USE OF MAPS AND COMPASSES

• Document Type: CREST
• Collection: General CIA Records
• Document Number (FOIA) /ESDN (CREST): CIA-RDP78-03581R000200110001-4
• Release Decision: RIPPUB
• Original Classification: K
• Document Page Count: 100
• Document Creation Date: December 9, 2016
• Document Release Date: March 22, 2001
• Sequence Number: 1
• Content Type: STUDY

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USE OF MAPS
AND
COMPASSES
MARCH 1959
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INSTRUCTIONS FOR USE
This manual can be used as a textbook directly by students, but
better results will be obtained if an instructor uses the manual as a
reference, adapting the material contained herein to the specific need
of the students and aiming it at their particular learning level. The
material is organized in a manner intended to make it easiest to learn.
Under certain conditions, if the students have no knowledge of map
reading, it might be desirable to present the section on conventional
signs first. All other portions of the manual are dependent on pre-
ceding sections, so should be revised if the order of instruction is
changed significantly.
Exercises are included for every mechanical operation discussed.
They can serve as a guide to the instructor in preparing exercises based
on maps of the local area. Exercises should be repeated until the opera-
tion concerned is thoroughly mastered and can be carried out smoothly
and quickly. The more complicated procedures are broken down into con-
secutive steps and usually it is not necessary to understand theory in
order to solve the problems successfully. Solutions to all problems
and exercises are given in Appendix B.
The amount of this subject matter presented to each student is
dependent on his specific requirement and should be tailored to his
need. This text is basic but is suitable for a review by more advanced
students. It has been found through experience that most persons
requiring a knowledge of map reading must review the subject at frequent
intervals unless they are constantly applying this knowledge. Even
after mastering a complete course on map reading, military officers and
others often need to review the subject as frequently as once a year to
maintain adequate competence.
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TABLE OF CONTENTS
INTRODUCTION
Instructions for Use
LIST OF ILLUSTRATIONS
LIST OF EXERCISES
I. LOCATION OF POINTS
A. Military Grids . . . . . . . . . . 1
1. Description and Use
2. Use
3. Kinds of Military Grids
B. Geographic Coordinates . . . . . . 9
1. Description and Use
2. Kinds of Measurements
a. Sexagesimal System
b. Centesimal System
c. Conversion from One System to the Other
d. Prime Meridians
C. Use of Compass
1. Description and Use
2. Use of Compass at Night
3. Declination Determination
a. True North
b. Magnetic North
c. Grid North
d. Declination Diagram
e. Converting Declinations
14. Azimuth and Back Azimuth
5. Intersection
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6. Resection
7. The Compass Course
8.. Suggestions for Designing and Operating
Field Compass Training Courses
II. MAP READING . . . . . . . . . . 39
A. Conventional Signs . . . . . . . 39
B. Marginal Information . . . . . . . . 41
C. Relief .
1. Contour Lines
2. Profiles
3. Visibility
. . . . . . . . . 53
D. Map Orientation 64
E. Scale 69
F. Map Identification . . . . . . . 7I
III. MAP SUBSTITUTES . . . . . . . . . 75
A. Definition . . . . . . . . . . 75
B. Map Overlays . . . . . . . . . . 75
C. Sketching . 78
IV. APPENDIX
A. Protractor and Coordinate Scale 85
B. Solutions to Exercises . . . . . . . 88
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LIST OF ILLUSTRATIONS
Figures
Page
1.
Military Grid Coordinates
2
2.
Russian Map, 1:50,000
5
3.
German Map
6
4.
German Map, 1:100,000
7
5.
Geographic Coordinates
10
6.
Map, 1:250,000
13
7.
Map, 1:100,000
15
8.
Conversion from Local Meridian to Greenwich
18
9.
Lensatic Compass
20
10.
East and West Magnetic Declination
22
11.
Grid Declination
24
12.
Declination Diagram
25
13.
Setting Compass for Grid Values
27
14.
Azimuth and, Back Azimuth
29
15.
Intersection Using Grid Azimuths
32
16.
Intersection Using Magnetic Azimuths
33
17.
Resection Using Magnetic Azimuths
314
18.
By-passing Obstruction on Course
36
19.
Following a Course by Sighting on Two Objects
37
STATINTL
20.
Symbol Legend
40
21.
Glossary from an American Map of Japan
tai
22.
Symbol Legend
142
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23.
Credit Note from an American Map
143
24.
Grid Reference Boxes
1
25.
Index to Adjoining Sheets
45
26.
Three Types of Graphic Scales
46
27.
Declination
147
28.
Declination Protractors
t8
29.
Slope Scale from Russian Map
49
30.
Compilation Diagram
50
31.
Hypsometric Diagram from Russian Map
50
32.
Boundary Index
51
33.
French Hachured Map
52
34.
Side View of Hill
54
35.
Oblique View of Hill
54
36.
Top View of Hill
55
37.
Hill Shown by Contours
55
38.
Elevation of Points
56
39.
Character of Slopes
57
40.
Map, 1:25,000
59
til.
Construction of a Profile
60
42.
Determination of Visibility by Profile Method
62
43.
Orienting Map by Inspection
64
44.
Orienting Map by Means of Distant Point
65
45.
Using Watch as Compass Substitute
67
46.
Finding North from the Stars
68
L7.
Finding South from the Stars
68
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48.
Using Graphic Scale to Measure Distance
70
1L9.
Measuring Distance Along a Winding Road
71
50.
Scale - Relation between Distance and Area
72
51.
A Typical Map Overlay for Reporting Information
77
52.
Comparison of Panoramic and Military Sketches
78
53.
Vanishing Point
79
54.
Various Types of Vanishing Points
80
55.
Steps in Preparing a Panoramic Sketch of a Road
81
56.
Delineation Showing the Order in Which a Sketch
is Built Up
82
A-I
Protractor
85
A-II
Military Grid Coordinate Scale
86
A-III Locating Points with Coordinate Scales
87
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LIST OF EXERCISES
Exercise
Page
I
Grid Coordinates
3
II
Reading Military Grid Coordinates
8
III
Reading Geographic Coordinates in Sexagesimal System
12
IV
Reading Geographic Coordinates in Centesimal System
14
V
Converting Geographic Coordinate Systems
Z6
VI
Converting Geographic Coordinates
19
VII
Use of Compass
20
VIII Using Compass at Night
21
IX
Declination
28
X
Azimuth and Back Azimuth
31
XI
Intersection
33
XII
Resection
35
XIII Contour Interpretation
58
XIV
Construction and Use of Profiles
63
XV
Map Orientation With and Without a Compass
66
XVI
Map Scale
73
XVII Overlays
76
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I. LOCATION OF POINTS
1. Description and Purpose. A military grid is a rectangular
system of coordinates composed of two sets of parallel lines drawn at
equal distances and at right angles (90 degrees) to each other upon a
plane, or two-dimensional, map surface. This network of straight lines
forms perfect squares covering the surface of all adjacent map sheets
in a given area. The military grid system is used in locating points
on the map, in measuring distances, and in determining directions.
When it is impossible or undesirable to measure distances or directions
directly on the ground it can be done rapidly on the map with the aid
of the grid. On maps at scales of 1:253,140 to 1:100,000 the grid lines
usually are spaced at intervals representing 10,000 meters; maps at
scales larger than 1:100,000 usually have grid lines at 1,000-meter
intervals. Al]. grid lines are numbered consecutively in multiples of
10,000 (or 1)000) meters, increasing from left to right and from bottom
to top of the map.
2. Use. If a given point on the map falls at the intersection of
a north-south and an east-west grid line, its exact location can be
described by giving the numbers of these lines. The number of the
north-south line is always given first, followed by the number of the
east-west line.
In Figure 1. notice that the grid lines form perfect squares
and may not be parallel to the borders of the map. The two sets of
lines are numbered increasing to the right and upward. The numbers
appearing nearest the lower left corner of the map are written out
in full in two sizes of numbers. Only the large digits of the numbers
for the other grid lines are printed. In reading grid coordinates only
the large numbers are used, as in Example A. Starting at the lower left
corner of the map, read to the right to 23 then read up to 99. In short,
READ-RIGHT-UP.
If a point falls between grid lines its exact location can be
determined by interpolating its distance between the lines. In example
B. point B falls between the lines numbered 20 and 21 and between 00 and
01. Read right to line 20 and estimate or measure to the nearest tenth
B's distance beyond line 20--in this case, 5 tenths--and write it as 205.
Next read up to line 00 and determine the tenths beyond--in this case,
7 tenths--and write it as 007. The complete coordinates for point B, to
the nearest 100 meters, are 205007. Notice that four digits indicate a
location within 1,000 meters and six digits describe a location to 100
meters. By further interpolation of two more digits for the coordinates,
the location can be stated within 10 meters.
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99
98
0
0
0
0
Or
Figure 1. Military grid coordinates.
Example A. Grid coordinates of point A is 2399.
Example B. Grid coordinates of point B to the
nearest 100 meters is 205007.
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On a series of maps covering a large area the numbering sequence
of grid coordinates is repeated every 100,000 meters. This makes it
necessary to identify the map on which the coordinates are to be read
(see section II F), or to give further grid identification which is
printed in a grid reference box in the margin (see section II B) or in
the body of the map. This reference usually is in the form of two
capital letters which are written preceding the coordinates. Example:
BG 250368. The two letters identify the specific 100,000 meter grid
square in which the map falls. An additional identification sometimes
found on the map indicates the zone, belt, or grid. This is not neces-
sary except when reporting over a great distance, or if the recipient
of the report does not know from what area the report originates.
EXERCISE I
Grid Coordinates
(Refer to Figure 1.)
1. Determine the grid coordinates within 100 meters for points:
C.
d.
e.
f.
(Note that point f does not fall within a full grid square.
The bordering grid lines should be extended to complete the
square so its correct distance between lines 19 and 20 can
be measured.)
2. Locate as accurately as possible on Figure 1. the following
grid coordinates:
g. 2201
h. 240973
i. 205997
J. 247013
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3. Kinds of Military Grids. This discussion has referred only to
grid intervals expresse h meters. On maps produced in the past, some
of which are still in use, other units of measurement can be found.
Examples include British yards, Indian yards, American yards on old
polyconic grids? and Russian versts. In most instances these older
maps are being replaced with maps containing grids expressed in meters.
A few countries may still be publishing maps with other than meter grid
intervals.
British and American mapping agencies are among the most pro-
ductive in the world; together they produce maps of most of the popu-
lated areas. Both countries now use the Universal Transverse Mercator
(UTM) grid for all areas between 800 south and 800 north latitude.
Polar areas are covered by companion Universal Polar Stereographic
(UPS) grids. Both grid systems express coordinates in meters. During
the transition to these new systems many maps contain both the U2 and
older grids.
A number of different grid systems have been used in the past
and several of them are still found on current maps. The most common
grid, other than the UTI, is the British grid system. This system employs
various disconnected zones, belts, and grids throughout large areas of
the world. Except for long-distance reporting where it is necessary to
identify the zone,, belt, or grid, British grids are similar to the UTM
grid. Another grid system that was formerly widely used was the World
Polyconic grid adopted by the United States during World War II. This
grid has been replaced bythe UTM grid but maystill be found on old
map copies. It is used in the same way as the UTM grid. Various
countries have used local grids which do not extend beyond a-single
map series and these may still be in use on some maps. Military grid
coordinates are read to the right and up with only -a few exceptions,
notably a Czechoslovak grid, which reads coordinates to the left and
down. The Russian grid zone system is slightly differentfrom the UTM
grid but poses no special problems in its use. If reading coordinates
from any grid ever causes a particular problem, identifying the specific
map (as described in section II F) will enable the recipient of the
report to identify the grid and the location in question. -
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W- J
79 r" I'' j
23 21i 25
~1~0 i~,
26 27 28
Figure 2. Section from Russian map, 1:50,000.
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29
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 STATINTL
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Ostgrenze des Westgrenze des
Gitterstreifens 21'1 Gitterstreifens 24'
Figure !t. Section of map from Reichkarte series, 1:100,000.
Notice the boundary between grid zones, the numbering system,
and the tick marks used to extend the grids of the two zones.
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EXERCISE II
Reading Military Grid Coordinates
Determine the military grid coordinates within 100 meters for
the ten features circled and numbered on Figure 2.
3.
lt.
6.
8.
