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Home , George Everest, Indian astronomy

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SURVEY of AN INTRODUCTION

Dr. Prithvish Nag, Surveyor General of India

he Survey of lndia has played an invaluable respite, whether on the slopes of the Western Ghats, role in the saga of India’s nation building. the swampy of the , ponds and TIt has seldom been realized that the founding tanks, oxbow lakes or the meandering rivers of of modern India coincides with the early activities of Bengal, Madurai or the Ganga basin. Neither were this department, and the contribution of the Survey the deserts spared, nor the soaring peaks of the has received little emphasis - not even by the , the marshlands of the Rann of Kutch, department itself. Scientific and development rivers such as the Chambal in the north and Gandak initiatives in the country could not have taken place to the east, the terai or the dooars.With purpose and without the anticipatory actions taken by the dedication the intrepid men of the Survey confronted department, which played an indispensable the waves of the Arabian Sea and Bay of Bengal, dust pioneering role in understanding the country’s storms of Rajasthan, cyclones of the eastern coast, the priorities in growth and defense. cold waves of the north and the widespread The path-breaking activities of the Survey came, monsoons and enervating heat. of course, at a price and with immense effort. The It was against this price, and with the scientific measurement of the country, which was the determination and missionary zeal of the Survey’s Survey’s primary task, had several ramifications. first participants that the mapping of the country was Surveyors had to traverse from region to region, done. The information collected over the years with waiting for an opportune time, free from natural, whatever technology then available proved to be man-made and logistic problems in order to invaluable. The process has reaped rich results in that continue with their efforts. Resistance from local new information packages, based on the latest people, dacoity, diseases, snakebites, battles and other technologies, such as aerial photography or global hazards came in the way of their mission. Despite positioning systems, are able to benefit from the data this, the surveyors penetrated the jungles, climbed generated by these pioneers. No piece of information mountains, crossed rivers and fixed poles, stations lies unused; all of it has relevance even after decades. and control points all over the country. There was no How was such an empire of knowledge built up?

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Not only are its technological achievements theAtharvaveda has no parallel in any other literature truth. Major exploration got underway at the end of published a map that put Indian geographical significant, but the work of the Survey stands written outside India. 15th century with Columbus crossing the Atlantic in knowledge on a definitive scientific footing. testimony to the pursuit of one of the longest The science of map-making could have not been 1492 and Vasco da Gama circumnavigating Africa in Pioneering work by French expeditions showed scientific experiments carried out in the world, that possible without a knowledge of the shape and size 1497. Magellan’s expeditions circumnavigating the that terrestrial measurements (angles and distances) is, mapping the nation against all odds. of the . This was, and is required for world took place between 1519 and 1522. The are the main tools for the task of relative positioning. The legacy and traditions of the Survey determining the coordinate of points on the earth’s Dutchman Snell (1591-1626) carried out the first The techniques of triangulation - astronomical continue but it is a matter of great interest to know surface, which are used for map-making. Efforts were measurement of angles and distances and made the determination of positions and - as well as how such a superstructure of information was built. made from the very beginning by various rigorous study of refraction. In 1670 the French levelling were started in the mid-17th century. How did these scientific experiments continue to be philosophers and scientists to determine the shape clergyman Picard, measured the size of the earth. His A landmark in mathematical and geographic undertaken for so long? What were the compulsions and size of the earth. Man’s first conception of the result of 6,275 km for the radius of the earth was the determination was the establishing of five and apparent benefits? Why did the colonial rulers earth’s shape was that it was a plane. Greek first improvement on ’ determination. astronomical by the Maharaja and later the independent government, with limited philosophers thought it to be a sphere. Sir Isaac Newton’s theory that the earth should be oblate Sawai Jai Singh II (1693 - 1743) at Jaipur, , resources, continue their interest in this expensive Newton proved that it was spheroid. The actual because of the centrifugal force caused by the spin , and to calculate