UC-NRLF 7M 1M.7 V REESE LIBRARY UNIVERSITY OF CALIFORNIA. l^eceived /V^/is^f > ,Q~J^~ ? Accessions No . which are furnished with steel points, fold together so that the picket may be carried like a lance. Each picket weighs about 31b. 5 oz., and is 5 feet 6 inches long when folded. One of the pickets (called the A picket) is fitted with a move- able crosshead and with a brass button to take the S hook of * The earlier patterns of picket now obsolete were One picket of tubular steel with iron points, furnished with white enamel leather discs having black crosses on them. Two pickets of male bamboo shod with steel furnished with leather disca as V 10 the metallic cord. This picket carries a flag with a black cross on a white ground, and takes one of the picket-straps. It has a small strap 011 one leg to go round the B picket when carried by No. .2 mounted. The other two pickets are identical, except that one (the B picket) carries a flag with a single black vertical line on a white ground, while the other (the C picket) has a flag like the A picket, and takes the second picket-strap, THE PICKET BUCKETS. The Mark IV buckets are of brown leather. They are in sets of 2, one for each stirrup, so that the picket may be carried on either side of the rider, as may be found convenient. The large buckets take two pickets each, the small ones one picket only. Each bucket is fitted with a loop, through which the stirrup leather is passed, and with a strap for attachment to the stirrup iron. The buckets receive the lower ends of the tripod pickets, the upper ends being slung by a strap to the arm of the rider. Buckets Marks I, II, and III are obsolete. 11 \ CHAPTER II. METHOD OP CARRYING THE EQUIPMENT BY A MOUNTED PARTY. A MOUNTED range-finding party consists of No. 1 the range- taker, No. 2 the assistant, No. 3 the horse-holder. The equipment is carried by Nos. 1 and 2 as follows : No. 1 carries the instrument in the case strapped over the left shoulder so that it may rest behind his right elbow just clear of the hip. The instrument is kept from jolting by the waist-belt, which is passed through the loop of the leather case and buckled in front. On the left side of the waist-belt are carried the metallic cord and steel tape in their leather pockets, through the loops of which the waist-belt is passed before it is buckled. The steel tape is put on to the front (about half-way between the seam and the buttons of the jacket or tunic), the cord is put on close behind it. N o. 1 also carries the C picket. It rests in one of the buckets (small size) which are attached to the stirrups. A strap is passed round the picket, under one of the small straps of the tiag, and then round the arm. The picket is thus carried like a lance. No. 2 carries the A and B pickets in a similar manner to the way No. 1 carries the C picket, but they are drawn together at the top by a loop on the picket strap, and strapped together at bottom by the little strap on the A picket. The buckets should be put on to the front of the stirrups so that they may be on the outside of the feet when mounted. Formation. The party ride in line ; No. 1 on the near side, No. 2 on the off side of the horse-holder. Dismounting. At the command from No. 1, Halt Dismount, No. 1 dismounts first. To do so, he takes up his picket and passes it from right to left across the saddle, point downwards under his left hand. He then dismounts in the usual way and giving his horse to No. 3, goes round by the front and takes the two pickets from No. 2. No. 2 then dismounts in the usual way, and giving his horse over to No. 3 receives back his pickets from No. 1. Nos. 1 and 2 proceed to the front on foot, and the horse-holder takes the horses under cover according to directions from No. 1. 12 Mounting. At a signal from No. 1 the horse-holder rides up with the horses, that of No. 1 on the near, that of No. 2 on the off side. At the command from No. 1, Mount, No. 2 mounts first and then receives his two pickets from No. 1, who, after giving them to him, goes round by the front to his own horse, and mounts with his picket held under the left hand point down- wards. When mounted, he takes up the picket in his right hand, and lifting it across the saddle, places it in its bucket. 13 CHAPTER TIL USE OF THE INSTRUMENT. THE principal application of the field range-finder in artillery operations is to solve practically, without calculation* or actual measurements, the following problem : To find the distance to any visible point, from the ground occupied ly the range-finding party. This is technically termed " taking a range." The physical conditions necessary in order to take a range with the Watkin range-finder from any point P to any object (fig. 1), are that a position may be found to the right or left of P from which both and P are visible, and at which a point Q may be marked such that either the angle P Q or the angle Q P shall be a right angle. FIG. 2. * There are certain cases when, although the limits of the instrument are exceeded, it is still possible to find the correct range. In these exceptional cases a simplelcalculation is required. (See Chapter VIII.) 14 In practice the mode of proceeding is usually as follows : The object being (figs. 2 and 3} a picket is placed at P, and the range-taker, by means of the instrument, finds the right angle point Q and places a second picket there. He then, standing at Q, reads with the instrument the base P Q by means of a sub -base P R, which is marked by a picket R, at right angles to P Q. After this, setting the base so found on the base bar of the instrument, he proceeds to P, and by an observation at that point reads off the range P on the graduated cylinder. Three things, therefore, have to be done by means of the instrument 1. To fix the right angle. 2. To find the base. 3. To take the range. It is best to consider 1 and 3 first. Step 1. To fix the right angle. The cylinder must be turned to zero and the rack knob pushed to " Range Right-angle " (this will set the mirror at 45), and the observer must look through the end eyehole marked for right angle and range. The sliding collar should be at the stop. Let the observer's position be Q' or Q" (fig. 3) to the left of the picket P, and the object the distance to which is required. ,nl p.. \ \ \ \ FIG. 3. 