True Meridian
Fig. 17
[1873]. The position of the true meridian may be found as follows ([Fig. 17]): Point the hour hand of a watch toward the sun; the line joining the pivot and the point midway between the hour hand and XII on the dial, will point toward the south; that is to say, if the observer stands so as to face the sun and the XII on the dial, he will be looking south. To point the hour hand exactly at the sun, stick a pin as at (a) [Fig. 17] and bring the hour hand into the shadow. At night, a line drawn toward the north star from the observer's position is approximately a true meridian.
Fig. 18
The line joining the "pointers" of the Great Bear or Dipper, prolonged about five times its length passes nearly through the North Star, which can be recognized by its brilliancy.
[1874]. Conventional Signs. In order that the person using a map may be able to tell what are roads, houses, woods, etc., each of these features are represented by particular signs, called conventional signs. In other words, conventional signs are certain marks or symbols shown on a map to designate physical features of the terrain. (See diagram, [Par. 1875] [Plate I] and [II].) On the [Elementary Map] the conventional signs are all labeled with the name of what they represent. By examining this map the student can quickly learn to distinguish the conventional signs of most of the ordinary features shown on maps. These conventional signs are usually graphical representations of the ground features they represent, and, therefore, can usually be recognized without explanation.
For example, the roads on the [Elementary Map] can be easily distinguished. They are represented by parallel lines (======). The student should be able to trace out the route of the Valley Pike, the Chester Pike, the County Road, and the direct road from Salem to Boling.