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B. GEOGRAPHIC COORDINATES
1. Description and Use. A map is a representation of a portion of
the eart s sur ace. Too determine the exact portion of the earth rep-
resented and to locate points on the map accurately, a frame of reference
is needed. A convenient system is a network composed of intersecting
horizontal and vertical lines. Numbers assigned to these lines can be
stated for any point at which they intersect, and since the network
covers the entire earth, these numbers are called geographic coordinates.
The horizontal and vertical lines of this network are parallels and
meridians.
The horizontal lines are all parallel to each other on the earth,
hence the name parallel. The parallel which circles the earth halfway
between the north n T south poles is the equator. Latitude is distance
measured north or south from the equator. Parallels of latitude are
drawn at uniform distances on the globe and map. The latitude, or
distance north or south of the equator, of any point on the earth can
be indicated by describing the parallel which passes through the point.
Since it takes the intersection of two lines to locate a point, it is
necessary to give also the description of another line which is perpen-
dicular to the parallel and passes through the point. This line extends
between the north and south poles and is called a meridian. Meridians
extend only halfway around the earth and the distance between them at
the equator is approximately equal to the distance between the parallels.
Since the meridians converge toward the poles, they are not the same
distance apart throughout their lengths.
Both parallels and meridians are designated by numbers. The
equator is numbered zero. Since there are 360 degrees in a circle, the
distance measured along the surface of the earth from the equator to either
of the poles is one-fourth of a circle, or 90 degrees. Therefore, paral-
lels are numbered from zero to 90 degrees, north or south of the equator.
For example, the parallel halfway between the equator and the north pole
is labeled 450 N. (See Figure 5.)
Unlike the parallel called the equator, there is no logical
meridian to label zero and from which to number the other meridians in
east and west directions. Therefore, the zero meridian, or prime
meridian, was selected arbitrarily, and for the sake of convenience the
meridian passing through the observatory at Greenwich, England, is most
commonly used as the prime meridian. Some countries use different prime
meridians, however, so it is necessary to know definitely which prime
meridian is used. Longitude is measured both east and west from the zero
meridian to the 180.-degree meridian halfway around the earth. By indi-
cating the latitude north or south of the equator and the longitude east
or west of the prime meridian, one can locate any point on the earth's
surface accurately and definitely.
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Figure 5. Geographic coordinates.
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Geographic coordinates
generally are used to locate points op
a map when the map does not include a military grid. When a point
falls between meridians and parallels on a map it often is more dif-
ficult to interpolate its exact position than when using military grids.
Geographic coordinates are most often used when reading medium or small
scale maps that do not contain a military grid. Many medium scale
maps (scales from 1:100,000 to 1:900,000) and most small scale maps
(smaller than 1:1,000,000) do not contain a military grid, and at
these smaller scales the quality of great accuracy does not exist. In
these cases geographic coordinates can be estimated or measured quickly,
since an approximation is all that can be expected.
2. Kinds of Measurements. Just as there are different origins for
longitude, so there are d=erent methods of representing geographic
coordinates. There are two methods of dividing a circle into its
smaller parts. The degree system was used above in the determination
of latitude and longitude distances from the zero lines. This is
called the sexagesimal system, which is based upon divisions of 60.
a. Sexagesimal System. The whole sexagesimal numbering system
evolved from ancient observation of, and reverence for, heavenly
bodies. The ancients noted that the moon waxed and waned every 30
days. The time between two full moons was called a "moonth.tt
Twelve "moonths" (months) elapsed from spring to spring. This
completed cycle or circle, or 30 x 12, made 360. All circles
were divided accordingly. Sixty was an even multiplier or divider
of]2 and 360, so was used to represent the number of units in one
degree and in one minute. Thus, one degree contains 60 minutes,
and one minute contains 60 seconds. The sexagesimal system became
the basis for the English units of measurements for many things
besides a circle.
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EXERCISE III
Geographic Coordinates in Sexagesimal System
Give the geographic coordinates (in degrees, minutes, and seconds)
for the following locations on the map, Figure 6:
1. Ap Tan Hoa in grid square 7.
2. Ap Phu in grid square 75.
3. Thot Not in grid square 53.
4. Thoi Lai in grid square 61.
Lai-Sung in grid square 63.
Give the names of the.towns located at the following geographic
coordinates:
6
N 10? 21'
48" E 105?
311 36"
.
7
N 10o 08'
29" E 105?
271 36"
.
8.
N 10? 24'
12" E
1050
321 13"
9.
N 100 19'
54"
E 1050
371 2511
10.
N 100 21'
30"
E 1050
271-12"
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 Approved For Release 2001/04/04: CIA-RDP78-03581 R000200110001-4
b. Centesimal System. Circles can be divided in another way
in spite o e sanction of long usage given to 360 degrees, 60
minutes and 60 seconds. The centesimal system was originated in
the 18th century. It is based on a decimal subdivision of the
circle. The complete circle is divided into 100 parts called
GRADS (or Grades). Each grad is divided into 100 minutes, or
centigrade, and each minute into 100 seconds, or decimilligrads.
Values may be written in grads, minutes and seconds or merely in
grads and a decimal fraction. For example: 4 grads, 91 minutes,
30 and 25 hundredths seconds equals 4G 97", 30.25` or 4.973025.
(Note that minute and second symbols slope in the reverse. direction
of sexigesimal symbols.)
EXERCISE IV
Geographic Coordinates in the Centesimal System
(Questions apply to map, Figure 7.)
1. What are the geographic coordinates (in grads, based on Paris)
for the center of Sontay?
2. Give the geographic coordinates for the road junction located
at grid coordinates 563338.
3. What are the geographic coordinates for the bridge at grid
coordinates 599278?
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 Approved For Release 2001/04/04: CIA-RDP78-03581 R000200110001-4
,05?28' 5'4 E.Granwich
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 Approved For Release 2001/04/04: CIA-RDP78-03581 R000200110001-4
c. Conversion from One System to the Other. To convert from
the centes-3'mal the sexagesimal system, or a reverse, work on
the basis of a quadrant (one-fourth circle) which equals 100 grads
or 90 degrees. Thus, one grad equals 9/10 (0.9) degree and one
degree equals 10/9 grads.
Example: To convert 49 974 30.25\1 to degrees, minutes and seconds:
0 .2 97' 30.254 4.973025
4?973025 x 0.9 - 4.4757225 or 4? .4757225
.47.57225 x 60 minutes - 28.54335 or 4? 28.54335'
.54335 x 60 seconds - 32.601 or 4? 28' 32.601'
Example: to convert 4? 28' 32.601" to grads:
32.601' ;. 60 - 0.54335'
213' + 0.54335' - 28.54335'
28.54335' = 60 - 0.4757225?
0?4757225? + 4? - 4.47572254
4.4757225? x 10 - 44.757225
1 9 9
44.757225: 9 - 4.973025 or 4G.973025 or 4G 97' 30.25'
EXERCISE V
Converting Geographic Coordinate Systems
Convert the following centesimal coordinates to the sexagesimal system:
1. N 12G.2363 E 106G.1407
2. N 47G51100.0 W 1 G08112.6'
3. S 3G 86' 40.126' W 66G &01.006'
Convert the following sexagesimal coordinates to the centesimal system:
4. N 43?15' E 16? 59`
5. S 150 28v 43'" E 1250 52' 12
6. N 85? 13' 57.11" E 1769 04' 00.00'
- 16
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 Approved For Release 2001/04/04: CIA-RDP78-03581 R000200110001-4
d. Prime Meridians. When reading longitude values from a map
based on a p e mer an other than the Greenwich meridian, it is
necessary to convert to Greenwich values before reporting the
coordinates. To convert longitude to Greenwich, add or subtract
the longitudinal distance between the prime meridian of the map
and the Greenwich meridian. This longitudinal distance is often
printed on the map, or it can be determined by consulting the
following table:
Table I. Longitudinal Distances of Various Prime Meridians
from Greenwich.
0 ' "
Amsterdam 4 53 05 E
Athens 23 42 59 E
Batavia 106 48 28 E
Bern 7 26 20 E
Brussels 4 22 13 E
Copenhagen 12 34 40 E
Ferro (French value) 17 39 46 W
(German value) 17 40 00 W
Istanbul 28 59 20 E
Lisbon 9 07 00 W
Madrid 3 41 15 W
Moscow 37 34 15 E
Oslo 10 43 23 E
Padang 100 22 01 E
Paris
Peking
Pulkovo
2 20 14 E
1162810E
30 19 38 E
Rome 12 27 08 E
Singkawang 108 59 41 E
Stockholm 18 18 30 E
Tokyo 139 44 41 E
If the prime meridian is east of Greenwich, add the difference
to convert to Greenwich values. If the prime meridian is west of
Greenwich, subtract the difference to determine Greenwich values..
For example: the Paris meridian is 20 201 14" East of Greenwich.
To convert a longitude of E 68013' 29" based on Paris to Greenwich,
add the longitudinal distance between Greenwich and Paris--E 680131 29"
+ 2? 20' 14" - 700'331 43" East of Greenwich. However, if the longi-
tude of a point is less than the difference between Green:a.d.ch and the
prime meridian, and in the opposite direction, the Greenwich value
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 Approved For Release 2001/04/04: CIA-RDP78-03581 R000200110001-4
will be the :Longitude of the point subtracted from the difference
between the prime meridian and Greenwich. For example: if the
longitude of a point is W 2?16' 1211, based on Istanbul, it will
have a Greenwich value less than the difference between Istanbul
and Greenwich. E 28? 59' 2011 (Greenwich) minus W 2? 16' 1211
(Istanbul) equals E 26? 43' 0811 (Greenwich). (See Figure 8.)
Since latitude is always based on the equator, no conversion is
necessary for that portion of the coordinates. On maps expressing
geographic coordinates in grads and a prime meridian other than
Greenwich, the coordinates must be converted to degrees, minutes,
and seconds before converting to the Greenwich meridian.
To convert longitude from Greenwich to another prime
meridian, the reverse procedure is employed--subtract the difference
if the other meridian is east of Greenwich, and add if it is west
of Greenwich. It is advisable to diagram the relationship between
the local prime meridian and the Greenwich meridian and the longi-
tude of the point to be converted, as in Figure 8. This will make
clear the east and west values and whether to add or subtract.
0? (Greenwich) 28? 59' 201, (Greenwich)
Meridian 00 (Istanbul)
i Meridian
Local
Meridian
W 2? 16' 1211 (Istanbul)
E 26? 43' 0811 (Greenwich)
280 59' 2011
2 16 12
2 6j - I t 3'
Figure 8.
Conversion from Local Meridian to
Greenwich
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 Approved For Release 2001/04/04: CIA-RDP78-03581 R000200110001-4
EXERCISE VI
Converting Geographic Coordinates
Convert the following geographic coordinates to Greenwich values:
1. N 80 131 E 60? 47' (based on Ferro, German value)
2. N 38? 06' 27" E 150 31' 59" (based on Rome)
3. N 62? 14' 23" E 65? 42' 48" (based on Moscow)
4. S 22? 141 38" W 32? 531 26" (based on Lisbon)
5. S 90 47' Olt" E 18? 31' 45" (based on Batavia)
6. N 4O? 16, 00" W 2? 11' 00" (based on Athens)
7. N 32? 1111 38" E 10 3111 53" (based on Madrid)
Convert the following geographic coordinates to the sexagesimal system
and Greenwich values:
8. N 20G 12'' 06' E 118G 19' 51" (based on Paris)
9. N 15G 59' 07' W 14G 20` 26"(based on Paris)
10. N iritG lilt` 10' E 14G 63' 89'' (based on Istanbul)
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 Approved For Release 2001/04/04: CIA-RDP78-03581 R000200110001-4
C. USE OF COMPASS
1. Descri tion and Use. A compass is an instrument for measuring
directions. It contains aointer which always points in a northerly
direction. The face of the compass, under the pointer, is circular and
calibrated in either 'b mpass directions; 360 degrees, or 4100 grade, mills,
or bearings. A military compass usually has a front eight and a rear eye-
piece to aid in lining up the compass on a distant object. A leneatic com-
pass has a magnifying lens to aid in reading the numbers on the dial while
it is held close to the eye. Prismatic compasses contain a prism instead
of a magnifying lens.
