Chapter III: Instruction in Aiming

Section =15=.--General Remarks.

=1. Principles of Instruction.=--The instruction of recruits in aiming and firing should be carried out on a systematic method. The progression of training must in every case lead by gradual steps from simple to more difficult stages. Instructors must necessarily teach by explanation to some extent, but they must limit explanation to short and very clear statements, and rely chiefly upon practical demonstration for training their men. With regard to results they must aim at insuring _accuracy_ in every stage of training before they permit men to attempt _rapidity_. Any sacrifice of accuracy for rapidity must be guarded against carefully and corrected at once. Short daily lectures, followed by questions to test the knowledge of men, should form part of the scheme of instruction.

=2. Progression of Instruction in Aiming and Firing.=--The progressive stages of instruction in aiming and firing are set out in a definite order in this and the following chapter which deal respectively with these subjects. Instructors, however, are not bound to follow this order, and may modify it at their discretion.

=3. Concurrent Instruction in Aiming and Firing.=--Aiming instruction should proceed simultaneously with firing instruction and muscle exercises to develop speed and facility in handling the rifle and steadiness in firing it. The following scheme of concurrent instruction in aiming and firing is suggested for the guidance of instructors, who may modify it at their discretion:

AIMING FIRING

A. A.

1. Aiming at bull’s-eye target 1. Correct position for firing
with the foresight and standing.
backsight.

2. Explanation of trajectory 2. Practice in loading
and and the need for elevation by unloading in standing position.
sighting.

3. Laying an aim with Legret 3. Adjustment of sights and
Aim-Teacher.[8] standard tests of same.

4. Rules of aiming. 4. Trigger-pressing and
adjustment of sights with
rifle rested.

5. Common faults in aiming
and their results.

6. Aiming at bull’s-eye target
from a rest.

7. Test of aim by triangle of
error.

8. Aiming at figure targets
and at ground.

B. B.

9. Aiming practice (_a_) at 5. Practice in assuming the
bull’s-eye and (_b_) figure targets different firing positions with
with (i) rifle rested, (ii) rifle standard tests of same.
unsupported.[9]

10. Test of aim by aiming-disc. 6. Practice in combining
aiming with trigger-pressing.

11. Aiming and trigger-pressing 7. Practice in muscle exercises
combined, practised with in the standing and lying
eye-disc or aim-corrector. firing positions.

12. Practice in firing at
bull’s-eye target on miniature
range and 30-yards range.

C. C.

13. Explain influence of side 8. Practice kneeling and
wind. sitting firing positions, and
taking cover in these positions.

14. Explain aiming-off for
wind, and wind table for 500
yards. Apply tests in aiming-off
for wind.

15. Explain aiming-off for
movement. Practise same on
miniature range and check
with aim-corrector.

D. D.

16. When accuracy in deliberate 9. Practise firing over and
firing at elementary and round cover in various firing
service targets is assured, explain positions at elementary and
the nature and practical service targets.
value in warfare of snapshooting
and rapid firing.

17. Practise gradually quickening
the aim with aiming-disc,
and on miniature and 30-yard
ranges. Apply grouping and
application tests.

E.

18. When the recruit has shown proficiency in grouping, deliberate firing, and snapshooting, on the miniature, 30-yard, and open range, explain and practise adjusting long-range sights.

19. Practise aiming from a rest at figure targets and ground.

20. Practise snapshooting and rapid fire at figure targets and ground on miniature, 30-yard, and open range.

21. Practise aiming-off for movement at figure targets on miniature range.

_Note._--(1) Ample time should be devoted to trigger-pressing and declaring the point of aim on discharge. This instruction may conveniently be given indoors.

(2) The aiming position should not be taught until aiming has been taught.

(3) Aiming and trigger-pressing should not be combined until trigger-pressing has been taught.

(4) The test for trigger-pressing should not be applied until after the lying position has been taught.

(5) The miniature range may be used when assurance of reasonable proficiency has been ascertained by means of the aiming discs.

(6) The 30-yards range with service ammunition may be used when the results on the miniature range are satisfactory.

(7) Grouping on the open range may be commenced when the recruit is able to make good groups on the 30-yards range.

