Page 73 - Geography_n_Environment

(i) Stretch the thread and lay it along the linear scale with
the first knot on zero (0) and the second knot on the right
side of the scale;

(ii) if the second knot aligns with a certain number on the linear
scale, that number represents the real ground distance
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between the two points;

(iii) if the second knot is between two numbers, record the
left number and mark its position on the string, as shown
in red in Figure 15. For example, the left number recorded
in Figure 15 is 1 km. Then, move the thread to the left until

the second knot aligned with zero (0) and the marked point
is on the left side of the scale; and

(iv) finally, record the number at the linear scale close to
where a string red mark anded. For example, 500 metres
is recorded as shown in Figure 15. Therefore, the ground

distance between points A and B is 1 km and 500 metres.

1000 (1)
Metre 500 0 1 2 3 Kilometre

(3) (2)
1000 500
Metre 0 1 2 3 Kilometre

Figure 15: Converting map distance measured by thread into the ground
distance

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