15 From this position, looking at through the unsilvered portion of the horizon glass, the observer will see the image of the picket P reflected in the silvered portion of the glass towards P' or P" at right angles to P Q' or P Q" (figs. 4 and 5). FIG. 6. Then, by advancing or retiring as may be necessary he will be able to reach a point Q at which the object and the reflected image of P coincide in the glass (fig. 6-). This will fix the right angle. Step II L To take the range. Assuming that the right angle has been fixed and marked by a picket Q (fig. 7), and that the length of the base P Q has been ascertained (by step 2, which remains to be described), it is desired to take the range to 0. First the base P Q must be marked on the base arm by means of the sliding collar, and then the instrument, being in other respects set as for finding the right angle, must be taken to the picket P, and placed upon it with the ring which is marked on the case exactly over the picket head. The observer using the end eyehole marked " Range Right angle " will now see the image Q' of the picket Q reflected at right angles to P Q in a direction S to the right of (figs. 7 and 8). m \ N 902 \ FIG. 8. FIG. 7. FIG. 9. 16 He must now revolve the cylinder (thus causing Q' to move towards 0) until the object seen direct and the reflected image Q' exactly coincide (figs. 7 and 9) ; when this has been done, the reading on the cylinder will be the required range. What has been described as steps 1 and 3 amounts to this : Two right angles inwards are made ; first Q P at Q, and then Q P S at P (fig. 7), in doing which the instrument is used like a common sextant, the mirrors being inclined to one another at 45. After this, the instrument remaining in its last position, P, the right angle at that point is altered by revolving the cylinder so that Q' (the image of Q) is no longer reflected at right angles Q P S, but at the smaller angle Q P 0. Now the longer the range is, the less does the angle Q P differ from the right angle Q P S, and therefore the fewer are the turns wliicli it is necessary to give to the cylinder to make Q' move from S and coincide ivith O. From the above it is easy to see how by engraving a scale on the cylinder, such scale can be made to record the actual range, that is, the particular value of P in every instance. So far, hoivever, it may not appear liow the reading on the cylinder is applicable to every range independent of the length of the base, for it is evident that ifPQ (fig. 7) were shorter, the angle P Q would be greater and vice versa, although the length of Q O remained unaltered. This difficulty is met by the use of the base bar, ivhich enables the movement given to the index glass by each turn of the cylinder to be increased or diminished according to the position of the sliding collar. By this contrivance it is arranged that in proportion as the base is longer for any given range, the greater is the movement of the index glass corresponding to any given number of turns of the cylinder, and therefore (Jig. 7) the greater the result- ing deviation of the reflected image Q' from the right angle OPS. Thus within certain limits the necessary compensation is effected to enable the one scale in the cylinder to be made use of whatever the length of base may be. Step II. To find the base. Following the lettering of figures 3 and 1, Q is the right angle picket in position with reference to the range picket P (fig. 10). The base to be found is P Q. FIG. 10. FIG. 11. A P A' FIG. 12. 17 From P at right angles to P Q a sub- base P R (which is usually the length of the metallic cord, i.e., 6 yards) is marked by a picket R. The cylinder must be turned to zero, the rack knob pushed to Base (thereby setting the mirrors parallel), and the length of the sub-base recorded on the base bar. The observer should now stand at Q facing Q R, holding the instrument immediately over the picket Q, and should look through the side eyehole marked JBase, when he will see the pickets P and R with their reflected images immediately undei their natural ones in the horizon glass (fig. 11). If he now commences to revolve the cylinder the images seen by reflection will travel to the left (tig. 12), and he will finally be able to make the reflected image of R coincide with the natural image of P. In this position the reading on the cylinder scale will be the distance P Q required. The principle involved in the operation just described is the same as that already investigated when considering step 3. As long as the cylinder is at zero, the glasses are parallel, and the natural and reflected images coincide, but when the cylinder is revolved the index glass is displaced and the reflected images are thrown to one side, to an extent proportional to the number of turns given to the cylinder. 7 Fm. 13. The sub-base P }{,jig. 13, being fixed at 6 yards,* the smaller P Q is, the greater is the required movement of the index glass, and Ihe amount of this movement, as registered by the scale on ihr. cylinder, is a measure of the distance P Q. * If a sub-base other than 6 yards is made use of, the compensating action of the base bar comes into play ; for example, if P R be 12 yards, the base bar is set to 12 instead of 6, and the movement of the cylinder is regulated accordingly. (See p. 15, Explanation, Step TIL) (4899) 18 READING THE SCALES. FIG. 14. i o t i - 1 -' 1 1 i 1 1 1 T \ J t Si ' ( FIG. 15. Fm. 16. 1. The scale on the base bar serves two purposes 1. For marking a sub-base. 2. For marking a base. For a sub-base the numbered divisions read yards, and the sub-divisions are not made use of; thus fig. 16 shows how the usual sub-base of 6 yards is set. For a base the numbered divisions really mean tens of yards, and the sub-divisions yards, but in practice the numbered divisions are treated for convenience as reading hundreds of yards, and the sub-divisions as tens of yards. 2. The cylinder scale serves two purposes 1. For reading a range. 