440 yards = 15,840 inches
15,840 ÷ 220 = 72, or his stride in inches
then 880 strides = 1 mile or 6" on the scale.
It is better to have a scale of 1,000 strides which is easily done by the proportion:
1,000 sts. : 880 sts. :: x : 6
x = 6.8
now draw a line 6.8 inches long and a diagonal line from it; divide this diagonal line into 10 equal parts for each 100 paces at any convenient scale and draw a line from the end of the tenth part to the end of the 6.8 inches line; draw lines parallel to this line from each of the divisions. The 6.8" line is then divided into 10 equal parts; each of these parts may be divided in the same manner into tenths.
Your scale is ready to be pasted or transferred to the alidade and each 6.8. inches on the map will equal 1,000 of your strides on the ground, or about 1-1/12 miles (2,000 yards).
There are two general classes of sketches:
1. Road Sketch.—A traverse (passing over) made along a definite rout showing all features of military importance for a distance of 200 or 300 yards on each side of the road. A road sketch is always made on a scale of 3 inches to 1 mile.