Just a Few Weeks After George Washington's Sixteenth Birthday, in 1748, Lord Fairfax, Owner of a Large Estate in Virginia, Took Him into His Employ as a Surveyor
Besides the plane table itself and a sheet of paper, only a small carpenter's level, a tape to measure a few distances with, and some spikes for markers, a hard lead pencil, a ruler, and a few needles are absolutely necessary for this sort of a map.
Three Stations are Used for Setting the Plane Table in Succession to Locate the Various Objects
TABLE AT STA. A - TABLE AT STA. B - TABLE AT STA. C
To start a plane-table map, a station must first be selected from which as many as possible of the objects to be located on the finished map can be seen. Ordinarily, the objects one would locate are corners of buildings, fence corners, intersections of roads, corners of lots, banks of streams, possibly trees, and section and quarter-section corners in the country. A railroad, a lake, a mountain, or anything which forms a noticeable landmark in any particular locality, ought to be on the map. In mapping a territory which has never been surveyed before, the first surveyor may name the hills and streams.
After the first station has been selected, it is marked by a pile of stones, a stake, or, if precise work is to be done, a tack in the top of a stake. The table is then set up over this station point and leveled so that the surface of the paper will be truly horizontal. Generally, too, the board is "oriented," that is, placed so that two of its edges point north and south and two east and west. It is then clamped so that it will not move while working on it.
To begin the map, a point on the table is chosen to represent the station on the ground over which the table is set. This point is marked by sticking a fine needle into the paper, vertically. A small triangle should be drawn around the needle hole in the paper and labeled "Sta. A," so that it will not be lost in the maze of points which will soon cover the sheet. By sighting past this needle toward some object which is wanted on the map, like the corner of a house, its direction can be marked by setting another needle on the far side of the table, in line with the first and the given object. Then, if a ruler or straightedge be placed against these two needles and a fine line drawn connecting them, this line will show the exact direction of the object from Sta. A. All the other objects which are wanted on the finished map and can be seen from Sta. A are located by direction in the same way.
The first points to have their direction thus marked ought to be the next stations to be occupied. If all the objects to be located can be seen from three stations, or even two of three stations, three stations will be sufficient. The distance to one of them from Sta. A should be carefully measured and laid off to scale along its direction line on the map. Its place on the map should be marked exactly as the first station was, substituting B for A. It is wise, after every few sights at other objects, to take a sight along the line AB to make sure that the board has not turned. A good map is impossible if the board twists.
To measure the distance between stations, a 50 or 100-ft. tape, or some accurate substitute, is necessary. An ordinary piece of iron telegraph wire, 105 ft. long, is a good substitute. A point, about 2-1/2 ft. from one end, is marked with a little lump of solder. A chisel dent in this solder will mark one end of the 100-ft. section. Then, with a borrowed tape or a good rule, measure off and mark every 10 ft., just as the first point was marked, until the entire 100 ft. have been laid off. The last 10 ft. should be divided into feet. In all this measuring and marking, the wire must be stretched out taut and straight. The extra 2-1/2 ft. at each end are used for making handles. By estimating the tenths of a foot, measurements can be made with such a tape, or "chain," as an old-time surveyor might call it, just as accurately as they can be laid off on the map.