U G SB Iketching and Reading Grieves 00 ?5 10 MILITARY SKETCHING AND MAP READING BY CAPT. LOREN C. GRIEVES INFANTRY THIRD EDITION REVISED and ENLARGED WASHINGTON UNITED STATES INFANTRY ASSOCIATION 1917, Copyright 1918 By Capt. Loren C. Grieves .* TABLE OF CONTENTS INTRODUCTION PART I. MAP READING LESSON I Page Length of Pace or Stride 5-6 LESSON II Individual Scale of Paces or Strides 7-13 LESSON III Solution of Scale Problems 14-16 LESSON IV Miscellaneous Scale Problems 17-18 LESSON V Orientation, Distance and Direction 19-27 LESSON VI Conventional Signs 28-35 LESSON VII Relief Maps 36-42 LESSON VIII Method of Determining Difference of Elevation . 43-48 LESSON IX Exercises in Contouring 49-52 LESSON X Visibility 53-56 PART II. MILITARY SKETCHING LESSON XI Flat Sketch 62-71 LESSON XII Road Sketch 72-76 iii 381427 ^i TABLE OF CONTEXTS LESSON XIII Position and Outpost Sketches 77-82 LESSON XIV Place Sketch 83-85 LESSON XV Miscellaneous 86-90 PART III. PANORAMIC OR LANDSCAPE SKETCHING Introduction 91 LESSON XVI Delineations 92-94 LESSON XVII Delineations (Continued) 95-99 LESSON XVIII Outdoor Exercises 100-107 LESSON XIX Sub-sketch 108-110 LESSON XX Range Data 111-115 APPENDIX Suggestions for Training Camps ....... 116-120 PREFACE In writing this book an effort has been made to produce a text-book on Military Sketching and Map Reading meeting the requirements of the curriculum prescribed for educational institutions operating under the pro- visions of the War Department, also to meet the require- ments prescribed in the examination of candidates for commissions in the Regular Army and the Reserve Officer's Training Corps, and to provide a suitable course for the officers of the National Guard, and thus stand- ardize the instruction throughout the service. In view of the above, attention is invited to War Department orders prescribing text-books. It has been the aim to produce a suitable text-book at the minimum price, free from all extraneous matter and yet completely fulfilling the requirements. The author acknowledges with thanks the valuable assistance rendered by Captain A. W. Bjornstad in co-ordinating the subject matter of the text to meet the requirements of the various branches of the military establishment. INTRODUCTION The first duty of the instructor is to eradicate from the mind of the student the mistaken idea of many that this is a difficult subject. Many have the idea that one must possess artistic abilities in order to become proficient. That is not true. Simply master the basic principles and apply them. Some may be able to turn in neater and more artistic sketches than others, but the reader is looking for facts, and, if the facts are shown, the sketch answers the purpose. The subject, in so far as this text is concerned, is divided into two parts. Part I treats of Military Map Reading, or, the classification of maps; the natural and artificial objects represented on the map; methods of interpretation and military uses of maps. Part II treats of Military Topographical Sketching, or the means and methods employed in making military road and area sketches, and the reports pertaining to them. It is enjoined upon the instructor to employ the means and methods suggested, and to anticipate the require- ments of each lesson as to equipment. Large classes may be instructed successfully by one instructor if the right methods are pursued. The suggestions given in the Appendix which pertains to training camps apply in so far as the equipment is concerned to the work in organizations and educational institutions. PART I LESSON I LENGTH OF PACE OR STRIDE Before taking up the subject of scales, the student should determine the length of his pace or stride. An accurately measured course of at least one thousand yards should be selected. A thousand yards on the target range will answer the purpose, or, if a target range is not available, a course may be measured, prefer- ably on turf rather than on a macadamized road or side- walk. While pacing, one should take an easy, natural, and uniform gait. This is important as there is always a tendency on the part of the beginner to consider pacing and his natural gait as entirely distinct, which usually results in his first scale of paces or strides being too long. This may be obviated by pacing a sufficiently long course several times (four times is suggested), first impressing upon the student's mind the necessity of taking a natural and uniform gait. Let us assume that each student has paced the course four times, and that his four results of pacing a course 1,000 yards long are: 1118 paces. 1109 " 1120 " 1117 " Total 4464 paces. 4464-^4 = 1116 paces (average number of his paces for 1,000 yards). To determine the length of his pace in inches: 1,000 yards = 36,000 inches. 36,000-^1116 = 32.2 inches, the length of his pace. Before computing the length of his pace, each student should present his results of pacing to the instructor for verification, and, if any wide discrepancies exist, the stu- dent should be required to pace the course again. To avoid error in pacing, the student should keep a record 6 MILITARY SKETCHING of the number of paces by making a mark for each 100 paces. A pace tally may be used if available. A hand instrument known as a "Tallying Register" may be used in recording the number of strides, if a scale of strides is desired. To accurately determine the length of pace or stride of each student, without doubt, will occupy the time avail- able for the first lesson, and the construction of scales will be taken up in the next lesson. REVIEW Explain, as to a beginner, exactly how to determine the length of one's pace or stride. LESSON II INDIVIDUAL SCALE OF PACES OR STRIDES, READING SCALES Having determined the length of our pace or stride, let us now consider the subject of scales of maps. It is very clear that the ground and all of the objects upon it cannot be represented as large on the map as they ac- tually are. They must be reduced in size. In other words, any distance on the map is a certain fixed part of the corresponding distance on the ground, and this re- lation between map distance and ground distance is called the scale of the map. The scale should be no larger than is necessary to bring out all of the required details. For example, it has been found that the scale, 3 inches = 1 mile (meaning that 3 inches on the map represents 1 mile on the ground), is the proper scale for "Road Sketches." It gives just enough room to insert all of the details of military impor- tance, while, if we were to use the scale, 1 inch = 1 mile, for 44 Road Sketches," there would not be enough room, and by using the scale 6 inches = 1 mile, we would burden our- selves and those reading the map with an unnecessary amount of paper. There are three ways in which the scale of a map may be represented. 1st. A plain statement, as, for example, 3 inches equals 1 mile. 2nd. Represented by a fraction. To determine the fraction representing any scale, as 3 inches = 1 mile, let the map distance be the numerator and the ground dis- tance the denominator, BOTH TERMS OF THE FRACTION BEING OF THE SAME DENOMINA- TION, then reduce the fraction so that the numerator will be unity, as, for example: 3 inches on map _ 3 inches 1 _ Representative Fraction 1 mile on ground "63360 inches ~~ 21120 ~ (abbreviated R. F.) 8 MILITARY SKETCHING 3rd. Graphically, in which the scale is actually repre- sented on the map, or on a ruler by a line divided into equal parts, each division being marked by the distance which it represents on the ground. There are two kinds of graphical scales: one for mak- ing the map, called a working scale, and one for reading the map, called a reading scale. If the same units of measure were used for both map making and map read- ing, one scale would answer for both purposes; but this is seldom the case, as we may obtain our distances in terms of paces or strides of various lengths depending upon the individual, while the party reading the map neces- sarily must have the distances expressed in terms of well- known units such as yards or miles. To CONSTRUCT A WORKING SCALE OF PACES Let us assume that a student has paced a course of a thousand yards four times with the following results: 1st result, 1118 paces. 2nd result, 1109 paces. 3rd result, 1120 paces. 4th result, 1117 paces. He wishes to construct a working scale, 3 inches on the scale representing 1 mile on the ground. To do so he should proceed as follows: 1st. Find the length of his pace. 2nd. Find how many of his paces will be represented by one inch on the map. 3rd. Find the length in inches of his working scale. 4th. Construct the scale. 1st To FIND THE LENGTH OF His PACE (See Lesson I) 2nd To FIND How MANY OF His PACES WILL BE REPRE- SENTED BY ONE INCH ON THE MAP 3 inches on the map = 63360 inches on the ground. 1 inch on the map = 21120 inches on the ground. 21,120-^32 = 660 of his paces. INDIVIDUAL SCALE OF PACES OR STRIDES 9 3rd To FIND THE LENGTH IN INCHES OF A CONVENIENT WORKING SCALE REPRESENTING SAY 2,400 PACES 660 paces = 1 inch. 2,400-^-660=3.63 inches, length of scale. To CONSTRUCT THE SCALE Lay off the line AB (Fig. 1), 3.63 inches long, which represents 2,400 paces. Divide this line into 24 equal divisions representing 100 paces each. Divide the first one of these divisions on the left into five equal parts repre- senting 20 paces each. Transfer these divisions to a suit- able straight-edge ruler and the working scale is com- pleted. Working scales of 1", 6", and 12" to the mile may be constructed in a similar manner, also working scales of strides. To divide the line AB (Fig. 1) into 24 equal divisions, lay off any line AC that can be conveniently divided into 24 equal parts. Draw a straight line connecting B and (7, then draw lines parallel to BC as shown in the figure. These lines will divide AB into 24 equal divisions of 100 paces each. Use the same method for the divisions repre- senting 20 paces. The ruler shown in Fig. 2 is the most suitable for sketch- ing. It is made of a triangular, straight-edged piece of hard wood. A hole 3/8 inch in diameter and 2 inches deep may be bored into each end of the ruler and filled with lead to give it weight. This form of ruler furnishes a well-defined sighting line, and is the most convenient of any working scale yet devised. The material may be obtained by the instructor and cut into 6-inch strips, and, if practicable, filled with lead; or they may be obtained at a nominal price from the Book Department, Army Service Schools, providing the Book Department is fur- nished with the necessary data as to the various lengths of paces or strides desired. After determining the length of your pace or stride, the working scale may be transferred to the ruler directly 10 MILITARY SKETCHING 8 OQ INDIVIDUAL SCALE OF PACES OR STRIDES 11 from the consolidated scales shown in Fig. 3 by placing the edge of the ruler on the proper line or interpolating between lines. This is sometimes found to be more practicable with certain non-commissioned officers than attempting to require them to solve the problems. / !'"M 1 1 I 1 1 1 1 1 1 1 1 I 1 1 1 \ \ \ \ \ \ \ 1 I \ ,||lO 2 4 6 8 1O12 14 16 18 20 23 24OO] 3in. Imi. 32ft, 32 il i.l*ace8 FlG. 2 To CONSTRUCT A READING SCALE OF YARDS After a sketch has been completed, you wish to place upon the sketch a reading scale of yards so that any other person may be able to read distances correctly from your sketch. Assume that the scale of your sketch is 3 inches = 1 mile, or 1 inch = 21120 inches = 596.66 yards. Say that you desire a reading scale that reads to 3,000 yards. 3,000-=- 596.66 = 5. 11 inches, the length of your scale. With a box-wood scale, lay off a line 5.11 inches long, and by the method explained in Fig. 1 divide it into 30 equal parts, or any other number of equal parts, and your reading scale of yards is completed. REVIEW 1. What is meant by the scale of a map? 2. In what three ways may scales be represented? 3. Six inches on a certain map represents 1 mile on the ground. Represent the scale of this map by the three methods. 4. Construct a working scale of paces for your own use for making a map on a scale 3" = 1 mile, also a working - scale of paces for your own use for making a map on a scale of 6"= 1 mile. 5. How may the above working scales be converted into working scales of strides? MILITARY SKETCHING SCAL.C C2N20 3 lN.=tMi. 68 10 12 14 16 18 20 22 Z4 26 28 3000 \\' \ \\\\\\\\\v \\\\\\\\\\ \\\\\\\\\v \\\\\\\\\ \ \ \ \ \ \ VA \\\\\\\ \ \\\\\\ \ \\\\\\ \ \ \ \ \ \ \ \ \ \ \ \ \\ \ \ \ \\ \ \ \ \ \ \ VA 10 II 12 13 14 1500 I 2 3 4 5 6 700 Paces 03 6 9 12 15 18 21 24 27 30 33 36 39 4200 Paces FIG. INDIVIDUAL SCALE OF^PACES OB STRIDES 13 SCALE. 1:21120 3 IN. = i MI. 89 10 II 12 13 14 1500 Z7 I Paces 500 Paces 3000 Paces LESSON III SOLUTION OF SCALE PROBLEMS PROBLEM No. 1 Scale of minutes to be used by mounted sketcher. A sketcher's horse trots 1 mile in 8 minutes. Construct a scale of minutes for an R. F. of QIIQQ- Solution: 8 minutes = 63360 inches. 1 minute = 7920 inches. 1 inch on map = 21120 inches on the ground. 21120 a . . , 7920 = F mmu ^ es to cover one inch on map. Let us construct a scale 6" long. A 2 X6= 16 minutes to cover 6 inches. 8 Construct the scale by dividing a line 6 inches long into 16 equal parts, each part representing the distance traveled in one minute. Divide the space on the left into 4 equal parts giving the distance traveled in a quarter of a minute. PROBLEM No. 2 Foreign Maps You are given a foreign map, scale, 1 centimeter = 1 Kilometer. (a) Required, the R. F. Solution: Simply reduce 1 Kilometer to centimeters, and we have the R. F. 1 100,000* (6) How many inches to the mile in this scale? RULE: To determine the number of inches to the mile of any R. F., divide 63360 by the denominator of the R. F. 14 SOLUTION OF SCALE PROBLEMS 15 PROBLEM No. 3 Foreign Maps You are given a foreign map with a reading scale only. By measuring the reading scale, you find that 1 Kilometer = .92 inch. What is the R. F. of the map? Solution: 1 KM. = 1,000 meters. 1 meter = 39.37 inches. 1 KM. = 39370 inches. . 92 inch on map = 39370 inches on the ground. 39370 42793 PROBLEM No. 4 Map of Local Terrain with no Scale To Determine the R. F. Measure the distance between two points on the ground that are located on the map, then measure the map distance between the two points. Let the map distance be the numerator and the ground distance the denom- inator, BOTH BEING REPRESENTED IN THE SAME DENOMINATION. Reduce the fraction so that the numerator is unity and you have the R. F. PROBLEM No. 5 Relation of Scale to Area of Maps Rule To change the area of a map, multiply each of its linear dimensions by the square root of the change. Example: A map 12" by 20" is to be reduced to of its present area, yy !*"-". ^20" =10". So it is seen that 6"xlO" are the reduced dimensions. Also, a map 12"x#0" is to be enlarged to 4 times its present area, 16 MILITARY SKETCHING Applying the same rule, we find that the new dimen- sions are 24"x40". PROBLEM No. 6 Correction of Erroneous Scales You are directed to make a road sketch, scale 3" = 1 mile. You use a working scale of 32" paces. Later you find that your pace is actually 30". What is the R. F. of the sketch actually made? Solution: If your pace had actually been 32" long, the R. F., of course, would have been . The result of your shorter pace is the en- largement of the scale of the map, that is, a R. F. with a smaller 30 1 denominator by , making ino/m the proper R. F. LESSON IV MISCELLANEOUS SCALE PROBLEMS 1. Construct a working scale of paces for a map on the scale of 12" = 1 mile, 110 paces being equal to 100 yards. 2. A sketcher's horse trots a mile in 7 minutes. Con- struct a scale of minutes and quarter minutes for a 3. A foreign map is reproduced on a scale of -inn (a) Construct a reading scale to show 10 miles on the map. (6) Construct a reading scale to show 10 Kilometers. (1 Meter equals 39.37 inches.) 