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| Text 7
From the History of Geodetic Tools There is some evidence that, in addition to a marked cord, wooden rods were used by the Egyptians for distance measurement. They had the groma, which was used to establish right angles. It was made of a horizontal wooden cross pivoted at the middle and supported from above. From the end of each of the four arms hung a plumb bob. By sighting along each pair of a plumb bob cords in turn, the right angle could be established. There is no record of any angle-measuring instruments of that time, but there was a level, consisting of a vertical wooden A-frame with a plumb bob supported at the peak of the A so that its cord hung past an indicator on the horizontal bar. The Greeks used a form of a log line for recording the distances run from point to point along the coast while making their slow voyages from the Indus to the Persian Gulf about 325 BC. The magnetic compass was brought to the West by Arab traders in the 12th century AD. The astrolabe was introduced by the Greeks in the 2nd century BC. During their occupation of Egypt, the Romans acquired Egyptian surveying instruments, which they improved slightly and to which they added the water level and the plane table. The water level consisted of a through or a tube turned upward at the ends and filled with water. At each end there was a sight made of crossed horizontal and vertical slits. In laying out their great road system, the Romans are said to have used the plane table. It was the first device capable for recording angles. Plane tables were in use in Europe in the 16th century, and the principle of graphic triangulation and intersection was practiced by surveyors. In 1620 the English mathematician Edmund Gunter developed a surveying chain, which is also called Gunter’s chain. It is still widely used in English-speaking countries. Gunter’s chain is exactly 22 yards (about 20 m) long and divided into 100 links. In the device each link is a solid bar. Measurement of the public land systems of the United States and Canada is based on Gunter’s chain. An area of 10 square chains is equal to one acre. The study of astronomy resulted in the development of angle-reading devices. With the publication of logarithmic tables in 1620, portable angle-measuring instruments came into use. They were called topographic instruments, or theodolites. The vernier, an auxiliary scale permitting more accurate readings (1631), the micrometer microscope (1638), telescopic sights (1669), and spirit levels (about 1700) were all incorporated in theodolites. By the late 18th century modern surveying can be said to have begun. Many improvements and refinements have been incorporated in all the basic surveying instruments. These have resulted in increased accuracy and speed of operations. In addition to modification of existing instruments, two revolutionary mapping and surveying changes have been introduced: photogrammetry, or mapping from aerial photographs (about 1920), and electronic distance measurement (in the 1960s).
Revision
accuracy applications area distance geodetic height horizon level levelling rod precision readings self-aligning station surveying targets Carl Zeiss introduced the model Ni 002 automatic geodetic 1) ... around 1973, terming it a 2) ... level of maximum 3) .... When the NI 002 was presented to the 4) ... community in 1973, nobody foresaw that this opened a new chapter in 5) ... levelling. The NI 002 was designed to satisfy the most exacting demands of 6) ... transfer in general. The instrument's well-proven 7) ... of + 0.2 mm/km is achieved by its design concept. The elements provide what is called a "quasi-absolute 8) ...". The mean of the two 9) ... is nearly independent of the 10) ... between instrument and 11) .... With the NI 002 it is possible to carry out precise lines of levels without equalizing backsight and foresight distances to within 10 cm. The greater freedom of instrument stationing is an advantage also in industrial 12) .... Before, precise 13) ... levelling was only possible with relocating the instrument several times, while the NI 002 and its successors can remain at a single 14) ..., from which sightings can be taken to 15) ... at different distances.
Part 2. Mapping and Surveying
Text 1 Cartography in the Ancient World and Middle Ages Centuries before the Christian Era, Babylonians drew maps on (sand, clay, paper) tablets, of which the oldest specimens found so far have been dated about 2300 BCE. This is the earliest evidence of graphic (representations, measurements, fields) of parts of the Earth. Certain land drawings found in Egypt and paintings discovered in early tombs are nearly as old. The Greeks were outstanding among peoples of the ancient world for their pursuit and development of geographic (area, importance, knowledge). The shortage of (arable, big, poor) land in their own region led to maritime exploration and the development of commerce and colonies. By the mid-4th century the theory of a spherical (Sun, Earth, Venus) was accepted among Greek scholars, and about 350 BC Aristotle formulated six arguments to (prove, divide, calculate) that the Earth was a (cube, triangle, sphere). The greatest figure of the ancient world in the advancement of geography and cartography was Claudius Ptolemaeus or Ptolemy (AD 90 – 168). An astronomer and mathematician, he spent many years studying at the library in Alexandria. His monumental work, the Guide to Geography, was produced in eight volumes. The first volume discussed basic principles and dealt with map projection and (house, globe, town) construction. The next six volumes carried a list of the names of some 8,000 places and their approximate latitudes and longitudes. The eighth volume was the most important contribution, containing instructions for preparing maps of the world and other fundamental principles of (cartography, map, philosophy). Ptolemy’s map of the world marked the culmination of Greek cartography. One fundamental error that had far-reaching effects was attributed to Ptolemy – an underestimation of the (shape, size, volume) of the Earth.  Ptolemy’s map of the world He showed Europe and Asia as extending over half the globe, instead of the 130 degrees of their true extent. Similarly, the span of the Mediterranean was proved to be 20 degrees less than Ptolemy’s estimate. The main difference between the Greek and Roman cartography was indicated by their maps. The Romans were less (interested, used, defined) in mathematical geography and tended toward more practical needs for military (companies, teams, campaigns) and provincial administration. They reverted to the older concepts of a disc-shaped world for maps of great areas because they met their needs and were easier to read and understand. Progress in mapmaking during the Middle Ages was slight. The medieval mapmaker was dominated by the church, reflecting in his work dogmas and interpretations of Scripture. During the Europe’s dark Ages Arab and Chinese cartography made progress. The Arabs translated Ptolemy’s treatises and carried on his traditions. In Baghdad astronomers used the compass long before Europeans. The oldest known Chinese map is dated about 1137. Text 2 Cartography in the Age of Discovery and Exploration Progress in other technologies such as navigation, ship design and construction, instruments for observation and astronomy, and general use of the compass tended to improve existing map information. The great discoveries of Columbus, da Gama, Vespucci, Cabot, Magellan, and others gradually (transformed, bought, increased) the world maps of those days. The most important aspect of the postmedieval maps was their increasing (definition, stability, accuracy). The principal centers of cartographic (land, activity, map) were Spain, Portugal, the Netherlands and Switzerland. England and France with their growing colonial power were soon to become primary map centers. Text 3 Cartography of the 18th Century Reformation in mapmaking at that time was characterized by (scientific, agricultural, military) trends and more accurate detail. Monsters, lions, and swash lines disappeared and were replaced by more actual content. The new cartography was also based on better instruments, such as the telescope and the chronometer. Many countries of Europe began to undertake the systematic topographic mapping for their territories. Such surveys required facilities and capabilities far beyond the means of private cartographers. Military, national survey organizations gradually became civilian. The Ordnance Survey of Britain, the Institut Geographique National of France, and the Landestopographie of Switzerland are examples. Progress in mapping stimulated the English to start a national (survey, chart, cartography) which was completed in 1787. Text 4 Modern Cartography The instrumentation, procedures, and standards involved in making surveys have improved remarkably in recent years. Geodetic, topographic, hydrographic, and cadastral surveys have been facilitated by the application of electronics and (soil, social, computer) sciences. At the same time, superior optics and more refined instruments have enhanced the precision of observations and accuracies of the end product.
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