2. For reading a base. Up to 2,000 yards the scale is graduated for every 10 yards ; from that to 3,000 yards for every 25 yards, and from 3,000 to the end of the scale for every 50 yards. The numbers read from right to left. In reading a range the numbers from 450 to 990 give the actual range in yards, while those from 10 to 50 (that is, for the remainder of the scale) express hundreds of yards. Thus the 19 arrow-head pointing to 850 would indicate a range of 850 yards, and when pointing to 23 it would indicate a range of 2,300 yards. In reading a base the actual distance is the reading on the cylinder divided by 10 ; but, as already explained, in practice a base is read as if it were a range, and set on the base bar with- out calculation (treating the numbered divisions of the base bar as hundreds of yards). Thus, if the arrow-head points as in fig. 14 it would indicate a range of 1,015 yards. If a base were being read the figures would really mean 101J yards, but they would be read in practice as 1,015 and set on the base bar as in fig. 15. Again, if a base happened to be 60 yards it would be read on the cylinder as 600 and marked on the base bar as shown in fig. 16. ' (4899N CHAPTER IV. CORRECTING THE ADJUSTMENT OF THE INSTRUMENT (COMMONLY CALLED ADJUSTING THE INSTRUMENT.) SOME experience is necessary to know when the adjustment is mperfect, and a practised hand and eye are needed to correct it properly ; it should therefore never be attempted by any one who has not been trained for the purpose. A good instrument will seldom require the adjustment corrected, but it should invariably be tested before commencing a day's work, and again, if possible, after riding long distances, or over very rough ground. There are two adjustments 1. The horizontal or ordinary adjustment, the correction of which, when necessary, is a part of the range-taker's everyday duty. 2. The vertical adjustment, which is rarely imperfect, and the correction of which, except on active service, should be considered an instrument-maker's repair. To test the adjustment, open the lid, set the cylinder to zero, the rack knob to base, and the sliding collar to the stop (that is to 6 on the scale). If in proper adjustment the ii:dex and horizon glasses are now parallel, and by looking through the side eyehole at any sharply defined vertical line at from 200 to 300 yards distance, it willVppear in the upper and lower part of the horizon glass as a single unbroken line (fig. 17). If the line he broken (fig. 18) when the instrument is held level to the object, the horizontal adjustment requires correction. FIG. 37. FIG. 18. The best objects to look at are the sides of buildings, poles, sign-posts, or corners of walls, but the stems of trees can b& made use of, and on an emergency a picket folded and held upright will answer the purpose. To correct the. horizontal adjustment, unscrew the adjusting key, apply it to the square shoulder of the regulator, and turn it towards the lower portion of the line until the two come together. After this shift the rack knob from base to right angle, and back again twice, and look again to see if the adjustment remains correct ;* if it does so, nothing further is required. * It is desirable to gel a small piece of pointed steel made to fit the capstan screw of the jaws which hold the regulator, and to tighten these jaws occasionally. If they work loose, the instrunj'jnt will get out of adjustment very quickly, A very gentle pressure should be applied, however. 21 To connect the vertical adjustment, a small screw-driver is required. First put the instrument in exact horizontal adjustment, then look at some well-defined object as before, only let it be one which has some point on it which can be distinctly recognised. Bring this point to the dividing line in the horizon glass. Give a very slight turn to the cylinder and note if the two images as they separate appear on a level. If not, and one is below the other as in fig. 19, the vertical adjustment needs correction. Apply the screw-driver to the small screw just above tbe horizon glass. If the reflected image is too low turn from left to right when facing the screw, and vice versa. FIG. 19 incorrect. [ XJNIVER8IT1 " " CHAPTER V. CARE OF INSTRUMENTS AND EQUIPMENT. Care of Instruments. IF properly cared for, an instrument should remain in good order for several years. Constant wear will in time cause a falling off in accuracy, but the process is a very gradual one, and can never account for an instrument becoming suddenly unfit for use. Range-finders should never be exposed to rough treatment. Like hunting watches they will bear a considerable amount of fair wear and tear, but are put entirely out of order by ill-usage. The following points are of importance : 1. Service instruments (as distinguished from those appro- priated for instruction) should never be handled by persons untrained in the proper way of using them. 2. On no account should any of the small screws be taken out or interfered with ; the adjustment and the occasional tightening of the regulator is all that should be attempted by range-takers. ' 3. An instrument should always be carried by the range- taker, never on a limber or wagon. It should never be sent with baggage unless packed in a separate box, as glass is packed, with some soft material round it to form an elastic cushion. 4. In barracks or camp, and on the inarch in wet weather, the cylinder screw and all the steel parts should be slightly oiled with mineral oil to prevent rust. 5. Before use, the oil should invariably be removed. This should also always be done before a march in dry dusty weather. 6. The mirrors should be wiped occasionally with a piece of clean chamois leather or soft linen. ?. In moving the rack knob from " base " to *' range," and vice versa, care should be taken not to do it with a violent jerk, but by a firm pressure to ensure actual contact with the blocks. A slight click only should be heard. Care of Equipment. 1. The leather parts of the equipment require the same treatment as saddlery. Special precautions must be .taken in tropical climates to prevent its perishing. 2. The tripod flags when soiled, should be taken off and washed. 23 3. The metallic cord should be kept as dry as possible, and always wound up after use. It should not be trodden on, nor should it be knotted (except at the end outside the shuttle). A good cord may be known by its being perfectly flexible, where a bad one will easily kink, and soon split. 4. The steel tape should be wiped dry, and carefully wound up after use. If damp it will rust, and if twisted it will easily break. The handle must never be reversed. The tape should not be used for measuring sub-bases, but only for testing the c6rd. It should be oiled occasionally. CHAPTER VI. PRELIMINARY OR POSITION DRILLS. THIS part of the subject can only be acquired by practice under a competent instructor, who will show how each operation is performed by going through the various movements himself. For reference, however, the various positions are here described. PLANTING PICKETS. The A picket is planted with the flag to the left. Jo plant a C picket (fig. 20). FAR PICKET LC LEFT_ ~ TEC RIGHT PICKET L Fm. 20. The picket is held about the middle point in the right hand, the instrument reversed being held up to the eye just over the right foot, which is slightly advanced. The picket is turned with the flag to the right, the two near picket legs being held in the whole hand, with the exception of the forefinger, which is circled round the far picket leg. To plant the picket, the right foot is held quite steady and the weight of the body thrown upon it. 1. The far picket leg is thrown to the right front. 