4. Your pace is 32" long. You are given a map of local terrain which has no scale. Two points on the ground which are located on the map have a ground distance of 4,000 of your paces. The map distance is 6.3 inches. What is the R. F. of the map? 5. You are given a French map with a reading scale only. By measuring the reading scale, you find that 1 Kilometer = .76 inch. What is the R. F. of the map? 6. The dimensions of a map with a R. F. of o5,*>oO is 6" by 8"; What will be the dimensions of the map of a R. F. of How much is its area increased? 10,56 7. You are directed to make a position sketch, scale 6" = 1 mile. You use a working scale of 64" strides. Later you find that your stride is actually 60". What is the R. F. of the sketch actually made? 8. Draw a reading scale of yards for a map 15 by 18 inches to show an area of 6 square miles. 9. Our geological maps have a R. F. of o/ 17 18 MILITARY SKETCHING Construct a reading scale of miles, halves, and quarters. One inch on our geological maps equals how many yards? 10. Compare the scales of various maps, such as our geological maps, maps of your city, geographical maps of states, county maps, construction maps, etc. Always note the scale of a map before attempting to read the map. LESSON V ORIENTATION, DISTANCE, AND DIRECTION In the practical use of a map in the field, the next step, after determining its scale, is to "Orient" the map. In order to compare the map with the ground that it represents, we must first see that the directions on the map and on the ground coincide. This is called "Orient- ing the map." All complete maps have both the magnetic and true meridian indicated. The true meridian is a straight line joining the observer's position and the north pole of the earth. The magnetic meridian is a straight line that coincides in direction with the magnetic needle of the compass at the observer's position. The directions of the needle at different places on the earth's surface converge approximately toward the magnetic? poles of the earth. These poles do not coincide with the poles of the earth's axis, and therefore the magnetic and true meridians do not generally coincide. The angle between the magnetic and true meridian at any place is called the "Declination of the needle" for that place. There is a certain irregular line on the earth's surface at all points of which the true and magnetic meridians coincide and the declination is zero. This line is called the "agonic" line. In the United States it passes in a southeasterly direction from Michigan through inter- vening states to South Carolina. The agonic line is not permanent, but is slowly moving westward. At all points in the United States east of the agonic line, the north end of the needle inclines to the west of the true meridian. To the west of the agonic line the needle in- clines to the east of the true meridian. Psogonic lines are lines joining points of the same declination of the needle. As the agonic and isogonic lines are gradually changing, maps should always have the true as well as the magnetic meridian indicated. 19 20 MILITARY SKETCHING There are a few simple methods of determining the true meridian (true north and south line), with a degree of ac- curacy sufficient for military sketching and map reading. For an accurate instrumental survey, an observation on Polaris (North Star) should be taken. This is not in- eluded in the text, as it properly comes under the head of advanced surveying. First Method By means of the North Star. Without instruments, it can be determined approximately by placing two cords, with weights attached, in line with the star. The cords should be about 12 feet apart, and to see the forward one, it will be necessary to throw a light upon it. This line can readily be prolonged by daylight. ^Second Method By aid of the sun and plumb-bob (see Fig. 4). On a level piece of ground lean a pole toward the north, and rest it in a crotch made by two sticks as shown. Sus- pend a weight from the end of the pole so that it nearly touches the ground; then, about an hour before noon, at- tach a string to a peg driven directly under the weight, and, with a sharpened stick attached to the other end of the string, describe an arc with a radius equal to the dis- tance from the peg to the shadow of the tip of the pole. Drive a peg on the arc where the shadow of the tip of the pole rested. About an hour after noon watch the shadow of the tip as it approaches the eastern side of the arc, and drive another peg where it crosses. By means of a tape or string, find the middle point of the straight line joining the last two pegs mentioned. A straight line joining this middle point and the peg under the weight will be in the true meridian. Place a pole about a hundred yards in prolongation of this line, and with the compass sight back on the tip of the inclined pole, and the declina- tion will be obtained. ORIENTATION, DISTANCE, AND DIRECTION Third Method By aid of the watch and sun. Lay the watch on some level surface and revolve it until the hour hand points di- rectly under the sun. Then by reference to the divisions FIG. 4 on the dial, determine a point on it midway between the hour hand and twelve o'clock. A line through this point and the pivot of the hands will be approximately in the true meridian. (See Fig. 5.) The operation of pointing the hour hand directly under the sun is made^easy by casting^the^shadow of a vertical FIG. 5 straight stick across the face of the watch and then bring- ing the hour hand into this shadow. The watch method will not answer during certain sea- sons in^the tropics when the sun passes directly overhead, 22 MILITARY SKETCHING There is also another slight error due to the fact that in some sections there is a difference of half an hour be- tween standard and sun time. ORIENTING THE MAP As heretofore stated, all complete maps have both the true and the magnetic meridian indicated. However, it is assumed that you have found the declination of the needle for your particular locality, so, if either the true or the magnetic meridian be given, the other can be readily determined. First Method When the map has the magnetic meridian marked on it: Place the compass on the map, so that the needle pivot rests on the magnetic meridian; revolve the map until the north end of the needle and the magnetic meridian point in the same direction, whereupon the map is oriented. Suppose that only the true meridian is given on the map. Knowing the declination of the needle, construct a mag- netic meridian and proceed as above. Second Method Suppose that neither the magnetic nor the true meri- dian is indicated on the map. (a) Take position on the ground corresponding to some point on the map. Identify another point on the map that you can see on the ground. Join the two map positions by a straight line. Hold the map so that this line points toward the distant point seen on the ground, whereupon the map is oriented. (6) Place yourself on the line of any two points visible on the ground and plotted on the map, rotate the map until the line joining the two points on the map points towards the two points on the ground, whereupon the map is oriented. (c) Observation, co-ordinating map with the various visible terrain features. ORIENTATION, DISTANCE, AND DIRECTION 23 To LOCATE YOUR MAP POSITION First Method After the map is oriented by the compass: Sight along the rule at an object on the ground at the same time keeping the rule on the plotted position of this object on the map. Draw a line toward your body. Find another point on the ground that is plotted on the map and repeat the process. The intersection of the two lines is your map position. The two points selected should be so located that the angle formed at the inter- section of the lines should be not less than 30 degrees nor greater than 120 degrees, otherwise the two intersecting lines are so nearly parallel that it is difficult to locate the exact point of intersection. Second Method If the map has been oriented by means of a straight line drawn between two map points, then it will be necessary to draw but one line from the object on the ground, and the intersection of this line with the line already on the map will be your location on the map. Third Method Observation. MAP DISTANCES Knowing the scale of our map and having oriented it, we should now be able to determine from the map the distance between objects on the ground and the direction of one from another. We will first consider converting map distance into ground distance. Every complete map has a reading scale of some well-known unit as yards or miles, so all that is necessary to determine the ground distance be- tween points on the map is to apply the reading scale to the map distance or the map distance to the reading scale. There are several simple methods of taking distances from the map: 24 MILITARY SKETCHING First Method Suppose that you have no reading scale except the one printed on the map. If such is the case, apply a piece of straight-edged paper to the distance between the two points to be measured. Mark the distance on the paper, and apply the paper to the reading scale of the map, or copy off the reading scale on a piece of paper and apply the paper to the map. Second Method A scale of inches may be applied to the distance be- tween the two points to be measured, then multiply the number of inches between the two points by the number of miles per inch given on the map. (Caution: do not confuse the terms "miles per inch," and "inches per mile.") Third Method The Geological Survey maps made on a scale of 1-62,500 are much used by the army, but as there is a difference of but about 1 per cent between these maps and maps made on the scale of 1-inch equals Imile, the 1-inch reading scale is sufficiently accurate for most purposes. Fourth Method It is often necessary to take off distances from the map in terms of one's paces or strides. To do so, simply apply your scale of paces for 1, 3, or 6 inches to the mile to maps of those scales, and for maps of 2, 4, or 5, or any other whole number not represented on your scale of paces, apply your 1-inch scale of paces and divide the result by two, four, or five as the case may be. Fifth Method Map Measurer. A small instrument so constructed that it may be rolled over the surface of the map, and will record on a dial the distance passed over. Complete instructions for its use are given with each instrument, ORIENTATION, DISTANCE, AND DIRECTION 25 This instrument is especially valuable for use in map prob- lems and war games. MAP DIRECTIONS As the captain consults his chart and compass in guid- ing his ship, so must the soldier consult his map and com- pass in traveling through unknown regions. The usual style of box compass or other small compasses has the four cardinal points, N., E., S., and W. (North, East, South, and West), marked on its surface, and a circle graduated in degrees reading zero, clockwise around to 360 degrees, beginning and ending at N. In order to travel by the compass, one must be able to convert map directions into compass directions; in other words, we must be able to determine the MAGNETIC AZIMUTH of any line. By the Magnetic Azimuth of a line is meant the hori- zontal angle that the line makes with the compass needle measuring from the north point clockwise around the circle. The True Azimuth is measured in the same direc- tion from the north point of the True Meridian (true north and south line). A protractor is an instrument for measuring and plotting angles. A protractor is usually so graduated that it is laid on the east side of the meridian through the plotted position for plotting angles from zero to 180 degrees, and from 180 degrees to 360 degrees the protractor is placed on the west side of the meridian. To illustrate you are at the point A, Fig. 6, and you wish to obtain the magnetic azimuth of the line AB. Draw a line AC through A parallel to the magnetic north and south line. Lay your protractor along AC, the center of the protractor at A. (The center of the pro- tractor is indicated by an arrow point.) Read the number of degrees between AC and AB. It is found to be 63 degrees, which is the magnetic azimuth of the line AB. Then suppose that you are at A, and wish to proceed in the direction of B. Simply hold the compass so that 10 ISO 20 200 \ x SS \ e \ \ u = ^ ORIENTATION, DISTANCE, AND DIRECTION 27 the needle is at N 9 then follow in prolongation of a line drawn through the pivot of the needle and the 63-degree point. The course is kept by an occasional reference to the compass which is held in front of you or placed upon the ground. Maps of various scales should be issued to members of the class, who should determine the distance in terms of yards, miles, or paces, and the magnetic azimuth between designated points in accordance with instructions given in this lesson, QUESTIONS FOR REVIEW 1. What is meant by the expression, "orienting the map?" 2. What is meant by the true and magnetic meridians? 3. What is meant by the declination of the needle? 4. What is the agonic line? 5. What are isogonic lines? 6. What is the declination of the needle to the east of the agonic line? To the west? 7. Describe three methods of determining approxi- mately the true meridian. 8. Describe two methods of orienting the map. 9. Describe two methods of locating your position on the map. 10. Describe the methods of scaling distances on the map. 11. What is meant by the magnetic azimuth of a line? The true azimuth of a line? 12. What is a protractor? 13. Describe the use of the protractor in determining the true and magnetic azimuth of lines. 14. Practical problems in determining distance and azimuth of points on the map should be given the class. LESSON VI CONVENTIONAL SIGNS Having learned how to read distances and directions on the map, we will now consider the many natural and artificial ground features of importance and the method of representing them on the map. In order that all may be able to read the map when completed, we must have some fixed method of repre- senting these ground features. With this in view the United States Geographic Board adopted, in 1912, a system of conventional signs for the use of all map- making departments of the government. At the close of the lesson are those that pertain to the work to be covered by this book. Members of the class should be required to reproduce these signs as neatly as possible, and this lesson should be devoted to that purpose. The instructor should superintend and criticise the work; especially should he avoid the usual tendency of making the signs too large. The ability to neatly reproduce these conventional signs should be included in the examination over this subject. When you find some idle moments with a pencil and paper at hand, your time may be profitably employed by practicing the con- struction of conventional signs. Just a few words about pencils would not be amiss at this particular point. The best for plotting are the hard kinds corresponding to Faber's Siberian HHHH and HHHHHH, especially for drawing fine lines and making points. For most kinds of work, a sharp-pointed pencil is used. For drawing long, straight lines, a chisel-pointed pencil should be used to produce a line of uniform "breadth. For sketching and filling in conventional signs, softer pencils are preferable, such as correspond to Faber's HB. To keep the point always in good condition one should have a piece of fine sandpaper at hand for that purpose, CONVENTIONAL SIGNS 1 MI n ! : ^ ii 1 | ! 1 i LyJ L i i . ! 1 ? \i j Poor or Private... 1 On small-scale m Hi 1 i It 1 f tjijl c ^ 8 -5 1 ^ M fc s o 1 3 1 1 i ; r 1 ; ' t !l t- i- ; f i * * i 5 j > : r ^+ h I ! i ; < Xj E < c v * * " "i J 5 j 111 it 1 S5 S * \* r T ^ ^-S *Q "^^ .2 1 > 1 t ^ Railroa* } i 30 MILITARY SKETCHING < t ! 1 > i > i i i l ^ f 1 , > . \ > i j| 2 for bo, Stone.. i 1 I 9 -1 ' , ' i 1 1 k >^ Church.... 1 Schoolhouse 1 1 1 Wafer wor/ra Windmill . I I fe CONVENTIONAL SIGNS 31 MILITARY SKETCHING <> 5? a CONVENTIONAL SIGNS 33 - 6 o Jl {HHHHHJ Jl MJBflBBQ JQ^- 04 *^*!^^ o> /* ^ttefj u : u - 11 - i "1 1 -^ ! i ^r 5- 1 t ^i I I ; ^1 W* ^ : ) ^ sS .5 C : i ! ^ ilii r * 5 ^ s 1 i i 4 1 1 1 ! i I 1 i \ t 1 ! 1 Infantry in column... f*.a\/atr\t in Una ^ ? : 1 1 ^ *^ i 1 J j " i . ] ii ? s l ^ 1j f '1 1 i i 4 t- ! ? Is | I .1 | ! 