North pointer or -arrow
Figure 9. Lensatic Compass
A compass is held as steady as possible in front of the body (the
lensatic compass is held close to the eye) with the front of the compass
pointed toward the desired object until the pointer stops moving. The
dial of the military compass will turn with the pointer so that the angular
direction can be read directly under the index mark at the front of the
compass. A hand compass usually can be read to an accuracy only of two
degrees. Since auy object made of iron will attract the compass pointer,
be sure to keep an adequate distance from any such local disturbance. Power
lines and telegraph lines also will deflect the compass from an accurate
reading. This attraction can be demonstrated by holding a compass close
to an iron object or near a power line.
EXERCISE VII
Use of Compass
Using the compass available to you, determine the angular direction
of at least six objects within might of your location.
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 Approved For Release 2001/04/04: CIA-RDP78-03581 R000200110001-4
2. Use of Compass at Night. Some compasses are designed so that
they can a used at night without a light. One type contains under the
transparent dial an area coated with luminous paint which makes the
numbers of the dial visible in darkness. Another type has luminous
dots to mark the front sight and points on the compass body correspond-
ing to 90?, 1800, and 270. The glass covering the dial will rotate
with a series of clicks, each click equal to three degrees. This glass
contains a luminous index line. The pointer is also luminous. To read
angular directions at night with this type compass, hold it and sight on
the desired object in the normal manner, then, holding the instrument
steady, slowly turn the glass dial cover in a counterclockwise direction,
counting the clicks, until the luminous index mark falls over the luminous
pointer. The number of clicks counted times three degrees will equal the
desired angle.
For example: be sure the luminous index line is set to fall
exactly over the fixed index mark at the front of the compass dial,
then sight the compass on an object. Holding the compass steady, turn
the cover glass in a counterclockwise direction until the luminous
index line falls over the luminous pointer and count the number of clicks
(in this example, assume 10 clicks). Since each click equals three
degrees, 10 clicks equal 30 degrees, which is the angle of the object.
EXERCISE VIII
Using Compass at Night
Practice the above procedure in the dark until you can.read directions
quickly and accurately.
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 Ap7,ov d For Release 2001/04/04: CIA-RDP78-03581 R000200110001-4
3. Deal tion Determination.
a. True North. Determination of any location is always relative
to some frame reference. For example, longitude is determined
from the prime meridian, latitude is determined from the equator,
elevation is determined from sea level. The north pole is an imagi-
nary point in the arctic toward which all the meridians converge.
This point is a convenient reference in determining the north direc-
tion. The direction of the meridians is easy to determine because
each meridian intersects the path of the sun at a right angle (90
degrees). Therefore, by following any meridian northward to the
north pole a specific point is reached which is north of every other
point on the earth. This is the north direction, or true north,
referred to when using -geographic coordinates.
b. Magnetic, North. Use of a compass to determine directions
requires a diree en reference point because the compass pointer
does not point exactly to the north pole, but to a point near the
north pole usually located in northern Canada. This magnetic pole
is not stationary but moves constantly within a limited area. Since
the geographic north pole and the magnetic pole are not located at
the same place, from most locations on the earth the compass will
point either to the east of the north pole or to the west of it.
(See Figure 10.) This difference between true north and magnetic
north, called magnetic declination, varies from zero degrees at some
places on the earth to more than 90 degrees in some higher latitudes,
-and must be referred to as east declination or west declination. If
the compass points to-the east of true north, it is east magnetic
declination; if the compass points to the west of true north, it is
west magnetic declination. Maps usually contain a note indicating
the amountof annual change in magnetic declination.
Figure 10.
East and West Magnetic Declination
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 Approved For Release 2001/04/04: CIA-RDP78-03581 R0002001 10001-4
c. Grid North. The third north direction indicated on maps is
grid north. This is the direction indicated by the vertical grid
lines. Grid lines are straight and meridians are curved; therefore
they get farther apart as the lines are extended north from the
equator. Grid declination is the angular distance between the
vertical grid lines and the meridians (See Figure 11.) Grid north
is constant for each grid zone but may be different on different
maps. Along the central meridian of each grid zone grid north and
true north are the same and there is no grid declination since the
central grid line falls on the central meridian of the zone. Along
all other meridians there will be an east or west grid declination.
Magnetic north usually does not correspond with grid north. Al-
though the relationship of true north to grid north remains constant
for each point, the relationship between magnetic north and grid
north is not constant, since the magnetic declination gradually
changes each year. The grid-magnetic declination for any year can
be determined by consulting the information printed on each map.
- 23 -
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 Appo ed For Release 2001/04/04: CIA-RDP78-03581 R000200110001-4
I 0
Figure 11. Grid declination.
2!
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 r
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d. Declination Diagram. A declination diagram appeaislo most
maps to show the relationships among true north, magnetic north, and
grid north. The diagram consists of three lines; a star indicates
the true north line, an arrow indicates the magnetic north line, and
a Y or initials indicate the grid north line. At the sides of the
diagram are numbers indicating the amounts of grid declination and
magnetic declination, expressed in degrees or grads. The declination
angles are not always drawn accurately in the diagram so it is
important to refer to the size of the angles as expressed by the
numbers. The declination, as expressed by the diagram, will usually
be different for each map sheet. Often below the diagram will be a
note indicating the amount of annual magnetic change, westerly or
easterly, and the year for which the diagram is drawn.
Y
4?151
7?301
Declination for 1955
Annual Magnetic Change 61 Westerly
Figure 12.
Declination Diagram
To determine the grid-magnetic angle for a map from the
declination diagram, add or subtract from the magnetic declination
the amount of annual magnetic change times the number of years since
the date of the diagram, and subtract from or add to the amount of
the grid declination.
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 App,ox~ed For Release 2001/04/04: CIA-RDP78-03581 R000200110001-4
Example: Use the diagram in Figure 12 and determine the
grid-magnetic angle for 1958
7? 30' - 18' - 7? 12'
70 12' t 4? 15' - 110 27', the grid-magnetic angle
In this example the change for three years (18')
is subtracted because the change is westerly.
Example: Determine grid-magnetic angle for 1958.
31 x 8 years - 24'
8012' +24' -8036'
80 36' - 2? - 6? 36',-the grid-magnetic angle
2?OO1
1950 - Annual Change 3' Easterly
Example: Determine grid-magnetic angle for 1959.
1' x 14 years - 14'
2? 45' - 19' - 20 31t
2? 31' + 3 15' - 5? 46'
2 0451
.CI
1945 - Annual Change 1' Easterly
- 26 -
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 Approved For Release 2001/04/04: CIA-RDP78-03581 R00020011 1-4
e. Converting Declinations. Tactical use of a map containing
a military grid usually nvo ves converting all compass readings to
grid values. To avoid making a computation for each reading, the
movable index mark on the compass can be set to the proper number
of degrees east or west of the fixed index mark, and then angles
based on the grid can be read directly under the movable index mark.
Figure 13.
Shows the movable index mark set for reading
grid values directly when the grid-magnetic
angle is 120, and grid north is west of
magnetic north.
The compass is sighted in the usual manner. Similarly, compass
readings can be converted to true directions by using the magnetic
declination angle in the manner described above.
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 Approved For Release 2001/04/04: CIA-RDP78-03581 R000200110001-4
EXERCISE IX
Declination
From the following declination diagrams, determine the magnetic declination
and the grid declination for 1960.
1. 2.
2?00,
1955
Annual change 81 Easterly
1950
Annual Change 21 Westerly
From the following declination diagrams, determine the grid-magnetic angles
for 1959.
3. 14.
1008,
:1948
No annual change
5. 6.
1956
Annual change 51 Westerly
4 ?y
1.9
2g19
Annual change 0:093 Easterly
1958
Annual change 61 Easterly
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 Approved For Release 2001/04/04: CIA-RDP78-03581 R000200110001-4
4. Azimuth and Back Azimuth. The azimuth is a method of indicating
direction military map rea g. An azimuth is a horizontal angle
measured clockwise from a north reference line. The point from which
the direction is measured is presumed to be at the center of an imaginary
horizontal circle. This circle is divided into units of degrees, grads,
or mils. The units are numbered in a clockwise direction with the zero
point at the north. If the circle is divided into degrees, zero degrees
and 360 degrees will be at the north, 90 degrees will be due east, 180
degrees will be to the south, and 270 degrees will be due west. Direction
by the azimuth method is expressed by giving the number of the degrees
on the circle at which a line, drawn from the initial point through the
point desired, will pass. The azimuth from the observer to an observed
position is known as the forward azimuth to that point. However, every
observed line of sight has a forward azimuth and a back azimuth. The
back azimuth of any line varies from its forward azimuth by exactly 180
degrees. To determine the back azimuth of a line whose forward azimuth
is less than 180 degrees, add 180 degrees. If the forward azimuth is
greater than 180 degrees, subtract 180 degrees.
180
South
Figure 14.
Azimuth and Back Azimuth
29
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 Approved For Release 2001/04/04: CIA-RDP78-03581 R000200110001-4
In Figure 14 the azimuth of point _B is 40 degrees. Therefore,
the back azimuth. of point B is Lao plus 180, or 220 degrees. The azimuth
of point C is 300 degrees. Its back azimuth is 300 minus 180, or 120
degrees.
Azimuth can be determined by reading the angle directly from
the lensatic compass, and it would then be magnetic azimuth. If the
movable index mark of the compass is first set to correct for the
magnetic declination of that locality, the reading would be true azi-
muths. If the grid-magnetic angle is set into the compass, the reading
will be expressed in grid azimuths. When reporting azimuths to other
persons it is important to indicate-the kind of azimuths--magnetic,
true, or grid.
If a night patrol wishes to move to a nearby hill and return,
its outward course will be along the azimuth to the hill as determined
from the starting point. Then, when the patrol is ready to return it
is not necessary to take a new reading on the starting point, which may
not be visible, because the return course will be the back azimuth of
the outward course.
When using a compass calibrated in grads, back azimuth is
determined by adding or subtracting 200 to or from the azimuth. This
figure is used because 200 grads equal one-half circle.
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 Approved For Release 2001/04/04: CIA-RDP78-03581 R000200110001-4
EXERCISE X
Azimuth and Back Azimuth
What are the azimuths (in degrees) of the four cardinal points
of the compass?
1. North
2. East
3. South
4. West
Give the back azimuths of each of the above azimuths.
6.
7.
8.
Determine the back azimuths for the following azimuths:
9. 63?
10. 450
11. 261?
12. 389G
13. What is the back azimuth (true) of 1800 magnetic azimuth
if the magnetic declination is 14? east?
14. Determine the grid back azimuth of 250? magnetic azimuth
when the grid magnetic angle is 6? 151 and grid north is west of mag-
netic north.
15. Give the magnetic back azimuth of grid azimuth 1050 determined
from a map with this declination diagram:
0086
* 9
2.10
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5. Intersection. Intersection is the method of -locating an unknown,
unoccupieTpponT"b taking sights to the unknown point from at least: two
known occupied positions. To determine the exact location of a point
that is not on the map, move to -a terrain feature, A (Figure 15) which
can be identified on the map, and take -a compass sight on the object, C,
you wish to locate. Move to another identifiable feature, B. and again
sight on the object C with your compass. Then change the magnetic
azimuths to grid azimuths and plot the grid-azimuths through the
-respective positions where you obtained the sights, or draw a magnetic
north reference line through points A and B on the map and plot the
magnetic azimuths. (Figure 16) The intersection of the two lines is
the location of the object.
Grid azimuth of C
measured at A = 32?
Grid azimuth of C
measured at B = 315
Figure 15.
Intersection using Grid Azimuths
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Magnetic Magnetic
north north
Magnetic azimuth of C
measured at B = 3230
323? B
Figure 16.
Intersection Using Magnetic Azimuths
EXERCISE XI
Intersection
1. Using the protractor in Appendix A in place of a compass,
determine the grid coordinates of the point on the map in Figure 3.
described in the following intersection problem: Flom grid location
40200270 an object is seen on a grid azimuth of 284 , from grid
location 39750422 the same object is seen on a grid azimuth of 235?.
What are the grid coordinates of the object?
2. From gridlocation 37420174, an object is seen on a magnetic
azimuth of 700; from grid location 40120050 the same object is seen
on a magnetic azimuth of 345?. The grid magnetic angle of this map
is 40, with grid north east of magnetic north. What are the grid
coordinates of the object?