2. The left picket leg being released by the hand is caught by the left foot and extended straight to the left, while at the same time the right picket leg is drawn by the right hand to the right rear, and the picket thus extended so that its head is exactly over the right foot and the flag pointing to the right. 25 A slight adjustment by the right hand sets the picket in correct position. After being thus planted the picket ought not to need moving more than an inch or two when the instrument is placed upon it. Any such movement is performed by the right hand applied to one picket leg at a time. To plant a B picket and lay out a 6-yard sub-base. The A and C pickets being planted, No. 2 turns the crosshead of the A picket on to the C picket, and then with the metallic cord in his right hand and the B picket in his left, looks over the line of the crosshead which is at right angles to the base, and takes up a line for the sub-base. He then proceeds as follows : 1. Hooks the S hook of the cord to the button of the A picket. 2. Extends the cord in the correct line, letting it run loosely through the right hand till fully extended, but not drawing it taut. 3. Still holding the cord slackly, takes the two near legs of the B picket (flag towards the C picket) and throws out the far leg to the front, at the same time placing the others in position, the right leg straight to the right, the left one to the left rear. 4. Changes the shuttle to the left hand. 5. Extends the cord to full length, and with the other hand adjusts the head of the B picket to the exact end of the cord, keeping it in the correct line. 6. Drops the shuttle, steps up to the A picket, lifts the hook of the cord carefully from the button of the picket, and then winds up the cord. POSITION OF THE HANDS IN USING THE INSTRUMENT. Fixing the Right Angle. First Position. (Before planting the picket.) The instrument open and reversed is held in the left hand, with the thumb (pointing upwards) on the left, the forefinger doubled under the adjusting key, and the other fingers (pointing towards the observer) on the right. The thumb must hold the body of the instrument so that it may not tip forward, and at the same time the hollow of the hand must be kept away from the sharp edges of the cover. Second Position. (Verification after planting the picket.) This position is the first position with the forefinger still under the adjusting key resting on the head of the picket, while the little finger is extended outwards to clear the picket head. 26 Finding the Base. The instrument is held in both hands with the middle or base eyehole in use. On the left the forefinger (outermost) and thumb (innermost) of the left hand grasp the base, and on the right the forefinger and thumb of the right hand are appplied to the cylinder, while the remaining fingers support the instrument. The instrument should not touch the picket, for fear of disturbing the right angle, but should be held immediately over it, to insure which the little finger of the left hand may be allowed just to feel the picket head. Taking the Range. The instrument is placed on the picket with the ring upon the base resting on the picket head. The thumb and fore- finger of the right hand turn the cylinder while the middle finger underneath steadies the movement. The left hand is circled round the picket head, the forefinger and thumb extended so that the instrument may rest partly upon them. POSITIONS OF THE BODY. When using the instrument before planting the C picket, the body should be upright with the right foot slightly advanced. When the instrument rests on the A or C picket the body should be thrown forward on the left leg, with bent knee and toes to the front, the right leg being extended backwards and kept straight with the toes to the right.* Exceptional heights of picket often require exceptional positions, such, for example, as kneeling when the head of the picket is very low down. * Never separate the legs and bend both knees, as the position arrived at in that way is very unsteady. 27 CHAPTER VII. SERVICE DRILL. THE range-finding party consists of No. 1 the range-taker, and No. 2 the assistant. These having dismounted, and left their horses in charge of the horse-holder, advance in Indian file under the command of an officer, who, if necessary, first reconnoitres the position, and who points out the object to both numbers. No. 1 carries the instrument and the rest of the equipment, except two pickets (the A and the B) carried by No. 2. If time admits of it, No. 1 will, before advancing, test the metallic cord and look to the adjustment of the instrument, assisted by No. 2. Having reached the spot chosen for commencing to take the range, No. 1 estimates the distance, and the length of base required, and directs No. 2 to plant the A picket ; this done, he ascertains that it is correctly placed, and that the object is visible from the head of the picket when planted. He then takes the metallic cord from its pocket and hands it to No. 2. If the sub-base is to be 12 yards, No. 1 assists No. 2 in laying it out. The A and B pickets are planted with their flags to the left. DUTIES OF No. 1. (Figs. 3 to 9, pp. 14, 15.) No. 1 takes the instrument from its case, opens it,* and holding it in his left hand upside down, with the picket in his right, stands on the left of the A picket facing the object. The cylinder should be at zero, the sliding collar as far from the cylinder end of the base bar as it will go, and the rack knob pushed to Eight angle. Looking over his left shoulder he takes up a guide point a little to the front of his exact left, fig. 21, and then keeping his eye on the precise point of the object he intends observing, he doubles at a quiet pacef towards the guide point till he has covered sufficient distance for his base.| X GUIDE POINT Fig. 21. * When the ground is very uneven, or the distance to be traversed considerable, it is best not to do this till the other end of the base is reached. f About 70 paces go to 100 yards at the proper " double." J It is sometimes necessary to take the guide point on the other side of the A picket, a little to the right rear of No. 1, who afterwards lines himself on this and the A picket. 