the exercise? These are some of the questions that will development of the science of surveying and was validated by the measurements of two meridian position and movement of celestial bodies and continue to baffle those who are interested in the mapping of the earth’s surface in an orderly manner arcs, one at the equator and the other closer to the forecast relevant information. In the early days of the scientific history of this country. is, however, ascribed to Eratosthenes (276-198 BC) pole, measured by two survey expeditions by the imperial powers in India, the geographical knowledge who based the compilation of his comprehensive French Academy of Sciences. of the southern parts of the country was greatly MAPPING KNOWLEDGE map of the world upon his famous determination of The dissemination of geographical know- increased during the wars of political supremacy The basic concepts of map-making, that is, scale, the circumference of the earth. Claudius , a ledge was limited till the 15th century, before the between the colonial powers, but information about generalization of features, etc, were known in India mathematician, and geographer invention of printing techniques, due to the labour the north remained sketchy. Nevertheless, attempts from ancient times, as is evident from the Puranas. produced a map of India in the 2nd century AD. and skill involved in duplicating graphic data. were being made from very early times to establish Various references in the testify to this: The of India’s scientific renaissance Once lithographic techniques were discovered, the geographical locations of important places. Chatvaraha prithvi naga dharayanti chatur disham started in the 5th century, when the genius Aryabhat map-making got a stimulus, particularly in Europe, During the middle of the 18th century, Vardhamana suvri-dhrishcha ativridha prithishrava calculated the earth’s circumference to be 25,080 miles where adventurous men went out to conquer new could be easily determined by observing the meridian (Garga Samhita quoted in Adbhut Sagara). and wrote the Surya Sidhanta.Indian worlds for religion and commerce. Father altitude of the or stars. For longitude The art of surveying or the technique of and mathematicians such as Aryabhat, Baraha-Mihir Monserrate, a Jesuit, brought out a map after a determination, one had to wait for favorable mensuration of areas was well developed in ancient and Bhaskaracharya discovered several truths such as visit to the Mughal Emperor ’s court. This was phenomenon such as an eclipse of the sun, or India as is established in the manual Sulva Sutra the shape of the earth, its rotation around the sun, and the first of those maps based on measured routes satellites in clear sky, with similar observations being (science of mensuration). In Vedic literature, sutras even the force of gravitation. In their contribution to and astronomical observations. Akbar’s revenue made at several known places. In 1787, astronomical (formulae) are provided for the measurement of Indian geography they were followed by Chinese and minister Todar Mal’s maps and those of the brilliant observations for latitude and longitude at various angles, distances and areas. Our ancient knowledge of Arab travellers who left many interesting detailed administrator Sher Shah Suri, based on regular land places were made covering India, and proper centres , astrology, rocketry and geography is well accounts of their journey. It is no wonder that this survey systems, were well known in their time and of astronomy were established in due course of time known and it is apparent to Indian scholars that the mystic land attracted so many adventurers. continued to be used in the mid-18th century. using sextants, chronometers and . The Vedas and later Sanskrit works contain these truths. Although the foundations of geographical Information is available on the surveys instituted by results of these instruments were, however, inaccurate In the Vedas, Upanishads, the great epics Ramayana knowledge and their subsequent developments were Akbar during the 16th century, measurements being because of faulty mathematical tables. An interesting and Mahabharata, the Puranas, the Manusmriti, laid from the very beginnings of civilization, that is made by a hempen rope which was replaced by a observation is that because of the difficulty in works of Panini, Patanjali and Kautilya, and even in the domain of history. The knowledge of mapping ‘jarib’ of bamboos joined by iron rings. Other noted determining longitude, early maps of India do not the poems of Kalidasa, there have been references of as a science grew with time and even religious cartographers of the time also published their indicate longitude with reference to the geographical accounts of India. The Vedic concept of thinkers started delving into its mysteries. The age of versions of maps of India. In 1752 the French meridian but to the arbitrary meridian passing the motherland, mentioned in the Prithvi Sukta of great exploration started with the quest for absolute geographer, Jean-Baptiste Bougigon d’Anville through Madras or Calcutta.