1 5 ? 1 I * 2 !** j | r vj 34 MILITARY SKETCHING * " 2 >>- S^.u-^^w^'J? o tf> E c > . e o o i- o u u O D o Q uj EL 5 1 CONVENTIONAL SIGNS 35 being careful to remove any lead dust from the point before using. Much more depends upon the proper sharpening of a pencil, and afterwards keeping it so, than is commonly supposed. Most drawings to be inked are first constructed in pencil, the lines being made with as little pressure and as fine as is possible to show distinctly. LESSON VII RELIEF MAPS We have learned how to determine from the map the horizontal distances between points on the ground, the direction of one point from another, and the conventional signs representing the various terrain features, but, in order to have a better knowledge of the earth's surface, we must have some method of rapidly determining eleva- tions. In other words, we must know how high the hills are and how deep the valleys are. This is done by means of CONTOURS, which are lines cut from the earth's surface by imaginary horizontal planes at equal intervals from each other. Suppose that the territory represented by map, Fig. 8, were submerged, and later the water begins to subside by a succession of falls of the water level of 20 feet, each time leaving a deposit of silt at the water line. Even- tually the whole terrain emerges, and would appear roughly as shown in Fig. 9. The silt deposits of the various water lines would represent actual contours on the terrain itself. The whole subject of contours may be made absolutely clear by the construction of relief maps. The method which will be described is a decided departure from previous methods. Instead of the sand box, moulder's wax is used. This material lends itself admirably to this class of work, due to the fact that it is very plastic, retains its consistency, and, when the relief is completed, permits of vivid representation of all terrain features by means of indentations in the wax. In order to be successful in this work the moulder's wax must be used. Do not attempt to use the sand table. The latter answers the purpose very well for indoor work in field fortifications, but it will not do for topographical work. Every organization and military institution should secure enough of the wax for relief 86 RELIEF MAPS 37 map construction in connection with map reading and instruction in Minor Tactics. CONSTRUCTION OF RELIEF MAPS The first necessity is a table constructed as shown in Fig. 7. The two "enclosures on top of the table are 18" square, interior measurements (the same dimensions as the Gettysburg-Antietam 12" sheets). The flange en- closing the squares is one-fifth of an inch thick and an inch and a half in width. The top of the table should be perfectly level, and the flange of uniform thickness and planed. Also secure a rolling pin of hard wood, Space I 18" I 18" to at+ach I Mould/net I I Moulding Map I Frame I I Frame Box to hold moulders wax FIG. 7 22" long and about 4" in diameter. A sufficient amount of moulder's wax should be secured. This may be purchased from Stewart & Company, 24 Broadway, New York City, and presumedly from other dealers. The wax comes in different colors; the olive-green is preferable for this work. The price of the wax in small orders is about twenty cents per pound, and, when ordered in large quantities, it may be secured at a reduced rate. It takes about twenty pounds to construct one of the Gettysburg- Antietam 12" sheets, but is well worth the investment. As, without doubt, you will have need to use the Gettysburg-Antietam 12" sheets in connection with studies of minor tactics, such as "Studies in Minor Tactics, 1915," and "Small Problems," etc., let us construct a relief map of one of those sheets. The necessary 12" sheets, unmounted, included in the texts 38 MILITARY SKETCHING referred to above may be secured from the Book Depart- ment, Army Service Schools, Fort Leavenworth, at a surprisingly cheap price. The table, moulder's wax, and maps having been se- cured, the actual method of construction is as follows: FIG. 8 Place a sufficient amount of wax in each of the squares, and roll off flush with the top of the squares, so that you now have two sheets of wax each one-fifth of an inch thick. If the wax sticks to the tray and roller, apply a little talcum powder Place the map over one of the RELIEF MAPS 39 squares, and, with a blunt stylus, trace over^the'lowest heavy contour (20 feet) on the map, leaving an impres- sion of same on the wax. Cut out that portion of the wax the surface of which, according to the map, FIG. 9 would be below the contour just traced. Take the remainder of the sheet of wax and place it upon the base established in the other square. Refill the square from which the wax has just been removed, roll as before, 40 MILITARY SKETCHING and trace the next heavy contour. Continue this opera- tion, which will result in an incomplete relief map similar to that shown in Fig. 9. FIG. 10 Next, slope off abrupt surfaces between the heavy contours by moulding in small pieces of wax by hand, and the map is then completed in so far as the relief is concerned. Next, all of the natural and artificial features of the terrain are represented by indentations in the wax. This is easily done RELIEF MAPS 41 by whittling out small, soft pine sticks to represent the vari- ous conventional signs, as, for example, a square end stick for buildings, a round end for trees, etc. Roads and railroads may be draw in by means of a stylus and a straight-edge. Let- ters and figures may be drawn in, or, better, stamped in with rubber stamps or steel type. Every feature is easily repre- sented, and quickly indented on the surface of the wax. When you have no further use for a particular relief map, it may be torn up and another one constructed from the same material. Fig. 10 represents the completed relief map. With the mechanical means explained above, the student is absolutely sure of constructing the relief map correctly. Hav- ing done this work, it follows automatically that he is able to read a military map. The following principles of contouring may be noted in con- nection with Fig. 9 : 1. That all points on a contour line have the same elevation above the datum plane. 2. That, where the contours are equally spaced, the slope is uniform. 3. That, where contours are straight and evenly spaced, the ground is a sloping plane. 4. That the contours of a vertical surface lie on top of one another as in palisades. 5. That, if the slope in rocky formations is over the base, then only can contours cross. 6. That every contour closes upon itself or extends entirely across the map. 7. That on water-sheds the contours are convexed toward the base of the slopes. 8. That in water courses the contours are convex toward the sources of the stream. 9. That contours far apart indicate gentle slopes. 10. That contours near together indicate steep slopes. SUGGESTIONS TO INSTRUCTORS As a knowledge of map reading goes hand in hand with the study of tactics, it is believed that a few words at this 42 MILITARY SKETCHING point regarding the co-ordination of the work would not be amiss. It has been found by the author that pleasing results with beginners may be obtained by constructing relief maps of the terrain involved in small tactical problems. Attention is invited to Sketch No. 1, page 5, "Studies in Minor Tactics, 1915." Select the 12" sheets comprised in this section; build up each sheet as above described; join the sheets together and you have the desired area for the first part of the prob- lem. Then, with the war game set, you are ready to proceed with the text. Detail two or three students each day to con- struct the area for the following day. The relief map work, after the class has been properly instructed, should be con- ducted by detail outside of the class, and eventually all will have an opportunity to construct a relief map without seri- ously interfering with their work or recitations. Having all of the paraphernalia necessary for the work at hand, two men should be able to construct a relief map of one of the 12" sheets in about two hours. Assuming that Part I of the text referred to will constitute part of the course: it deals with an infantry regiment that detrains, advances, reconnoiters, and attacks an enemy in position, pursues, halts for the night, establishes outposts, pre- pares and occupies a defensive position, withdraws therefrom and retreats. All of these dispositions are clearly and vividly brought before the mind of the beginner by the aid of the relief map, and gains his interest at the start. Later, when all have become more proficient in map reading and tactical disposi- tions, the ordinary map may be substituted. This is considered an important lesson, and, to obtain suc- cessful results, much depends upon the demonstrations and explanations of the instructor. LESSON VIII METHODS OF DETERMINING DIFFERENCES OF ELEVATION From the relief map constructed in the previous lesson, the student should now understand what contour lines are, and the necessity of placing contour lines on maps in order to form a correct idea of the locations and extent of elevations and depressions of the earth's surface. The surface of the ground is either level or sloping. As one walks along a level course, his elevation naturally remains the same, while, if he walks along a sloping course, his elevation increases or decreases according as he is going up or down hill. It has been found that the up-hill end of a line 57.3 feet long which has a slope of one degree is one foot higher than the down-hill end. Computing from these figures, we are able to determine the difference of elevation between any two points if we know the distance and the angle of slope between them. The angle of slope may be determined by various instruments especially prepared for that purpose. A very practicable method of ascertaining angles of slope is by means of the slope-board, which is inexpensive, easy of construction, and never gets out of adjustment. CONSTRUCTION OF SLOPE-BOARD On your drawing board (see Fig. 11), construct DC per- pendicular ' to AB, then when a point is sighted along the straight-edge AB, the plumb line attached at D makes the same angle with the perpendicular DC that AB makes with the horizontal. This, of course, assumes that your drawing board is perfectly square. Lay off DE 5.73 inches long on DC, then, with the radius DE describe the semicircle FEG. Lay off from E toward F and G successive distances of one-tenth inch along the arc. These divisions represent degrees, because one degree in a circle of 5.73 inches radius gives a chord of one-tenth inch. 43 44 MILITARY SKETCHING Extend these degree marks to the foot of the board with a ruler as shown in Fig. 11. To read slopes, attach a plumb line at D, sight along AB at the object, keeping the board in a vertical plane. When the plumb line comes to rest, press the string against the edge of the board with the fingers and read the angle marked. OTHER LEVELING INSTRUMENTS There are several varieties of clinometers (hand instruments for reading angles of elevation). These instruments, although more convenient than the slope-board, are rather expensive to issue to a large class, or for individuals to purchase. If purchased, full directions accompany them. SCALES OF MAP DISTANCES AND THEIR USE Before taking up the subject of scales of map distances, a few terms which will be used frequently in the future will bear explanation at this point. V. I. means the vertical interval between contours. H. E. (Horizontal Equivalent) means the horizontal distance on the ground between two contours. M. D. (Map Distance) means the horizontal distance be- tween two contours on the map. A Normal System of scales has been prescribed for the U. S. Army field sketches as follows: Sketches of large areas ... 1 inch = 1 mile, V. I., 60 feet. Road sketches 3 inches = 1 mile, V. I., 20 feet. Position sketches 6 inches = 1 mile, V. I., 10 feet. Fortification sketches 12 inches = 1 mile, V. I., 5 feet. It will be seen that as the scale is increased the vertical inter- val between contours is proportionally decreased, so that by this system the M. D. is always the same for the same angle of slope whatever the scale of the map may be. The M. D. for any angle of slope may be computed from the following equation: 688XR.F.XV.L_ M D Angle of slope. In which 688 equals the horizontal distance in inches on a one-degree slope necessary to give a rise of one foot. DETERMINING DIFFERENCES OF ELEVATION 45 The V. I. is expressed in terms of feet. However, its func- tion in the equation is only a relative one without regard to denomination. A f f 1 1 1 1 1 1 1 n IO FIG. 11 If the R. F. and V. I. for any sketch made in accordance with the Normal System be substituted in the above equation, the M. D. will be the same for any particular angle. In view of this let us substitute: 1 R. F.= 63360 V. I. = 60. Angle of slope = 1 degree. and we have the following: ^xeo = .65 inch 688 X 63360 (the M. D. for one degree slope for any sketch under the Normal System). 46 MILITARY SKETCHING 1 1 9 I Dividing .65 by - -> - 1, 2, 3, 4, etc., we have the M. D. for 113 7 "i* 4' *> ^' ^' ^' e ^'' degrees from which data a scale may be easily constructed. (See Fig. 12.) ii lVi FIG. 12 As we have reading and working scales of distances, the same applies with elevations. Fig. 12 is a reading scale of M. D.'s (Map Distances). By applying this scale to any contoured map under the Normal System, we can readily determine the degree of slope between contours, and, by means of the table below, decide upon the practicability of military operations for the various degrees of slope. Students should be given an opportunity to study contoured maps in connection with the reading scale of M. D.'s and the table given below. The scale shown in Fig. 12 may also be used as a working scale, but a more convenient working scale will be explained later in the lesson. Degrees of slope. Operations. 14 to 15 18H 26 Maximum for railroads. Maximum for first-class roads. Practicable for all arms. Somewhat difficult for cavalry to charge descending. Maximum for cavalry to charge in mass ascending. Infantry in close order descends with some difficulty. Cavalry can descend at a trot. Not practicable for heavily loaded vehicles. Field artillery can no longer maneuver. Maximum up to which all arms can move. Light vehicles can ascend. Foot troops can ascend or descend aided by hands. WORKING SCALE OF ELEVATIONS We have learned that a horizontal distance of 57 . 3 feet for 1 degree slope gives a rise of 1 foot. or 5730 feet = 100 feet rise. 5730 feet = 69760 inches = 100 feet rise. DETERMINING DIFFERENCES OF ELEVATION 47 Suppose that we are using a scale 3" = 1 mile, then 1 inch on the map equals 21120 inches on the ground. 68760-i- 21120 = 3J4 inches on the map. Lay off a line 3J4 inches long and divide it into ten equal parts of 10 feet each, and subdivide each of the ten feet divi- sions into five equal parts of 2 feet each. Place this scale on the same ruler as your working scale of paces or strides, the left of this scale immediately below the left of your working scale of paces or strides. (See Fig. 13.) 10 .12 1ft 16 IS 20 23 3ra. = Imi. 33 to. 50 60 7O 8O 9O 1OO Ft . I . i l . . I \ I I 1 I 1 1 I 1 1 1 . . l 1 1 I 1 I I 1 FIG. 13 Now suppose that you have paced a course 500 paces long with a 3-degree slope. Lay off your distance of 500 paces from your working scale of paces (the upper scale), then glance at your working scale of elevations immediately below the 500- point on the upper scale, and you have the elevation for a one- degree slope; multiply this result by three, and you have the difference in elevation between the two points considered. In a similar manner a reading scale of elevations may be con- structed under your 6-inch scale of paces or strides. This will cover two faces of your triangular working scale. On the third face should be inscribed a scale of yards for 3 and 6 inches to the mile to be used when the distances are estimated, as may frequently be the case in hasty sketching. The scale shown in Fig. 13 has been found to be much more practicable at the Army Service Schools as a working scale than the one shown in Fig. 12. Slopes may be expressed in three ways: 1. In Degrees: A one degree slope indicates that the angle between the horizontal and the given line is 1 degree. 