For examples of the use of bridges of this description we would refer to Caesar's celebrated bridge across the Rhine; the passage of the Scheldt in 1588 by the Spaniards; the passage of the Lech in 1631 by Gustavus Adolphus; the passage of the Danube in 1740 by Marshal Saxe; the great bridge across the Var during Napoleon's Italian campaigns; the passage of the Lech in 1800 by Lecourbe; the bridges across the Piava, the Isonso, &c., in the subsequent operations of the army in Italy; the celebrated passage of the Danube at the island of Lobau in 1809; the passage of the Agueda in 1811 by the English; the passages of the Dwina, the Moscowa, the Dneiper, the Beresina, &c., in the campaign of 1812; the repairing of the bridge near Dresden, and the passage of the Elbe in 1813, &c. _Rafts_ formed of timbers, casks, barrels, &c., are frequently used as military bridges. They may be made to bear almost any weight, and will answer for the passage of rivers of any depth and width, provided the current be not rapid. Where the bridge is to be supported by rafts made of solid timbers, these timbers should be first placed in the water, to ascertain their natural position of stability, and then the larger ends cut away on the under side, so as to present the least possible resistance to the action of the current. They are afterwards lashed together by strong rope or withe lashing, or fastened by cross-pieces let into the timbers, and held firm by bolts, or wooden pins. These rafts are kept in place by anchors and cables placed up and down stream. The roadway is formed in nearly the same manner as for a bridge supported on trestles. Empty casks, and other floating bodies, may be substituted in place of logs in the construction of rafts. For examples of the use of rafts in the construction of military bridges, we would refer to the passage of the Seine in 1465 by Count Charolais; the passage of the Meuse in 1579, by Alexander Farnese; the passage of the Vistula in 1704, the Borysthenese in 1709, and the Sound in 1718, by Charles XII.; the passage of the Adige in 1796; the passage of the Po in 1807; and the subsequent military operations in the Spanish Peninsula. Military bridges are frequently made of _boats_, and the ordinary river-craft found in the vicinity of the intended passage. Flat-bottomed boats are the most suitable for this purpose, but if these cannot be obtained, keel boats will serve as a substitute. When these water-craft are of very unequal sizes, (as is frequently the case,) two smaller ones may be lashed together to form a single support; they can be brought to the same level by means of stone ballast. The gunwales must be suitably arranged for supporting the balks, or else frameworks should be erected for this purpose from the centre of the boat. The arrangement of the roadway, anchors, &c., is the same as before.