An easier slope makes too sharp an inclination for the movable bridge; a steeper slope, which would make the bridge more nearly horizontal, would make, on the other hand, too difficult an approach for wheeled vehicles. THE “HALVE PONT” OR “PIJPER”. [Sidenote: III 60-64] In order to send the pontoon across, oars or a sprit sail can be used. The boat is then steered with an oar. Instead of using a pontoon with a movable bridge at each end, a “Halve Pont” (half pontoon) is the more generally in service. This is a boat with the bow of an ake and the stern of a pontoon. Sometimes this half pontoon is called a “Pijper”. Vehicles come an board the ferry over the stern and must leave in the same way. The vehicles must go ashore backward as they cannot turn end for end on the boat itself. If the current of the river be strong enough, it is utilized to carry the ferry back und forth by means of a cable. It is needless to say that large pontoons with a movable part at each end are used for the purpose. THE “GIERPONT”. [Sidenote: III 63] The “Gierpont” (flying bridge) allows a stream to be crossed as follows: The operating cable is attached at one end to an anchor put down upstream near the middle of the river and at the other end to the middle of the upstream side of the boat. The two ends of the pontoon are then fastened by special lines to the swinging cable. The pontoon can, in this way, be made to lie at an angle to the current. The component of the current normal to the side of the boat causes it to cross in describing an arc of a circle around the anchor as a centre and with the length of the cable as a radius. The speed is regulated by changing the angle which the axis of the pontoon makes with the direction of the current. In order to assist the action of the current on the pontoon, two or four lee-boards are fastened to the upstream side, that is: the side next to the cable, one or two of them serving to cross the stream to the right bank, the other one or two, to the left bank. In order to diminish the resistance of the cable in the water, it is supported by a few small boats called “onderlegaakjes”. A “Gierpont” of this kind works, among others on the Meuse, at the Gravenbicht-Rothem (Limbourg) and Grave crossings. THE KABELVEERPONT. [Sidenote: III 62]