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GROUP XXVI. 47 between these is filled, and the upper part of the embankment is made with earth and sand. The slopes are first covered to a thickness of about one meter with clay, and then sheathed with stone work to about the highest reach of the waves. The higher parts are covered with sods; the work stands uncommonly well, without being affected by the waves of the heaviest storms. The longer of these dikes measures about five thousand meters, three thousand six hundred and thirty-seven meters of it in tide water, with an extreme variation of tide of six and nine-tenths meters. The whole dike was necessarily completed in one summer season. 54. J. F. W. Conrad, Haarlem, Netherlands. LOCK WILLIAM III. Report.—This is an admirable example of the method of hydraulic construction peculiar to Holland. It is economically planned and thoroughly built. Though, of great size, ade quate to the entire traffic of the North Holland Canal, it is built on a wooden floor supported by a forest of piles of Norway pine driven through the mud to the hard ground. 55. H. S. J. Rose, The Hague, Netherlands. RIVER IMPROVEMENTS OF THE NEW MEREWEDE. Report.—It is an example of the methods by which Dutch engineers overcome the con stantly-recurring difficulties arising from the deposit of silt and the formation of ice dams in their rivers. These difficulties increased until the necessity for relief became of national importance. The map shows the principle adopted, consisting in giving a regular width to the river proportionate to the quantity of its flow. As a consequence, the action of the current secures in most cases a regular depth of channel for navigation. The width of the stream is regulated by the use of jetties (of sunken cribs of osier wicker work) thrown out from the banks. A special drawing gives all the details of these constructions. 56. A. K. P. F. R. van Hasselt, Hilversum, Netherlands. DESIGNS FOR FOUNDATIONS^ FOR THE PIERS IN THE RAILWAY BRIDGE AT ROTTERDAM. Report.—Commended for the good conception of its most interesting details and for its thorough execution. The piers of the railway bridge over the Maas at Rotterdam stand upon filled caissons, which were sunk by the aid of compressed air to the hard bottom through from nine to ten meters of soft mud. The works were made under the general man agement of N. F. Michaelis, of ’s Gravenhage (The Hague), Director of the Netherlands Railways, with the assistance of—1st, the above-named Engineer van Hasselt; 2d. M. Simons, of Rotterdam, State Railway Engineer; and 3d, Thr. L. A. Sandberg, of Rotter dam, State Railway Engineer. 57. J. Strootman, Assen, Netherlands. DRY DOCKS AT THE HELDER. Report.—These works are extensive and complete. Great engineering difficulties had to be overcome. They are very well worthy of attention. 58. The Amsterdam Canal Co., Amsterdam, Netherlands. DESIGNS AND MODEL OF CANAL FROM AMSTERDAM TO THE NORTH SEA. Report.—Commended for its grand conception and thorough execution. The Amster dam North Sea Canal is the largest work of its kind after the Suez Canal. It has been ten years in progress, and will be completed in about two years more. A large harbor of refuge of sufficient capacity for the largest vessels is being constructed at its outlet into the North Sea.