Between Suresnes and Lavallois the Seine is divided into two arms that are separated by the isles of Puteaux and Grande-Jabbe. The left arm was dammed at Suresnes, and here was established the sluice that allowed boats to cross the falls. The right arm was dammed at Levallois. A law of April 6, 1878, decided the increase of the depth of the Seine between Paris and Rouen in order to allow boats of a draught of ten feet to reach Paris, and to bring thither, without transfer, English coal and Bordeaux wines. The Consul-General of the Seine having offered to contribute toward the expense, on condition that such boats might have it in their power to ascend as far as to Bercy, a law of July 21, 1880, decided that the Suresnes dam should be raised about three feet in order to increase the anchorage. To effect this, the dams of 1867 were entirely rebuilt, the new ones being located at Suresnes, across the two arms of the river. At the same time, the existing sluice was doubled by another one that was larger and deeper. This great work was executed under the able direction of Mr. Boule, engineer in chief of roads and bridges, who has in charge the navigation of the Seine, outside of Paris, between Montereau and Poissy. The new sluice was constructed in 1880 and 1881, the dam to the left and the intermediate weir in 1882 and 1883, and the pass to the right in 1884. The width of the Seine at this point is about 820 feet, the length of the passes varies between 209 and 236 feet, and the two sluices occupy a width of 98 feet. In the construction of the three passes there were established, up and down stream, dikes about 325 feet apart, thus giving considerable space for the installation of work yards, and much facilitating operations. The new dam is closed by movable mechanisms of the kind invented by Engineer Poiret in 1834. The iron trestles that support the wickets are the largest that have ever been constructed, their height being nearly 20 feet and their weight 3,950 pounds. During freshets they are laid upon the bed of the sluice, and when the water subsides they are raised vertically. Upon these supports are placed swinging wickets, like those of mills, according to a system devised by Mr. Boulet in 1874, and which has been tried since then with success at the Port-a-l'Anglais dam near Paris. This system has likewise been successfully applied upon the Moskowa, below Moscow, and upon the Saone, at the Mulatiere dam, near Lyons.[9] [9] See SUPPLEMENT No. 264 for an illustrated description.