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6. Resection,, Resection is the method of locating an unknown
occupied po 3'ti ffi- by taking sights on two or more identifiable points
whose positions are known. To determine the location of the position
you are occupying,, select two visible objects which can be identified
on the map and which are situated so that lines from-you to them make
an angle greater than 30 degrees and less than 150 degrees. With the
compass determine the magnetic azimuths to both points A and B (Figure
17). Draw magnetic north guide lines through the map positions of
each object, A and B. From points A and B lay off the respective
magnetic azimuths and extend these lines back towards your position
until they meet? The intersection of these lines is the location you
occupied while measuring the azimuths with the compass.
Extend lines until
they meet
7- Viillii V YY11
position
Figure 17.
Resection Using Magnetic Azimuths
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EXERCISE XII
Resection
1. You are located somewhere on the map, Figure 40, and want to
determine your exact position. The cluster of buildings at 832717
at the top of the bluff can be seen on a grid azimuth of 153 degrees.
The point where the road crosses Ihagee Creek in grid square 8072 is
seen on a grid azimuth of 251 degrees. What are the coordinates of
your location?
7. The Compass Course. When it is necessary to move from one
point to another, ere is not always a convenient road directly
connecting the two points. One method of finding your way along a
predetermined route without going too far out of your way is to
follow the direction indicated by your compass. Even if the course
leads you through forests, over mountains, or across rivers, you can
arrive at your destination by travelling in the predetermined direction
shown by your compass. Military units often need to travel in the most
direct route or desire to keep off the roads, and they can do this by
following a compass course.
The compass course to follow can be determined by reading the
azimuth of the destination directly with the compass, if the destination
is within sight of the starting point. The azimuth to follow to the
objective can be measured directly from a map, if one is available, and
both the starting point and the destination can be identified on the
map.
It usually is necessary to determine exactly how far to travel
on the given azimuth to arrive at the destination. When travelling on
foot the most practical method of determining distance is to count the
number of steps or strides. A step or pace is the distance travelled
with one foot while walking naturally. A stride is the distance between
the heel of one foot and the point at which the same heel meets the
ground again while walking. It is equal to two steps. The length of
a person's pace or stride can be determined by walking a measured distance
many times and taking the average count. A suitable course for deter-
mining one's average pace or stride should be at least 100 meters long
and over approximately level terrain with normal ground cover. Remember
that a step tends to be shorter going up or down hill.
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When ascending slopes up to 40%, the horizontal distance travel-
led per stride or pace will average 1.2% less for each percent of slope.
For example, if you walk up a 10% slope, after 100 strides you still
would have to take an extra 12 strides to cover the same horizontal dis-
tance you would walk in 100 strides on a level. When descending slopes
up to 30%, the horizontal distance travelled will average 0.5% less for
each percent of slope. For example, in descending a 20% slope you would
have to take 110 strides to cover the horizontal distance equivalent to
100 strides on a level. This assumes, of course, that you continue to
walk in a normal. manner and do not attempt to maintain a uniform stride
on different slopes. The character of the ground surface, such as sand,
rocks, short or high grass, smooth or rough, soft or hard, trees or
brush, will affect the length of the step. Other factors having an
effect on the length of pace are wind, the elements, clothing, and per-
sonal stamina. Each of these factors must be taken into consideration
when pacing a distance. -Sometimes extreme conditions, such as dense
vegetative cover, can make accurate pacing impossible without clearing
a path.
There are two common causes for error in pacing distances. It
is a natural human tendency to overestimate distances when walking. Also,
when measuring distances from a map, horizontal distances are obtained.
The distance along the ground in hilly terrain may be considerably
greater than the horizontal map distance.
When pacing over extended distances, keeping track of the steps
or strides becomes a problem. It usually is easiest to count by hundreds
and record each hundred strides by placing small objects (sticks or peb-
bles) into an empty pocket. If it is important to measure short distances
very accurately, the course should be paced several times in both direc-
tions to arrive at the average.
Obstructions along a compass course can be by-passed by walking
at right angles (90 degrees) to the course a sufficient distance, then
continuing parallel to the course until past the obstruction, and finally
returning at right angles to the course the sse distance previously
recorded. (See Figure 18.) Do not include the paces taken at right
angles to the course in computing the distance travelled along the course.
U& - UL - I Direction
I l of course
AUL
Figure 18.
By-passing Obstruction on Course
ALL
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If the destination cannot be seen while travelling a compass
course, care must be taken to avoid drifting off the course to the
right or left. The direction of travel should be noted with the com-
pass. Then observe two objects, such as trees, along the route which
you can sight on and keep lined up as you walk. (See Figure 19.)
When you reach the first object, stop, use your compass and note a new
object beyond the second one. You can then walk to,the second object
keeping it lined up with the third, when the process is repeated. This
procedure enables you to walk without constantly keeping your eyes on
the compass. Even though you keep the compass pointed on the correct
azimuth, there is danger of your walking slightly to the side and
arriving considerably off course. If several persons are travelling a
compass course together, two can move ahead and be lined up on the courrse
by the third person with the compass. The first two then stand still
while the third person walks to the nearest one. The procedure is then
repeated.
1st 2nd 3rd
obyect object object
Figure 19.
Following a Course by Sighting on Two Objects
While travelling a compass course, if the destination is not
visible but the starting point is visible, you can make a check to be sure
you are still on the course. Determine the back azimuth of the course and
sight the compass in that direction. If you are still on the course the
starting point will appear in line with your compass sights. If this is
not the case, move the necessary distance to the right or left until the
starting point appears at exactly the back azimuth of the course.
Following a compass course at night usually is much more difficult
than travel during the day. Depending on visibility, any of the principles
applicable to daytime travel can be used at night. If no light is avail-
able or security prevents use of artificial light, a compass with luminous
dial is necessary. Before starting, set your compass on the required azi-
muth by turning it until the proper azimuth appears under the fixed index
mark at the front of the compass. Then, holding the compass still, set the
movable luminous index.mark directly over the north pointer. After setting
the compass, check it carefully for accuracy. The course can then be fol-
lowed by holding the compass in front of you with the front directly ahead,
and keeping the luminous index mark over the north pointer. If enough
natural light is available, sight on objects along the course (Figure 19)
so it will not be necessary to keep your eyes on the compass.
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8. Sugestions for Designing and Operating Field Compass Training
Courses.'
a. Select an area where students are free to move about without
interference from other persons, and where power lines and other
compass disturbances are not too close.
b. Design two or more courses of varing degrees of difficulty.
Send students through the easiest course until they can complete
it satisfactorily, before trying harder courses.
c. Each course should be composed of five or more legs, no leg
to exceed 1,000 meters in length.
d. Select the path for each leg to provide a variety of ter-
rain and obstacles, and different azimuths and distances. Select
realistic terrain conditions that can be negotiated. This should
not be an endurance contest. Obstacles on the course should be -
limited in size so that they can be by-passed as shown in Figure
18. Ordinarily -a different course should be used for day and night
practice.
e. Mark the end of each leg with a numbered stake that is not
visible from a greater di-stance than 10% of the length of that leg.
For example, if the leg is 500 meters long, the end stake should not
be visible at a distance greater than 50 meters. This requires that
the student follow the course with no morethan 10% error in azimuth
and distance. The quality of the compass and the difficulty of the
course should determine amount of error allowed. If there is not
sufficient natural cover to conceal the stake from the desired dis-
tance, locate several stakes within the 10% radius area, each with a
different number. The student then will have to select the correct
stake as the start of the next leg.
f. Give each student the azimuth and distance for each leg of
the course. If a single stake marks each leg, instructions for the
next leg can be placed at the stake. Each student should negotiate
the course individually and be timed. Starting times should be at
least at 15--minute intervals. Have each student record the number
of the stakeat the endof each leg and his distance error in ar-
riving at it. The stakesshould -not be numbered in consecutive
order.
g. Test each course yourself before sending the students over
it, to check azimuths, distances, possible hazards, time, and
degree of difficulty.
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A. CONVENTIONAL SIGNS
Conventional signs are a graphic method of portraying on a map
the various features of the earth's surface. These map symbols usually are
drawn to resemble as much as possible the actual object represented. In
this way the symbol suggests the feature even to the uninitiated and thus
becomes a diagrammatic picture of a portion of the earth. The standard
or conventional symbols are much the same on maps produced by any country.
Individual map publishers, however, may use a number of non-standard
symbols that must be learned. Also, symbols used to depict military
installations, units, and activities may vary considerably. But symbols
for such features as streams, roads, railroads, bridges, vegetation,
relief, etc., are much the same everywhere or else are self-explanatory.
All non-standard symbols used on a map should be shown in the legend, but
this is not always the case in practice.
For the sake of convenience and clarity, conventional signs may be
divided into categories, each of which usually is printed on the map in
a distinctive color. Symbols representing man-made features, administra-
tive boundaries, and names are termed cultural symbols and are shown in
black. Examples of cultural features are buildings, roads, railroads,
cemeteries, dams, airfields, storage tanks, international and provincial
boundaries, and names. Relief of the ground surface most commonly is
indicated with contour lines printed in brown. Less precise relief
symbols are hachures and shading. Green is generally used for printing
vegetation symbols. Individual tree types or crops may be shown by
symbols, or wooded areas may be indicated with a solid green overprint.
Water features, such as rivers, lakes, shorelines, springs, swamps, and
wells, are represented in blue. Other colors sometimes are added to
maps to make them easier to read. Certain other features can be em-
phasized by printing them in color. Many maps are printed in fewer
colors for the sake of economy, and it is not unusual to find maps with
all conventional signs in black. A monochrome map usually is difficult
to read. An example of detailed symbolization is shown in Figure 20.
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Railways Normal gauge, 2 a more tracks . . . . . .
Normal gauge, single track . . . . . . . . .
Narrow gauge . . . . . . . . . . . . . . .
Tramway or Mineral railway. . . . . . . . . . . .`~
Cable railway.............
Statist Haft . . . . . . . . . . . . . . .
Embankment Cothrig . . . . . . . . . . . . .
Roads Motor highways ? Reichsautobahnen (independent of
road eys4'm) Two metalled carriage ways, each 7-5 metres
fuouto Number . t . . . . .
Roads 8 moires wde or over metalled . I
? 4.6 . metalled. . . . . . . . . . __.~J'1
? Less than 4 metres wide metalled . . . . . .
Minor cart t tracks. Width v. .. not always mob. r,Z..T
$ ~yST'
ol and
and often ar rocks
i . T ,
.j
Lanes. hack; paths . . . . . . . . .
NOTE Road crassilicaftoe is NOT based on reconnelssance.
Reliability uncertain
Kilometre alone, signpost . . . . . . . . . . . ,
Boundaries : International. Provincial. . . . . . . . . ...hnla.e.a.........w
District. Town or parish . . . . . . . . . . . ......_ ._.~._.~
Wire fence, hedge.e . . . . . ... . . . . . . . .
Walt, fence . . . . . . . . . . . . . . . . ~~.
Monument windmill . . . . . . . . . . . . . . AP
Chimney. water tower. . . . . . . . . . . . . . a D Cry
Shrine, chapel, church . . . . . . . . . . . . . t ?. par
Cemetery . . . . . . . . . . . . . . . . . . ..... ... u
High tension cable. . . . . . . . .
WIT Station, and with town over 200 ft. high . . . . .
Ouarry, mine . . . . . . . . . . . . .
Spotheight (in metres), bench mark . . . . . . . . .
Trigonometrical point . . . . . . . . . . . . . .
Bridges, etc.
.4 CR. RC
113.1 saran
Iron. stone, wood, pontoon, footbridge, ferries . . . . =Mlliw
Canal, weir, lock,- sluice . . . . . . . . . . . . .
Drainage ditch, dry river bed . . . . . . . . . .
Well, spring . . . . . . . . . . . . . . . . .
Lighthouse, beacon . . . . . . . . . . . . . . . r ?~ t
Woods, etc.
Deciduous, coniferous . . . . . . . . . . a ban as?A,7.a
Scrub, reefibrestltlon 1
Orchard-plantation, park . . . . . . . . . . . .;?ef~ieati. tli?r.
Heath, peat college . . . . . . . . . . . . . i.~aU hs%M;
Sand (or grevel). . . . . ... . . . . . .
Meadow-swamp.. . . . . . . . . . . . . .
