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Length of a Building
This is your scale drawing of the
base line which you have paced out (e.g.
50 foot).
Scale 1" = 10' (One inch equals 10 feet)
Place markers (say 50 feet apart). This is your base line. Make a scale drawing of it (5"). At points A and B on the sketch draw in the North point bearing. Take bearings from North at A for each of the church at X and Y. Take bearings of X and Y at B. Mark in these bearings on your sketch using a protractor. Join up line X. and Y between the two points where the lines cross.... If the line X Y measures 2" then the church is 20 feet long.
Personal Measurements
It is important to know your own personal measurements. It also can help to find a measurement on yourself that is exactly one centimeter (maybe a fingernail width), then also find a 10 cm and a 1 meter measurement.
Remember that Scouts' bodies are still growing so personal measurements should be checked an a regular basis.
Here are some more ways of making fairly close estimates of height and distance. You'll be making practical use of some of the basic geometry learned in school.
Pencil Method
Have a friend whose height you know stand against the object for which you want to find the height. Now follow these steps:
1. Hold a pencil or short stick at arm's length, and sight across top of it to the top of your friend's head.
2. Move your thumb down on the pencil until you sight across it to your friend's feet.
3. Raise your arm until your line of sight over your thumb hits the top of you friends head.
4. Note where your line of vision across the top of the pencil cuts object to be measured.
5. Move your arm up again and repeat step 4.
6. Keep repeating steps 4 and 5, counting as you go up, until you reach the top of the object.
How many sightings did you take, including the first one friend? That is the number of times higher the cliff is than the height your friend. Multiply that number by your friend's height to find the height of the object.
Height by Shadow
You might try guessing the height of a tree by using shadow.
1. Get a stick of known length and notch it in meters and centimeter
2. Stand the stick upright in the sun and measure the length of the shadow.
3. Measure the length of the shadow cast by the tree.
4. Multiply the stick length by the length of the tree's shadow.
5 Divide by the length of the shadow cast by the stick. The result is the height of the tree. Here is the formula: Tree height = Stick length x tree shadow
1 Stick shadow or Tux ss [?]
For example, if the stick's length is 2 m, the tree's shadow is 20m long, and the stick's shadow is 5m long:
2 x 20/5 = 40/5 = 8 so the tree is 8 meters high
Line of Sight and a Measured Stick
Here is another method you can use to measure a tree or building:
1. Measure along the ground from the base of the building out far enough so you can sight the top of the building from ground level at a comfortable angle.
2 Mark this distance off in nine units of equal length say, nine measured stick lengths.
3. Nine stick lengths out from the building, stand your stick upright and have a friend hold it.
4. Measure off one more unit past the stick.
5. Put your head to the ground and, getting your eye as close to the ground as possible, sight the top of the building.
6. Where your sighting line cuts the stick, have your friend make a mark.
7. Measure the number of centimeters front that mark to the ground. This will closely equal the height of the building in meters This works out to the formula below:
Estimating the Width of a River
Here is a handy estimating method for Golfers and for groups setting out to erect pioneering structures.
1: Pick out a point across the river, such as a tree (A).
2. Drive a stake (B) into the ground on your side of the river, in line with the tree.
3. Walking parallel to the river bank, make a baseline of any convenient length, say 40 m.
4. Drive a stake (C) into the ground.
5. Continue along the bank in the same direction for half the first distance you measured (20 m).
6. Mark the spot D.
7. Make a 90° turn (your back to the river) and walk inland until you can sight your first stake C in a line with the tree across the river.
8. Mark the spot E.
9. Measure the distance between the stakes D and E.
10. Double this distance and you will come close to the actual width providing, of course, the sighting, measurements and angles are correct.
Judging Distance
Learn the exact length of your pace. Try to learn to pace an exact 3 meters distance with five of your paces (if you do this one kilometer will equal 1665 paces).
Remember things can appear nearer or further than they really are depending on how clearly you can see the outline. Also, if there is water between you and an object, the distance can be deceptive.
1. Objects seem further away:
(a) When they are in the shade,
(b) Across a valley,
(c) When they are the same color as the background,
(d) In a heat haze,
(e) When you are lying down or kneeling.
2. Objects seem closer:
(a) With the sun behind you,
(b) In very clear air,
(c) When a different color from the background,
(d) When the ground is fiat (or snow covered),
(e) When it is larger than other objects nearby,
(f) When you are looking across water, or a deep valley.
3. Visible objects seen nearer at night than during the day.
Remember they eye measures distance "as the crow flies', and does not allow for uneven terrain. In other words actual distance may be greater than visual distance.
Examples
 | At 700 meters a man looks like a post. |
| At 650 meters the head is not yet visible. |
| At 550 meters the head is visible as a dot. |
| At 450 meters he appears bottle shaped. |
| At 350 meters movement of the legs can be seen. |
| At 250 meters the face can be seen. |
| At 200 meters details of clothing are recognizable. |
| At 100 meters eyes and mouth can be seen clearly. |
See Also:
Estimation for Scouts
White Man's Woodcraft
Traditional
Training Handbook
©2003 Baden-Powell Scouts Association
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