SECTION III.

Bridges of Boats.

The command of water communication being ofthe first importance to the operations of anarmy, a rapid and well disguised movementshould be made to secure all boats on therivers which it may be intended to pass, oruseful to navigate.

Boats, collected for the purpose of constructinga bridge, should be classed according to theirdimensions; and if a sufficient number of nearlyequal size can be obtained, no unequal boatsshould be used in the same bridge; for as vesselsof different magnitudes are immersed unequallyby like weights, and their gunwales not in thesame plane, the floor of a bridge laid on themwould be sunk unequally, and out of level. Ifthe boats be very capacious, though of differentsizes, the difference of vertical immersion willbe so trifling, even when the heaviest bodies arepassing in march, as not to affect, materially, thestability of the construction, from this cause, orto require any other precaution on account of