2. In Percentages: A slope is said to be 1, 2, 3, etc., per cent when 100 horizontal units correspond to a rise of 1, 2, 3, etc., of the same vertical units. 48 MILITARY SKETCHING 3. In Gradients: Expressed as a fraction in which the numerator represents the difference in elevation, and the denominator the horizontal distance between the two points. Degrees of slopes are used mostly in military matters, percentages for highway and railway construction purposes, and gradients for trench construction. Approximately, 1 degree slope = 1.7 per cent slope =^ gradient. QUESTIONS FOR REVIEW 1. Explain how to construct an attachment to your drawing board for reading angles of slopes. 2. Explain vertical interval, horizontal equivalent, map distance. 3. What is the Normal System of scales for use in the U. S. Army? 4. By making proper substitutions, determine the map dis- tance for J^, J^, %, 1 up to 10 degrees of slope, and construct a scale of M. D's. for same. 5. A contoured map is given to you. From this map deter- mine the various degrees of slope, and decide upon the prac- ticability of these slopes for military operations. 6. Construct a working scale of elevations for 3" = 1 mile and 6" = 1 mile, each to read to an elevation of 100 feet. Inscribe these scales on your triangular rule as explained in this lesson. (See Fig. 13.) 7. In what three ways may slopes be expressed? Illustrate. 8. Express a 5-degree slope (a) in percentage; (6) in gradient. LESSON IX EXERCISES IN CONTOURING We should now have a very good idea of what contours are and how to determine the elevations of locations by means of our scale of elevations. Before taking up the subject of sketching, much may be learned about contouring the ground to be sketched by working out the exercises suggested in this lesson. In actual sketching, the contour lines are entirely drawn in by eye, first having given or assumed the elevation of a certain location of the ground to be sketched as a datum plane, and also having outlined the drainage by means of stream lines and elevations of certain controlling points. These controlling points are commonly called CRITICAL POINTS. Critical points, as applied to contours, are points indicating an abrupt change of elevation, as the top of a hill, or an abrupt change in the slope of the hill, also the head and foot of a ravine or water course, the junction of stream lines, etc. Having previously located on your sketch the stream lines and critical points in other words, thoroughly outlined the drainage of the area you should proceed to as many .of these critical points as will be necessary to obtain a view of the entire area; usually two or three will prove sufficient, and you will find that from these points all of the contour lines may be drawn in by eye with a surprising degree of accuracy. Figure 14 illustrates the idea. Without even seeing the area, one is able, by means of the stream lines, dry water courses, and elevations given, to draw in the contours about as they would appear if this sketch were actually completed on the ground. In drawing in the contour lines, the student should bear in mind the principles of contouring given in Lesson VII. Each student should draw in the contours on this sketch with a soft pencil and then compare the results. This exercise will impress upon the mind the importance in sketching of first carefully outlining the drainage of the area to be sketched. 49 50 MILITARY SKETCHING Students should be given tracing paper and contoured maps with instructions to trace upon the paper the stream lines and elevations of critical points, then remove the tracing paper from the map, and interpolate the contours, afterwards com- paring the contours interpolated with those of the original map. One may obtain a great variety of these control sketches from the Book Department, Army Service Schools. Order a complete set of them which will cost but a few cents, and then make mimeograph copies for use of the class. It will be found that, by the methods suggested above, the student will soon obtain a very accurate idea of what points are really critical in correctly contouring an area, and, wnen he begins to sketch, these points will stand out vividly on the terrain before him. PROBLEM The point A, on a 3-inch map, has an elevation of 780 feet. Given the azimuth and a distance from A, and the elevation of the following points: Azimuth, Distance from A , Elevation, Point degrees yards feet B 20 1,000 920 C 35 500 865 D 50 800 820 E 70 300 820 F 75 1,200 920 G 90 800 840 H 110 500 785 I 115 1,000 890 J 125 700 780 K 150 400 745 L 160 1,100 700 M 180 tfoo 780 N 200 900 845 220 400 800 P 245 1,000 895 Q 270 900 860 R 290 400 None given. 8 320 800 880 T 340 300 810 U 355 900 840 EXERCISES IN CONTOURING 51 870 860 S/O 797 1=1 I ace /O' Contours on the above sketch The fiaures c/ive elevations in fee+ FIG. 14 52 MILITARY SKETCHING A stream flows in the general direction U-A-K-L. A branch of this stream flows in the general direction D-K, passing mid- way between E and H. Another branch in the direction R-A flowing for some distance in the same general direction. The latter branch has a uniform slope of one degree. From the notes given above, plot the stream lines and critical points given and interpolate the contours so as to make a pos- sible representation of the relief under the conditions given. Remember that a 3-inch map under the normal system has a V. I. of 20 feet. NOTE. All information necessary in the solution of this problem has been given in this lesson and in the lessons preceding it. LESSON X VISIBILITY It is often necessary in military operations to determine from the map whether one point is visible from another,; whether a certain line of march is concealed from the enemy; how much of a certain area can be seen from a given point; and whether slopes are uniform, concave, or convex. If the map is cor- rect, the above information may be determined very accurately, but it must be remembered that most maps have more or less minor errors in relief so that the visibility of points, lines, and areas cannot be determined to the degree of accuracy that many may assume; also the natural and artificial objects upon the earth's surface interfere in many cases, so when there is a reasonable doubt, and if the opportunity permits, the better method would be to actually verify the visibility by visiting the points concerned. VISIBILITY BY INSPECTION By studying the relief map, Fig. 9, the following principles of visibility are obvious: (a) Contours closely spaced on the top of a hill, and grad- ually getting farther apart toward the bottom, show a con- cave slope, and all points of the intervening surface are visible from both the top and bottom of the slope. (6) Contours spaced far apart at the top and gradually closer toward the bottom show a convex slope, and neither end of the slope is visible from the other. (c) Contours equally spaced indicate a plane surface, and all intervening points are visible from top to bottom of the slope. Bearing the above principles in mind, one is often able to tell at a glance whether or not one point may be seen from another. VISIBILITY BY PROPORTION The line of sight is determined by drawing a line from the observing point tangent to the point of probable obstruction. 63 54 MILITARY SKETCHING The visibility of any point, whether determined by proportion or graphically, depends upon the following simple proportion : Difference in Difference in Horizontal Horizontal elevation of elevation of distance be- distance be- observing . observing .. tween ob- . tween ob- point and point and " serving ' serving point of elevation point and point and obstruction. necessary point of point in for point in obstruction. question. question to be seen. The second term of the above proportion is the unknown quantity, and will be represented by "X." Example An observing point has an elevation of 600 feet, the point of probable obstruction an elevation of 400 feet. These points are 800 yards apart. 800 yards in prolongation of this line is a hill 300 feet high. Can this hill be seen from the observing point? Following out the proportion given above we have: 200' :X'i: 800': 1600' or X= 400 feet. 600 400 = 200 feet, the necessary elevation of the point in question in order to be visible from the observing point, con- sequently the point may be seen. So it is clear that in many cases the visibility of a point may be determined by a mental calculation of the horizontal dis- tances and the difference in elevation between the observing point, and the point of obstruction. The student should assume points and distances and construct a diagram illus- trating the above proportion. By a few exercises of this nature from a contoured map, the student should be able, from inspection, to solve the more simple problems in visibility. PROFILE METHOD The more complicated problems in visibility may be readily solved by the profile method. A profile is a line supposed to be cut from the earth's surface by an imaginary vertical plane. To construct the profile, project this line to scale upon a vertical VISIBILITY 55 plane. (See Fig. 17.) You wish to construct a profile of the line ABC. Place the lower edge of a piece of cross-section paper along the line ABC. Pick out the lowest contour lines along ABC. Naturally they are along the two streams, and both have an elevation of 500 feet. Mark dots on the lower edge of the paper indicating these lowest contours. Guided by the parallel and perpendicular lines of the cross- section paper, dot in the elevations of the remaining contours, allowing one horizontal space for each contour interval. Connect these dots by smooth curved lines, and you have the irregular line shown in Fig. 17. This is the profile of the line ABC. Then, by drawing lines of sight from the observing point tangent to the points of obstruction, the visible portions of the line ABC are determined. Visibility problems may be divided into three classes? 1. To determine whether or not one point is visible from another. 2. To determine how much of the ground line connecting the two points is visible from either point. 3. To determine how much of a certain area is visible from a given point. VISIBILITY OF A POINT See Fig. 15. Let A be the observing point, B the point of probable obstruction. To determine whether the point C is visible from A. (Note that the contour interval is 20'.) As shown in Fig. 16, place the lower edge of the cross-section paper on the line ABC. Observing the points, A, B, and C, we find that A is the lowest point, B is 40 feet higher, and C is 115 feet higher than A. Let the space between the parallel lines on the cross-section paper represent one contour interval, so B will be two spaces higher than A, and C will be 5% spaces higher than A. As A is the lowest of the three points, its profile position will be at the lower edge of the cross-section paper, or is identical with its map position. The profile position of B is 6, two spaces directly over B; the profile location of C is c, 5 % spaces directly over C. Draw the line of sight from a tangent to b. It is found to pass beneath r. consequently C is visible from A. The visibility of any 56 MILITARY SKETCHING point may be determined in a similar manner. If there are several points of probable obstruction, locate the profile positions of each point, and, from the point of observation, draw tangents to each profile location and, if these lines fall below the profile location of the point in question, that point is visible. VISIBILITY OF A LINE Construct the profile of the line as previously explained. From a, Fig. 17, draw lines tangent to the points of obstruc- tion, x and b. (These are the lines of sight.) From the extremities of the visible portions of the profile, drop per- pendiculars to the line ABC, and we find, of the line ABC, that AX, YB, and ZC are visible portions. VISIBILITY OF AREAS From the point of observation, draw several radiating lines through the critical points of the area in question. Find the visible portions of these lines by method suggested above, and connect their extremities, and you have approximately the visible area. (See Fig. 18.) If the student is provided with a well -contoured map, some cross-section paper, and a pencil, he should be able in an hour's time, by the careful study of this lesson, to master the subject of visibility. REVIEW Each student should be given a contoured map, and required to solve the following problems: 1. To determine the visibility of a point by observation. 2. To determine the visibility of a point by proportion. 3. To determine the visibility of a point by the profile method. 4. To determine the visible portion of a straight line by the profile method, the point of observation being in the same straight line. 5. To determine the visible portion of an irregular line, such as a crooked road, the point of observation being outside the irregular line. 6. To determine the visible portion of a given area. J> "i ~"6 t- ii e\j ^ s d C0> S 03 o 0) PART II MILITARY SKETCHING Attention is invited to the B-H Relief Map designed by Capt. A. W. Bjornstad. Most of the leading educational institutions which include military instruction have installed these sets. They are also extensively used in organizations throughout the Regular Army and National Guard. Figs. 25, 26, 27, and 28, illustrating the Road Sketch, Position Sketch, Outpost Sketch, and Place Sketch, are taken directly from the B-H Relief Map. By the use of this relief map the student is able to pursue a course of indoor instruction in map reading, and a course in topographical sketching which is every bit as realistic and instructive as actually sketching the terrain. The relief map is of inestimable value when one considers the factors of time, suitable terrain, and climatic conditions, to say nothing of the great advantage it affords in pursuing a course in tactics, fortification, etc. In following the course of instruction in sketching outlined in this text in connection with the B-H Relief Map and its special equipment, the student is afforded the same opportunities for the actual work of sketching that present themselves outdoors on actual terrain. 61 LESSON XI FLAT SKETCH Having completed the course outlined for map reading, we will now take up the subject of military sketching. In a way these two subjects go hand in hand, as one is taught the other is learned. If one thoroughly understands military sketching, he naturally will be able to read a military map, but, for conveni- ence of instruction, the subjects have been divided. Before taking up the subject of sketching each student should be equipped with a drawing board with an attachment for reading angles of slope, compass, a working scale as shown in Fig. 13, Faber's HB pencil or one of about the same degree of hardness, an eraser, and a pocket knife or pencil sharpener. A tripod in connection with the drawing board is of assistance to the beginner, although not absolutely necessary. The Engineer drawing board with attached compass and tripod, although excellent, is very expensive, and would not be found practicable on that account with large classes such as would be the case at educational institutions. The improvised drawing board and tripod shown in Fig. 21 are suggested. They are easy of construction and will be found entirely practicable. DRAWING BOARD Soft pine board, IS" by 14" by 1". This will allow a surface of 4 square miles for a position sketch, and still enough extra space to secure the paper to the board. The compass may be set into the middle of one side of the drawing board by cutting or boring into the board. The author will not attempt to recommend any particular compass. What is known as the watch compass is issued to organizations of the regular army at present. Some good round case compass that could be set into a round hole in the board is recommended. In anticipat- ing this course, the instructor should write to some dealer for samples, and select the most practicable compass as to cost and efficiency, and then endeavor to secure a discount by ordering for the entire class. c.