By means of a pocket watch it is possible to determine on a sunny day with sufficient accuracy for practical purposes the four directions of the world on the horizon, i.e.. north direction, noon, east and west. The method is so simple and easy to understand, that you should be surprised, that it has not yet found widespread use.
The determination of the direction consists in the following manipulation:
Hold the pocket watch in your hand and turn it like this, so that the hour hand points towards the sun; then the point lying on the circumference of the circle in the middle between the hour hand and the number XII will give us the direction of the south.
So for example, if the hour hand shows IV (as in our drawing), we shall find this by directing this clue towards the sun, that the middle dot between the indicated hour IV and the number XII, that is, a dot representing hour II, will determine the direction of the south. It will be north in the opposite direction, left - east, to the right - west.
The previous rule can be modified as follows: find the midpoint between the hours on the perimeter of the dial, which the girl shows (hourly) tip, and a dot above the number XII - and direct this central dot towards the sun; then 12 o'clock will indicate the direction of noon.
E.g, if the watch shows IV, then the scale above 2 o'clock should be directed towards the Sun. Then a line drawn from the center of the watch to the number XII will point south.
To confirm the above, it is enough to recall, that at 12 noon the sun, the hour hand and the graduation above XII are on a single line facing south. Then and the sun, and the hour hand move in the same direction, but the hour hand will make one full turn w 12 hours, and the sun in 24 hours, that is, twice as long. This is what the above rules are based on.
Should be added, that in the morning one should look for the midpoint between the hand and 12 o'clock in the direction of the hand rotation, in the afternoon, in the opposite direction.
Caution. Of course, the direction found in this way will not be exact. The defect is caused by this, that we place the watch in a horizontal plane instead of in the plane of the celestial equator. It does not take into account the difference between the true solar time and the statutory time, according to which the clocks go (it is Central European time for us). But for practical purposes, the above rule gives quite satisfactory results.
If the reader of this book is in the southern hemisphere, these rules must be amended as follows:
When the point marked on the face of the watch above the hour hand we point towards the sun, then the line bisecting the angle between the hour hand and the dot above the number XII will mark the north direction.