Maeyard,, hnpfield . . . . . . . . . . . . . ;~; ' titia;K:art~
Butt-up areas, gardens . . . . . . . . . . . . . ?Y9/m? aNti'?~
Broken urstabte ground, slag hasps, etc . . . . . . 4411111011.
Tarrecearochy cliff . . . . . . . . . .
. . . . . . . . . . . . M.
Heights in metres Wig;
Cultural
(black)
Water
(blue)
Vegetation
(green)
Relief
(brown)
Figure 20e Legend symbols from a British
map of Germany.
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The information printed in the margin of a map is vital to a
correct interpretation of the data included within the body of the map.
This information helps the user gain the proper perspective when reading
the map, and provides the correct referencing for the map. The material
is included to make map reading easier and more accurate, and to assist the
user in his evaluation of its contents. Thus, it is strongly advisable to
inspect the marginal information each time you start to use a different
map. While there is a great variety in the amount of marginal information
included on different map sheets, it all tends to fall into several categories.
1. The title of the map or sheet name usually is shown prominently in
the upper margin in large type. Some publishers group adjacent and similar
maps into series and assign a name or number to each series. Series identi-
fication usually appears in the upper margin.
2. Scale of the map is always shown and may be expressed as a ratio,
a representative fraction, or as a relative distance, i. e., one inch
equals one mile. Examples: 1x50,000; Quarter Inch (to the mile).
The scale is given usually in the center of the lower margin but also may
appear in the upper margin.
3. Many maps contain a glossary of generic terms appearing on the
map. These terms often are presented in more than one language (See Figure
21).
GLOSSARY
VARIANTS IN PARENTHESES
-boo (-hoe) ------------- rock
-kojima _-__-.______ small isle
-bakufu ----------- waterfall
-machi (-ch'o) _______ township
-bama (-hama) ___ beach, field
-mine mountain peak
-bona (-hang) ---------- point
-misaki (-saki, -saki) ____ cape
-bara (-hara) ----- plain, field
-mori --------------- _ forest
-cho (-machi) ___j___ township
-mura ------------- township
-dai (-tai) ----- plateau, plain
-nada _____________ - sea
-dake (-take) ------- mountain
-no ___________ _ plain, field
-daki (-taki) --------- waterfall
-onsen -------- hot spring, spa
-dani (-toni) ___ valley, stream
-retto ----------- island chain
-gun (-iwa) --------- rock, cliff
-saki (-zaki, -misaki) _ - cape
-gota _ ----- bay, inlet, lake
-son (-zan, -yama)_ __ mt. chain
-gawa (-kawa) --------- river
-se --------- reef, shoal, rapid
-goe (-koe) ____ mountain pass
-seto __________-__ strait
-gun ------ ------ -- county
-shi -------- municipality, city
-gunto ___ archipelago
-shima (-Jima, -t5) __ _ island
hama (-bama) beach, field
-shs reef, shoal
-hana (-bona) __ point
-shots ---------- island group
-hant3--------------- peninsula
-suido __________- channel
-har
a (-bara) ----- plain, field
-tai (-dai) plateau, plain
-ike
.------------------_ pond
-take (-dake) ------ mountain
-ishi
_____--------- rock, cliff
-taki (-daki) ____ - waterfall
-iso
------------------ beach
-tani (-dani) __._ valley, stream
-iwa
(-gan) -___ ___ rock, cliff
-tt (-shims, -Jima) island
-jima
(-shima, -to) ___ _ island
g! __ mountain pass or ridge
-to-
-kai
(-umi) --------- bay, gulf
-uchi ------------------- inlet
-kaik
yo strait
-umi (-kai) --------- bay, gulf
-kaw
a (-gowa) -------- river
-ura ------------- inlet, beach
-ken
-------------- prefecture
-wan- ---- --------------- bay
-ko
--------------------- lake
-yama (-son, -ran) _ mt. chain
-ko
harbor
-yu_______ mineral spring, spa
-
-koe (?goe) ____ mountain pass
zaki (-saki, -misaki)_ __.---cape
-ran (-son, -yama)___ mt. chain
Figure 21
Glossary from an American Map of Japan
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4. A legend explaining the symbols used on the map usually includes
all non-standard symbols. (See Figure 22.)
ROADS
Hard surface, all weather, mom than two lanes >.a ~"aa...r'sr -
Hard surface, all weather, two lanes ,-..- .~....~.
Nerd surface, all weather, less than two lanes-
F
Native settlement
RAILROADS
36 gauge, single iack
3'6" gauge, double track
Narrow gauge. single track (gauge in feet)
Narrow gauge, double track (gauge In feet) __ a r*
In street (gauge in feet)..
Hsien boundary ._.-
Power Iransmisslon line
Shrine; Temple __._ _ 1 i
-Windmill; Water mill; lighthouse is
Rice or'sugar cane; Orchard
Woods or brushwood; Vineyard
Lame surface, graded, all weather ___
Lome surlaae, dry weather or dirt ...........
Track; Trail -
Prominent wall.
Levee; Road on levee
Depth curves and soundings In tafhoms -
Land subject to inundation
Sett evaporators
ror.sfwre flats
dock, bare or awash
Sunken rocks; Reel ~.~
Submerged reel
e:E~3
Limit of danger
Wrecks: Sunken; Exposed
Marsh or swamp ___.______.._--_
Figure 22.
Symbol Legend
5. The credit note is a combination of references which aid the map
reader in evaluating the accuracy of the map and which clarify any unusual
conditions for which no explanation exists anywhere else on the map. In-
formation in the credit note usually designates the preparing agency,
explains the method and date of preparation, and lists the source materials.
This provides information on which to base an evaluation of the dependa-
bility of the map. (See Figure 23.)
142
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Prepared under the direction of the Chief of Engineers by the Corps of Engineers, U. S. Army Map Service (AM),
Washington, D. C. Redrawn In 1949 from Maryland, 1:25,000, AMS, Sheet 5662 III SE, 1946. Planimetric detail
revised by photo-planimetric methods. Contours in Fort Meade Military Reservation Firing Area compiled by
photogrammetric (multiplex) methods. Aerial photography Dec. 1947, Jan., April 1948. Original mapping by
plane-table and photogrammetric (multiplex) methods by Soil Conservation Service, 1943. Horizontal and ver-
tical control by USC&GS, USGS, CE and Soil Conservation Service. Map field checked. This map complies with
the national standard map accuracy requirements.
Figure 23.
Credit Note from an American Map
6. To help the map user identify the military grid and determine
grid coordinates, many maps contain a grid reference box in the margin.
(See Figure 24.)
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GRID ZONE DESIGNATION:
TO GIVE A STANDARD REFERENCE ON
18S
THIS SHEET TO NEAREST 100 METERS
100,000 M. SQUARE IDENTIFICATION
SAMPLE POINT: JOHN WESLEY CHURCH
1. Locate first VERTICAL grid line to LEFT of
point and read LARGE figures labeling the
line either In the top or bottom margin, or
-
on the line Itself:
70
Estimate tenths from grid line to point:
4
U U
2. Locate first HORIZONTAL grid line BELOW
point and read LARGE figures labeling the
Ilse either In the left or right margin, or
I
f
12
on the line
:
tsel
Estimate tenths from grid line to pant:
4
IGNORE the SMALLER figures of any
SAMPLE REFERENCE:
1111
124
grid number; these are for finding
If repgrting beyond 100,000 meters or If 'h so
the full coordinates. Use ONLY the
bears an overlapping grid, prefix 100,000
LARGER figures of the grid number;
Meter Square Identification, as:
UU704124
example: 43_a000 I
If reporting beyond l8?In + direction, prefix
YS
Grid Lone Designation as,
IBSUU704124
TO GIVE A GRID REFERENCE ON THIS SHEET
Use only LARGER Grid figures viz -------- t80ooo
POINT OLIG
LETTER famface ofmap-------- _ ________________.._-
L
EASTINGS.
ThAe figure of Went edge of small square in which point /less-_ - _ - _ _
29
fsGmate tenths eastwards______________
_____________-_--__-.--.
_
NORTHINGS.
298
Take Agura of South edge of small squaro in ioh,ch point lies ----- . -
00,
fst,maie tenths northwards ..
..... ...
..
.. ............. -
7
.
.
.
L 2980
007
REFERENCE -------------------------- ------------- ..---
Unit._..motre. Square-._...1000. Reforence to nearost __.100.
Nearest similar reference on this grid 500 Kin distant
TO GIVE A GRID REFERENCE ON THIS SHEET
Pay no attention to the smaller coordinate figures at the corners
and in margins. They are for finding full coordinates. viz.
56581216
PAY ATTENTION TO LARGER MARGINAL FIGURES AND TO
THOSE PRINTED ON THE FACE OF THE MAP VIZ. 110
POINT HRAUNTON
LETTER
East
North
Take west edge or sgvee. in
Tak. $outh edge ofsgaare /n
uA/ch point lies end read the
5
V J
whtch point Ilea and read the
n 1
G
figures printed on CAls //ne;
figuraa piloted on thin lines.
Estimate Tenths eastwards
Estimate tenths northwrds
East
658
North
216
REFERENCE 658216
Unit ........................................metre
Square :_.:......-.._ ....... ................. 1,000
Reference to nearest. ... ........ 100
Near.at similar reference distant -60 miles
Figure 2)4. Grid reference boxes.
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7. Names of adjacent sheets may be shown by printing the names
around the borders of the map or by an index to sheets diagram in the
margin. (See Figure 25.)
Figure 25.
Index to adjoining sheets from French North Africa Series,
1:500,00, G.S.G.s. 11175
8. Graphic or bar scales appear on all maps and enable the user to _
measure distances directly on the map in given units of measure (kilometers-
meters or miles-yards). The scale is divided into units (kilometers or
miles) with a section further divided into smaller units to provide greater
accuracy in measuring distances (See Figure 26 and Section II E.)
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SCALE 1., 50,000
Yards 1000 0 1 2 3 Miles
I , uu1 1 I I
Metres 1000 0
I 2 3 4 $ Kilometres
I I I I I
Yards 1000 sod 0
Metres 1000 500 0
Schaal 1:50 000.
0 t 2 3 4 5 6 7 8 9 10 cm
rrn-rrrrrcrTr-~ _
0 112 1 2 3 4 5 km
Figure 26.
Three Types of Graphic Scales
9. The map publisher is indicated in the margin either by name or
by coded initials. An organization which printed the map may be dif-
ferent from the one which compiled it, and the reputation of the publisher
may give an indication of the map's reliability.
10. Several dates may appear on a map.. the date of information, com-
pilation date, publishing date, printing date, and revision date. One
of these dates will be considered the significant date. Usually it is
the date of information or the revision date.
11. Declination diagrams appear in most map margins to show graphic-
ally the relationships between magnetic north, grid north, and true north.
Different styles may be used but the information is essentially the same.
Figure 27 shows several methods of giving declination information.
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C. - 000 11' 21"E.
A. i
T.N. G.N.
Magnetic Declination from True North
for centre of sheet is 0I?21E. Jan. 1942.
(Annual Variatjon - 04r E.)
MAGNETIC INFORMATION 1941
SHEET N? 36 (CENTRE)
S. E.
MAGNETIC-NORTH 25'4B'W?f GRID NORTH
GRID NORTH 1?53 W. of TRUE NORTH
Annual change in Magnetic North. 13 E.
TI
So it' W.
1941
GN
0011171
Annual change 8'8.
Grid North is 0?39'W.af True North
in centre of sheet
c
z
0
Figure 27.
Declination
6?07
OR
107 MILS
OR
20 MILS
APPROXIMATE MEAN DECLINATION 190
FOR CENTER OF SHEET
NO ANNUAL MAGNETIC CHANGE
Use diagram only to obtain numerical
values. To determine magnetic north line,
connect the pivot point "P" on the south
edge of the map with the value of the
angle between GRID. NORTH and MAG-
NETIC NORTH, as plolled on the degree
scale at the north edge of the maF.
1000'
Magnetic Declination
from Grid North for
center of shAet
Annual Variation 21 Increase)
1942
12. Declination protractors often are printed along the border of the
map to enable accurate plotting of the current grid magnetic angle, as
determined fran the declination diagram. The degree (or grad) scales
shown in figure 28. are used in conjunction with the pivot point (P)
printed on the opposite border of the map. A line should be drawn from
the pivot point to the proper angle shown on the scale.