-t FLAT SKETCH THE TRIPOD Select a piece of "Two by four" 5 inches long (see Fig. , and three sticks 4' by 1" by J^", the latter of some tough material which will not be easily broken. About %" from the end of these sticks bore holes / " in diameter. At the mid- Fio. 19 64 MILITARY SKETCHING die of one end of the block saw out a slit % " wide and extend- ing an inch and a half into the block. By means of wire nails driven as shown in Fig. 21c, attach the three legs to the block, N D N N W E B s FIG 20 FLAT SKETCH 65 one leg in the slit and the remaining two legs at the other end of the block. Then drive a wire nail into the center of the bot- tom of the block; the nail being of sufficient length so that it will protrude %" out of the block. (See Fig. 21c.) When all of this has been completed, you will have a tripod something like Fig. 21d. Now bore a hole %?' deep into the center of the bottom of your drawing board, the diameter of this hole being just sufficient to accommodate the wire nail protruding from the top of the tripod. Now attach the drawing board to the tripod by means of the nail and hole just described, and you will have a drawing board and tripod complete, by means of which the drawing board may be quickly oriented and leveled; also the board may be easily detached from the tripod when it becomes necessary to read angles of slope from the attachment on the board. As stated hereto- fore, the tripod is of assistance to the beginner, although not really necessary, but is usually discarded by the experienced sketcher as being too much bother in hasty military sketching. The student, being equipped as noted above, is now ready to begin sketching. Fig. 19 represents the road ABCD to be sketched. On your paper draw a straight line representing the magnetic north. Mark one end of this line N. In sketching, always hold your drawing board in such a posi- tion that the north end of the compass needle and the arrow end of the magnetic north indicated on the paper are pointing in the same direction. In the future we will refer to this operation as "Orienting the board." Go to the point A on the road. (See Fig. 20.) Orient the board. From any convenient point a on the 'board, draw a straight line in the direction Ab. Next, pace the distance from A to B, and, with your scale of paces, 3" = 1 mile, lay off the line, ab, representing the distance AB. In locating the initial point a, one usually knows the general direction of the course to be sketched, and should select a point of beginning which will afford the greatest use of the paper. For example, if your course takes in an easterly direction, your point of beginning should be near the west margin of the paper. Fig.b Fig. c. SKETCH OF COUNTRY NORTH-WEST OF GREENVILLE By Sgt James Brown, Co. 0. 24th Inf. June 16, 1916. Scale 3 inches = I mile FIG. 22 68 MILITARY SKETCHING FIQ. 23 FIAT SKETCH 69 Now orient the board at B, draw a straight line in the direc- tion BC, pace BC 9 and lay off the line be. Orient the board at (7, draw a line in the direction CD, pace CD, and lay off the line CD. The instructor should require each student to plot a short course having several changes of direction. The scale 6" = 1 mile might be used instead of the 3-inch scale, this making more evident all errors in distance and direction. Results should be compared and errors pointed out. An accurate sketch of the route should be exhibited, and each student's sketch compared with it. The instructor should then select some longer course in which the points of beginning and ending are the same, as, for example, the course ABCDEFAFig. 22. This will serve as an excellent check on the work. The methods employed will be the same as described above except that important points to the right and left of the course should be located by intersec- tion, and locations along the course should be verified by resection. To LOCATE A POINT BY INTERSECTION NOTE. Contouring will not be attempted in this sketch, which is known as a "Flat Sketch." Vegetation may be indicated in writing, and hill tops indicated by a dot or star. (See Fig. 22.) To locate a point by intersection as, for example, the hill- top G, Fig. 22 orient the board at A (see Fig. 23 in con- nection with Fig. 22) ; mark the point a on the board to cor- respond to A on the ground. Sight in the direction of B, and from a draw a straight line in the direction of B 9 then sight at the hill G, then draw a straight line in the direction of G. (Care must be taken to keep the board constantly oriented. In determining the line of sight from the point of observation on the map to some distant point on the ground, pivot the ruler at the point of observation and sight along the upper edge to- ward the object.) Pace the distance AB, orient the board at B, and lay off the map distance, ab t corresponding to the ground distance, AB, then sight at the hill, G, and draw a 70 MILITARY SKETCHING straight line from 6 in the direction of G. The lines drawn from a toward G and from b toward G intersect at g, which is the map location of the hill, G. In a similar man- ner any other points, as H and /, Fig. 22, may be located by intersection from any two favorable points. / ' /- / ., X. y^ / ^ " :; " V v r " - ;; "^ : - ^'Sh. ,.- - ..... ;] """ /^."-'- -- / --'"' ^... - - v^., ./ ...,.^-t -~ /... ,. M.. . .\* , - - O' . / * ,../. -- / .. """ /"- * /- ^ ;- ----- - ^ . y^ g tfjlnr^' ./ ^ y .. % . (> - / Mg*ctic Nrtt / - --"" .... _;_,_ - . ' ,-. ...... -": \ i/ ,**..* r - ..-. ^ FIG. 24 Angles of less than 30 degrees or greater than 120 degrees at the point of intersection should be avoided, as the two intersecting lines are so nearly parallel that it is difficult to locate the exact point of intersection. FLAT SKETCH 71 To LOCATE A POINT BY RESECTION Suppose that at the point F of the course ABCDEFA, Fig. 22, you wish to verify your location. The points G and A on the ground have already been correctly located on the map at g and a (see Fig. 24). The sketcher is at the point F, which he wishes to locate on the map. He orients the board with the compass, pivots the ruler at g, at the same time sighting the hill G, and draws a line along the ruler toward his body. Similarly pivot the ruler at a, sighting A, and drawing a line along the ruler toward his body. This line cuts the Gg. The intersection of the lines at / is the sketcher 's map location. As the sketcher passes over the course, he should note in writing on his sketch such ground features as bridges, fords, ferries, houses, woods, cultivated fields, villages, high hills, streams, or any other information of importance. (See Fig. 22.) As stated before, the sketch shown in Fig. 22 is known as a "Flat Sketch," no relief being shown. When completed, the following information should be indicated at some convenient place on the sketch : 1. Location of sketch. 2. Name and organization of sketcher. 3. Date of sketch. 4. Scale of sketch. 5. The magnetic north, and, if the declination of the needle is known at the particular locality, the true north should be indicated also. 6. Reading scale. 7. Contour interval. 8. Scale of map distances. Nos. 7 and 8 need not be indicated unless the sketch is con- toured. LESSON XII ROAD SKETCH We have learned how to plot on the map ground distances, directions, elevations, and the various natural and artificial ground features of military importance. We will now make a complete road sketch. The instructor should designate some road; a course of about two miles with several changes of direction is sufficiently long for the beginner. Each student will go over the designated road, plotting distances, directions, elevations, and important ground features. The sketch should not only include the road itself, but an area extending about 400 yards each side of the road. As a rule, most of this area may be seen from high elevations along the road bed, but occasionally it may become necessary to go to an elevated point outside the road proper to secure all of the details. Objects of military importance, such as high hills, towns, etc., which are more than 400 yards from the road, should be located by intersection. Whenever hills are located by intersection, their elevations should be noted. The most practicable method of indicating details on sketches made in the field is shown in Fig. 25. Vegetation, especially, should be indicated by words rather than by the proper conventional signs. In .short, the best field method is the shortest and most accurate method. In order that the student may become familiar with all of the conventional signs, which is very important when it comes to map reading, the field sketches may be retouched at leisure, employing the proper conventional signs in each case. The beginner should sketch in every detail of military importance in order to train the eye to observe details. Later he may be called upon to submit sketches showing only such information as may be required for particular expeditions. After the field work has been completed, the instructor should collect the sketches, and note on each sketch all of the glaring defects. Although only one lesson for each of the 72 ROAD SKETCH 73 various classes of sketches is given in this text, yet the same old rule of "practice makes perfect" applies. It must be remembered that there are no hard and fast rules to be observed in sketching. There are a few general prin- ciples which must always be applied, but, when it comes to the details of the work, each road or area to be sketched pre- sents new features, and the sketcher must use his judgment as to the shortest and most accurate methods; but, having clearly fixed in his mind the basic principles such as distance, direction, intersection, resection, elevations, and possessing a keen eye for critical points in connection with the drainage of the ground, all of which have been previously explained, he should experience no difficulty in applying the proper principles at the proper time. A method of sketching the road represented in Fig. 25 will be given in detail. There may be other methods equally good as to the minor details of accomplishing the same results. You are directed to sketch the road beginning at the bridge near the Langford house, thence about two miles to the north, Fig. 25. It will be noted that this road has frequent changes of direction, which will require more "Set ups" than in the case of a more direct route. It is assumed that the elevation of the floor of the bridge is 90 feet. In case the elevation of the point of beginning is not known, it always may be assumed, and your elevations will be relatively correct throughout the sketch. Orient the board at 1, and indicate your magnetic meridian as explained heretofore. Sight in the direction of 2 (the first change of direction in the road), and draw a straight line in the direction of 2. Then proceed to 2, and on arriving there you have determined the distance. Note down the location of 2, and, from points 1 and 2, plot in such details as the stream railroad, buildings at the Langford house, etc. Continue the work along the same lines at 3, 4, 5, 6, 7, 8, etc. Now the subject of contours comes in. If the correct methods are pursued, the contouring will be found to be very simple and interesting. Do not attempt to get the angles of slope to 2, 3, 4, and 5, as the change of elevation is so slight. Remember the principles of contouring brought out in Lesson ROAD SKETCH NEAR LANGFORD BRIDGE June 16,1916 By 1st Lieut F B SMITHjCHh Inf Scale 3" = lnr>.le M.D V.I. 20' FIG. 4 ROAD SKETCH 75 IX. Bearing in mind those principles, what are the critical points which determine the drainage of this route? They are 1, 6, and the stream crossing north of 8, also A, B, C, and D. How are those elevations determined? Intersect on A from 1 and 6, then, knowing the elevation of 1, the elevations of A and 6 are determined by methods previously explained. Inter- sect on B and C from 6 and stream crossing north of 8, and so on throughout the sketch. Never attempt to determine the slope at each change of elevation in the road. It is an endless task, your error multiplies, and in a short time you have lost control of your relief entirely. Then, as explained in Lesson IX, having determined the elevations of the three stream crossings and A 9 B,C, and D, and noting, as you pass along the road, the direction of the stream lines and the general directions of the spurs leading down from the hill tops, you cannot go far stray in interpolating your contours from good observing points along the road bed or in close proximity thereto. A FEW RULES TO BE OBSERVED 1. The beginner should not attempt to hurry, even if he is unable to complete the task assigned to him. 2. Devote equal time and care to all parts of the sketch. 3. Be sure that your orientations are correct, and that your board is kept oriented at all times. 4. Do not leave a station until all of the necessary details up to that point have been put in. 5. Do not attempt to show too minute details. You must get the distances, directions, elevations of critical points, and by intersection locate such land marks as may assist you in identifying your location later, or that are of military impor- tance, such as high hills, towns, etc. By close observation and taking a few notes as you pass along the road, the remain- ing details such as fences, cultivated fields, buildings, cuts and fills, bridges, railroad crossings, telegraph lines, etc., may be filled in from good observing points. 6. Be sure that the drainage has been properly outlined be- fore attempting to put in the contour lines, in other words, 76 MILITARY SKETCHING first locate conspicuous hill tops, the directions of spurs leading therefrom, and the courses of stream beds and valleys. This is most important, as the drawing in of contour lines without first indicating what may be called the framework of the drainage would be like fitting a garment without making previous measurements. 7. To become a rapid and accurate sketcher, one must be able to estimate distances with a considerable degree of accu- racy (see estimating distances, Small Arms Firing Regulations, U. S. Army). LESSON XIII POSITION AND OUTPOST SKETCHES Military sketches may be classified as "Road Sketches" and "Area Sketches." We have already discussed the road sketch in Lesson XII. Area sketches are classified as follows: 1 The Position Sketch. This is a sketch of any military position, such as a camp site, or any position to be occupied by a body of troops. Conditions are such that the sketcher is at liberty to visit any part of the area to be sketched. 2. Outpost Sketch. A sketch of a friendly outpost line. The sketcher is usually at liberty to visit all portions of the area in rear of the line of observation. Details between the line of observation and the hostile position are usually obtained by intersection and observation. 3. Place Sketch. A sketch of an area made by the sketcher from one point of observation, as the sketch of an area or a road from an advanced point of an outpost line toward the hostile position. In this lesson we will consider the position sketch and the outpost sketch. The scale of these sketches is 6" = 1 mile with a contour interval (V. I.) of 10 feet. POSITION SKETCH The work involved in making a position sketch may be summarized as follows: 1. Look over the ground to be sketched from some good point of observation. 2. Select and measure a base line. 3. Locate by intersection as many critical points as possible from the extremities of the base line. 4. Select and traverse the most practicable route in the area such as roads. If there are no roads, then the route which will most assist you in the location of details. In traversing, check your horizontal and vertical locations by resection. 