=4. Selecting Rifles for Recruits.=--(i) Before the instruction of recruits in aiming and firing commences they must be fitted with rifles having long, normal, or short butts, according to the build and preference of the men. The choice should be made after tests carried out in the standing and lying positions, and should be based on the readiness with which the firer brings his rifle up to the firing position, and aligns his sights without letting his nose and mouth come into close proximity to the thumb and fingers of the right hand.

(ii) The principal consideration is _the distance of the nose from the shoulder_, and it is as a rule the broad-shouldered and long-necked men that require the long butts. A bad trigger release, due to incorrect holding of the small of the butt, will often result from the use of too short a butt. _The butt selected should be the shortest which can be used comfortably when firing, both standing and lying down, in the correct positions._ These rules for fitting rifles of course apply also to non-commissioned officers.

=5. Sights.=--Special care must be taken that _the sights of any rifle used in aiming instruction are in perfect order_. Instructors must inspect the sights frequently to insure that they are _correctly adjusted_ in accordance with his orders.

=6. Appliances for Aiming and Firing Instruction.=--(i) The following appliances will be needed by instructors:

(_a_) Diagrams showing position of sights correctly and
incorrectly aligned.

(_b_) The Legret aim-teacher.

(_c_) Aim-corrector.

(_d_) Aiming-disc.

(_e_) Aiming-rest.

(_f_) Firing-rest.

(_g_) Charger and dummy cartridges.

(_h_) Measuring rings [see Sec. 49, para. 6 (xi)].

=Note.=--_The method of using the aim-teacher, aim-corrector, and aiming disc, and grouping gauges is described in the Appendix. Aiming- and firing-rests are described in “Musketry Regulations,” Part II._

(ii) =Aiming Marks.=--(i) The aiming marks to be used in aiming instruction will consist of elementary bull’s-eye targets for the early stage of instruction, and of a variety of figure targets similar to those used for firing practices for later stages.

(ii) When the habit of accuracy has been acquired in aiming at elementary targets, service targets will only be used and care will be taken that there is no falling off in accuracy owing to the shape and comparative invisibility of these targets. A list of figures for use on miniature ranges will be found in the Appendix, VII, para. 5.

Section =16=.--Aiming Instruction.

=1. Rules for Aiming.=--The instructor will explain the following rules, and demonstrate the results to be anticipated from common errors in aiming:

(i) The backsight must be kept upright.

(ii) The left or right eye, according to the shoulder from which the man shoots, must be closed.[10]

(iii) Aim must be taken by aligning the sights on the centre of the lowest part of the mark, the top of the foresight being in the centre of, and in line with, the shoulders of the =U= or =V= of the backsight (Fig. 11).

_Note._--The low point of aim is essential in firing at service targets, as it facilitates a clear view of marks which are usually difficult to discern, and also because service targets are frequently in movement towards the firer, thus necessitating aiming down to alter elevation owing to their decreasing distance.

=2. Method of Instruction.=--(i) When these principles have been mastered, the instructor will loosen the sling of the rifle, adjust the sights for any given range, and aim from a rest at the target, taking care that _his eye is immediately above the butt-plate_. It will be convenient to use a sandbag aiming-rest to steady the head during the aiming.

(ii) Having aimed, he will make each recruit observe the correct method of aligning the sights on a mark. Each recruit in turn will then be made to align the sights on a mark, after which the instructor will verify his aim, point out errors, and explain how they would have affected the accuracy of the shot, and how they are to be avoided. For example, Fig. 11 shows incorrect sighting, the rifle being inclined to the right, aimed to the right, and aimed too low, the top of the foresight being well below and to one side of, instead of in the centre of and in line with, the shoulders of the =U= of the backsight. The obvious result of these errors would be to fire low to the right of the mark.

(iii) The instructor should also make recruits verify their comrades’ aim under his supervision as above described, and point out any errors which may have been made. _Extreme accuracy of aim must be insisted on even during the first lesson._

(iv) =Long-Range Sights.=--In aiming with the long-range sights a similar procedure to that which is described above will be pursued, but the eye will be placed _about 1 inch behind the small of the butt_, and the top of the head of the dial sight will be seen in the centre of the aperture (Fig. 12). _Unless special care is taken, lateral error will be made in centring the head of the dial sight._

Section =17=.--Common Faults in Aiming.

