Global Positioning System Reference
In-Depth Information
CHAPTER THREE
Surveying
We have seen the results of geodetic surveys. Now we get down to basics and
see how surveys are done on the ground (or the oceans) by examining the
tools of the trade and describing how these tools and the science of surveying
evolved from peg and rope to GPS.
The First Surveying Instruments
Surveying has accompanied activities such as farming and empire-building
since the dawn of history. Farmers needed to know where their land joined
a neighbor's; conquerors needed to inventory the assets that they had
acquired. Consequently, surveying tools have been around for a very long
time. Later and more sophisticated tools are developments of earlier, sim-
pler ones, as you will see. Here, I survey the development of surveying
tools.
1
PEG AND ROPE
The ancient Egyptians of about 3000 BCE used ropes attached to pegs
to lay out land. Recent research suggests that Stonehenge (constructed
around 2500 BCE) was also laid out with peg and rope technology. Given
the cultural and geographical distance between the ancient Egyptians and
the mysterious people who built Stonehenge, it seems likely that the peg
and rope idea was widespread in Europe by the third millennium BCE.
Applying a length of rope attached to a peg suggests strongly an apprecia-
tion of plane geometry because it is equivalent to the compass-and-ruler
type of geometrical construction that I (and millions of others who exceed
1. For early surveying instruments, see, e.g., Lewis (2001).
