A weight attached to an ordinary crane may be moved with the utmost facility; and it is well known that the employment of friction wheels furnishes a ready medium of conveyance for masses of iron and stone of the greatest magnitude.
No. XXVIII.
A bridge, portable upon a cart, with six horses, which, in a few hours' time, may be placed over a river half a mile broad, whereon, with much expedition, may be transported, horse, foot, and cannon.
NOTE.
A portable bridge, or rather ferry boat, calculated for crossing wide and deep rivers, was frequently employed in ancient warfare, and is still used for the conveyance of horses and passengers in many parts of Europe. The apparatus for this purpose may readily be attached to the banks of the most rapid river, as it merely consists in the employment of two ropes or wires, tightened by means of a winch, on which slide pullies connected with a large floating tank or waggon, that is afterwards intended to be employed as a medium of conveyance. The apparatus being thus prepared, a communication may readily be opened by means of two cords between the opposite banks of the river.
No. XXIX.
A portable fortification, able to contain five hundred fighting men, and yet, in six hours' time, may be set up and made cannon proof, upon the side of a river or pass, with cannon mounted upon it, and as complete as a regular fortification, with half-moons and counterscarps.
NOTE.