to 54,000,000 tons, to be raised on an average 16 feet, and it might happen that as much as 35,000,000 tons of that amount would have to be raised in one month. _The North Sea Canal_ was constructed for the purpose of facilitating the navigation of the Zuyder Zee, which, by reason of its numerous shallows, was very intricate and difficult, and in order that vessels might avoid the Pampus—a bank that rises where the =Y= joins the Zuyder Zee, and formerly compelled large vessels to load and unload a part of their cargoes in the roads. These obstacles frequently detained vessels for as much as three weeks.[89] M’Cullough spoke of this canal as “the greatest work of its kind in Holland, and probably in the world.”[90] It was begun in 1819, and completed in 1825. The length of the canal is about 50½ miles; the breadth at the surface, 124½ English feet, and at the bottom 30 feet, while the depth is 20 feet 9 inches. It is a tide-level canal, and is provided with two tide-locks at each end. Intermediately, there are two sluices, with flood-gates. The locks and sluices are double. The canal is crossed by about eighteen drawbridges. The cost of the undertaking was about million sterling. At the further end of the canal, at Niewdiep, a harbour was constructed, which has been very much frequented by the shipping of Amsterdam. About eighteen hours were formerly occupied in towing ships from Niewdiep to Amsterdam. _The Amsterdam Ship Canal._—The Amsterdam Ship Canal, designed by Mr. Hawkshaw, and Heer J. Dirks, of Holland, is a gigantic example of engineering compressed within a limited extent. The burgesses of Amsterdam had spent millions in improving the access to that great commercial port—first, on long previous operations in the Zuyder Zee, and, subsequently, on the North Holland Ship Canal, which stretches nearly due north from their city to the Helder, between which point and the Texel Island opposite is the entrance from the North Sea, which was then the only available channel for large vessels. The exigiencies of their trade calling imperatively for further improvements, the engineers furnished them with the design for a new ship canal, which reduces the navigable distance to 15½ miles, on a course about west from Amsterdam to the North Sea, available for larger vessels than formerly entered the port—and has provided a new harbour on the coast, with an area of 250 acres, bounded by breakwaters formed of concrete blocks set in regular courses, with 853 feet of entrance between the pier heads, and 26¼ feet minimum depth of water. The width of the sea canal is 197 feet at the surface, and 88 feet at the bottom; minimum depth, 23 feet; the locks are 59 feet wide, and of proportionate length.