28 No. 1 then halts, and facing the object applies his eye to the right-angle eyehole of the instrument (the C picket remaining in his right hand sloped so as not to impede the view), and by reflecting the A picket on the object fixes the right angle, advancing or retiring as may be necessary in order to do so. If the A picket appears to the right of the object he retires, if to the left he advances. (Rule, Right retire.) Having approximately fixed the right angle point, No. 1 plants the C picket, and placing the instrument upon it verifies the observation, pushing the picket forward or drawing it back slightly as may be necessary to obtain exact coincidence. Having firmly planted the C picket at the right angle, No. 1 now faces the A picket, turns the instrument lid uppermost, sets the rack knob to base, and reads the base by turning the cylinder* until the B or right-hand picket of the sub-base is reflected on to the A or left-hand picket. This he does holding the instrument immediately over the C picket, but not resting on it. Having found the base, he sets it on the base bar, and pushes the rack knob back to range. No. 1 then doubles back to the A picket, and resting the instrument lid uppermost upon it takes the range by turning the cylinder until the C picket is reflected on to the object. It should be remarked that the taking up of a guide point is not absolutely necessary, but is of great assistance when the base is long, to save loss of time in advancing and retiring. DUTIES OF No. 2. No. 2, as soon as the A picket has been planted, places himself on the left of it, facing in the direction towards which No. 1 is to run. He holds the B picket in his left hand and the cord in his right. As soon as No. 1 commences to plant his C picket, No. 2 turns the crosshead of the A picket upon No. 1, and then look- ing over the other line of the cross, lays out the sub-base, planting the B picket with the flag towards No. 1. He then returns to his position at the A picket, and keeps his eye on No. 1, ready at a signal from him to stand behind the picket if required. If No. 1 takes up his C picket and moves his position. No. 2 will lower the B picket, and lay out a fresh sub-base as soon as the C picket is planted again. As soon as No. 1 leaves the C picket, No. 2 will lower the B picket, and, leaving it on the ground, will double out to the C picket and stand by it, placing himself behind it, if signalled to do so. On a signal from No. 1 that he has taken the range, No. 2 will bring in the C picket. * In practice, to avoid fatiguing the eye, it is convenient to begin by setting the cylinder to the point which indicates the approximate base. 29 It at any time, by accident, either A, B, or C picket is shifted while No. 1 is *at the other end of the base or crossing, No. 2 will at once lower that picket, and not set it up again until No. 1 indicates by a signal that he understands what has occurred. VARIATIONS IN THE DRILL FOR CASUALTIES. The variations which are recognised in the drill are those necessary to meet the following casualties : 1. DIMINISHED NUMBERS WITH COMPLETE EQUIPMENT. (a) No. 1 disabled. No. 2, if qualified, becomes No. 1 and works alone. No. 3 carries one picket when mounted. (b) No. 2 disabled. No. I works alone, and No. 3 carries one picket. (c) No. 3 disabled. No. 2 remains with the horses, and No. 1 works alone. No. 1 working alone, in the above three cases. When No. 1 works alone he has to lay out the sub-base for himself as follows : Having planted the A picket he lines himself with it and the object at cord's length, and then, if the range is estimated io be under 3,000 yards, takes a side pace in the direction of the C picket (that is, to the right or left according as the base is to be to the right or left). The side pace so taken must be in length according to the estimated range, as follows, for a sub-base of 6 yards : Estimated Range 1,000 yards . . pace of 18 inches. 2,000 . . half pace of 9 inches. 2. FULL NUMBERS WITH EQUIPMENT INCOMPLETE. (a) B or C picket wanting. The A picket is planted as usual, and the remaining picket is used as a C picket ; No. 2 marks the end of the sub-base by holding the shuttle at arm's length towards the A picket. (b) The A picket wanting. One of the remaining pickets must be placed for the A picket, and the other be used as a C picket. No. 2 must mark out the sub-base as in (a), but he will have to hook the cord to the leather ring of the flag, and must get the direction of the sub-base as described for No. 1 working alone. No. 1 will therefore be required, if the object admits of a doubt, to put No. 2 in position before'leaving the A picket to fix the right angle, (c) Two pickets wanting. The one remaining picket is used in this case as an A picket. No. 2 gives the base as in (a) or (b). 30 No. 1, if he cannot mark the right angle point with a sword or other substitute for a picket, proceeds as follows : Having fixed the right angle he finds the base as usual, and then summoning No. 2 to him causes him to stand in exactly the position he has himself occupied when fixing the right angle, and thus supply the place of a C picket while the range is being taken.* (d) The cord lost. Lay out the sub-base with the tape. (e) Cord and tape lost. Where the ground admits of it, the base is found at once by pacing ; but if this cannot be done, a sub-base of any length from 6 to 12 yards is put out and measured by pacing, and this sub-base is set on the base bar. The pacing should be done more than once, and the mean taken. N.B. Much care is needed to obtain good results in the last two cases. 3. DIMINISHED NUMBERS WITH EQUIPMENT INCOMPLETE. The following is the only case for which special directions can be given : No. 1 working alone with only two pickets. No. 1 plants one picket as an A picket (A, fig. 22) ; then having fixed the right angle C and planted the other picket as a C picket, he obtains the base A C thus : Stretching the cord from the C picket in line with the object he stands so that o 1 OBSERVER FlG. 22. * A good way to make sure that No. 2 stands on the exact spot is for No. 1 to make a half turn on one foot so as to mark the ground, and for No. 2 to place his heel in the place thus marked. 