_CONVOYS._—A waggon with four horses occupies about sixteen paces; a mile will therefore hold about 117 waggons: but allowing a short distance between, each waggon in travelling, a mile may be said to contain 100 waggons. Waggons in convoy may travel from one to two miles _per_ hour, according to the roads and other circumstances. A great object in convoys is to preserve the horses as much as possible from fatigue. For this purpose, if the convoy amounts to many hundred waggons, they must be divided into divisions of not more than 500 each. Should it consist of thousands, it will be adviseable to divide them into _grand_ divisions, and then again into subdivisions of 500 each: by this means, and the time of departure being calculated by the following rules, each division may remain at rest, till just before its time of movement; and which will prevent the necessity of the latter part of a large convoy being harassed for a considerable time before its turn to move. RULE 1. _To find the time in which any number of waggons may be driven off_: Divide the number of waggons by 100, and multiply by the time of travelling one mile. RULE 2. _To find the time in which any number of waggons will drive over any number of miles_: To the time they take in driving off, add the time any one of the waggons takes to travel the distance. The different divisions of the convoy should be numbered, and obliged each day to change the order of their marching. Whenever the progress of a train of waggons is arrested by the breaking down of any one of them, or other delay, all the waggons in the rear of the stoppage, should immediately drive up into the first open space, to as great a number as the open space will hold; this keeps the convoy together and better under the care of the escort. The escort for a convoy should be divided into front, center, 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 five or seven miles per day. TEMPLEHOFT. _DISPART._—The dispart of a gun is the half difference between the diameter of the gun at the base ring, and at the swell of the muzzle. The general dispart of all guns is about the ¹/₅₆ part of their length. See the disparts of French and English guns under the word _Tangent Scale_. [Illustration: _Fig. 1._] _DISTANCES._—Inaccessible distances may be found several ways; the most correct of which of course is by means of proper mathematical instruments; which, however, are not always to be had in the field. The following different methods are laid down by several authors, where instruments cannot be had.