6 Surveying, as usually practiced, is imperfect to the extent that two
surveys begun at the same point and following the same field notes would
not likely follow the same exact path for any great distance unless there
were recognizable landmarks--stakes, rocks, witness trees, etc.--against
which to check the course. The fact that surveying is done on the earth,
which is spherical, and platted on maps, which are flat, further compli-
cates one's difficulties in following, on maps, a route surveyed on the earth.
