The escort for a convoy should be divided into front, centre, and rear guards; beside the divisions for the flanks, which should never be beyond musquet shot, or at most 400 yards from each other. The whole escort should never be so separated that they could not be collected in an hour. Under proper precautions against an enemy, a convoy of any size cannot travel more than ten or fifteen miles per day. _To_ CO-OPERATE, to put a well digested plan into execution, so that forces, however divided, may act upon one principle and towards one end. COOK, each troop or company has cooks, who are excused from other duties. COPPER. No other metal is allowed to the magazines, or barrels of gunpowder. COQUILLES _à boulet_, _Fr._ shells or moulds. They are made either of brass or iron; two are required for the casting of a cannon ball; but they never close so effectually as to prevent the liquid metal, which has been poured in, from running somewhat out of the part where they join. This excrescence is called the beard, which is broken off to render the ball completely round. CORBEILLES, _Fr._ Large baskets, which being filled with earth, and placed one by another along the parapet, serve to cover the besieged from the shot of the besieging enemy. They are made wider at top than at the bottom, in order to afford loop-holes, through which the men may fire upon the besiegers. Their usual dimensions are one foot and a half high, as much in breadth at the top, and eight or ten inches at the bottom. See GABION. CORDE, _Fr._ Cord, in geometry and fortification, means a straight line which cuts the circumference into two parts, without running through the centre. CORDEAU, _Fr._ a cord which is used in measuring ground. It is divided into toises, feet, and inches, for the purpose of ascertaining with precision, the opening of angles and the extent of lines. In wet weather a small chain made of wire is substituted to prevent mistakes that would necessarily occur, from the cord becoming shorter or longer, according to the influence of the weather. The technical terms among French Engineers, are Manier le _cordeau_, Pendre le _cordeau_, Travailler au _cordeau_. CORDON, in fortification, is a row of stones made round on the outside, and placed between the termination of the slope of the wall, and the parapet which stands perpendicular, in such a manner, that this difference may not be offensive to the eye; whence those cordons serve only as ornaments in walled fortifications. _The_ CORDON of the revetement of the rampart is often on a level with the terre pleine of the rampart. It has been observed in a late French military publication, that it might be more advantageously placed some feet lower; especially when there is a wall attached to the parapet, to shield the rounds from the enemy’s fire. CORDON, in military history, is a chain of posts, or an imaginary line of separation between two armies, either in the field or in winter quarters.