31 his eye may be just the distance of the cord from the C picket, and in this position he reflects A picket upon the object by turning the cylinder (sliding collar set 6). This will give the base A C. TWELVE- YARD SUB-BASE. To lay out a 12-yard sub-base, the three pickets are used and No. 1 superintends. First, a six-yard sub-base is laid out in the usual way from the A picket ; and the C picket is placed to mark the end of it. Then a second length of 6 yards is laid out from the C picket in exact line with the A and C pickets, and the B picket is planted to mark the end of it. The C picket is then taken away. N.B. No. 1, working alone, can not lay out a 12-yard sub- base unless he has three pickets. CHAPTER VIII. APPLICATION OF THE DRILL. SECTION I. SERVICE RANGE-FINDING. FOR ordinary artillery ranges taken from fairly favourable ground, no calculation whatever is required. Actually the scales on the base bar and cylinder admit of finding ranges without calculation from 450 to 5,000 yards with bases from (30 to 130 yards, and sub-bases of either 6 or 12 yards ; but though possible up to 5,000 yards, range-finding without calculation should generally be restricted to ranges under 3,500 yards. The telescope should be used for distances of 3,000 yards or upwards. TABLE FOR RANGE-FINDING WITHOUT CALCULATION, SHOWING APPROXIMATE LENGTH OF BASE DESIRABLE AND THE MAXIMUM TIME ADMISSIBLE FOR QUICK WORK ON FLAT GROUND. Range. Base with sub-base yards. Time, counting from the moment the A picket is planted. yards. yards. min. sec. 500 to 1,000 GO 2 1,500 75 2 15 2,000 to 2,500 100 3 [3 30 Beyond 2,500 120 to 130 \ to U 30 SECTION II. EXCEPTIONAL RANGE-FINDING. As before stated, there are certain cases in range-finding in which some simple calculation must be resorted to. These cases are 1. When the only baise available is under 60 yards.* 2. When the base is over 130 yards, either because a shorU-r base cannot be got, or because the range being very long a longer base than 130 yards is desirable for the sake of accuracy. Calculation is also required in certain range-finding problems. The principle which governs all cases of calculation is that the scales on the base bar and cylinder do not necessarily refer to yards, but will answer for any linear unit it is found convenient to work in, as for example metres. It is usual to work in half yards, and double yards. Half yards for bases under 60 and not less than 30 yards long-, with ranges not exceeding 2,500. * A base under (U> .y..';-.7j should never be taken, if one between 60 and 120 yards 13 available. 33 Double yards for bases over 130 yards (120 in Mark III), with ranges not exceeding 10,000 yards. Working in half yards. For this the sub-base of 6 yards is treated as 12 half yards, and is accordingly set as twelve on the base bar. The working is otherwise exactly as usual, but the range finally obtained is read in half yards, and must therefore be halved for the distance in yards. Example Sub-base of 6 yards is set 12 on the base bar. Base reads 700, and is set on the base bar. Range reads 1,900 (half yards). yards. Working in double yards. A sub-base of either 6 yards or 12 yards may be used. (a) When the sub-base is 6 yards it is set 6, the base is read as usual in yards and divided by 2 to get it in double yards. This base (in double yards) is then set on the base bar. The range finally is read in double yards, and must therefore be doubled for the distance in yards. Example Sub-base, 6. Base reads . . . . 160/0 yards. Divide by 2 . , 80/0 double yards. Sliding collar set to 8. Range reads 2,300. 2,300 x 2 = 4,600 = distance required in yards. The above case (a) is the only one in which a calculation is required before setting the base. (b) When the sub-base is 12 yards. In this case the sub-base is treated as 6 double yards, and set accordingly at 6 on the base bar. The rest of the working is as usual. The range finally obtained is read in double yards, and must be multiplied by '2 for the distance in yards. Example Sub-base 12 yards is set 6 on the base bar. Base reads 900 and is set 9 on the base bar. Range reads 2,100 (double yards). 2,100x2 = 4,200 yards. (4899) Q TABLE FOR WORKING IN DOUBLE YARDS. SHOWING SUITABLE LENGTHS OF BASE AND SUB-BASE, AND APPROXIMATE TIME REQUIRED ON FLAT GROUND. Range. Base. Sub-base. Time. yards. yards. yards. r // 3,500 140 6 5 4,000 4,500 160 180 6 or 12 12 1 5 30 5,000 200 12 6 6,000 to 8,000 240 12 7 The following is convenient to remember : Working in half yards halve the reading on the cylinder. double double Hence the rule "Half halve," Double double." CHAPTER IX. APPLICATION OF THE DRILL CONTINUED.* SECTION I. To FIND THE RANGE BETWEEN TWO DISTANT VISIBLE POINTS. THIS will enable the officer commanding a battery, before advancing to a new position, to obtain some of the ranges he will probably require on arriving there. It will also be possible, by the assistance of a signalling party, to furnish batteries with their ranges from a central position of observation, if time permit, and circumstances render such a proceeding desirable. Let A be the point of observation, P and Q the distant points (figs. 23 and 24). Fm. 23. FIG. 24. First take the two ranges A P, A Q, then lay out straight lines A j9, A q, in the lines A P, A Q, respectively, either towards P and Q (fig. 23) or from them (fig. 24), making A p a convenient proportion of A P, and A q the same proportion of A Q. Measure p q which will be the same proportional of P Q. This will give the desired range P Q. For example Let A P = 2,000 yards. A Q= 2,500 yards. A P Make A = =20 yards. AQ = =25 yards. * To understand this chapter, a practical acquaintance with the instrument is necessary. (4899) 2 36 Measure p q, say it measures 21 yards. 21 x 100 = 2,100 = P Q. In practice, No. 1 should pace the line A p, and, having planted a picket at p should pace the line A q and then the line p q. Calculation may be avoided thus: No. 1 when pacing Ap t A ) If the commanding officer has reason to believe that the range-taker is not the best qualified non-commissioned officer for the appointment serving in the battery, a competitive examination in range-finding may be held, in accordance with the instructions for the classes at the School of Range-finding at Aldershot, hereafter detailed. Should the result of this examination show that the holder of the appointment possesses inferior qualifications, to any appreciable extent, to those of any other non-commissioned officer serving in the battery at the time, and holding a certificate from the school at Aldershot, the latter non-commissioned officer may, subject to the approval of the Lieutenant-Colonel * See E. a. O., No. 14, 1885, paras. 1 to 14; also GK 0. 138, Nov., 1886 ; and K. GL 0. 