The Causes of Bad Shooting. Estimating Distances. Range-finding. Rule for Sighting. General Duties of Artillery Commanders. Target Practice. How Conducted. Projectiles Used. Kinds of Target. Night-firing.

THE CAUSES OF BAD SHOOTING.

1. Variation in the density of loading.

2. Bad aiming.

3. Faults in handling ammunition, fuzes, etc.

4. Variable weights of charges and projectiles.

5. Inability to judge correctly the position of the bursts of the shell.

6. Failure to take into account the age and condition of the powder.

7. Variable wind.

Variation in the Density of Loading.—This is beyond the province of the cannoneer, and need not, therefore, be considered.

Bad Aiming.—To obviate this, the men found to have the necessary quickness of hand and eye should be utilized for this work, though all should receive instruction in aiming. The sight should be carefully examined before each shot, the same amount of the target should be brought into the angle of the cross-wires, and a constant distance between the eye and the rear sight should be maintained.

Faults in Handling Ammunition, Fuzes, etc.; Variable Weights of Cartridges and Projectiles; Failure to Take into Account the Age and Condition of the Powder.—Cartridges should be weighed, gauged, and felt when received; otherwise there will be variations in range due to more or less powder, to the make of the cartridge, or to caking. If the cartridges of a battery vary much as to age, brand, etc. or if they have travelled much, it would be well, when opportunity offers, to break the lot up, mix the powder thoroughly, remake and reweigh them. Be careful to use the copper measures and funnels, which can be obtained from the Ordnance Department.

Time-fuzes are sometimes carelessly cut, or the safety-pin not removed.

Inability to Judge Correctly the Position of Bursts of Projectiles.—The needful correction in elevation and fuzes cannot be given unless it can be seen by the eye or glass, or by the aid of observers, how the shells are bursting. While no provision has been yet made therefor, a good telescope, with a tripod, and capable of being moved by a micrometer screw, should be supplied to each battery in service.

In making allowance for the wind move the sight into the wind; e.g., if the projectile is carried too far to the right, on account of the wind blowing from the left, move the sight to the left, and vice versa.

ESTIMATING DISTANCES.

The light, the state of the atmosphere, and the nature of the ground are the chief disturbing causes in estimating distances and admit of no rules.

The sun on one's back, a light background, water or snow to look over, ground that is uniform and offers no prominent points of reference, or when the air is particularly clear, as after a rain, tend to make objects appear near.

A dark background, the sun in one's eyes, undulating ground to look over, or when it is cut by ravines or covered by trees or dwellings, or seen dimly at evening and in misty weather, tend to make objects appear distant.

In estimating distance under the usual conditions:

Men's features can be distinguished at 300 yards, head-dress at 600 yards, movement of legs and arms at 1000 yards.

Infantry can readily be distinguished from cavalry at 1200 yards.

Individual men become vertical lines at 1500 yards.

Distinguishing between infantry and cavalry only by mode of motion at 1500 yards.

A mounted man looks like a speck or dot at 2000 yards.

One can perceive men and horses at 2200 yards.

One can count the windows of a house at 4300 yards.

By day the glittering of the sun upon the arms of troops in motion indicates the direction of their march. If the rays are perpendicular, they are moving directly toward you; if slanting from left to right downwards, they are moving towards your right, and vice versa; if the rays are intermittent and varied, they are moving away from you.

Dust raised by cavalry forms a high light cloud, by infantry a lower and denser one, by wheeled vehicles denser still.

RANGE-FINDING.

The range is found by sound, by observation, by taking measurements from the map, by means of range-finders, and by trial shots.

By Sound.—Multiply the number of seconds between burst of projectile and report of same by 370 to obtain the approximate range in yards.

By Observation.—As indicated in the rules given above regarding the appearance of objects.

By Taking Measurements from the Maps.—This can be done on a good topographical map on a large scale, taking care to fix thereon accurately the position of the target and also the position of the gun.

By Means of Range-finders.—No range-finder has been adopted for our service; but several instruments are now under consideration.

Whatever range-finder may be used, and with whatever care the range may be taken, errors will exist; but they may be reduced to a minimum by a good instrument and skilled observers.

Trial Shots.—If the range be doubtful or unknown, trial shots will be used, but it must be remembered that trial shots disclose your position.

