(5) Draw the details of the country between A and B and in the vicinity of this line, using the conventional signs for roads, houses, etc.
(6) The lines from station (b), [Fig. 1], X, to any of the other located points may now be used as a new base line to carry the work over additional area.
(7) In case parts of the area are not visible from a base line, these parts are located by traversing as before explained.
(8) Having learned by several repetitions the above steps, the sketcher will then combine contouring with his horizontal locations.
[1890]. Outpost sketching. The same instruments are used as in position sketching, and so are the methods the same, except that the sketcher cannot advance beyond the outpost line, toward the supposed position of the enemy. It is often possible to select a measurable base line well in rear of the line of observation,—for instance, along the line of resistance. Secondary base lines may then be taken on or near the line of observation, from the extremities of which additional base lines may be selected, if necessary, and points toward the enemy's position located by intersection. Details are sketched in as in position sketching. For obvious reasons, no traversing should be done along the line of observation.
[1891]. Road sketching. The following are the instruments used in road sketching:
- Drawing board or sketching case;
- Loose ruler;
- Scale of strides, or paces, if made dismounted; scale of time trotting or walking, if mounted;
- Scale of hundreds of yards, at three inches to 1 mile;
- Scale of M. D.'s;
- Slope board (if clinometer is not available).
Methods to be used
(1) At station 1, [Fig. 10], orient the board as described in [par. 1872], holding the board in the hands, in front of the body of the sketcher, who faces toward station 2.