108, Nov., 1887. / 72 Commanding the Division, be appointed range-taker to the battery in place of the existing range-taker. Except in cases of proved inefficiency as stated in (a), the range-taker of a battery is not to be removed from his appoint- ment until he has held it for one year. No non-commissioned officer is to be appointed range-taker to a battery at home who has not been through a course at Aldershot, and been reported qualified by the Instructor in Range-finding, but when batteries abroad have no qualified non-commissioned officer the position may be filled temporarily by any non-commissioned officer who can take ranges with not more than 5 per cent, of error, as proved by an examination in the presence of a Regimental Board, to be carried out in accordance with the instructions for preparatory classes hereafter detailed. When the officer commanding a battery is unable to fill up the appointment from the rank and file non-commissioned officers under his command, he will report the vacancy through the Officer Commanding Royal Artillery in the District to Head- quarters, stating in the case of batteries abroad whether a temporary appointment has been made or not. In batteries abroad a non-commissioned officer who has been reduced to the ranks, or a Serjeant, may, in the absence of any other qualified candidate, be employed as range-taker, but in the former case he will draw no extra-duty pay until he has been re-appointed a non-commissioned officer. If the range-taker of a battery, returning from foreign service, has been temporarily appointed under the foregoing regulations, or under any special regulations in force in India, the officer commanding the battery is to report the fact without delay, in view to the range-taker being sent to join a class at the School of Range-finding at Aldershot, for a qualifying course of instruction and examination. Non-commissioned officers who have qualified and are recom- mended for appointment as range-takers, are to be shown in the Monthly Qualification Return, Army Form B 92. The range-taker and assistant range-taker will be exempt from such ordinary duties as will give them full time for practice. They are not to be appointed clerks, or employed in positions which interfere with their special duties as range-takers, unless they vacate the latter appointments for this purpose. Besides practising by themselves they will be exercised once a fortnight, weather permitting, under the officers of the battery, who will note the results obtained (see Form I), and verify them by reference to the Ordnance Survey Maps, which have been issued to Districts for the purpose. A report that this has been done is to be rendered monthly to the Lieutenant-Colonel Commanding the Division. Officers commanding districts are responsible that these maps are returned to the District office before batteries leave their commands. Range-finding is to be carried out, when practicable, at battery 73 drills, field days, manoeuvres and route-marching, and invariably at battery practice, and may be usefully combined with judging distance. Three or four of the horses in every battery should be trained so as to be accustomed to carry range-takers, as much time may be lost in mounting and dismounting, with the tripods, from unsteady horses. Officers commanding batteries are held responsible that the instruments and range-finding equipment of their batteries are of correct pattern* and in working order. They should cause their range-takers to examine all new issues, and report to them before they are taken over. The instruments should be in the immediate charge of the range-takers, and when not in use should be kept in a secure place. They are not to be handled by any uu authorized person nor used except in the presence of an officer or one of the range- takers. A report, on the range-finding of each battery will be made in the confidential report, Army Form B 224. The number of non-commissioned officers in each battery qualified to be range- takers is also to be shown. * Whatever mark of range-finder may be in possession of a battery it is to be used on the occasions detailed, but officers commanding batteries are responsible that there is no delay in demanding the authorized service equipment if it has not been already supplied. 74 1 i li 1 t+H O 0) 2 S 4H g i ! i | 1 .5? s J o 8 3; ! Pi S bD'S flj C S 03 1 if -2> ~0 t-l GO ,-5 9 I if a | r^ li o s I o 1 jli 1 iy 8 I ! 1 il to 1 1 H * 75 FORM II. EANGE-FINDING CERTIFICATE. R. A. Attended a course of instruction at the School of Range-finding 1 , Aldershot, from to and passed af Examination, obtaining a decimal of He is qualified to act as Battery Range-taker with the Watkin Range-finder, and to instruct in the use of the instrument. Instructor in Range-finding. Date Commanding R.A., Aldershot. Date * Regimental Number, Rank, Name, Battery, and Brigade, t " G-ood," or Yery good." 76 SECTION III. CLASSES AT THE SCHOOL OF RANGE-FINDING, ALDERSHOT.* A School of Range-finding having been established at Aldershot the system of drill and instruction in field range- finding throughout the regiment will be in strict accordance with that authorized there. There will be occasional classes for officers as well as for non-commissioned officers. Non-commissioned officers selected for the classes at Aldershot must be under the rank of serjeant, and be certified by their respective commanding officers to be good riders, and not shortsighted. They should, if possible, have gone through a preparatory course of instruction, as hereafter detailed. Preference should be given to any who have learned signalling. The course for non-commissioned officers will last about eight weeks. An examination will be held at the end of the course, and certificates (see Form II) awarded to those who pass, according to the credits assigned, by the Instructor in Range-finding. The following are the regulations for examination of classes of non-commissioned officers : (a) The examination will be divided into three sections, A, B, and C, and 100 marks will be given as full credits, viz. : 4 S i 1 g g 1 S 5! S S S S A 2 o o ^- co < o I S S S si 1 .2 i 00 8 g 8 S 8 -H PH CN CN CO CO 8 8 8 8 g 8 -i Tj< >* iO O CO S b a fez OS ^ 8 CO 00 CO O 00 c T 1 s 8 S S 1 8 OO -* 00 OJ CO i-i CO CO * t< 10 1 rf 1 s o o o o o o 00 EJ 2 S S S 1 1 1 1 (3 o CO " S S 2 J 8 t>- O CO r ^-t lA CO CO CO ^ ^ to ! SH O O O O O O g 1 1 1 1 V cc * 1 S co oJ 2 2 B CO c5 S CO CO CO p 2 | g g 2 00000 Tl t~ O CO CO CM O) CO CO CO g 0> SS 2 g S g m CN 5 S o co CM CN CM CO CO o 1 1 00 iO t- O CN i t~ go U3 O O O O CN O t^- O ?! CN CN N eo 9 s w 5 * - 5 S s 2 9 S 8 S S a o CO S 1 CO g 8 ^ co oo o OJ ^ A! C8 g OQ o 10 CO S5 t^ 00 O CN 8 S s S S g A 3 g <* CO CO S 8 CO CN CO iO CO 00 g ^j "8 A &c eo CM co >o co r- oo o o c*i o r o 65 o ~ CN co S bo c ;l CN s g g o o o o o o CN 00 O> O r-t CN c? * S 3 8 55 3 S iO O t~ iO CN O rt CO CO t~ 00 05 1 O .73 fc S 2 CN CO CO G O iO O i O rH ^* -^ 3 O CO o Deduction for overtime. 