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Most early maps were based on local surveys carried with theodolites, with pocket for measurement of a series of triangles was carried out theodolite was used by Lambton and his assistant and out by a cursory method. In 1776, comprehensive determining the direction of the road, etc. The up to Mysore and the second base was measured near then by Everest and others till 1866. Various other instructions for preparing maps on the scale of two technique of plane tabling was first used in 1792. Bangalore in 1804. The station of origin was the theodolites were used for observations for the miles to an inch were formulated in which distances Plane tabling survey was subsequently developed into primary reference station of the Astronomical meridional series, namely, the 36-inch theodolite, were measured by parambulators rather than with an art and has been used extensively down to present at Madras. Having connected the two which was built up from Lambton’s great theodolite, chains and bearing to conspicuous hills. Short base times for topographical surveys in all types of terrain. sides of the peninsula, Lambton devoted much of his the 34-inch theodolite, 24-inch, 18-inch and 15-inch lines were laid and measured and distant points were Even now, with the emergence of modern techniques labour to the measurement of an arc of meridian. theodolites. For the purpose of laying out the series fixed by triangulation. of surveying, this simple technique is widely used in The series measured for the purpose is known as the and running secondary and minor triangulation, various surveys such as large-scale mapping, ‘Great Arc Series’. In addition to the measurements of small theodolites were used, that is, 14 inches, 12 SURVEY OF INDIA engineering surveys, cadastral surveys, and the like. this series, webs of triangles were extended in order inches and 7 inches. For baseline measurements, The Survey of lndia traces its birth to Major James to establish the positions of main cities. This idea of compensation bars and other baseline apparatus were Rennell’s appointment as the Surveyor General of BEGINNING OF SCIENTIFIC SURVEYS the web was replaced due to cost effectiveness by an used. The compensation bars remained, however, the Bengal on 1 January, 1767. In those days, there was The period of piecemeal surveying came to an end by all-India grid composed of criss-crossing ‘chains’ or only means available for measuring the baseline of an urgent need for pictures of the country showing the close of the 18th century. A new era began with ‘bars’ of triangles centered on the Great Arc. The the main triangulation framework. Vizagapatnam the general course of main rivers and the location of William Lambton and George Everest, which holes on the grid could be filled later by cheaper and and Cape Comorin bases were measured between principal towns. This task was taken up with speed signalled the consolidation of coordinated efforts. less rigorous topographical surveys. The idea gave 1862 and 1869. In 1856 standard yard arrived from and the result was that serviceable maps of the The foundation of a truly scientific Survey of India birth to the term ‘grid-iron’. England and the following year a special room at of Bengal and Bihar were produced in less than was laid, the beginning of a period of stupendous The grid-iron layout generally consisted of an Dehra Dun was set aside where subsidiary standard twelve years. These maps, however, could lay no claim work,which occupied the lifetime of scores of noble outer frame of two extreme meridional and two could be laid off or compared by microscope as and to accuracy of details but were sufficient to meet the and devoted surveyors. A network of primary longitudinal series closing at each junction on a when marking of staves for levelling operations needs of the time. Rennell also produced the ‘Map of triangles was established by the trigonometrical measured baseline. To bring the Great Arc across the required. Standard spirit levels were used during Hindoostan’ in 1783 after relinquishing the post of surveys. It was a magnificent scheme, timely plains, masonry tower stations were built which were those days. Surveyor General. conceived and brilliantly executed. Although about 50 feet high. The first essentials of every Triangulation or levelling computation was The progress of topographical surveys in techniques of triangulation, astronomical observation station, whether on hill top or tower or made to a regular routine, adapting rules and Madras and Bombay presidencies was a more or less determination of positioning and azimuths as well as otherwise was the stability of the instrument and formulae to the requirements of the department. independent exercise and not coordinated with the levelling were started in the mid-17th century, immovability of the mark over which the instrument Computation forms were lithographed at Calcutta work of the Bengal presidency till the beginning of scientific procedures started only by the end of the and signals were centred. These marks were under the direction of the Chief Computer. One of the 19th century. This was not a satisfactory state of 18th century when a project for the measurements of established after great effort, and were then handed the greatest contributions which Radhanath Sickdhar, affairs and retarded the progress considerably. It was an arc of the meridian through a network of over to the civil authorities when all corrections had Chief Computer, made to the Great Trigonometrical only in 1787 that an accurate