Estimate the range, give the elevation indicated for it by the range table, and the necessary drift (or deflection), each unit of the deflection scale on the sight corresponding to ¹/₃₄₅[8] of the range, and proceed as indicated under Target Practice, page 379.

Sighting.—The nearer the eye is to the rear sight the better will the front sight be seen, and the finer can the sight be taken. The same distance should be taken for each shot, if possible. In setting the sight it is well to bear in mind that the deviation of the projectile follows the motion of the rear-sight point: thus, if it be moved up further than is required, the projectile will strike high; if it be moved too far to the right, the projectile will go too far to the right of the object aimed at. Also in allowing for the wind move the sight into the wind, i.e, in the direction the wind comes from.

GENERAL DUTIES OF ARTILLERY COMMANDERS.

THE CHIEF OF ARTILLERY.

The chief of artillery to the general commanding issues the orders for the distribution and concentration of fire, according to the phases of the battle and the plans of the general. As a rule, the method of carrying out these orders, the projectile used, the rapidity and order of fire, will be left to the commanders of groups of batteries.

THE CHIEF OF CORPS ARTILLERY.

The officer commanding the corps artillery designates the target for each of his battalions, and controls the fire of the corps artillery in accordance with the instructions he receives.

THE BATTALION COMMANDER.

Fire Control.—The commander of an artillery battalion prescribes the method to be used for finding the range, designates the target for each battery, and prescribes the projectile to be used, the rate and order of fire, and the concentration or distribution of fire on the targets in range. His orders and directions that cannot be given by voice or trumpet are conveyed by his staff or non-commissioned staff.

THE BATTERY COMMANDER.

Regulation of Fire.—This includes control over all the details of the service of the guns, the corrections in observation, deflection, the length of fuze, and the concentration and distribution of fire within the limits of a designated target that are necessary in order to obtain the most effective fire upon it.

The captain regulates the fire of his battery, and, if acting independently, he also controls it. He remains mounted or dismounted at pleasure, and places himself, as a rule, near one of the flanks and sufficiently close to the battery that his orders may be readily understood. The corrections for lateral deviations are generally intrusted to the chiefs of platoons.

Finding the range by the method designated, and the regulation of the fire according to the target, range, projectile, and observed effect, are intrusted to the captains of batteries, and it is only in exceptional cases that the battalion commander takes personal command in order to find the range or to regulate the fire.

Artillery fire is effective in proportion to its concentration. The long range of the guns permits a concentration of their fire on many different points without change of position. When practicable, the groups that are intended to fire on the same target should be placed under the control of one officer. In the advance-guard action the artillery of the assailant covers, and the artillery of the defence opposes, the deployment and advance of the advance-guard infantry. In the preliminary stages of a battle and the commencement of the artillery duel the fire is usually directed on the targets immediately opposite the batteries engaged; as soon as portions of the enemy's artillery-line are subdued the fire is concentrated on the different targets in succession, taking them in the order of their relative importance; during the preparation and delivery of the assault the fire of the assailants is concentrated against the point of attack; the fire of the defence is concentrated against the attacking infantry as soon as it shows itself.

Fire should be directed against batteries that are changing positions, and in order that this brief opportunity of inflicting serious damage may not be lost a part of the batteries of the defence should be especially instructed to open fire on hostile batteries while limbering or in movement without waiting for orders.

The defence generally offers more favorable opportunities for long-range fire than the offence, but whether advantage is to be taken of these opportunities must be determined by the general commanding, who will have to decide whether the effect of the fire will compensate for the partial or complete disclosure of the position that it involves. Ordinarily artillery should avoid opening fire at a greater range than 3000 yards. Beyond this distance it is difficult to observe the effect of fire even with good glasses. Longer range fire is used in exceptional cases against objects that are clearly seen and are of considerable extent, such as villages, camps, or large bodies of troops. Ineffective cannonades at long distances, and shelling woods or other localities not positively known to be occupied by the enemy, should not be permitted. The position from which fire is first opened may necessarily be much less than 3000 yards, in order to obtain view of the enemy.

Firing over friendly troops should be avoided as much as possible. Batteries that support an assault from a distance continue their fire upon the point of attack until it becomes dangerous to the assailants; they then either increase the range considerably in order to cover the ground beyond, or they direct their fire on other points of the enemy's line. Artillery does not fire at long ranges from positions in rear during a pursuit, on account of the danger to the pursuing troops; in such cases it should advance rapidly and endeavor to establish itself on the flanks of the enemy's line of retreat, where it will find the most advantageous positions.