=1. Taking too much or too little Foresight into the U or V of the Backsight.=--(i) It should be explained that a fine or half sight will cause the bullet to strike with Mark VI ammunition about 5 inches and 3 inches lower respectively, and with Mark VII 7 inches and 4 inches lower respectively per 100 yards of range, than when the correct sight is taken.

(ii) The following method will be found useful to guide the soldier in taking the correct amount of foresight: Lay the edge of a piece of paper on the upper edge of the backsight cap, when the sight will appear as shown in one of the subjoined diagrams. A piece of cardboard laid on the cap and held in place by an elastic band will answer the same purpose.

Incorrect: Incorrect: Correct
Too much Too little
foresight. foresight.

=Fig. 13.=--FAULTS IN AIMING.]

=2. Inaccurate Centring of the Foresight in the Notch of the Backsight.=--The soldier should understand that this inaccuracy will deflect the muzzle of the rifle to the side on which the line of aim is taken. For example, if aim be taken over the right edge of the notch the direction of the line of fire will be to the right of the line of sight.

=3. Inclining the Backsight to one Side.=--In this case the bullet will strike low and to the side towards which the sights are inclined. The resulting error will be considerable at long ranges.

=4. Fixing the Eyes on the Foresight and not on the Object.=--(i) If the eye is focussed on the foresight, the firer _will retain only a blurred image of the target_. This may not affect the result of his shooting at the distinct stationary bull’s-eye target, but when firing at troops in neutral-tinted uniforms, whether stationary or in movement, or at natural features of ground, _it is essential for fire effect that the eye should be focussed not on the foresight, but on the target, which must be watched closely while firing_.[11]

(ii) Unless service targets are closely watched while aiming, the firer will be apt to lose them altogether, or see them as a blurred image at the moment of firing, with consequent loss of fire effect. For this reason it is of great importance that recruits should, from the earliest stage of their training, be taught to aim at service targets _with the eye focussed on the target_, and not on the foresight. If early stages of instruction were confined to the aiming at the bull’s-eye target, the fault of focussing the eye on the foresight in aiming might be contracted owing to the distinct nature of this mark, which makes it possible to aim at it with the eye fixed on the foresight. (See Appendix, VII., para. 2.)

Section =18=.--Triangle of Error.

=1.= The following method of recording a triangle of error will be employed to test proficiency in aiming, and to demonstrate the errors which will arise from inaccuracies.

=2.= The rifle will be placed on an aiming-rest, and pointed at a sheet of blank white paper, fixed to any convenient object at a distance of about 10 yards from the muzzle. A second aiming-rest should be used to steady the head in aiming.

=3.= A marker will hold an aiming-disc flat on the paper, the front facing the instructor. The instructor will align the sights on it correctly, and its position on the paper will then be marked by a dot made with a pencil passed through the hole in its centre.

=4.= Each man in succession will then be called up and ordered to look along the sights, but without touching the rifle, and when he has satisfied himself as to the correctness of the aim, the disc will be removed. It will then be replaced on the paper as before, and moved at his direction until the lower edge of the bull’s-eye is brought into the line of sight, when its position will be marked as before. This operation will be repeated three times in the case of each man, and the points thus fixed will be joined in such a way as to form a triangle.

A. _Vertical_

=Fig. 14.=--TRIANGLE OF ERROR]

=5.= The position of these points in relation to the _instructor’s aim_ will expose any constant error in aiming. If the recruit’s aim is below that of the instructor, it shows that he has taken too full a sight; if above, that his sighting has been too fine; if to the right, that the foresight was on the left of a perpendicular drawn through the centre of the notch; if to the left, _vice versa_.

=6.= The position of the points in regard _to one another_ will show _inconsistency_. If the triangle is formed so that its greatest side lies vertically on the paper, it proves that the soldier’s principal fault is inconsistency in respect of _the amount of foresight taken up into the line of sight_ (Fig. 14, A); if the greatest side of the triangle lies horizontally it shows that his principal error is _inaccurate centring of the foresight_ (Fig. 14, B).

=7.= If any one of the sides of the triangle exceeds ⅓ inch from the instructor’s aim, the recruit will be noted for further instruction.

=8. Aim-Corrector.=--The aim-corrector will also be used to enable the instructor to supervise the soldier’s methods and test his progress, the aim being taken from an aiming or firing rest.

Section =19=.--Aiming at Service Targets, Aiming at Ground, and Marking Down the Enemy.