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APPROXIMATE MEAN DECLINATION 1945
FOR CENTER OF SHEET
ANNUAL MAGNETIC CHANGE 6' WESTERLY
Use diagram only to obtain numerical values.
To determine magnetic north line connect the
pivot point "P" on the south edge of the map
with the value of the angle between GRID
NORTH and MAGNETIC NORTH, as plotted on
the degree scale at the north edge of the map.
(1) Declination protractor oriented on a line of the grid from which
the magnetic angle is given. Protractor is based on the data
shown by the sample declination diagram on the left.
(2) Degree scale of German declination protractor.
8? 70 6? 5? 40
t.. Mt. TO U. S. I W, JEWXP 2 Mt.
346
47'30?/ R
347
(3) Degree scale of United States declination protractok.
Figure 28. Declination protractors.
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13. Some topographic maps contain a diagram showing the percentage
of slope for various contour intervals. This aids in determining the
exact slope of the ground surface as indicated by the contour lines. (See
Figure 29.)
Translation. 1. For levels of contour interval 10 meters.
2. For levels of contour interval 50 meters.
J. For levels of contour interval 100 meters.
Figure 29.
Slope Scale from Russian Map at 1:50,000
14. There are often several information notes in the margin, par-
ticularly on United-States maps, intended to increase the value of the
map to the user. These notes may refer to a variety of subjects.
15. Compilation and reliability diagrams show the sources of
information used in the preparation of various portions of the map
and give an indication of the reliability of each source. These are most
often found on maps published by Unted States agencies (See Figure 30.)
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P-0 Photo-planlmetrlc
I Map
A. Maryland, 1:25,000, AMS, 5662 111 SE,
1946 (photogremmetrlc
compilation, reliability good).
Dates of aerial photography
1.1946, 2-1947.
Figure 30.
Compilation Diagram
16. Hypsometric diagrams are used'on maps at certain scales to aid
in interpreting the relief of the area. These diagrams show the areas of
different elevations. (See Figure 31.)
- 2LIO-260
-220-240
00-220
_180-200
-160-180
-140160
Figure 31.
Hypsometric diagram from Russia series, 1:50,000
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17. To help in locating the political subdivisions of the map area,
an index to boundaries sometimes is included in the margin. This is
particularly helpful when there are several categories of boundaries on
the face of the map. (See Figure 32.)
A. Howard County
B. Anne Arundel County
C. Prince Georges County
Figure 32.
Boundary Index
18. Grid numbers for each grid line usually are located in the
margins of the map immediately outside the body of the map. Only the
large grid numbers are shown for each line, except at the corners of
the map where full grid coordinates are given.
19. If the map contains an indication of the meridians and paral-
lels, their values will be shown around the borders of the map. Sometimes
the border consists of a scale giving the subdivisions of the meridian and
parallel intervals. There may be a scale for both degrees and grads as
shown on the map in Figure 33.
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Figure 33. French hachured map, 1:80,000.
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1
C. RELIEF
Since a map is a plane surface, some type of conventional sign
must be used in order to represent relief and elevation. On most modern
topographic maps, this is accomplished by the use of contours. Relief
is the shape of the surface of the earth. By elevation is meant the
vertical distance of any specified point on the earth's surface above
the reference plane of mean (average) sea level. Some maps use hill and
valley shading to indicate the relief. This system assumes the sun is
shining on one side of the hills and the opposite side is in shadow.
Relief is suggested pictorially so that even an unskilled person can
recognize the hills and valleys. Another method of showing relief is
the use of hachures, which are short lines drawn parallel to the direc-
tion in which the ground slopes at each point. Figure 33 shows a French
hachured map at a scale of 1:80,000. Hachures indicate the direction
water would flow on the ground surface, and the relative steepness of
the slope is shown by increasing the density of the lines on steeper
slopes.
1. Contour Lines. Contour lines are the conventional signs drawn on
a map to sow the 3ferent ground forms. After practice the map reader
can not only visualize shapes of hills, mountains, and valleys, but can
also find elevations of points and determine slope and visibility along
given lines. A contour is a line drawn on a map which represents an
imaginary line on the ground, all points of which are at the same eleva-
tion. For a better understanding of this let us consider the zero contour
line to be sea level. If the sea were to rise ten feet the new shore line
would, be the ten-foot contour line. Similarly, the next higher contour
line would be marked for each rise in elevation of ten feet. Figure 314
shows the successive increases in sea level which indicate contours.
Figure 35 gives an oblique view of this same hill. From directly above,
the hill would appear as in Figure 36. Wiping out the picture of the
hill itself, it would appear on a map as in Figure 37 when indicated by
contours alone. Contour lines are closer together where the slope is
steep, and mountainous areas appear relatively dark on the map. Con-
versely, in the more gently sloping areas the contours appear relatively
farther apart. Where a contour line crosses a stream it must bend upstream
in order to remain at its same elevation, and thus will form a pronounced
''V" pointing upstream. A small closed contour will indicate the top of a
hill. The plane of a contour will always be horizontal and each contour
line will be perpendicular to the direction of running water on that sur-
face. Within the limits of the contour interval, the height of every
point can be read directly from the map, and the angle of slope can be
determined. The elevation of any point that falls on a contour line will
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Figure 40. Map, 1:25,000.
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2. Profiles. A profile is an exaggerated cross-sectional view of a
portion of the earth's surface. Profiles give useful and exact information
concerning the type of terrain, slopes, elevation and visibility. If you
are unable to visualize the character of the terrain from the vertical
view represented by the contours, -a profile view will show the shapes of
the hills from ground level as we are used to viewing them. To construct
a profile along line A - B in Figure 1i, draw -a line between the two points.
O
20
Figure 141.
Construction of a Profile
Then take a piece of ruled paper consisting of equally spaced horizontal
lines, each line to represent the elevation of a contour, and the spaces
between the lines representing the vertical contour interval. The number
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of spaces must be sufficient to accommodate the total number of contour
intervals between the highest and lowest points involved on the profile.
Lines are numbered in sequence, starting at the bottom with the lowest
contour number and ending at the top with the highest contour number.
This piece of paper is placed over the map with its lines parallel to
the profile line A - B previously drawn on the map. From every point on
the map where a contour line crosses the profile line, a perpendicular
is drawn.down and a small tick mark is made on that line on the profile
paper corresponding to the contour line on the map. This method main-
tains the proper horizontal spacing of these points which is essential
to the accuracy of the profile. The tick marks are then connected by a
smooth curve (line a - b in Figure 41 (2)). Profiles normally show the
vertical scale exaggerated in order to emphasize the relief features.
They may be drawn to any desired vertical scale by merely changing the
distance between the parallel lines on the profile paper. To aid in
visualizing the relief as shown by the contours, a hasty profile can be
made by plotting only the high points along the profile line.
3. Visibility. One of the important uses of maps for military pur-
poses isle ermermine whether a point, a route of travel or an area is
visible from a given point or position. The extent of the area visible
affects selection of targets, siting of weapons, and location of defiladed
areas or dead space. Many problems of visibility may be solved by in-
specting the map and determining from the contours the ground slope
represented. This can be done exactly by constructing a profile. Figure
!2 shows the shaded area which is invisible to an observer at point A.
These areas are screened from the observer by the mask at point c and
by the convex slops between a and c. The extent of defiladed or invisible
areas can be accurately determined by constructing several profiles along
lines radiating from the observer's position.
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fl
so
110
O
Lin
e of
, A t
o mask
C
-
~
~
C
e
h
a
gure 4 Figure Ia.
Determination of Visibility by Profile Method
EDGE OF PAPER
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EXERCISE XIV
Construction and Use of Profiles
Refer to the map in Figure 40 for this exercise.
1. Construct a profile along a line between the road junctions
at 820715 and at 822732. Use a vertical scale exaggeration
of ten times by drawing the parallel lines on the profile
paper four millimeters apart.
2. If a man were standing at each of these two road intersections,
would they be able to see each other?
3. Construct a profile along a line between spot height 374 at
812721 and spot height 3112 located at 828739, with a
vertical scale exaggeration of 20 times.
4. Are any points along this profile line not visible from spot
height 374?
5. Are any points along this profile line not visible from spot
height 342?
6. From which end of the profile line is the most terrain along
the line visible?
7. Is any point along the line not visible from either end?
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1. A map is oriented when, in a horizontal position, its north side is
toward the north and all lines of the map are parallel to the corresponding
lines on the ground. A map reader is oriented when he knows his position
on an oriented map and the cardinal directions on the ground. A map will
be of small use in the field unless its possessor can orient himself readily.
It follows that command of the simpler methods of practical orientation is
of prime importance to the map reader.
Figure 43.
Orienting Map by Inspection
2. Approximate orientation of a map can be done by inspection. Figure
43 shows how a map may be oriented by carefully observing the road system
and features in the immediate vicinity. The map has been rotated horizon-
tally until the road on the map parallels the road on the ground. Care must
be used to see that positions of nearby ground features are in similar rela-
tion to their corresponding conventional signs as shown on the map. Any
group of features identifiable both on the map and on the ground can be used
for orientation. If you can identify your position on the map and can see
some distant ground feature also on the map, the map can be oriented by
sighting along the surface of the map from your position to the distant
feature, turning the map until the symbol for the feature falls on your
line of sight. (See Figure 44 .) This is the most practical method for
ordinary purposes and may be used as a rough check on more accurate methods.
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Figure 44.
Orienting Map by Means of Distant Point
3. The most accurate method of orienting a map is by use of a compass.
Orientation is along the, magnetic north line. Determine the magnetic
declination for the current year by referring to the declination diagram.
Somewhere on the map draw a straight line whose north end points toward
magnetic north. This can be done by measuring with a protractor the proper
grid-magnetic angle from a grid line, or the angle for magnetic declination
measured from a meridian. Then place the front and rear sights of the
compass along the magnetic north line with the.front sight toward the
north, and turn the map and compass together until the north pointer of
the compass falls under the fixed index mark. If your map contains a pro-
tractor scale (See Figure 28), draw a straight line from the pivot (P) to
the correct degree (or grad) mark on the scale for magnetic declination
of the present year. This line will be the magnetic north line.
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EXERCISE XV
Map orientation with and without a Compass
1. Using the protractor scale and declination diagram shown
in Figure 28 (1), describe in detail how you could orient your
map with a compass.
2. If you are located at 833756 on the map, Figure 40, and do not
have a compass, how would you orient your map?
3. If your map, Figure 40, did not have a protractor scale but
you had a ;protractor (Figure A-1),, and the map contained
this declination diagram:
* GN
2?1
1?00,
1952
No magnetic
change
how would you draw the magnetic north line for orienting
your map with a compass?
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4. Determining Directions with a Watch. A watch set on local standard
time can a use determine direction. n the north temperate zone
(from 231 degrees to 671 degrees), point the hour hand at the sun. South
is halfway between the hour hand and 12. Directly opposite from south is
north. In the south temperate zone, point 12 on the watch toward the sun.
North is halfway between 12 and the hour hand. (See Figure 45.) This
system usually will not work in the tropics. Reading directions from a
watch can be accurate to within eight degrees.
Figure 45.
Using Watch as Compass Substitute
5. Finding North from the Stars. In the northern hemisphere, the
north direction can bete ne locating the north star (or pole
star). The north star is approximately over the north pole of the earth.
It is the brightest star in its immediate vicinity and is about halfway
between the big dipper and the cluster of bright stare resembling abig M or W. The two stare in the big dipper opposite the handle point
toward the north star which is at a distance about five times the distance
between the pointer stars. (See Figure 46.)
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North star
North pole
Figure 46.
Finding North from the Stars
6. Finding South from the Stars. There is no bright star directly over
the south TTii the southern em sphere four bright stars form the
Southern Cross, which can be used as a guide. The-Southern Cross also re-
sembles the shape of a kite with the long axis pointing toward a point in
the sky directly over the south pole. This point in the sky over the pole
is at a distance 41 times the long axis of the Cross. (See Figure 47.)
1 42
Point over South pole
South pole
Figure 1.7.
Finding South from the Stars
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In map reading, the scale of the map is a first consideration.
The scale is the relation between measurements on the map and actual
distances on the ground. The scale of a map is expressed in one or more
ways.
1. Actual equivalents given in words and figures, as one inch to a
mile, means that one inch on the map equals one mile on the ground;
quarter-inch scale means-that one-fourth inch on the map equals one mile
on the ground. This is a common method for expressing scale on British
maps.