As a general rule, the fire of artillery is directed against that arm of the enemy which at the time is predominant, or which is capable of inflicting the greatest loss on the infantry or cavalry that the artillery is supporting. During the artillery duel the artillery generally avoids firing at the other arms; but if large bodies of infantry or cavalry appear in open ground within effective range a portion of the guns should be directed upon them.

TARGET PRACTICE.

The artillery that first finds the range will have a great advantage in the artillery duel, and in all cases its correct establishment is the first condition of accurate shooting.

Observation of Fire.—Correct observation of the effects of fire is necessary in order to make the required corrections, and is indispensable to good shooting. It can only be acquired by much practice under the varying conditions of the wind, light, state of the atmosphere, background, foreground, and nature of the target, and is rendered more difficult in action by smoke and the liability of mistakes when more than one battery is firing at the same target. For medium as well as long ranges a good field-glass is required.

As a rule, the observation is limited to ascertaining whether the shots are short or over. The observation of direct hits is unreliable except at very short ranges, or when palpable effects are produced in the enemy's ranks, limbers are blown up, or there are other manifest indications of the effect produced. When a target is on a height or behind a parapet, it is possible to distinguish hits on the slope of the hill or on the parapet, and to estimate correctly the error in range of the projectiles that fall short. There are no means of estimating the error in range of the projectiles that fall beyond the target, except when a battery is on an elevation and firing at a target on a plane below it; here shots striking beyond the target may be observed and the error estimated.

When several batteries are firing at the same target, and it is difficult to distinguish the individual rounds, a fire by battery will give a group of shots that may be recognized.

The observation of the fire will be facilitated by the reports of an officer or non-commissioned officer stationed some distance in advance and outside one of the flanks of the guns.

Smoke.—When the wind is across the range and blows the smoke in front of the guns, it will be difficult to correctly aim and properly observe the effects of the fire. In the case of a single battalion this inconvenience may be diminished by increasing the interval between the batteries, or may be avoided by advancing the batteries in echelon from the leeward flank so that the smoke of each windward battery will drift behind those to the leeward of it. This last measure has the disadvantage of making the leeward batteries conspicuous against the white background of smoke, and besides is not always practicable, especially when the position is on the brow of a hill. If neither of the above expedients can be adopted, and it is not possible to sufficiently increase the interval of time between the guns in each battery to permit the smoke to blow away, the fire by battery or platoon may be used, or the battalion commander may order the battalion to fire by piece, commencing on the leeward flank. When several battalions are together, as large intervals as possible should be left between them, or, if the ground permits, the battalions should be advanced in echelon from the leeward flank, in order to diminish or avoid the inconvenience of smoke drifting across the range.

When the target cannot be seen on account of smoke which hangs in front of the guns, or on account of fog, rain, or darkness, the pieces may be aimed by means of auxiliary targets.

Finding the Range.—This is the work of the battery commander. He and the range party precede the battery to the position, and as soon as the exact position of his battery is indicated by the battalion commander he observes carefully the position of the target, its nature and extent, and estimates the range by means of a map, any source available, or range-finder (all if possible), very carefully, and especially so when the fire is to be over the heads of other troops.

He estimates the ranges to other points within the field of fire which might subsequently become targets, and observes:

Nature and position of any covering mass.

Zones of ground which ought to be cannonaded.

Nature of soil in vicinity of target, if possible.

Exact part of target on which to aim his guns in determining the range.

If the range be determined only by observation, it will be necessary to use trial shots.

In finding the range by trial shots it is of great importance that the object and the particular part of it to be fired at should be clearly understood. In order to avoid mistakes the captain may direct one of the officers or non-commissioned officers to rectify the aim of all the guns after they have been pointed. Care should be taken that all the guns are aimed at exactly the same point; that the exact elevation ordered by the battery commander is used, and not changed until ordered by him; and that the result of every shot is carefully observed.

The range can be more accurately and quickly found when each battery has a different target and one directly in front of it to fire at. If the target is a long line, it should be divided into as many sections as there are batteries to fire at it, and each captain should select a gun or object in the part assigned him. In such case the battalion commander can compare the elevations obtained by the several batteries, and if they agree, and the observation of the fire indicates good results, it is fair to assume that the range is correct. When several batteries are to open a long-range fire on a small target, the battalion commander generally designates the battery, and preferably that on the leeward flank, to find the range. Batteries that come into action at short distances from the enemy's line generally find the range by firing salvos at a prominent point of the target.

