The expression that "Those who do not remember the past are bound to repeat it" probably comes from the experience of the Israelites in Egypt and their subsequent celebration of the Passover. However, it is applicable to all of the human race, and Ā the surveying profession is certainly not exempt. Ā It is in this spirit that I would like to start a discussion that relates to the history of surveying and surveying instrumentation.It is difficult to know where to start or where it will lead, but I will start with the story of the Egyptians and their surveying of land boundaries along the Nile River. Along the Nile was some of the most fertile and valuable land in all of Egypt, and as a result the owners of it did not to give up "even one inch" of it to their neighbors. They were smart enough to mark their boundaries with monuments, but when the Nile flooded many of these monuments would be washed away, thus creating serious boundary line problems. However, they came up with a very simple solution. They put monuments on the uplands on every property line, which provided them with the ability to measure from the monuments and extend the property lines back to the River. Thus monumentation became one of the most important aspects of surveying property lines.
However, another very important dilemma had to be solved...the changes of the boundaries of the Nile River, or what we now call Riparian Rights.
I hope this will be the beginning of a vigorous discussion of surveying history.
David C. Garcelon
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Love this David!
something whipped together
the device, instrument change lots but the main point still bearing and distance. thanks for information
A few more thoughts about surveying history.
Let's go back to surveying in the era of the pyramids. Ā It is my personal belief belief that the three most important contributions to surveying in that era were:
1) The use of monuments to fix property lines and corners.
2) The use of trigonometry to measure angles of any size (for example, it was during this era that surveyors used the 3-4 5 relationship to lay off right angles with a length measuring tool)
3) The application of astronomy to surveying. (The Egyptians were the first known civilization that were able to consistently lay out lines of latitude (true east and west) and lines of longitude
(true north and south) by knowing the relationship of the stars to the earth Ā and to time (they were very cognizant of when the spring and autumnal equinoxes and winter and summer solstices happened).
The "foundations" for surveying were laid AND REFINED LONG BEFORE the North American continent was settled (early 1600's), and certainly long before the United States of America came into being (1783). Ā HOWEVER, due to the immensity of North America, the fact that most of the people who came here wanted to own their own property, and the need to create property lines for large tracts of land in a short period of time, created the need for refinements in surveying instrumentation and methods that would facilitate the need for Ā CREATING property lines where there had never been any before!!! (We have had hundreds of conversations and debates about original monuments and original property lines, and probably will until the end of time).
David Garcelon
My personal research is on ancient Chinese surveying. It appears that by the 13th century BC the Chinese were making surveyor plats and that property was clearly defined on their bronze ritual vessels.
Ā Ā Ā What would be the best book for me to study up on Egyptian surveying?
As many know from surveying textbooks, Egypt was the home of the first known surveyors. The textbooks explain how surveying was necessary in Ancient Egypt because the annual floods buried or destroyed boundary markers, which then had to be re-established for ownership of the fields. But surveying in Ancient Egypt went beyond re-establishing boundaries. Scribed control marks on the pyramids, architectural markings in tombs, and a few surviving sketch plans of tombs and shrines show that surveyors also performed construction surveys.
Scribes, the educated professional class in Ancient Egypt, had the practical and mathematical knowledge to supervise surveys. These scribes saw themselves as a special class of people who maintained order in society by running the bureaucracy. The symmetry and proportion of the monuments of Egypt well attest to the skills of these *ancient egyptians surveyors*.
I love the Sextant instrument. Ā Two men independently rediscovered the sextant around 1730: John Hadley (1682-1744), an English mathematician, and Thomas Godfrey (1704-1749), an American inventor. A sextant is a navigation instrument used for measuring angles, primarily altitudes of celestial bodies. Originally, the sextant had an arc of 60Ā°, or 1/6 of a circle, from which the instrument derived its name. Because of the double-reflecting principle used, such an instrument could measure angles as large as 120Ā°. The image shown is of an early sextant by John Bird which was invented in 1759. The frame is mahogany with an ivory scale. It is so large and heavy that it needed a support that fitted into a socket on the observers belt.
In terms of chronology, the order, from oldest to latest navigation instruments is the astrolabe, backstaff, octant, quadrant, and sextant. Ā All of these instruments were designed for mariners with the intent to determine latitude, not longitude. (Longitude was determined, very inaccurately, with taffrail logs and hourglasses). It was not until the British, French, Dutch and Spanish began exploring the America's that accurate position fixing became important, and that led to the refinement of quadrants and sextants, as well as the invention of accurate timepieces (chronometers) by John Harrison in the late 18th century (At least 160 years after America began to be settled).
Backstaffs, quadrant's, octants, and sextants all were designed to sight the sun and superimpose it on the horizon by the use of plumb lines and/or mirrors. The height of the noonday sun above the horizon determined your latitude. Octants and sextants both had smoked glass eyepieces which could be used between the observors eye and the sun's ray so his eye would not suffer damage (the use of backstaffs and quadrants was considered very dangerous to a navigators eyes). Ā Yes, a quadrants scales were 90 degrees long, a octants scales were 45 degrees long, and a sextants scales were 60 degrees long. With both the quadrant and sextant the reflection through mirrors made it possible to read double those angles (the angle of reflection equals the angle of incidence).
Remember, the Atlantic Coast's first settlement was at Popham Colony (Maine) in 1607. The English knew its approximate latitude and longitude (within 350 miles) because that was the best that they could determine with a quadrant, taffrail log and hourglass. HOWEVER, when John Hunt drew his map of Popham Colony, he used a plain table, blade alidade and measuring chain!!
I will try and add to this at a later date....this has been long winded enough.
David C. Garcelon
Wow.. i am learning a LOT from you Mr. Garcelon and I appreciate every bit of this knowledge. Ā Future Gold!
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