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.
A _bridge-equipage_ made to follow an army in its movements in the field, is generally composed of light skiffs or batteaux, and the necessary timbers, planks, anchors, &c., for forming the roadway, and keeping the bridge in its position.