As a rule, percussion-shell are used to find the range, and all the guns of a battery are aimed at one point of the target; if shrapnel with percussion-fuze be used, the same principles apply.

In firing at intrenchments, however, the fire may be distributed from the first, even for obtaining the range, as the hits, as a rule, can be easily observed.

The enemy's flanks are designated, and the guns in his batteries are numbered, as he himself would designate or number them.

The firing to obtain the range should be slow and deliberate, and ample time afforded to observe each shot and make the necessary corrections.

When a battery unlimbers near another battery already in action and opens fire upon the same target, it should obtain the range from the latter.

The duty of finding the range generally devolves upon the captain of each battery, even when several batteries open fire upon the same target. Whenever several batteries open simultaneously to find the range of a target of limited dimensions, the fire of each battery must be concentrated upon an entirely distinct point, and all of the points must be far enough apart to enable each battery commander to distinguish the fall of his own projectiles from those of the neighboring battery.

It is only in very exceptional circumstances that the battalion commander would take personal charge of the firing of his battalion in order to establish the range himself.

Trial Shots.—A percussion-shell is fired with the elevation corresponding to the estimated range at a clearly visible and sharply defined fixed point of the target.

If the first shot strikes short, or beyond the target, the range for the second is either increased or decreased, according to the case, so as to throw the shot beyond or short of the target.

These corrections are generally made as follows:

When firing at short ranges,	100	yards.
When firing at medium ranges,	200	"
When firing at long ranges,	400	"

Such firing is pursued until two consecutive shots fall, one short of and the other beyond the target, which establishes "the long bracket, or fork."

No round should be taken as a basis for correction if there is any doubt as to the reliability of the observations.

A mean range is taken from those two which determined the long fork for the next shot, and then another shot is fired at a range obtained by taking the mean of the last range and the one of the long fork whose shot fell on the opposite side of the target. So proceed until the target is enclosed between two consecutive shots only 50 yards apart. This is called "the short fork, or bracket." Then a verifying group, generally a shot from each gun is fired with the elevation corresponding to the mean range of the short fork. If four out of six of the shots fall short, the range is established; and if shrapnel-fire is then resorted to the range is still further reduced by 50 yards. When the range has been measured, and not estimated, the short fork may be obtained from the first two shots.

If the elevation has not been obtained as above indicated, at known ranges shrapnel-fire may commence, as if the range had already been determined by shell-fire; at unknown ranges the trial-shot firing with shrapnel is conducted as with shell; that is to say, the elevation is increased or reduced from shot to shot (by 100 yards at short range, 200 yards at medium range) until the target is enclosed between at least two accurately observed shots, one over and the other short. The difference is reduced as already described until the mean of the short fork is obtained. The large fork should be established by percussion-shrapnel, and then fire time-shrapnel.

During the ranging platoon commanders indicate exactly the point to aim at, see that the sights are properly set, especially during the first rounds, observe similarly the time-fuze, and make any necessary correction for deflection; which deflection pertains to a particular gun, and is not carried to another. Bear in mind that each unit of the scale for deflection corresponds to ¹/₃₄₅ of the range for sights now used.[9]

After the ranging has been completed, if a gun makes a constant error, the platoon commander may be permitted to change the elevation ± 25 yards.

The general rule for vertical and lateral corrections is: when the deviation exceeds the amount of mean dispersion, a correction should be made after one round; but if it is equal to or less than this several rounds are fired with the same elevation or deflection, and a correction made according to their mean deviation.

The battery commander indicates the length of fuze for time-shrapnel.

If firing at artillery and all the guns are equally conspicuous, the fire should be directed upon one of the central guns, otherwise at the most conspicuous gun; if the wind is blowing across the range, the fire should be directed upon the most conspicuous gun on the windward flank. If firing upon masses of troops, the fire should be directed upon the centre of the first line; if firing upon skirmishers, it should be directed first upon one point, then another, close in front of the line.

PROJECTILES TO BE USED.

Percussion-shell.—For ranging, against material, and in default of shrapnel against living targets.

