On the trail you can come across many obstacles that you need to cross to get to the other side ... and safety and possible rescue. Maybe you need to cross a river or a chasm by laying a tree trunk across. You might need to throw a line across a white water section to enable the crossing. How can you tell what the width of the river or chasm is? It is for times like these that your days in school and what you learnt in geometry class will come in handy.
Stand at the edge of the chasm and mark the spot “A”. Visually select a point across the chasm and mark it “B”. Now walk at right angles to this imaginary line. After walking a few steps, maybe a hundred, mark this spot “C”. Continue in that same straight line for an equal number of steps to a point and mark it “D”. From point “D” walk away from the chasm at right angles to the line formed by points “A”, “C” and “D”. Walk for a few steps till such time as the place where you are, point “C” and point “B” across the chasm are in a straight line. Mark this point “E”.
The distance between points “D” and “E” is the distance between points “A” and “B”, the width of the river or gorge or chasm in front of you.
You can use the brim of your cap to estimate the distance across the depression. Stand facing the direction of the river or ravine or gorge you are trying to judge the width of. Place your chin against your chest. Without raising your head, raise your eyes and adjust the camp brim to align with the edge of the other bank. Once you have that, without lifting your head, turn around, look at solid ground ahead of you and mark the point where the cap brim meets the ground. Mark this point. Using pace count, measure the distance from where you are to this second marker. This is also the distance between the two banks.