=1. Aiming at Service Targets.=--From an early stage in his instruction the soldier’s eye must be trained to discern and aim at service targets. Elementary instruction may be carried out in barracks, on the range, on ground in the vicinity of barracks, or on miniature ranges. Figures should be used representing men in the various firing positions at different distances in the open, or partly behind cover.

=2. Aiming at Ground.=--(i) Service targets will frequently consist of ground or cover occupied by the enemy. Fire-unit commanders will verbally indicate such targets to men, who must be trained to recognize and fire at them. This training should be carried out concurrently with instruction in aiming at figures and marking down the enemy--the latter practices to some extent will also train men to aim at ground.

(ii) Practice in aiming at ground may be carried out on miniature ranges, as described in Sec. 72, para. 2 (i), as well as in open country. It must always be carried out under practical conditions, and will include aiming at various ill-defined targets, such as a spot on a bare hillside or a stretch of grass-land. Targets will be indicated verbally by the instructor, and recruits will aim at them with rifles on aiming-rests. The instructor will then criticize each man’s aim and correct faults. Practice in aiming at ground will prove a useful preparation for training in recognition of targets (Sec. 45) and fire discipline (Sec. 47).

=3. Marking down the Enemy.=--(i) It is of the utmost importance that soldiers should be trained to mark down the exact position of an enemy seen to occupy ground or cover. This duty refers equally to individual enemies at close range and to hostile troops at longer ranges. Individual soldiers will mark down the enemy within close range, and fire-unit commanders and observers at longer ranges. If the position marked down affords concealment from view without protection from fire, fire may be opened after the range has been ascertained or estimated. If it affords protection from fire, the range should be ascertained or estimated, and fire-units or individual men should remain ready to open fire the instant the enemy exposes himself or resumes movement. Delay in opening fire in the latter case will lead to the loss of a favourable opportunity (see Practices, Nos. 3 and 4, pp. 217, 218).

(ii) =Method of Instruction.=--Instruction will best be carried out on the ground or on the miniature range as described in Chapter X. When carried out on the ground a fatigue-man will be sent out to the front, and directed to move from cover to cover to the front of the class which will be provided with rifles on aiming-rests. At each halt, when the fatigue-man has taken cover, recruits will note the point on the ground or cover which conceals him, and take aim at it. After an arranged interval the fatigue-man will expose himself to view, and remain stationary while the instructor criticizes each man’s aim and corrects faults.

Section =20=.--Aiming-Off for Wind.

=1. The Wind-Gauge.=--_The use of the wind-gauge is not the normal means of making allowance for wind under service conditions._

=2. Judging Strength and Direction of Wind.=--The soldier should be taught to discriminate between mild, fresh, and strong winds, or winds blowing ten, twenty, or thirty miles an hour. The strength of the wind may be judged partly by sensation and partly by its effect on natural objects, such as clouds, water, trees, crops, hedges, bushes, undergrowth, dust, and smoke. The soldier may judge the direction of the wind, as front, rear, side, or oblique, by turning his face fully towards the wind.

=3. Wind Deflection Table for Side Winds= (=Right-Angle Winds=).--The following figures give the approximate deflection of the bullet due to winds of varying direction and velocity at different ranges, and provide a rough guide for aiming-off for wind which is sufficiently accurate for practical purposes:

+-------------+-----------------------------------------------------+
| | Strength of Wind. |
| +-----------------------------------------------------+
| Range. | Mild. | Fresh. | Strong. |
| | Miles per hour, | Miles per hour, | Miles per hour, |
| | 10. | 20. | 30. |
+ ------------+-----------------+-----------------+-----------------+
| | Deflection. | Deflection. | Deflection. |
| 500 yards | 2 feet | 4 feet | 6 feet |
| 1,000 ” | 3 yards | 6 yards | 9 yards |
| 1,500 ” | 6 ” | 12 ” | 18 ” |
| 2,000 ” | 12 ” | 24 ” | 36 ” |
+-------------+-----------------+-----------------+-----------------+

=Note--Oblique Winds.=--For oblique winds the approximate deflection at the above ranges may roughly be estimated as _half that of a side wind of the same velocity_ and allowance in aiming-off may be made accordingly.