0,0 5 o-a ' Pllll lillii yHII I Time allowed. g J g CJ .9 N N N cM ej eo CJ 10 CO CO C- i 1 111 ^ 8 g 8 8 8 2 J|,|I1S111 "S 1 ( ii t!!!!I! ! t? * llll ^ 1 Section . MarkB 20. 78 SECTION IV. PREPARATORY CLASSES.* At all stations where there are range-takers available to give instruction, classes will be occasionally formed for elementary range-finding. They should be conducted so as to interfere as little as possible with the ordinary routine of duty, and should be assembled in mild weather only. These classes are for the purpose of testing the capabilities of non-commissioned officers intended to be sent to the classes at Aldershot, and are intended as a preparation for more advanced instruction. The number under one instructor should not exceed six. About 12 attendances of three hours each will be sufficient, and they may be spread for convenience over six or eight weeks. The whole of the instruction should be given out of doors, and be strictly confined to drill and practice in taking ranges up to 2,000 yards without calculation. The adjustment of instruments will not form part of the course. A record of each day's work will be kept, and any ranges taken will be noted in Form I. (See page 74.) At the end of the course an examination will be held under an officer. It should be conducted according to the general rules laid down for the examination of classes at Aldershot (Form III, Section A),f but five ranges should be taken instead of two 20 marks being allowed for each. The ranges should not much exceed 1,500 yards. The objects should be well- defined, and the time allowed should be double that given in Form III. Seventy-five marks (*75) should be obtained at these examinations as a general rule to qualify candidates for joining an Aldershot class. At the examinations held abroad under paragraph 4, for the temporary appointment of range-taker, the rules laid down in paragraph 27 are to be observed, and o per cent, of error or a total of 60 marks (*6) will qualify for the appointment. Range-finders forming part of the service equipment of batteries are never to be used for instruction, but instruments, Class II, are to be specially demanded for that purpose. SECTION V. For the regulations relating to examination of officers in range-finding before promotion see orders issued with Army Orders, 1st March, 1889. * R.G-.O., No. 14, 1885, paragraphs 20 to 30. f This refers to the Section of the Examination. 79 APPENDIX B. OUTLINE OF A COURSE OF INSTRUCTION FOR PREPARATORY CLASSES. Assembled in accordance with Regimental General Order 14, 1885, paragraphs 20 to 30. (See Appendix C, Section III.) THE following is intended as a general guide only ; Instructors must vary the detail according to the progress of the class. 1st attendance : (1) Instructor having put out a sub-base of 6 yards will exercise the class in finding a base of about 60 yards, first with shutter open, afterwards with shutter closed. They will at the same time learn how to read the cylinder. (2) Those not occupied in the above, will be employed in ascertaining by trial, several times over, how many of their paces at the double go to 100 yards, also in learning to pace yards at the quick march. 2nd attendance : (1) Each man will be taught in succession to lay a 6-yard sub-base with reference to a C picket placed by the Instructor, and will afterwards learn how to plant a C picket. (2) Those not occupied in the above, will be employed in finding a base set out by the Instructor with the sliding collar at a different point from the correct one. One of them will take down the readings in a note-book, and the Instructor will afterwards turn the readings into yards, and see what accuracy each man has attained to, the same instrument being used through- out. 3rd attendance ; (1) Instructor having put out a C picket, and set the base himself, will exercise the class in taking an easy range (about 800 yards), first with shutters open, afterwards closed. (2) Those not employed in the above will practice picket drill. 4th attendance : (1) First part of last lesson will be repeated with a longer range (shutter closed), and class will also be taught how to fiat a right angle, and will each in succession do so, and plant a C picket with reference to aii A 80 picket placed in position by the Instructor. The Instructor will follow each, and make those who fail repeat their observations. (2) Those not employed as above will be exercised by taking a range, A and C pickets being placed by the Instructor, and an untrue base given to be set on the base bar. One of the class will write down the readings, and the Instructor, who knows the real base, will afterwards turn these readings into yards, and judge of each man's work. 5th attendance : The class being told off in squads of two will be taught how to take an easy range in slow time, the Instructor following each one's work. 6th attendance : Repeat yesterday's lesson in quicker time, with a range of about 1,200 yards. 7th, 8th, and 9th attendances : Range-finding with and without telescope on easy ground. Distances up to 2,000 yards. Bases 60 to 110 yards. No calculations. 10th, llth, and 12th attendances: Range-finding on difficult ground, including steep slopes. Distances up to 3,000 yards. Bases 60 to 120 yards. No calculations. The class to measure cords every day before beginning work. The Instructor must pay great attention to the positions of the hands at drill, and to the accuracy of the work, on no account insisting on quickness at the expense of accuracy. ^ ^ : ' I I Tli Hi! I ^'8 I 4 t "*$> 1 I i > LJ U UJ ac u CL o: LJ LI I 9 u u: X J. < -J a. DC U kl S Ld J u o -J Ul I I > bJ Id 0. I Q ui /& H-N I \ UNIVERSITY OF CALIFORNIA LIBRARY BERKELEY THIS BOOK IS DUE ON THE LAST DATE STAMPED BELOW Books not returned on time are subject to a fine of 50c per volume after the third day overdue, increasing to $1.00 per volume after the sixth day. Books not in demand may be renewed if application is made before expiration of loan period. OCT 30 1917 FED 16 i927 50w-7,'16 YC 64390 UNIVERSITY OF CALIFORNIA LIBRARY - I c ~. IK m.