5. Then go to some good points of observation and complete the sketch as to the remaining topographical details and T7 78 MILITARY SKETCHING contour lines not completed in the traverse. (As to the inter- polation of contours, see Lesson IX.) Many experienced sketchers may have other methods of approaching the work, but the method outlined above is a practicable one for the beginner, from which he may depart in some particulars as he becomes more experienced. The nature of the terrain to be sketched is also a factor in the methods to be pursued. BASE LINE The mapping of areas, either by hasty sketching methods, or by means of an accurate instrumental survey, depends primarily upon some system of triangulation. By triangula- tion is meant the establishing of a series of triangles covering the area to be mapped, by means of which critical points are located horizontally and vertically. As heretofore stated, the angles of these triangles should not be less than 30 degrees nor greater than 120 degrees. The base line should be located as near the center of the area as practicable, and, in sketching small areas, should be about one-third as long as the greatest dimension of the area. It should be on as level ground as practicable with a good view over the ground to be sketched, and its ends, if possible, should be identified by some conspicuous natural or artificial objects. Naturally, it is not always possible to fulfill all of these condi- tions. In hasty sketching, the length of the base line is determined by pacing or strides, exercising as much care as possible, as it is obvious that the accuracy of the sketch depends upon the measurement of the base line. The horizontal and vertical positions of the vertices of the triangles are located either by intersection or resection. (See Fig. 26 and Fig. 27.) Points 1 and 2 locate the extremities of the base line. Points 3 and 4 are located by resection, and points A, B, C, D, E, F, and G by intersection. Method of orienting, determining distances and directions, the location of points by intersection and resection have been previously explained. In view of this, it will not be necessary to go into detail in explaining the method of opera- POSITION AND OUTPOST SKETCHES 79 tions pursued in obtaining Fig. 26, which is the triangulation scheme involved in the position sketch shown in Fig. 27. A brief description of methods pursued in the position sketch shown in Fig. 27 will be given, however, in which the terms 90 3^/20 \ \ \ 4- Frame Work POSITION SKETCH Scale 6" = I mile 80 MILITARY SKETCHING used in this paragraph will be used freely without further explanation. METHOD IN DETAIL OF SKETCHING POSITION SKETCH, FIG. 27 Assume that from some good observing point you have selected the line, 1-2, as the base line. You are given the altitude at 1, or the altitude may be computed from some nearby bench mark, or the altitude of 1 may be assumed. In this case we will assume that the altitude at 1 is 228 feet. Set up and orient at 1. Draw a straight line in the direction of 2, also determine the angle of slope from 1 to 2. Before leaving, draw radiating lines to as many critical points as will assist you in outlining the drainage of the area. The nature of these points has been explained in previous lessons. In selecting the critical points, select such points as will probably be seen from 2. Next, pace the distance to 2. In doing so, note the distance to the road and to the stream, also the elevation of each of these points. Arriving at 2, lay off the distance and note the elevation of 2, and set up. At 2 complete the intersection of points sighted from 1, and note the elevations of these points. Next, proceed to the road near by, and locate your map position either by resection or by traversing the distance, then traverse the entire road, following out methods suggested under "Road Sketch" in the previous lesson. Then by setting up at a few good observation points such as 1 and 2, and possibly some others, and aided by the traverse and critical points located, you are able to complete the sketch from observation, filling in the remaining topographical details, and interpolating the contours as suggested in Lesson IX. One of the greatest assets to the sketcher is an eye for critical points. REMEMBER THAT THE CORRECT LOCA- TION OF THE CRITICAL POINTS DETERMINES THE DRAINAGE OF THE AREA, AND WITH THE CORRECT DRAINAGE ESTABLISHED, YOU HAVE THE KEY TO THE SKETCH. The sketcher soon discovers many short cuts in the work. Every area to be sketched is different, and requires a brief too o POSITION SKETCH NEAR BENSONS CORNERS June 16 1916 By Is* Lieuf F.B. SMITH ,10th. Inf. Scale 6" Imile 500 lOOOYDC i 2* I 3* I 4*1 6 16 V.I. 10' Fio. 7 82 MILITARY SKETCHING estimate of the situation from some good observing point be- fore taking up the work in order to take the greatest advantage of the terrain. However, by following out the suggestions of this lesson, the beginner will not go astray, and, with experience, the short cuts will dawn upon him. OUTPOST SKETCH The general plan of making an outpost sketch is the same as with the position sketch, with some few exceptions as follows : The base line must be along the line of observation or a sufficient distance in rear with a view of locating as many points along the line of observation as possible, these latter points to be used in locating points toward the hostile position either by intersection or observation. In making an outpost sketch, it is usually impossible to visit that portion of the area beyond the line of observation, hence all points beyond this line must be located either by intersection or observation. In addition to the topographical features of military im- portance, the locations of the various parts of the outpost should be indicated. In this connection, the student should consult the Field Service Regulations, 1914, paragraphs 60-83 inclusive. REVIEW 1. Describe the nature of a Position Sketch; an Outpost Sketch; a Place Sketch. 2. What are the various steps to be taken in making a posi- tion sketch? 3. What is meant by the triangulation of an area? 4. What is the base line and what conditions should it fulfill? 5. In what two ways are the vertices of the various triangles located? 6. What are the degree limits of angles of the triangles? 7. What is the key to successful sketching? 8. In what particulars does an outpost sketch differ from a position sketch? LESSON XIV PLACE SKETCH It is often necessary to sketch a certain area from one point of observation. This is called a "Place Sketch." It is also made on the same scale and with the same V. I. as the position sketch. In time of war there is a great demand for sketches of this class. Fig. 28 illustrates the method of construction which is very simple, providing that the student understands the basic principles of sketching brought out heretofore. However, in order to produce a place sketch of value, the sketcher must possess the ability to estimate distances with a considerable degree of accuracy. Telephone and telegraph poles are usually set up at fixed distances which often are of great assistance. In many parts of the country the land is divided into sections, and the sections subdivided in such a manner as will aid the sketcher in making correct estimations. As estimations of distances are made in yards, a working scale of yards, 6" equals one mile, is necessary. The student has already been instructed to place a scale of yards on his triangular working scale. You are in charge of a patrol operating in hostile territory. Your patrol is concealed at some point north of A, Fig. 28. You proceed to the high point A, and discover that a hostile force consisting of one infantry battalion is going into camp at Bethel Church. It is assumed that you are in hostile territory, and that you have no good maps of this particular terrain, as often may be the case. In that event, the message that you are about to send will be of much greater value to your com- manding officer if accompanied by a sketch. , As it is obvious the entire sketch must be made from the one point of observation, A, hence the term, place sketch. It is also obvious that the entire sketch must be made from observation. Sketches of this class are hastily made on the back of the message forms furnished organizations in the field. First orient your message book, then look over the area to be sketched, and endeavor to locate some feature or features at 84 MILITARY SKETCHING I Reverse slope arf hill which cannot be seen from A PLACE SKETCH NEAR BETHEL CHURCH June 16,1916 By 1st L.eui F,B.SMITH,lOth.lnf Scale 6"= Imile 500 IOOOYOS I M.D. 2 I 3*1 V.I. IO' FIG. 4 PLACE SKETCH 85 of the terrain which will best serve the purpose of a framework upon which to connect up the remaining details of the area. Roads, if available, will answer the purpose very well, espe- cially where there are telephone poles. The rifle sight leaf and the mil scale will be found of value in estimating dis- tances. In this case, by the aid of the telephone poles, and rays drawn to the various critical points of the area, a fairly accurate framework may soon be established upon which the remaining topographical features may be connected up. As to the contour lines, assume as the datum plane the down- stream end of the largest stream, and, for convenience, call this elevation zero, or assume some elevation for your lowest contour as 100 feet, as is the case in Fig. 28. Then compare your own elevation, with that of the datum plane and other critical points which have been located by rays drawn from A and estimation. It only remains then to interpolate your contours in the same manner as was explained in discussing the position sketch. Field glasses are of great assistance in making place sketches. A series of place sketches made along an outpost line is often of great advantage. All staff officers and artillery reconnais- sance officers should be skilled in making place sketches. As an exercise, the following is suggested: The instructor will post each member of the class in the same locations as he might the outguards of an outpost, and require each student to make a place sketch, including a certain well-defined sector in front of his position. When the sketches are completed, the instructor, accompanied by the entire class, will proceed in turn to each of the positions occupied by the sketchers. Members of the class, other than the sketcher who occupied the position, will be required to orient the sketch and check the distances and directions, and, in fact, review the entire sketch. By this method many points will be brought out, and, at the same time, each student will be keen to do his best, knowing that his work is to be reviewed by the entire class. A keen eye for critical points, the correct estimation of distances, and speed are qualities that a good place sketcher must possess. LESSON XV MISCELLANEOUS TOPOGRAPHICAL RECONNAISSANCE REPORTS A topographical reconnaissance usually consists of a sketch and a report. As many of the required details as possible should be shown on the sketch. Additional information, such as would be required, may be shown in marginal notes on the sketch, or, if this is not found to be practicable, a separate report may be made and appended to the sketch. The report should be as brief as possible consistent with rendering all of the desired information. Frequently sketches do not contain a sufficient number of reference points upon which to base a concise report, or to formulate a concise field order. If such is the case, additional reference points, such as letters or numbers, should be added to mark road crossings etc. Conspicuous hill tops and road crossings are commonly indicated by their elevations. These reference marks should be clearly indicated, and, on a sketch in connection with a re- port, they may be indicated in red or some other bright color that will immediately attract the reader's attention. The following pertaining to field orders is quoted from the Field Service Regulations, 1914, and apply equally as well in Topographical Reconnaissance Reports: "Field orders must be clear and definite. Expressions de- pending upon the viewpoint of the observer, such as right, left, in front of, behind, on this side, beyond, etc., are avoided, ref- erence being made to the points of the compass instead. The terms right and left, however, may be applied to individuals and bodies of men, or to the banks of a stream; in the latter case the observer is supposed to be facing down stream. The terms right flank and left flank are fixed designations. They apply primarily to the right and left of a command when facing an enemy, and do not change when the command is retreating. The head of a column is its leading element, no matter in what direction the column is facing; the other extremity is the tail. 86 MISCELLANEOUS 87 "To minimize the possibility of error, geographical names are written or printed in ROMAN CAPITALS ; when spelling does not conform to the pronunciation, the latter is shown phonetically in parentheses, thus: BICESTER (Bister), GILA (Hee'la). "When two or more places or features on the map have the same name they are distinguished by reference to other points. "A road is designated by connecting two or more names of places on the road with dashes, thus: LEAVENWORTH- LOWEMONT-ATCHINSON road." There are as many classes of topographical reports as there are demands for sketches, each case differing slightly according to the particular information desired, but always coming under a few general headings such as the reconnaissance of a road, a railroad, a river, camp sites, positions to be occupied by troops, etc. ROAD RECONNAISSANCE REPORT In addition to the information shown on the road sketch, the report might elaborate on such points as the following: steep grades, width of roadway; if paved, the width, class, drainage, and condition of paving; if dirt road, its soil and general con- dition. Can foot troops march along its side between the wagon track and fences? Advantageous infantry and artillery positions with range, etc. Bridges: Complete information regarding piers, abutments and superstructure; width, clear head room, safe load, also the nearest bridge above or below with similar information. Country: Any additional information pertaining to the vege- tation or soil that cannot be shown on the sketch. Streams Crossed: Additional information pertaining to streams crossed, such as width, depth, and surface velocity; velocity to be indicated as sluggish, moderate, quick, and swift; availability of water for various camp purposes; fords at or near crossing, with complete description of same; practicable for what class of shipping. Towns and Villages: Name and location on sketch; material and size of buildings; distribution of buildings; population; location of depots, telegraph and telephone offices; water sup- 88 MILITARY SKETCHING ply; sanitation; important public buildings and repair shops; food supply. In fact an exhaustive report would involve too many details to enumerate here. Railroads Crossed: Name, gauge, single or double track, sidings, loading facilities, name and description of nearest station, etc. RAILROAD RECONNAISSANCE REPORT In friendly territory all information necessary could be ob- tained from the proper railroad officials, but in hostile territory this information would have to be obtained by reconnaissance, and could be obtained better by an officer familiar with railroad conditions and the needs of the military service. Generally, the report would pertain to such matters as the following: The Line: Name, terminal points, stations and distances be- tween same, gauge, single or double track, ties, rails, condition of road bed, drainage, liability to washouts, material and facili- ties for repairs, marching of troops on right of way. Rolling Stock: Amount available for the particular section reported on; location of repair shops and their capacity; any other details depending upon the rolling stock. Stations: Name and location; entraining and detraining facilities such as sidings; ramps, turn tables, water tanks, fuel supply, storage facilities, derricks, etc. RIVER RECONNAISSANCE REPORT General description of river valley as to limiting ranges, roads paralleling river, passes, infantry and artillery positions controlling river, and any other data not shown on the sketch. The Stream: Its width, depth, velocity, navigability, any obstruction to navigation, information pertaining to high and low water marks, character of banks, quality of water, and source of contamination. Canals: Width, depth, navigability, all information per- taining to the locks, means of destroying locks and the effect. Bridges, Fords, and Ferries: For bridges, note the navigable width between piers, height of superstructure above water at the various water marks; with drawbridges, note dimensions MISCELLANEOUS 89 and method of operation. Note the exact location of fords, length, width, and nature of bottom, practicability of troops crossing (see page 208, F. S. Regs.). Practicability of ferries for the various classes of troops, class of ferry, power. Data pertaining to all classes of shipping available in the river. Suitable defensive positions for bridges, fords, and ferries. CAMP SITE AND POSITION RECONNAISSANCE REPORTS See F. S. Regs., 1914, for requisites of a camp site and of a defensive position. As a general rule, endeavor to place yourself in your com- manding officer's position and decide upon everything that he would naturally wish to know in each particular case. MAP REPRODUCTION Military maps, to be of any use, must be reproduced in sufficient numbers to accommodate all who need them in the field of operations. Of course there are many road, position, and place sketches which are hastily made in order to convey information of no general importance. In many cases of this kind the original sketch will answer all purposes and no repro- duction is necessary. Maps may be reproduced: 1. By Tracing. Attach a piece of tracing paper or tracing cloth over the map to be copied, then trace over the details with ink or pencil, 2. Carbon Paper. Place a sheet of carbon paper over the sheet on which the copy is to be made, then fasten the map on top of the carbon sheet and trace. 