=4. Exercises in Aiming-Off.=--(i) Having memorized the approximate allowances for side and oblique winds of varying direction and velocity, as stated in para. 3, the recruit will next be taught to make allowance in aiming-off for wind at a full-length figure target on the range, according to the strength and direction of the wind which is actually blowing, or which may be supposed to be blowing, as given by the instructor. In carrying out these exercises the recruit should be taught to aim-off with reference to the breadth of a full-length figure target, which is rather less than 2 feet wide. Thus the amount of allowance will be measured as one breadth, two breadths, etc., to right or left.

=5. Orders for Aiming-Off.=--Finally, the recruit must be exercised in aiming-off at all ranges according to orders, the amount of allowance being given as so many times the breadth of the target indicated, or so many times the width of the intervals between targets consisting of close formations. The amount of allowance may also be indicated by the use of auxiliary aiming or description points (Sec. 45), as, for instance, a tree or bush, the lateral distance of which from the target equals approximately the required allowance. When none of these methods of indicating allowances are possible men must be taught to aim-off so many feet or yards to the right or left of the target, these measurements being taken as representing the lateral distance between the sight of the rifle and the target aimed at.

=6. Method of Indicating Errors.=--In aiming-off exercises it is necessary to employ a fatigue-man at the target to indicate the correct point of aim with a marking-disc _after_ each aim taken by the recruit, which to commence with should be done with a rifle on an aiming-rest. He will carry out the duty according to previous instructions as to the correct point of aim for each exercise. The amount of allowance made by the recruit will be observed by the instructor with an aim-corrector, unless an aiming-rest is used. The recruit will be made to note his errors, which will be criticized by the instructor.

=7. Instruction on Miniature Ranges.=--Instruction in aiming-off can be carried out on miniature ranges, as described in Chapter X (see Practice No. 2, p. 227).

Section =21=.--Aiming Up and Down.

=1. When to Aim Up and Down.=--The rifle will be aimed up or down to increase or reduce elevation at all ranges when there is no time to alter sights, as, for example, in firing at targets in movement, in repulsing a charge at close range, in case of surprise, when very slight alterations of elevation are seen to be necessary, as the result of observation of fire, and to avoid frequent small changes of sighting which lead to loss of fire effect. _Correction of sighting in individual firing at close range is seldom possible in war. Therefore aiming up and down is the normal means of altering elevation in firing at targets within close range._

=2. Rules for Aiming Up and Down.=--There is no fixed rule for aiming up and down. As a general rule aim should be directed at a point not more than 3 feet above or below the six o’clock line, according to the position of the target beyond or short of the zone for which the sights are set. The degree of allowance in aiming up and down will depend on the rate and direction of movement and the range of the target, and will be a matter for individual judgment. _If the difference between the range and the sighting exceeds 200 yards it will be best to alter the sighting._

=3. Exercises in Aiming Up and Down.=--To practise aiming up and down, under conditions approximating to those of service, the sights should first be fixed for a given range, and then fatigue-men or standing-figure disappearing targets disposed at various ranges should be alternately brought into view for short periods of time, representing troops in movement. Men should be told whether targets represent retreating or advancing troops, and aim up or down accordingly. Aim maybe criticized by using aiming-rests or aim-correctors.

Section =22=.--Aiming-Off for Movement.

=1. Instruction.=--Instruction in aiming at moving targets will be carried out during the latter portion of preliminary training. It will consist of practice in shooting at crossing targets on 30 yards or miniature ranges (see Chapter X). The pace of movement should be regulated as far as possible in strict accordance with that of service targets (see Practice No. 2, p. 217).

=2. Crossing Targets.=--This term is applied to targets moving across the front of the firer, either at right angles from either side, or obliquely towards or away from him to either side. Such targets are not as a rule met with in battle except in the case of surprise, ambush, or a sudden encounter. Crossing targets may be met with by cavalry and infantry patrols, and by scouts during reconnaissance. _Fire will rarely be effective at a single man moving across the front at more than 300 yards range, or at a single horseman beyond 500 yards._

=3. Method of Aiming at Crossing Target.=--(i) When firing at crossing targets aim will first be taken on the object. Then, following it sideways, the aim will be carried in advance of the object, and kept in front of it at the desired distance until the rifle has been fired. The distance to which aim should be carried in advance of the target will vary according to the range, rate of movement, direction of movement and wind. For this reason no fixed rules can be laid down regarding aiming-off in firing at crossing targets. Fire effect will depend upon the judgment of individual men and fire-unit commanders, and on the fruits of practical experience.

