland:— 1. _The Walcheren Canal_, about seven miles long, from the new port of Flushing to Veere, which place, formerly known as Campvere, was a free port of the Scotch, who had a factory or trade station there for 300 years, from the year 1506. The maximum dimensions for vessels using this canal are:—Length, 120; breadth, 19·75; and draught, 7·10 metres.