2. The scale of a map may be shown as a representative fraction (RF).
This fraction expresses the ratio between a given distance on a map and
the corresponding distance on the ground. The RF is written either as a
ratio (1:25,000) or as a fraction (1/25,000), which means that one unit
of distance on the map equals 25,000 such units of distance on the ground.
The same kind of units of distance measured from the map must be applied
to distances on the ground. Any unit can be used, including millimeter,
centimeter, inch or foot. The greater the denominator of the fraction,
the smaller the scale--a 1:25,000 map is a large-scale map, and a
1:1,000,000 map is a small-scale map.
3. The graphic scale or bar scale is a means of expressing visually
or graphically the scale of the map. It is divided into parts, each
division being marked not with its actual length but with the distance
each length represents on the ground. Usually there will be one part
graduated into kilometer (or mile) units and fractions of them; this is
known as the primary scale. The other part is graduated in meters (or
yards) for more exact measurements, and is called the extension scale.
Many maps show both the kilometer and mile scales. (See Figure.26.)
a. To find the distance between two points on a map, lay the
straight edge of a piece of paper or other material along a line
between the two points, mark their location on the straight edge by
using short straight marks called "ticks" at right angles to the
edge of the paper. Take the marked straight edge and place it below
the graphic scale in the margin of the map to determine the ground
distance required. Where the distance is greater than the length of
the graphic scale, apply the primary scale one or more times until
the remainder can be measured on the extension scale. Figure 48'
illustrates this method of measurement and shows the houses at A and
B to be 1,000 yards apart.
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1000
Figure 18.
Using Graphic Scale to Measure Distance
1000 YARDS
H
b. To find. the distance along an irregular or curved line on the
map, divide the line into shorter segments, each of which is approxi-
mately straight. Take a straight edged piece of paper, lay it along
the first segment of the line and make a tick mark across the map and
paper. At every curve in the line, make another tick mark, turn the
paper so the edge again lies along the segment in question, and regis-
ter the last tick marks. Contimie this until the distance is completely
measured. The final position of the paper strip is illustrated in
Figure 1.9. The paper strip is then applied to the graphic scale as
in Figure 48, and the ground distance is read.
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EXERCISE XVI
Map Scale
1. Using one of the graphic scales in Figure 26, measure the
distance along the road on the map, Figure 2, between
points 5 and 6.
2. What is the total length of the railroad shown on this map?
3. What is the straight-line distance between the railroad
station at point !t, and point 3?
4. Suppose you have 12 maps at 1:50,000 which provide complete
coverage for your area of operations. How many map sheets
of approximately the same size would it require to depict
this area at 1:25,000?
5. If you are planning routes in and out of an area covering
approximately 400 square kilometers, would the best maps
to use be at the scale of 1:25,000, 1:50,000, 1:250,000 or
1:1,000,000?
6. To determine the greatest amount of detail about an area,
would you consult maps at the scale of 1:1,000,000,
1:250,000, 1:50,000, or 1:25,000?
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1. A map user must constantly refer in some manner to specific
maps. The map title is not an adequate identification of a par-
ticular map, since often there are several maps at different scales
with the same title. An individual map must be clearly and accurately
identified when you order it or refer another person to it. When
citing geographic or military grid coordinates, it is desirable to
identify the map from which they are taken as a double check on
accuracy. When reporting information obtained from a map, the accuracy
of that information is suggested by indicating the map used, and es-
pecially its scale. If a partial tracing or overlay is made from a map,
inclusion of proper map identification gives due credit to the source,
-to which another person can refer for further details.
2. Several kinds of information are necessary in order to identify
a map properly.
a. Title or Sheet Number. If -a map has a sheet number, that
usually s more s gni. scan han the title.
b. Series Name or Number. Identification of a map that is part
of a ser e~ must always contain the name of the series and/or the
series number.
c. Scale. The map scale must always be given.
d. Other Information. In certain instances the date of the map
should be given. For example, when tracing a part of a map on an
overlay, the date or edition should be indicated so that any changes
of map detail on subsequent editions can be understood by the overlay
user. Additional helpful information might be the nationality of the
map publisher. It is best to assume the other person has no knowledge
of the map or your specific project, and to give complete map identi-
fication,
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III. MAP SUBSTITUTES
A map and a map substitute are very similar, although not
identical. Each depicts a portion of the earthts surface, as a line
drawing or pictorially. The map substitute may not be to an exact
scale, but it does have a scale. Many of the properties of a map are
incorporated into map substitutes, and an item used as a map supple-
ment must have certain necessary map characteristics which justify its
use with a map. Although the term map substitute implies that it is
used only when a map is not available, such is not the case. It can
be used instead of a map, as a map substitute, or along with a map, as
a map supplement.
Two types of map substitutes are map overlays or tracings, and
sketch maps. Overlays combine a selective use of map data and additional
information that corrects, completes, or brings up to date data appearing
on the map, Information included on the overlay can serve purposes of
emphasis or reporting. For example, an overlay may include only the
railroad facilities of an area as traced from a map; or the overlay may
show only the new railroad facilities constructed since the map was pub-
lished. In the first instance the overlay would serve as a map substitute
or an incomplete map. In the second case the overlay would supplement
the map and bring it up to date with respect to the railroad information.
Sketch maps are hand-drawn representations of certain features, usually
from a different perspective. While maps show ground features as seen
from above, sketches represent ground features as seen from ground
observation points.
1. An overlay is a transparent or semi-transparent sheet giving
special map information. When the overlay is laid over the map on which
it is based, its details supplement or emphasize certain features of the
map. An overlay is a graphic method of explaining a situation which might
otherwise require many pages of writing. An overlay may be a tracing of
selected portions of the map from which it is copied, it may consist only
of additional details not on the map, or it may be a combination of both
kinds of data. The overlay need not cover the entire map, but may cover
any portion of the map desired.
2. When insufficient quantities of a particular map are available
for an operation, an overlay containing the pertinent map data often will
suffice. If there is access to a map only for a limited time, the informa-
tion of interest can be traced on an overlay for future reference. A map
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can be simplified and made easier to read by preparing an overlay con-
taining only the necessary details for an operation. To revise a map
and bring its information up to date, it is best to make all additions
and corrections on an overlay so as not to add to the congestion of
the map. An overlay is valuable for reporting information which is not
on the map, or in specifically identifying certain map data. The
physical relationship betweenthe data being reported on and nearby fea-
tures appearing on the map can be made clear. It is a simple matter to
add explanatory notes to the overlay, whereas the map may not have suf-
ficient blank spaces for notes.
3. To construct an overlay, place the overlay material on the map
to cover the area to be traced. Fasten the overlay paper securely to
the map along one side so that the two sheets will not move in relation
to each other. Leaving one side free will allow lifting the overlay to
inspect the map more closely while making the tracing. Next draw regis-
ter marks on the overlay paper to enable future orientation of the over-
lay with the map. These register marks should consist of small cross
marks traced over the intersection of vertical and horizontal grid lines,
or-other similar :Lines. There must be at least two such registermarks
located near opposite corners of the overlay, and it is preferable to
have four register marks, one near each corner. The register mark must
include the numbers of the grid lines or other exact identification of
the features represented. Before drawing any detail on the overlay,
record the correct identification of the map (see II F) so that another
person would have no difficulty knowing the map to which the overlay
applies. This identification is placed in the margin of the overlay
and includes the map title or sheet number, map series name or number,
scale of the map, the edition number or date of the map if appropriate,
and date of the overlay. Only after the above is completed should detail
be traced or drawn on the overlay.
4.' The amount of information included on an overlay should be the
least amount that will accomplish the desired purpose. Too much detail
clutters the overlay and tends to destroy its value. -However, all
pertinent data should be includedto provide adequate orientation for
any new details added and to make the overlay understandable without
always placing it over the map. Figure 51 illustrates an overlay.
EXERCISE XVII
Overlays
Construct an overlay of the map in Figure b, indicating proper map
identification, register ticks, and showing areas of forest and the major
drainage lines. Refer to the legend in Figure 20 for identification of
the symbols.
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10 July 1957
To Madras
37 kilometers
New alignment of railway
completed June 1957.
STATINTL
142
/ This portion of
I old track has
been removed.
Old RR station
converted to
warehouse.
Figure 51.
A typical map overlay for reporting information.
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1. The military sketch or hasty sketch map will not be discussed in
detail because usually it requires specially trained map-making personnel
and special materials such as aerial photographs and surveying equipment.
It is the term applied to military maps made in the field by military
units under emergency conditions when no adequate maps exist. A panoramic
sketch is a pictorial representation of terrain as seen from one point of
observation. This observation point is on the ground and shows the area
Figure 52.
Comparison of Panoramic and Military Sketches
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in the manner in which we are accustomed to viewing it. it includes the
horizon and intervening features such as topographic crests, roads, houses,
woods, and fences. Its great value lies in the rapidity with which it can
be made and read. A trained panoramic sketcher can prepare in a few minutes
a sketch which conveys information of value requiring little time or training
to interpret. A comparison of the manner in which the same piece of terrain
is depicted by a panoramic sketch and by a topographic map is shown in
Figure 52.
2. The principles of a panoramic sketch apply both to distant views
and to nearby objects which are sketched. These are the principles of
perspective drawing. The horizon line is the line formed by the inter-
section with the ground of a horizontal plane at the height of the sketcher's
eye. In level country and over water, the horizon line is coincident with
the sky line. In rolling country the horizon line usually is a little
below the lowest point in the sky line. Lines which are actually parallel
on the ground appear to converge as they recede from the viewer and appear
to meet or vanish at a point called the vanishing point of that system of
parallel lines. The correct effects of distance, direction, and slopes
which are commonly attributed to the artist's inspiration are in reality
at the command of amyone who will apply the following rules:
a. Parallel lines, which on the ground are horizontal, converge
and vanish at a point on the horizon. (See Figure 53.)
Figure 53.
Vanishing Point
b. Parallel lines which on the ground slope downward away from
the observer, vanish at a point below the horizon. (See Figure 54 (1).)
c. Parallel lines which on the ground slope upward away from the
observer, vanish at a paint above the horizon. (See Figure 54 (2).)
d. Parallel lines receding to the right vanish to the ri ht;
those receding to the left vanish to the left. (See Figure 5 (3).)
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O
Figure 54.
Various Types of Vanishing Points
e. Parallel lines nearly parallel to the observerts line of
sight appear to converge very rapidly while those at right angles
to the line of sight appear to remain parallel. Vertical lines on
the terrain remain vertical in perspective.
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f. The apparent size of any object decreases in proportion to
its increased distance from the observer.
g. The apparent distances between regularly spaced objects de-
crease in proportion to their increased distances from the observer.
(See Figure 55 (2) E.)
0
0 0 0 00 0
oll
VANISHING A
POINT
HORIZON 1
i - -- ---
J RIGHT SIDE
t OF ROAD
B
E
C
F
A All
Figure S.
Steps in Preparing a Panoramic Sketch of a Road
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3. The successive steps in the perspective drawing of a section of
flat terrain containing a road lined with trees approximately the same
height, are shown in Figure 55 (2). The sketcher is facing north. By rule
.a, the road stretches extending north will have a common vanishing point
in the horizon; and by rule -e-the sides of the road extending north will
converge very rapidly. Also by rule e, thesides of the road extending
eastremain parallel in perspective and the trees remain vertical. The
relative sizes of the trees and the relative distances between them are
governed by rules f and g.
4. Delineation is the portrayal of objects or features of the land-
scape as they appear to the observer. Absolute simplicity is essential
in a panoramic sketch. No line should be drawn without a definite idea
as to what it is to represent and as to the necessity therefor. The
sky line, topographic crests, and roads are the main control lines of
Figure 56.
Delineation showing the order in which a sketch is built up.
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the sketch and should be drawn in first to form a framework on which the
details are properly placed. Figure 56 shows how features should be
represented with a few, rather than many lines. Preferably a conventional
outline should be employed. This increases both speed and clearness and
leaves room for the addition of important details without overcrowding
the sketch. The effect of distance may be increased by making the lines
in the foreground heavy and distant hills very light. Full lines are
better than broken ones. Important details in the distance may be drawn
heavily or enlarged for emphasis. A light crosshatch or shading may be
employed to distinguish wooded areas from open fields when necessary.