3. Blue Print. Secure a sufficient amount of blue-print paper, a commercial product which may be secured from any photographer or local engineer office; also secure a suitable frame which is merely a rectangular frame holding a piece of glass. The back of the frame should be padded so as to fit close to the glass. The process of printing is simply to expose the tracing to the sunlight with the blue print paper under- neath, sensitized side next to the tracing. The length of time exposed depends upon the sensitiveness of the paper and the 90 MILITARY SKETCHING nature of the light. The time may vary from twenty seconds to several minutes. 4. Negative. From the negative of a map by photographic methods. 5. Also lithographic and photolithographic methods. REPRODUCTION WITH CHANGE OF SCALE 1. Pantograph. An instrument composed of several pieces of metal or wood joined in such a way as to form a parallelo- gram. The sections of the instrument are so arranged that, by tracing over the map with one of the bearing points, another bearing point will reproduce the map to the same or a different scale according to the adjustment. 2. By Squares. Divide the original map into squares of suitable dimensions. The size of the squares depend some- what upon the amount of detail to be shown. Divide the sheet upon which the copy is to be made into an equal number of squares, the dimensions of these squares being regulated by the scale of the map to be reproduced. Draw in each square the details of the corresponding square of the original. In order to avoid error, the squares of the original and the reproduction should be correspondingly numbered. PART III PANORAMIC OR LANDSCAPE SKETCHING INTRODUCTION The following five lessons are intended to convey to the student, in the simplest manner possible, the necessary basic principles of landscape sketching, and the use of range cards for the various arms. In military landscape sketching, it is indeed obvious that the results to be obtained are purely utilitarian and will in no wise be subject to artistic criticism. The principal reason why the average person finds it so difficult to draw what is before him, is that he fails to see, to comprehend what his eye surveys. This may sound like a contradiction, but to prove the point, ask the average man to look at a landscape for five minutes, then to turn away and describe what he has seen. His answer will quite likely prove that what was before him made but a slight impression on his mind, he being able to remember but few details with little or no idea as to relative positions. The following lessons have been planned as to time and sequence so that it is believed the average student should possess a fair working knowledge of the subject in the time allotted. Having pursued the subject thus far the student involuntarily continues. The importance of landscape sketching has been greatly enhanced by the application of more scientific methods to the control and direction of artillery and small arms. 01 LESSON XVI DELINEATIONS INDOOR WORK In order that a beginner in landscape sketching may be able to sketch freely and rapidly on the ground, he must first practice delineations or, if you please, conventional signs. The only difference between delineations and conventio al signs, is that the former includes an endeavor to represent actual shapes, whereas conventional signs represent only the general subject without any effort to represent the particular subject in the sketch. Delineations, therefore, include a certain type of conventional combinations of lines intended to assist the eye in imagining the actual shape of the subject represented. Refer to Figs. 29 and 30. Practice various combinations of straight lines without ruler, then combining various curves and lines, finally so combining them to represent actual ob- jects such as fences and houses, ground formations and trees. When individual figures can be made with ease, attempts should be made to combine them into imaginary landscapes. The parallel straight lines have two uses: shading interior of a delineation and as a conventional sign for plowed or cul- tivated land. No hard and fast rules apply. The various illustrations given in Figs. 29 and 30 furnish an ample variety in delinea- tion. Take care that the eye gets the outline carefully before any line is drawn. Lines must be made with one sweep and not slowly and laboriously. No erasures should be permitted during these exercises. If sketch does not suit, repeat the exercise. The student will find the work new and interesting, and will be most agreeably surprised with the progress made. For this lesson the student should be provided with the following : 1. Pencil, Faber's HB. 2. Improvised drawing board. 3. Four thumb tacks. 4. Good grade unglazed white paper. 02 DELINEATIONS FIG. 2fi 94 MILITARY SKETCHING FIG. 30 LESSON XVII DELINEATIONS (Continued) INDOOR WORK The student having become adept in the delineations in Lesson I, will now be given a number of model sketches with instructions to copy them to the best of his ability. He should be cautioned not to hurry but to study the given sketch care- fully in order to determine the most essential features. Note the form of the skyline. Draw this in lightly after first mak- ing light pencil marks where the most marked features appear to lie. Now draw in the lines that show the ground shapes, hills and ravines, being careful to make the lines somewhat heavier as the objects get nearer until the immediate fore- ground is reached near the bottom of the sketch which may be made by using the side of the pencil point to get proper weight. An illustration of the development of the copy of a sketch is given in Fig. 31 and Fig. 32. Starting with the skyline, the sketch finally develops into a very good copy in the sixth stage at (f). In some cases it may be necessary to erase parts of the lines already made, where nearer objects interrupt or obscure them. The student should be cautioned that the essential features only, are to be represented in the sketch. In other words, things of no military value should be omitted or simply out- lined and shaded in. It is here where a well made sketch is of more importance than a landscape photograph. The camera has no sense of selection but represents the whole truth and those in the foreground most accurately and care- fully. It will, for example, picture accurately each head of wheat for a hundred yards in front of the camera, while the sunken road bed will be slurred over almost unnoticed. The sketch would here dismiss the wheat field with four lines, with probably the word "wheat" written in, and give most careful detail to the sunken road and fences at the other end of the field. Keeping the above instruction in mind, let the student M 96 MILITARY SKETCHING make sketches from such photographs as are given in Figs. 33, 35 and 36. Fig. 34 is an example of sketch covering the same ground as that shown in Fig. 33. Note the prominence of the fence and observation tower in the sketch and compare with the camera's effort. For this lesson the student should be provided with the following: 1. Pencil, Faber's HB. 2. Improvised drawing board. 3. Four thumb tacks. 4. Good grade unglazed white paper. 5. Lead pencil eraser. DELINEATIONS 97 FIG. 31 MILITARY SKETCHING FIG. 32 FIG. 33 FIG. 34 FIG. 35 PIG. 86 LESSON XVIII OUTDOOR EXERCISES EXPLANATION or MIL SCALE AND IMPROVISED AIDS Having completed the preliminary exercises in "Delinea- tions" the student is now ready to proceed to outdoor sketch- ing as far as making representations on paper of the objects before him. There is, however, one important phase of mili- tary sketching that must not be lost sight of. A military sketch, when completed, should be of such a nature as to be readily understood by any other person. The information portrayed on the sketch includes not only the objects them- selves, but their relative positions, not only in distance, but often of more importance is the horizontal or lateral relation. It is also convenient to have all sketches drawn to the same scale, so that these relative distances will be portrayed in- stantly to the eye without the assistance of a special scale for each individual sketch. As the Mil system of measuring angles has already been introduced to our service, the student is presumed to understand its principles. For those who may not have had instruction with Mil measurement instruments, the following explanation may be of value. One Mil is that angle whose tangent is T^> or in other words, it is the angle formed at the eye by two lines that exactly subtend one yard at 1,000 yards away from the eye, or, by similar triangles, it subtends one-half yard at 500 yards. It will thus be seen that the linear distance of the tangent varies in proportion to the length of the radius, although the angle remains the same. If we were to interpose a ruler ex- actly one yard in front of the eye in the above case, the tangent would be 77^7, of a yard in length, or .036 inch. 1UUU The Musketry Rule is an instrument issued by the Ord- nance Department, designed to measure Mils when held at a fixed distance from the eye. The smallest divisions indicated measure angles of 5 Mils. The actual length of this division 100 OUTDOOR EXERCISES 101 is dependent on the length of the string, which determines the distance at which it is to be held from the eye. If, therefore, we fix the distance the ruler is held from the eye to 15 inches, the angle will vary in proportion to the number of divisions we would subtend on the rule by the legs. This is the principle that is made use of in landscape sketching for locating promi- nent features of the ground on the landscape sketch. There has been developed, at the Infantry School of Arms, what is known as the "Sketching Pad." It is a pad of speci- ally ruled paper for the convenience of the sketcher. (See Fig. 37, which represents one of the sheets on a reduced scale). In practical use, the sheet should be 8J^ by 5% inches. Ver- tical lines should be very light, preferably blue, or even un- inked, simply leaving a light crease. These vertical lines are of value as guides in dropping features of the landscape, located over the top of the paper, down to the sketch strip. The intercept between these vertical lines equals the 50 Mils divi- sion of the Musketry Rule. The pad should, therefore, be provided with a string so arranged through an eyelet near the center of the top, as to insure that the paper is held exactly 15 inches from the eye each time the pad is held up for orien- tation. With this length of string, the interval between the vertical lines subtends 50 Mils. The four horizontal lines drawn just below the center of the sheet should be of the same weight as the vertical lines just described. These horizontal lines are of value as guides in placing features of the land- scape located by mean$ of the vertical edge of the pad. The highest point of the sky-line must be located somewhere on the top line of these four horizontal lines. At the top of the paper are two heavy orientation marks and three horizontal black lines defining divisions marked for the Target, Range and Deflection. At the bottom, on the left, is a place for a description of the position from which the sketch was made. In the center is a circle to contain the number of the sketch. By the side of the circle will be drawn an arrow with one barb, to show the magnetic north. On the right are spaces for the time, date, name, rank and organiza- tion of the sketcher. 102 MILITARY SKETCHING The use of the sketching pad may perhaps be illustrated to the beginner by its analogy to a window, through which an observer is looking at a landscape. If the observer is stand- ing back from the window at a certain distance, each window pane will contain a certain section of the landscape, and the width of each pane will also correspond to a certain number of Mils. Therefore, if the size and shape of the window panes were altered to correspond to the section described on the sketching pad by the vertical and horizontal lines, it would serve as a transparent sketching pad. Now if, instead of the transparent window panes, we were to place a paper on which we could outline the landscape as seen through each pane, the result would be a landscape sketch covering the area seen through the window. The idea above expressed may be more readily understood by referring to Fig. 38. A T A RN DF SKETC MADE FPOI* { o 1 I 1 T IME-. ATE-. IAME-. tANK-C RGANI2 ATION. FIG. 37 Various methods analogous to the window have been im- provised to assist beginners in landscape sketching, as, for instance, the wire screen illustrated in Fig. 39. This screen OUTDOOR EXERCISES 103 could be improvised by almost any one, and by fixing the eye notch at a fixed distance perpendicular to the screen, the in- tercepts between any two wires may readily be made to cor- FIG. 38 respond to a certain fixed number of Mils. The appearance to the observer will be something like that illustrated in Fig. 40, and by having cross-section paper with the lines corre- 104 MILITARY SKETCHING spending to the screen wires, the view may very readily be transposed to paper by the sketcher. When this wire screen is used, it should, of course, be set up on a stake and remain stationary until the sketcher has completed his sketch for the area covered. In the absence of standard sketching pad blanks, the sketch may still be made to the same scale by other improvisations. Any ruler marked with uniform divisions held at a determined distance in front of the eye so that the prominent divisions will intercept a given number of Mils for example, let us assume that the ruler is marked in % inches, and we desire that one of the divisions shall equal 25 Mils. If we remember that one Mil equals one yard at 1,000 yards, at what distance will % inch equal 25 Mils? This can be determined by simply substituting values in the formula R = ^ , which for- mula expresses the whole principle of the Mil system. In this case, W = % inch, M = 25 Mils. Solving the formula with these values, R = 10 inches, therefore, if we make a cord 10 inches long, and always hold the ruler at cord's length from the eye, it will in fact be a true Mil rule. Of course, if no cord is used, the rule may be held approximately at the required distance from the eye, but it will then be only approximately correct in Mil measurement. This use is illustrated in Fig. 41. Another simple expedient that has long been in use by sketchers and painters is that of using a lead pencil, held at a uniform distance from the eye, to measure lateral distances between objects in the landscape that is being sketched. When the pencil is so used, it is usual to use the thumb as a sliding in- dicator. Examples of this use of a lead pencil are given in Figs. 42 and 43. For this lesson, the student should be provided with the following : 1. Sketch pad, with a stiff back and cord. 2. Pencil, Faber's HB. 3. Lead pencil eraser. 