Land Surveyor Forum

It seems to be appropriate in our discussions of "What is Your Position" to write a "Brief History of Position Fixing".  This is a very interesting subject (to me, at least) and I hope it will inspire more discussion.

"A  BRIEF  HISTORY  OF  POSITION  FIXING"

The first known attempt at position fixing began as an exercise in map making. Claudius Ptolemy  (c AD90 - c AD 168), a Greek-Roman Astronomer, Geographer and Mathematician created a grid system superimposed on a sphere and drew his map on a flat piece of paper. His map, re-created in 1486, shows the continents of Europa, Asia, Affrica, Ethiopa, etc. laid out on a grid system. The map did not include the eastern part of the Asian continent or any of the Americas. It did, however, make it clear that Ptolemy believed the part of the world he was depicting was on a curved surface. His map also made it clear he (a mathematician) thought each part of his map fell within areas laid out by mathematically defined grid lines which were curved lines.

In early mapmaking, the outline of land masses was very inaccurate. Then, like today, the land masses were defined by water boundaries. Most of the shores and rivers shown were from descriptions (verbal and written) from explorers and mariners. Some of the interpretation of the descriptions onto paper was so inaccurate that in the 1400's Africa was still being shown as an island. This type of mapmaking existed in America into the early 19th century!  In the State of Maine Moosehead Lake was drawn on maps without the benefit of a survey connecting it to other areas in Maine. As a result the early maps of Maine all show a different location and configuration of the lake. This happened because the mapmakers were satisfied with being told that the lake was "a big lake 50 miles northwest of here". Today, map collectors pay thousands of dollars for these maps!

In the middle of the 17th century, Rene Descartes (1596-1650) had developed the "Cartesian Coordinate" system, which defined points in both two and three dimensions.  Gerardus Mercator (1512-1594) had published his 1538 map which depicted both North and South America as part of the world. In the early 1600's Joan (John) Blaeu's map "Nova et Accuratissma Totius Serrtarum Orbis Tabula" depicted the World as two spheres with overlaying grids (longitude and latitude) and the equator, all in the same mathematical system we use today (360 degrees around the earth and 90 degrees from pole to equator).

As the America's began to be explored and settled the need for more accurate position for mariners became a necessity. Mariners were sailing from Europe to the eastern coastline of the America's and finding harbors and land which were suitable for settling. However,  the instruments they used (astrolabes, backstaffs, quadrants, octants and sextants) were highly inaccurate and only assisted in determining latitude. Making the same landfall twice was nearly impossible. An example of this inability was when the Popham Colony in Maine was settled in 1607. The inability of a ship's master to find the colony a second time and resupply it doomed it to failure; it lasted for only one year!

The mapping of the American Coast suffered from the same inaccurate measurements of position. In the early 1600's, Captain John Smith said of these maps "I have had six or seven plots of the northern parts, so unlike to each other, and most so differing from any true proportion, or resemblance of the country, as they did me me no more good than so much paper, though they cost me more".

The problem of determining longitude was not solved until John Harrison (1693-1776) built a chronometer in the mid 1700's. The chronometer was accurate within one second per month for a 14 month trial period. By the end of the 18th century, chronometer makers were able to consistently produce chronometers in the quantity and accuracy needed to solve longitude problems for mariners. By this time, America had been a group of British Colonies for 163 years and the United States of America was 17 years old. At that time there had been 180 years of boundary surveying in America and none of it had been done by position fixing.

In the early 1800's Thomas Jefferson was instrumental in the formation of the Coast Survey. The survey created triangulation and trilateration networks along the east coast with permanent monuments at each control point. The networks were expanded to the west coast and then to the interior. In its early days, the Coast Survey produced highly accurate maps of our coastlines and became one of the world's premier geodetic surveying organizations.  The Coast Survey has never taken on the task of establishing private property lines.  In a few instances the Survey has helped to solve political boundaries (State lines, etc.) simply because it was the organization best equipped to define them. The Coast Survey is considered the expert on Sea and Shore Boundaries, and the two volume "Sea and Shore Boundaries" by the USC&GS's  Aaron L. Shalowitz is still considered the basic reference.

The Coast Survey continues to upgrade its networks using the most modern technology, and has turned its nationwide system into a global system.

Today surveyors are able to take advantage of modern technology to determine global positions on any point they measure.  The conversation has gone from "We need to be able to do position fixing!" to Why do we need to do global position fixing?"

LETS DISCUSS IT!!

David Garcelon