Every scout must be able to judge distance from an inch up to a mile and more. You ought, first of all, to know exactly what is the span of your hand and the breadth of your thumb, and the length from your elbow to your wrist, and the length from one hand to the other with your arms stretched out to either side, and also the length of your feet; if you remember these accurately they are a great help to you in measuring things. Also it is useful to cut notches on your staff, showing such measurements as one inch, six inches, one foot, and one yard. These you can measure off with a tape measure before you use your staff, and they may come in very useful.
Judging the distance of objects from you is only gained by practice, and judging the distance of a journey is generally estimated by seeing how long you have been travelling, and at what rate; that is to say, supposing you walk at the rate of four miles an hour, if you have been walking for an hour and a half you know that you have done about six miles.
Distance can also be judged by sound; that is to say, if you see a gun fired in the distance, and you count the number of seconds between the flash and the sound of the explosion reaching you, you will be able to tell how far off you are from the gun.
Sound travels at the rate of 365 feet in a second; that is, as many feet as there are days in the year.
A scout must also be able to estimate heights, from a few inches up to two or three thousand feet or more; that is to say, he ought to be able to judge the height of a fence, the depth of a ditch, or the height of an embankment, of a house, tree, of a tower, or hill, or mountain. It is easy to do when once you have practised it for a few times, but it is very difficult to teach it by book.
You must also know how to estimate weights, from a letter of an ounce, or a fish, or a potato of one pound, or a sack of bran, or a cartload of coals; and also the probable weight of a man from his appearance—these, again, are only learnt by practice, but as a scout you should take care to learn them for yourself.
Also you should be able to judge of numbers; that is to say, you should be able to tell at a glance about how many people are in a group, or on a 'bus, or in a big crowd, how many sheep in a flock, how many marbles on a tray, and so on. These you can practise for yourself at all times in the street or field.
In the German Army instructions for judging distance are given as follows:
At fifty yards, mouth and eyes of the enemy can be clearly seen.
At 100 yards, eyes appear as dots; 200 yards, buttons and details of uniform can still be seen. At 300 yards, face can be seen; at 400 yards, the movement of the legs can be seen; at 500 yards the colour of the uniform can be seen.