Against troops behind loopholed walls,—if it explodes after passing through, use percussion-shrapnel,—stockades, abattis, barricades, entanglements, etc.

Direct hits are necessary when it is used against guns, limbers, earthworks, obstacles, etc., and its effects are then due to percussion, penetration, and the explosive force of the bursting-charge. When used against men or horses, it is burst on first graze close in front of the target, and its effects are then produced by its splinters. The smoke made by the large bursting-charge of the percussion-shell aids the observation of fire.

The effect of projectiles with percussion-fuzes is dependent on the nature of the ground in front of the target; soft marshy ground, hollows, and cuts diminish its effect, while hard smooth ground increases it.

Percussion-shell gives the best results when the fire is concentrated. It can sometimes be advantageously distributed, provided that several guns keep a part of the target under superior fire.

Shrapnel with Time-fuze is used against all living targets, provided they be not close behind cover, troops behind slight cover, such as shelter-trenches, banks, etc., gun-pits and epaulments, balloons, batteries limbered up or in action, ammunition and other trains, unless firing particularly against the material. With the fuze set at zero it can be used for close defence in default of canister.

The effect of shrapnel is due to the penetration of its bullets and splinters; this penetration is small, and it is therefore employed against men and horses only. It has a combination fuze and can be made to burst either in the air or on the first graze, and can therefore be made independent of the nature of the ground in front of the target. Made to burst high by means of its time-fuze, it can be used against living targets behind cover, against which percussion-shell could have but little effect.

Burst the projectiles 50 yards short and about 6 yards (at medium ranges) above, the object aimed at. A rough rule for height of burst is height of burst in feet=the number of hundred yards in range. In firing at troops behind cover, such as banks, rising ground, or earthworks, burst the projectiles about 25 yards, or less, in front of, and from 7 to 10 feet above, the cover.

Shrapnel with Percussion-fuze is generally used against moving targets, for rapid firing, and for firing over friendly troops; against enemy's troops in a village or woods; metal shields; and in cavalry combats as soon as the ground which was masked by one's own troops becomes cleared.

Shrapnel gives the best results when the fire is distributed, a part of the target being apportioned to each gun. When the time-fuze is used, it will often be advisable to vary the elevation and length of fuze in each battery so as to cover about 200 yards in depth, and thus bring the enemy's supports and reserves, as well as his front line, under fire.

Canister is used against living targets at close ranges. Its effect is largely diminished when the ground in front of the guns is rough or soft, and particularly when covered with brush or standing crops. It would be used against cavalry at 500 yards, and against infantry at 300 yards.

Order of Fire.—The order of fire is habitually by piece in each battery, and usually commences on the leeward flank. It is the most effective, as the errors in the service of any one gun can generally be observed, and therefore corrected.

Salvos, or the fire by battery, may be used to find the range under circumstances that render it difficult to observe a single shot, to avoid the inconvenience of smoke, and occasionally, instead of rapid fire by piece, to take advantage of quickly passing opportunities.

The fire at will is only used in the defence of the guns at very short ranges.

The fire by piece from one flank of a battalion to the other may be used to avoid smoke, or to enable the field-officer commanding the battalion to take personal charge of the firing in order to find the range under difficult circumstances, or to regulate the fire in exceptional cases.

The fire by platoon is only used to facilitate the observation of fire under exceptional circumstances that permit two shots to be observed more easily than one, and also to increase the interval of time between successive discharges, to allow the smoke to drift away, without diminishing the amount of fire. In most cases the fire by piece or by battery is preferable to it.

Rapidity of Fire.—The rapidity of fire is dependent on the range, the circumstances of the action, the facilities for the observation of the fire, and the amount of unexpended ammunition.

Slow Fire is used at long ranges and for obtaining the range, and generally in the commencement of the action and during the artillery duel; it is also used in prolonged actions, and when the ammunition is running short. The interval between successive shots should not be less than 30 seconds, and may be slower.

Ordinary Fire is used when the fire is effective, but when the circumstances of the action do not demand a rapid fire. It is at the rate of 1 shot every 20 seconds, or, in a six-gun battery, 6 rounds in 2 minutes.

Rapid Fire.—The rate is about one round in 7 seconds; it should be sufficient to enable the effect of a shot to be observed before firing the next one.

