inches square on the end. Five continuous lines of these were laid on the boats two feet ten inches apart.
The flooring of the bridge, called chesses
, consisted of boards having a uniform length of fourteen feet, a width of twelve inches, and a thickness of one and a half inches.
To secure the chesses in place, side-rails
of about the same dimensions as the balks were laid upon them over the outer balks, to which the rails were fastened by cords known as rack-lashings
The distance between the centres of two boats in position is called a bay
. The distance between the boats is thirteen feet ten inches. The distance between the side-rails is eleven feet, this being the width of the roadway.
had to be constructed at either end of a
An angle of Fort Hell (Sedgwick) showing Gabions, Chevaux-de-frise, Abatis and Fraise.
From a Photograph.|
bridge, which was generally done by settling a heavy timber horizontally in the ground, level with the top of the bridge, confining it there by stakes.
A proper approach was then made to this, sometimes by grading, sometimes by corduroying, sometimes by cutting away the bank.