=4. Rules for Aiming-Off for Movement=--(i) =Targets crossing Front at Right-Angles.=--The following general rules will serve as a guide in firing at crossing targets at close range _moving at right-angles across the firer’s front_.

(_a_) Up to 500 yards range, aim should be taken--

About 1 foot in front per 100 yards at a single man walking.

About 2 feet in front per 100 yards at a single man doubling.

About 3 feet in front per 100 yards at a single horseman trotting.

About 4 feet in front per 100 yards at a single horseman
galloping.

Thus, at 100 yards a soldier should aim about the breadth of a man in front of an individual walking, and at 200 yards about a horse-length in front of a single horseman trotting.

(_b_) Beyond close range aim should be taken _at the head of a body of troops moving to a flank_.

(ii) =Targets crossing Front Obliquely.=--The general rules regarding aiming up and down laid down in Sec. 21, para. 2, apply also to crossing targets moving obliquely towards or away from the firer. _In firing at such targets, allowance must be made for elevation as well as for aiming-off._ At short range both allowances will be made by individual men. At longer ranges men will allow for aiming up and down, and when necessary fire-unit commanders will allow for aiming-off in fire orders.

(iii) =Targets moving directly Towards or Away from the Firer.=--In aiming at an object moving _directly_ towards or away from the firer, allowance for elevation will usually be made _by aiming up or down_--not by waiting to alter sights (Sec. 21, paras. 1 and 2).

Section =23=.--Practice in Rapid Adjustment of Sights.[12]

=1.= This instruction should be carried out concurrently with instruction in loading in the various firing positions. Frequent small changes of sighting lead as a rule to loss of fire effect, and may be avoided by aiming up or down. _But when there is time the sights will be adjusted for every alteration in the range, and aim will be taken at the lowest part of the mark._ It is essential that men should be trained to adjust their sights accurately and rapidly, and that this power should become to all intents and purposes instinctive, so that this vitally important duty on which fire effect in a large measure depends will be carried out by the soldier with certainty in moments of the most extreme stress and excitement.

=2. Training in Rapid Adjustment.=--Instructors will frequently test their squads in setting their sights rapidly and accurately. They will give orders for aiming or firing at definite targets, but without naming the range, and require their squads to adjust their sights before they bring the rifle to the shoulder, judging the distance for themselves, which will help to make the careful adjustment of sights, which is essential for fire effect, habitual to the soldier. Adjustment of sights will also be practised under the same conditions in connection with the movement of the firer or the target, represented by fatigue-men.

=3. Rules for Adjusting Sights.=--(i) =To Adjust the Backsight.=--Hold the rifle in the loading position (Sec. 27), so that the lines on the backsight can be seen clearly. Press in the stud (or studs) on the side of the slide with the left or right hand; move the slide until the line is even with the place on the leaf giving the elevation for the distance named, taking care that it is firmly fixed. _Charger-Loading Lee-Enfield Rifle._--Loosen the clamping screw with the thumb and forefinger of the right hand, move the slide until the top is even with the line on the leaf giving the elevation for the distance named, and then tighten the clamping-screw.

(ii) =To Lower the Backsight.=--Press the stud or studs inwards with the left or right hand, and draw the slide backwards as far as possible. _Charger-Loading Lee-Enfield Rifle._--Loosen the clamping-screw, lower the slide to the bottom of the leaf with the firefinger and thumb of the right hand, then tighten the clamping-screw.

(iii) =Fine Adjustment of the Backsight.=--(_a_) _S.M.L.E. Rifle, Marks III and IV._--Press the stud on the slide with the thumb of the left hand till the worm-wheel can be easily revolved; turn the worm-wheel with the thumb-nail of the right hand until the required elevation is obtained. The stud must not be pressed to such an extent that the worm-wheel is entirely disengaged from the rack.

(_b_) _Other Marks._--Turn the fine adjustment screw with the forefinger and thumb of the right hand until the line on the leaf is level with the line on the fine adjustment scale giving the required elevation.

(iv) =To Adjust the Long-Range Sights.=--Hold the rifle in the loading position, so that the dial can be seen clearly. Move the pointer to the place on the dial giving the elevation for the distance named, and then raise the aperture sight.