When consecutive tree groups are partially superimposed, alternate groups
should be shaded. Crosshatching should follow the natural lines of an
object, such as the courses of masonry in a wall. Any attempt to include
artistic values in the sketch usually will prove detrimental.
5. In making a panoramic sketch, follow these steps in order:
a. Preliminary study of the terrain. - Before commencing a sketch,
the observer should carefully study the landscape so that he may dis-
tinguish the various topographic crest lines in their proper relation
to each other and to the larger features of the terrain. If a map is
available, it should be studied in conjunction with the terrain.
b. Adoption of a scale. - A suitable scale for panoramic sketches
is two centimeters on the sketch equals three degrees. This scale
should be used for both horizontal and vertical measurements.
c. Selection of reference point and reference line. - Select a
conspicuous and permanent reference point in the sector to be
sketched, preferably one not closer than 500 meters. Draw a vertical
line across the sketch sheet, so positioned that it will pass through
the reference point in the finished sketch. This line then becomes
the reference line for all horizontal measurements in the sketch.
d. Addition of marginal data. - An exact description of the point
from which the sketch is made must be included in the margin. Also
include an indication of the scale, the date and time, and a magnetic
north arrow.
e. Horizontal and vertical control. - Horizontal control is
obtained by measuring the deflection right or left of the vertical
reference line to prominent features that will appear on the sketch.
Consistent measurements to scale can be made by holding the sketch
pad vertically in front of your eyes so that you can just see the
desired feature over the top. For the scale 2 centimeters to 3
degrees, it should be held exactly 38 centimeters from your eyes.
Then, sighting across the edge of the pad, you will find that all
major features appear at scale distance from the reference line.
These features can then be transferred to their proper locations on
the sketch.
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To help determine the correct distance to hold the pad from
your eyes, you can prepare -a string with knots at the correct distance
and hold one end between your teeth, or cut a stick that length and
rest one end of it on your chin. For vertical control it is best to
use the sky line or some horizontal crest as a reference line from
which distances to objects are measured and transferred to the sketch.
It is necessary that this line be drawn in first and as accurately as
possible. It is best to prepare a measuring stick at the scale of
the sketch by marking several five-millimeter intervals on a short
-stick that can be held 38 centimeters from your eyes by the string or
measured stick. When using this scale it is not necessary to hold up
the sketch pad. As skill increases it will be found necessary to
measure the deflections to relatively few points, the others being
interpolated by eye. Sketch in lightly the sky line, crests, roads,
and any other main outlines to form the framework of the sketch. Then
compare these lines carefully with the terrain before adding details.
f. Addition of details. - Details should not be added simply
to fill up space or improve the appearance of the sketch. The amount
of detail will depend largely upon the purpose for which the sketch
is made. Select those details that will increase the value of the
sketch. Label those features on the sketch which require it for
clarity.
6. When sketching nearby objects to which you have access, actual
measurements should be made if possible. Show several views of the
object if that is necessary to make clear its significant features. Apply
the principles of perspective to the drawing and include only those details
which add to the value of the sketch. Label all significant dimensions.
If it is not possible to make direct measurements, dimensions can be
accurately estimated by comparing them with familiar objects which you
can measure. For example, if you are sketching in detail -a building
which you cannot closely approach, use a nearby automobile or railroad
car as a scale to estimate the building's dimensions. If the building
contains standard-sized windows, these can be used as -a scale. Heights
of-objects can be determined by measuring the length of their shadows
at a time of the day when the sun is 45 degrees above the horizon. Use
of the principles of geometry, particularly proportional triangles, will
permit many dimensions to be measured accurately-from a distance.
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o
Figure A-I. Protractor
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!TiiTf ~1rf 1111111111111111111111' 7iTi'1 'TP1TP IITP TT PE
AAAI AIn
0
N yb
1000 2000
3 4 5 6 7 8 9 I 3 4 5 6 7 8 9
Figure A-II. Grid coordinate scale.
-136-
004
0+
y
h
Q~
o
00
0 OO A ~~ I
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Cross section along line A - B on above map.
.Figure 39.
Character of Slopes
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EXERCISE XIII
Contour Interpretation
Refer to the map in Figure 40 regarding the following questions:
1. Is Iha,Fee Creek flowing generally east or west?
2. Does the ground slope upward more rapidly on the north or south
side of Ihagee Creek?
3. What is the elevation of Kite School at grid coordinates 83257527 ?
4. Give the elevation of the buildings at 821727.
5. What is the elevation of the small closed contour at 823752 ?
6. Draw a line between the stream junction at 824742 and the
building at 820739. Is the slope along this line convex or
concave?
7. Draw a line from the trail on the top of the ridge at 842750 to
the stream junction at 849744. Is the slope along this line
uniform?
8. Draw a line from the stream junction at 811729 to the :road
junction at 811735. Is the slope along this line convex
or concave?
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811k000200110001-4
Figure 49.
Measuring Distance Along a Winding Road
4. The scale at which a map is printed is significant for several
reasons. Figure 50 shows the relation between distances and areas on
maps at three different scales. A smaller scale map (1:20,000) is able
to depict a larger area of ground surface on the same size map sheet.
The distance between givers features appears four times as great at a
scale of 1:5,000 as it does at 1:20,000. This makes it possible to
include a greater amount of detail at the larger scales. Note in Figure
50 that the map at 1:5,000 includes more contours than the 1:20,000 map,
and also shows fences that cannot be drawn at the smaller scale. As the
scale becomes smaller, the accuracy of detail cannot be as great. It is
not possible to draw as many features to true scale, and symbols such as
houses and roads appear to cover more area than they actually do on the
ground. Tactical situations usually require use of large-scale maps so
that all pertinent features may be shown and detail may be accurate as
possible. Since large-scale maps depict a smaller area of the ground, more
large-scale map sheets are required to cover a given area than would be
necessary at a smaller scale. If operations range over a wide.area the
large quantity of maps required becomes a problem.
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Figure 50. Relation between distances and areas
on maps of different scale. (Scales of maps have
been reduced in printing.)
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Figure 37. Hill shown by contours.
ILLEGIB
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be the same as that of the contour. If a point falls between two con-
tours, its elevation will be proportional to its distance from the lower
to the higher line. For example, in Figure 38, point A is one-fourth
the distance from line 60 to line 80, so its elevation is approximately
65. The elevation of point B is about 33.
Figure 38.
Elevation of Points
If contour lines appear closer together near the top of a slope
and wider apart lower on the slope, the slope is concave and the bottom
would be visible from the top. If the contours are farther apart near
the top of a slope and closer toward the bottom, it is a convex slope
and the bottom probably would not be visible from the top. This is
illustrated in Figure 39. Contours that appear to be uniformly spaced
indicate a uniform slope. If the contours appear irregularly spaced, the
slope is not uniform but undulating.
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COORDINATE SCALES
Accurate and rapid readings of military grid coordinates can be
made by using a coordinate scale, two types of which are shown in Figure
A-III. These scales may be made of paper, metal, or plastic. The co-
ordinate scale must be designed for the scale of the map you are using,
e.g., 1:25,000, 1:50,000, etc. The L-shape type is easier to use but the
rectangular type is easy to construct by taking a rectangular piece of
paper and marking off the subdivisions along two of its edges from the
graphic scale on the map.
93 2bj-------- 600
9
O 600
4-
3-
2-
I I0099 TI 430 L
--9
1000 s TI s00 2 1 0
it
O
II
Figure A-III
Locating Points with Coordinate Scales
To read the coordinates of point P in Figure A-III, first identify
the square in which P lies and write the coordinates of the lower left
(southwest) corner of the square thus (65 91 ). Now place the coordinate
scale with its horizontal (east-west) edge once 91 grid line. Keeping
this edge on the 91 grid line, slide the scale along until its north-south
scale passes through the point P. The additional portion of the easting
coordinate is read on the horizontal (east-west) scale, where it is out by
the west boundary of the square (in this case the 65 grid line). The addi-
tional portion of the northing coordinate is read on the vertical (north-
south) scale, at the point P. These readings are then filled in at the
proper places after the coordinates already written down. Reading to the
nearest 100 meters, the coordinates of P are 657916. Reading to the nearest
10 meters, the coordinates are 65689162. The coordinates of K are 65259248.
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Solutions to the Exercises
1. C. 210975
d. 233980
e. 217992
f. 196982
Exercise II: 1. 271830
2. 241808
3. 276811
4. 255831
5. 296849
Exercise III: 1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
N 100 231 30"
N 10 0 281 00""
N 100 161 00""
N 100 031 501"
N 10? 151 24""
Lap Vo
Thanh Phu
Hoi An Dong
Vinh Thanh
Ap Long Dinh
6. 235805
7. 2-34792
8. 254806
9. 277784
10. 239842
E 1050 42, 00""
E 105? 421 28""
E-1050 321 18"
E 105? 34, 06""
E 105? 351 36"
Exercise IV: 1. N 23G,48\ 70Ny E 114G, 62~ 50'~
2: N 23G, 45" 2O' E 114G, 66 25
3. N 23G, 39\ 25` E 114G 70' 00"
Exercise V: 1. N 110 001 43.212" E 95?311 35.868"
2. N 42? 451 32.4" W 000 581 23.2392"
3. S 3? 281 39.400824" W 59? 34, 15.925944"
4. N 48G 05~ 55.55+ - E 18G 87; 03.33+?
5. S 17G 19' 84.5679" E 139G " 55.55+
6. N 94G 701 28.11728395" E 198 62` 96.296+
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Exercise VI: 1. N 8? 13' E 43? 07'
2. N 38? 06' 27" E 27? 59t 07"
3. N 62? 14' 2311 E 1030 171 03"
4. S 22? 141 38" W 42? 00' 26"
5. S 90 47' 011.ft E 126? 00' 13"
6. N 400 16' 00" E 21? 31' 59"
7. N 32? 141 38" W 2? 06' 22"
8. N 18? 06' 30.744" E 108? 42' 46.1241'
9. N 14? 01' 53.868" W 100 26' 42.424"
10. N 390 59t 48.84o" E 42? 09' 50.036"
Exercise IX: 1. Magnetic declination - 30 55' west of true north
Grid declination - 2? 00' east of true north
2. Magnetic declination = 2? 08' west of true north
Grid declination - 30 101 west of true north
3. 2? 07'
4. 1? 311
5. 3G. 991
6. 4? 04'
Exercise X: 1. 00 and 3600
2. 900
3. 1800
4. 270?
5. 1800
6. 2700
7. 0? and 360?
8. 90o
9 243?
10. 245G
11. 81?
12. 189G
13: 3'
14. 630 45'
15. 303G.96
Exercise XI: 1. 38200218
2. 39750243
Exercise XII: 1. 82627288
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Exercise XIIIit
1.
East
5.
420
2.
South
6.
Comex
3.
4l0
7.
No
4.
Approximately 325
8.
Concave
370
360
350
340
330
320
310
300
290
280
822732
3,.
374
380
370
360
35C
340
330
320
310
300
290
342
4. Yes
5. Yes
6. Spot height 374
7. Yes
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1. a. Refer to the declination diagram and determine the
magnetic declination for 1959 to be 25?511 (subtract
an additional 61 for each year beyond 1959).
b. Draw a straight line from the pivot (P) point to 25?-5i1
on the protractor scale.
c. Lay the compass on the map so the front and rear sights
fall directly over this magnetic north line, with the
front sight toward the north,
d. Rotate the map and compass together until the north
pointer falls directly under the fixed index mark. The
map is then correctly oriented.
2. By inspection. I would face up the road toward Kite school
and rotate the map horizontally until the school appeared
forward of my position and the road on the map appeared
parallel to the road ahead of me. Then the buildings and
side road would appear to my left and the fence line per-
pendicular to the main road would run off to my left rear.
If all these features appeared in their proper relationship
to each other, the map would be oriented correctly.
3. From the declination diagram I would determine that magnetic
north is 3? 151 west of grid north. Using the protractor
(Figure A-I) I would lay off to the left of one of the north-
south grid lines an angle of 30 1i5' and draw this magnetic
north line slightly longer than my compass.
1. 7.53 kilometers or 11.68 miles
2. 13.1 kilometers or 8.12 miles
3. 2.85 kilometers or 1.76 miles
4. !t8 sheets
5. 1:250,000
6. 1:25,000
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 ~l .
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