LECTURE 1 Engr. Meriam M. Santillan, M.Sc. Faculty

Transcription

1 LECTURE 1 Engr. Meriam M. Santillan, M.Sc. Faculty

2 One of the oldest arts practiced by man From the earliest times it has always been important to mark boundaries and divided tracts of land.

3 Through time, the use of surveying expanded such as: Engineering construction Planning and design are based on the results of surveys. Construction is controlled by surveying Surveys cover a wide range in scope and complexity staking out of simple structures the surveying of small parcels of land extensive and difficult surveys required in the construction of: Subdivisions Bridges Highways Canals dams Railroads wharves missile and rocket launching sites drainage and irrigation systems Or surveys of relatively large portions of the earth s surface.

4 Surveying is also required for: the laying out of industrial equipment preparing forestry and geological maps positioning massive and complex machinery in the construction of ships and airplanes well as in the survey and exploration of extraterrestrial bodies such as the moon and the planets.

5 This course will teach/ train students to: visualize and think logically Plan to work carefully and accurately Arrange the product of these efforts in a neat and orderly manner for record or presentation. Will provide worthwhile general experience Develop desirable traits and habits because: The nature of the subject with its related field measurements is will develop habits of accuracy, industry, and reliability In addition: The student will learn a great deal about the relative importance of measurements. Will be trained to decide on how accurate and precise measurements should be made. Acquire essential habits of checking numerical calculations, measurements and observations. ALL THESE ATTRIBUTES ARE EXPECTED TO ADD TO THE STRATURE AND TECHNICAL COMPETENCE OF A FUTURE PROFESSIONAL!!!

6 The oldest historical records in existence today that bear directly on the subject of surveying state that this science began in Egypt. Herodotus recorded that Sesostris (about 1400 B.C.) divided the land of Egypt into plots for the purpose of taxation. Annual floods of the Nile River swept away portions of these plots and surveyors were appointed to replace the boundaries. These early surveyors were called ropestretchers, since their measurements were made with ropes having markers at unit distances. As a consequence of this work, early Greek thinkers developed the science of geometry.

7 HERON stands out prominently for applying science to surveying in about 120 B.C. He was the author of several important treatises of interest to surveyors, including the Dioptra, which related the methods of surveying a field, drawing a plan, and making related calculations. It is also described one of the first pieces of surveying equipment recorded, the diopter. For many years Heron s work was the most authoritative among Greek and Egyptian surveyors.

8 A dioptra is a classical astronomical and surveying instrument The dioptra was a sighting tube or, alternatively, a rod with a sight at both ends, attached to a stand. If fitted with protractors, it could be used to measure angles.

9 Significant development in the art of surveying came from the practical-minded Romans, whose best-known writing on surveying was by Frontinus. Although the original manuscript disappeared, copied portions of his work have been preserved. This noted Roman engineer and surveyor, who lived in the first century, was a pioneer in the field, and his essay remained the standard for many years. The engineering ability of the Romans was demonstrated by their extensive construction work throughout the empire. Ingenious instruments were developed and used. Among these were the groma, libella, A-frame with plumb bob and chorobates.

10 One of the oldest Latin manuscripts in existence is the Codex Acerianus, written in about sixth century. It contains an account of surveying as practiced by the Romans and includes several pages from Frontinus s treatise. The manuscript was found in the 10 th century by Gerbert and served as the basis for his text on geometry, which was largely devoted to surveying.

11 During the Middle Ages, the Arabs kept Greek and Roman science alive. Little progress was made in the art of surveying, and the only writings pertaining to it were called practical geometry.

12 In the 13 th century, VON PISO wrote Practica Geometrica, which contained instructions on surveying. He also authored Liber Quadratorum, dealing chiefly with the quadrans, a square brass frame having a 90 degrees angle and other graduated scales. Other instruments of the period were the astrolabe, a metal circle with a pointer hinged at its center and held by a ring on the top, and the cross staff, a woodedn rod about 4 ft long with an adjustable cross arm at right angles to it.

13 Early civilizations assumed the Earth to be a flat surface. But by noting the Earth s circular shadow on the moon during the lunar eclipses and watching the ships gradually disappear as they sailed toward the horizon, it was slowly deduced that the planet actually curved in all directions.

14 Determining the true size and shape of the Earth has intrigued humans for centuries. History records that a Greek named Eratosthenes was among the first to compute its dimension. His procedure occurred around 200 B.C.

15 Eratosthenes had concluded that the Egyptian cities of Alexandria and Syene were located approximately on the same meridian, and he had observed that at noon on the summer solstice, the sun was directly over head at Syene. He reasoned that at that moment, the sun, Syene and Alexandria were in the common meridian plane, and if he could measure the arc length between the two cities, and the angle it subtended at the Earth s center, he could compute the earth s circumference. He determined the angle by measuring the length of the shadow cast at Alexandria from a vertical staff of known length. The arc length was found from multiplying the number of caravan days between Syene and Alexandria by the average daily distance traveled. From these measurements, Eratosthenes calculated the Earth s circumference to be about 25,000 miles.

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