The range being accurately known, it is used: when the enemy's batteries are coming into action; when there is a very favorable target; when a rush is made to pass a defile; when covering the advance of one's own artillery; when the decisive infantry attack is about to take place; when the advance is checked during a critical situation; when the opportunity to fire is very fleeting; at short ranges.

The instant the necessity for rapid fire ceases to exist the fire should revert to the ordinary rate.

TARGETS MOVING TOWARDS THE BATTERY.

The range is found by trial shots, the elevation being increased or reduced by stages of 100 or 200 yards, depending on circumstances.

As soon as a shell is observed to fall not too short (within 100 yards of the advancing target) all the guns fire a round rapidly.

If infantry is being fired at, each subsequent round should have its range diminished by 100 yards; if cavalry or artillery, at a trot or gallop, it should be diminished 200 and 300 yards respectively.

TARGETS MOVING FROM THE BATTERY.

Two elevations differing by 100 yards are obtained as before; with the lower of the two a salvo of shrapnel is fired from all the guns in the battery, the proceeding is then repeated, and so on.

TARGETS MOVING OBLIQUELY AND ACROSS THE FRONT OF THE BATTERY.

If the target is of great length, aim at the head of it; if not of great length or moving rapidly, aim in front of it.

Under certain circumstances it is advisable to ascertain the range of points in the line of march of the target. When the moving target reaches one of these points, fire rapidly. Infantry cover 1½ yards a second at a quick walk, and artillery and cavalry 2 yards a second at a quick walk, 4 yards at a trot, and 6 yards at a gallop. By multiplying the rate per second of the target by the time of flight of a shell, we obtain the distance the target has moved over during the flight of the shell.

INDIRECT FIRING.

In firing at an object which cannot be seen from the gun several methods are employed, depending on the circumstances of the case.

1st. Plant a picket for each gun on the crest of the ridge whence the object to be fired at can be seen; behind the ridge line a second picket with the first picket and the object, run the guns up to any convenient distance in rear of the pickets, and get them in line with each pair of pickets; the deflection-scale can be used to remedy any small lateral errors. The elevation is given by means of a gunner's quadrant or pointing-arc if available. If not, set a stake in front of the line of wheels and in rear of the muzzle, and immediately in the plane of sight, its height equal to the vertical distance from the top of the trunnion-sight to the ground; (for 3.2-inch gun 3' 10".68; for 3.6-inch gun 3' 11".16). Then give the rear sight the elevation corresponding to the range and aim at this point, using peep-and cross-hairs. An observer is necessary, and by means of his reports the necessary corrections are given until the elevation and length of fuze have been determined. After each shot care must be taken to run the gun up to the position it occupied before firing.

2d. In Firing at Troops in Ravines and Hollows when they cannot be seen from the battery select a stone or bush, or any distinguishable object, on the side of the ravine or hollow as an auxiliary target, and obtain the elevation and fuze for it; then by means of the lateral deviation of the sight change the direction of fire, and elevation and fuze if necessary. In such a case an observer on the flank or some commanding position is absolutely necessary.

3d. By Means of a Compass.—Select a distant auxiliary mark that can be seen from the gun; from a position as near the gun as possible obtain the angle between the auxiliary mark and the object; construct this angle at the gun and mark the position of the wheels; give elevation as previously explained, and make corrections by reports from an observer. The Germans have a device for measuring this angle: it consists practically of a horizontal graduated arc bearing an arm containing two vertical sights. It is placed on the gun, set at the angle indicated by the compass, and the gunner sights at the auxiliary object.

NIGHT-FIRING.

For night firing, or when there is much fog, a luminous aiming-point is required. This may be readily obtained by the use of a bull's-eye lantern. Soften the light by placing paper or other material over the glass, and draw thereon two right lines intersecting at right angles at the centre of the glass. At a convenient distance in front of the gun and in the plane of fire place the lantern on a post so that the point of intersection of the lines shall be at such a height that when the rear sight is at zero, and the axis of the gun horizontal, it can be directly aimed at. Establish a plumb-line between the lantern and the gun so that the plumb-line, the point of intersection of the lines on the lantern, and the object aimed at are in the same vertical plane. (The above requirements must of course be completed during the day, when the object can be seen.) Give the rear sight the elevation corresponding to the range, and aim at the point where the plumb-line covers the point of intersection of the two lines on the glass of the lantern.

If a gunner's quadrant or pointing-arc be available, simply determine and mark accurately the direction for each piece, and give elevation by either instrument.

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