ound, in a circular form, a number of small
pickets about an inch in diameter, and of the length required for the
gabion. Twigs are wattled between the pickets like ordinary basket-work,
and fastened at the ends by withs or packthread. Gabions are used in
forming saps, batteries, blindages, powder-magazines, and in revetting
the steep slopes of field-works.

The _fascine_ is a bundle of twigs closely bound up, from nine to twelve
inches in diameter, and from ten to fifteen or twenty feet in length.
The largest are sometimes called _saucissons_. In making a fascine,
straight twigs about the thickness of a man's finger are laid side by
side, and firmly compressed together by a strong rope or chain attached
to the extremities of two levers. While held in this position the twigs
are firmly bound together by withs or cords. Fascines are used in
constructing trenches, batteries, &c., and for filling up wet ditches.

The _sap-fagot_ is a strong fascine about ten inches in diameter and two
feet in length, with a picket inserted through the middle. It is used in
the double sap in connection with gabions.

_Sand-bags_ are usually made of coarse canvass. When filled with earth
they are some six or eight inches in diameter, and from eighteen inches
to two feet in length. From their perishable nature, they are used only
when other materials cannot be procured, and where it is important to
place the troops speedily under cover from the enemy's fire.

Bales of wool, cotton, hay, straw, &c., may be employed in sapping for
the same purposes as the above materials, when they can be procured in
sufficient quantity. Pork and flour barrels, which are usually in
abundance in a camp, are frequently filled with sand and used for
forming magazines, blindages, &c., in field-works.

A trench constructed in ordinary soil beyond the range of the enemy's
grape, is called a _simple sap_, or ordinary trench. The earth is thrown
up on the side towards the place besieged, so as to form a kind of
parapet to cover the men in the trench. The labor is here executed under
the supervision of engineer soldiers, by working parties detached from
the other arms. Fig. 50 represents a vertical section of a simple sap.

When within range of the enemy's grape, the _flying sap_ is resorted to
in order to place the workmen speedily under cover. In this operation,
gabions are placed in juxtaposition on the side towards the besieged
work, and filled with all possibl