4. Any improvised instruments, such as screen mentioned above, and ruler for use as Mil scale. 5. Compass. OUTDOOR EXERCISES 105 FiG. r 'S9 FIG. 40 106 MILITARY TRAINING FIG. 42 OuTDOORlEXERCISES 107 FIG. 43 LESSON XIX SUB-SKETCH Up to the present, the student has been concerned only with the making of the sketch proper. It may often happen that the scale of the sketch does not permit certain objects to be shown in sufficient detail. To draw the whole sketch to larger scale would entail unnecessary time and labor. It is, therefore, found convenient to draw a sub-sketch of very important features. The method shown in Fig. 44 is self-explanatory. The field glasses should be used for such sketching. In conjunction with road sketching, it is frequently of ut- most military importance to show the appearance of the land- scape from given points on the road, even though such features will actually be beyond the limit of the road sketch itself. This method is illustrated in Fig. 45. Usually, these sub- sketches are made to a standard scale, though sometimes it is permissible to exaggerate the vertical dimensions slightly. The sub-sketches made in conjunction with the road sketch are usually made by an assistant, numbers being placed at points on the road to correspond with the numbers placed on the sub-sketch. However, if there is no assistant for this purpose, the sketches may be placed on the road sketch paper itself, as illustrated in Fig. 45, lines being drawn to represent the approximate angle subtended by the view. Usually these views are made to include important features on the road itself, such as bridges, and cuts or fills. The student should equip himself the same as in Lesson III. 108 SUB-SKETCH 109 FIG. 44 ROAD SKETCH NEAR LANGFORD BRIDGE June 16,1916 By 1st. Lieuf. F. B. SMITHJOth. Inf. Scale 3" = I mile M.D. V.I. 20' FIG. 45 LESSON XX RANGE DATA The student should now be required to complete sketches on the standard sketch pad in the manner shown in Fig. 46, that is, all important military features should be shown, not only on the sketch itself, but a line should be drawn vertically from the sketch itself till it intersects the three horizontal lines near the top, and on this line should be written in the proper place, the target, the range to that target, and the deflection to that target from a given reference point. In all cases, the reference point will be similarly indicated with a zero deflection. Care should always be taken that the name of the place from which the sketch was made is not omitted from the lower left hand corner and that the single barbed arrow, giving the magnetic north, appears near the circle at the center. The number near the circle should always indicate the relative position of sketches from enemy right to enemy left. The range should, when practicable, be measured with a standard range finder. Frequently, when the principal thing needed is the military information of the sketch, the sketch itself may be omitted for the purpose of saving time, and direction lines only are then drawn from the small circle towards the targets. At an approximate distance (sometimes, but not always measured to scale), is drawn a quick sketch representing the target only, or sometimes only an X is placed on the line and a word written, such as " ford," " tree," etc., near this mark. An example of this case is given in Fig. 47, which represents what is called the range card, for the same ground given in Fig. 46. It is thus seen that a range card is a simplified landscape sketch which does not require any pictorial ability on the part of the sketcher. The necessary fire data are placed on the upper left-hand corner of the range card in the place provided on the blank. The deflection, however, is given near the top, and is measured in Mils from the reference point. The range is also frequently written along the direction line toward any target. Th ill MILITARY SKETCHING targets are also numbered from enemy right to enemy left, and the firing data for each target are recorded in the space provided. The illustration given in Fig. 47 is that of a ma- % chine-gun range card. These cards are made out for each individual gun, and the number in the circle may be supple- mented by such additional data as the particular case may require, for example, "No. 1 Gun, Company A, 335 M. G. Bat." The machine-gun range card remains at the position of the gun when the machine-gun crew is relieved. The sketch given in Fig. 48 is another illustration showing how firing data are expressed on a landscape sketch. Though it is desirable that all sketches should be uniform in appearance, the only essential feature that must be adhered to is that the firing data must be expressed directly above the target and near the top of the sketch. Fore/ 7~rer>ct) RN DF Sketch ( made < from / T.me Date Name Rank and Organization FIG. 46 RANGE DATA 113 Fig. 49 illustrates a landscape sketch as applied to giving firing data for field artillery. For artillery sketching purposes, the sketch pad blanks should be altered by adding additional horizontal black lines near the top for placing the artillery firing data. There should be at least a one-inch space above the upper horizontal line, used for writing in names of registra- tion points, targets, etc., and for entering their estimated and measured ranges; measured ranges should be underscored. The space covered by the six horizontal lines are used in the order given for entering deflection, deflection difference, site, corrector, and range for the gun position. The deflection difference arid corrector of any particular target should be entered only after this data have been determined by actual fire. The deflection (actual deflection from the aiming point) MACHINE GUN RANGE CARD Rank & Organ. FIG. 47 114 MILITARY SKETCHING should already be computed and entered before opening fire, but that data should be changed after delivering fire so as to show the actual data determined by fire. The space below the six horizontal lines and above the body of the sketch is used for noting the angular distances from the reference point to prominent points on targets shown. These angles should be recorded immediately below the lower of the six horizontal lines. Other data pertaining to targets, notes, reference to sub-sketches, etc., may also be placed in this space. The sketch proper is usually confined below the top dim horizontal line, in the same manner as in the sketch previously discussed. The space below the sketch proper should have the same nota- tion as the previous sketches discussed, adding condition of the weather, which is needed in calculating artillery data, and of course such other miscellaneous notations as may be necessary in any particular case. The student should equip himself the same as in Lesson III. oS WEATHER- - J. C. FIG. 48 RANGE DATA 115 f* DF 363.0 J670 Z1D OS* oo 9B 10 I C.O PLACE DATE- I Sept> 17 Hour^-o.- p// >X/EATHEF\ NAME- VW FIG. 49 APPENDIX SUGGESTIONS FOR INSTRUCTION AT TRAINING CAMPS The author has had considerable experience in instruction pertaining to this subject at training camps, and the following suggestions may prove of some value to those upon whom this duty may fall in the future. With the intensified course of training pursued at training camps, the time usually allotted to this subject is very limited, possibly not more than a half dozen periods of two hours each, so that it is a foregone conclusion that the instructor must work against time throughout the course. Another handicap is the limited number of instructors proportionate to those undergoing instruction, but, regardless of these serious disad- vantages, much may be accomplished if the right methods are pursued. Let us first consider the necessary preparations to be made by the instructor previous to the first instruction period. Aside from the authorized text-book, the student will require the following articles: 1. Drawing board with slope board attachment. 2. Compass. 3. Triangular ruler. 4. Pencil, Faber's HB. 5. Eraser. 6. Four thumb tacks. 7. Drawing paper. DRAWING BOARD With large classes it is obvious that it would not be practi- cable to provide Engineer drawing boards. The tripod, al- though a convenience for the beginner, is not essential. The following plan proved successful at the Plattsburg Training Camps of 1915: purchase a sufficient amount of soft pine material 12" by 1" and saw into boards about a foot square. The drawing board may be suspended around the neck by 116 SUGGESTIONS FOR INSTRUCTION AT TRAINING CAMPS 117 means of a strong cord attached to the sides of the board in such a manner as to hold it in a horizontal position at the proper height for sketching. COMPASS Write to the Keuffel & Esser Cmpany, or any other reliable dealer, for samples, and select some good round compass that may be set into the drawing board by means of boring a hole of the same diameter as the compass, and of a sufficient depth to make the top of the compass flush with the surface of the board. By purchasing the compasses in lot, a considerable reduction may be obtained. ATTACHMENT FOR READING SLOPES With the many duties incident to training camp life, the men will not have the time nor the paraphernalia for construc- ing the slope board attachment. These should be placed on the boards before the camp begins. (See Fig. 11.) The process is simple, and with the aid of a few trained enlisted men, the work can soon be accomplished. TRIANGULAR RULER Go to some plaining mill and secure a sufficient number of triangular rulers similar to one shown in Fig. 2. Only the plain triangular pieces 6 inches long need be obtained. PENCILS, ERASERS, THUMB TACKS, AND PAPER These articles should all be secured in advance by the camp exchange officer. The Faber HB pencil is recommended, or any other pencil of about the same degree of hardness. As to the paper, transparent sheets may be obtained at a reasonable rate. This class of paper is of advantage as the rain will not affect it to any great extent, and prints may be made directly from the field sketches; however, for instruction purposes, the ordinary sheets of drawing paper will answer the purpose. Do not fail to have the equipment as outlined ready for issue at the first period of instruction or previous to that time. The cost of the entire equipment as given above will not amount to 118 MILITARY SKETCHING much. The compass will be the largest item, but, as a matter of fact, it is a very essential part of a soldier's equipment. Pos- sibly, funds allotted for training camp purposes may be avail- able, especially for the drawing boards and the labor in con- nection with the attachment for reading angles of slope. Do not attempt to have several work at the same drawing board. The plan has not proven successful. One or two will do the work and the remaining men will accomplish little. Each must do the work individually. FIRST PERIOD This period may be employed as follows : Having assembled the class a conference may be held involving the principles outlined in Lessons I and II, also pointing out the necessity of being able to make a sketch and read a military map. Then take the entire class to the target range, if one is available; if not, then to some suitable course previously measured, and let each man determine the length of his pace or stride as described in Lesson I. When this has been done, without doubt the time allotted will have been used up, and the class mat be dismissed with instructions to inscribe on their tri- angular ruler, aided by Figs. 2 and 3, a working scale of paces or strides for 3" equals one mile and 6" equals one mile. The following text references for the second period should also be given out : Lessons VI and XL There will probably be very little time for any preparation, but those who do find a few minutes to read over the text references for the following day will be in a more receptive mood to grasp the practical w r ork. SECOND PERIOD Explain by the aid of the blackboard the following basic principles of sketching: orientation, distance, direction, inter- section, resection, and conventional signs. Students may consult the text freely regarding the latter until they become familiar with the various signs. Then assign some short, irregular course, not over a mile and a half in length, and, if practicable, a closed course. With a large class it will be found better to divide the class into sections, appointing such SUGGESTIONS FOR INSTRUCTION AT TRAINING CAMPS 119 assistants as you may have in charge of the various sections, and prescribing several courses. Many members of the camp will be found to be experienced engineers, although not familiar with the hasty sketching methods followed out in the army. Such men should be distributed among the various sections, as they naturally acquire a knowledge of the work more readily and will render valuable assistance in helping the less fortunate over difficulties. THIRD PERIOD Relief Map and Contours Before the opening of the camp, secure a sufficient amount of moulder's wax and construct a relief map similar to the one shown in Fig. 9, exhibiting the original map along with the relief map. These maps may be displayed in a vertical and elevated position at the conference, and the nature and object of contours explained therefrom. Following this explanation, mimeographed copies of Fig. 14 or some similar illustration should be issued to the class, and each member should be required to interpolate the contours. In other words, impress on the student's mind the importance of first outlining the drainage. An explanation of the auxiliary scale of elevations shown in Fig. 13 and its use should be given. Each man should place this scale for 3" and 6" equals one mile on his triangular work- ing scale. Fig. 13 is a correct scale of elevations for 3" equals one mile. By using every other division, a scale of elevations for 6" equals one mile may be constructed. Also explain the use of the slope-board. This entire period is devoted to conference. Text reference for following period: read over Lesson XII. FOURTH PERIOD Road Sketch Pick out about one and a half miles of road, preferably with as much relief as possible. If practicable, select several routes so that the roads will not be too congested with sketchers. Text reference for following period: read over Lesson XIII. 120 MILITARY SKETCHING FIFTH PERIOD Position and Outpost Sketch Select several areas of about half of a square mile, and assign sections to their tasks, first explaining basic principles as outlined in Lesson XIII. Text reference for following period : read over Lesson XIV. SIXTH PERIOD Place Sketch Deploy the entire class along some crest, and require each to sketch a prescribed sector, first explaining basic principles as outlined in Lesson XIV. It was found at the Plattsburg Training Camps that, after a course of six periods as outlined above, nearly every man was able to turn in very creditable road, position, and place sketches. Their idea of drainage was good, and, along with the practical work, they had automatically learned much about reading a military map. YC 53893 381427 UNIVERSITY OF CAUFORN1A LIBRARY