survey of the sea coast trigonometrical surveys covering the Indian been completed. In 1866, it was ordered that all Survey was the preparation and publication of a set from Madras to the southernmost extremity of the peninsula was formulated. stations of the Great Trigonometrical Survey should of tables to be used with departmental formulae and peninsula was taken up by running a 300-mile line of The actual work of the Great Trigonometrical be placed under the official protection of district computation forms. The first official list of triangles along the coast with the aim not only of Survey was commenced on 10 April, 1802 by the magistrates and visited periodically. This practice still geographical coordinates was published in 1842 and ascertaining the actual line of the sea coast but measurement of a baseline near Madras. This exists today for all primary GT stations and bench the first edition entitled ‘Tables to Facilitate the undertaking a complete survey of peninsular India. baseline was established using a steel chain which marks. Computation of a Trigonometrical Survey and the 1 This survey was the first Indian survey based on the consisted of 40 links of 2 ⁄2 feet each, measuring in Lambton’s main instrument was referred to as Projection of Maps’ was published in 1851. Auxiliary system of triangulation. total 100 feet. The baseline was measured with the the Great Theodolite which was a marvel of tables to facilitate the calculations of the Survey Towards the close of the 18th century, aid of coffers (long boxes) as it was required for the workmanship in those days. The horizontal circle was department were published in 1868. theodolites, now considered primitive, had been triangulation of the ‘Great Arc’ where utmost possible 36 inches in diameter and the vertical circle 18 For the dispersal of triangular error, the method brought in use. Angles and bearings were measured accuracy was the aim. From this baseline, the inches; each was read by two microscopes. This followed by Everest was tested against the new

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method devised by Gauss. Radhanath first tried two triangulation series was advanced eastward to the The Great Trigonometrical Survey Triangulation scale half inch or larger. Mapping activities opened simple figures and obtained results closely agreeing Ganga valley up to Calcutta and all the way to Network of India and adjacent countries was started up new possibilities with the introduction of aerial with the old method. He tested this on complicated Assam. Regular observations of the Himalayan peaks in the year 1802 and by about 1880, a number of photographs in the early years of World War I. The figures that occur in the trigonometrical survey. The were recorded. It was under Waugh that the highest triangulation series had been observed to warrant science of photogrammetry had not developed but results were highly satisfactory, showing that the mountain in the world, 29,002 feet above the sea, was their simultaneous adjustment. This triangulation the immense value of aerial photos impressed the greatest discrepancy between Gauss’s and Everest’s discovered and he recommended that it should be network was first adjusted to form a self consistent surveyors. Air survey techniques were not, however, methods would not exceed 0.14 arc seconds. named after George Everest, who had built up the whole in 1880. Adjustment of this horizontal network used very much in the department up to 1939 except The final distribution of errors and reduction triangulation system by which the discovery was was based on the Indian Geodetic Datum. Here, the for training for military survey purposes and for the of results of the triangulation of the Great made possible. Everest ellipsoid is used as the reference surface survey of inaccessible areas. The primary map scale Trigonometrical Survey was carried out under the Regular astronomical observations for (Indian Geodetic Datum) in India. This reference 1 inch to a mile was adopted by the Survey of India direction of General James Walker whilst he was and meridian were continued along both meridional surface has been named after Sir George Everest. in 1905. It was also decided that these maps be superintendent of the trigonometrical survey. For and longitudinal chains of triangle as a check against A reference ellipsoid is defined by various produced in colour and that the relief be shown by this purpose the whole triangulation was divided into accumulation of errors in direction. Both Lambton components, namely, semi-major axis (a), flattening rigorous contourings. five zones - Northwest, Northeast, Southwest, and Everest had been well aware that their (f), and coordinates, namely, latitude, longitude and The requirement for printed maps increased Southeast quadrilaterals and the Southern trigon. observations were influenced by visible mountain deflections of the vertical: meridional and prime greatly during 1939 but the main printing organiza- Lambton and Everest did not go deeply into the masses and variation of density. Various other vertical, and geoidal undulation at the origin. Everest tion at Calcutta was unable to meet the demand. The subject of heights above sea level. Lambton first mathematicians and geodesists worked on this adopted Kalianpur in central India as the point of present site at Dehra Dun was therefore selected and connected to the sea at Madras in 1802, but for his subject and attracted wide attention. They suggested origin. Various components of the Everest ellipsoid printing machines installed here and by mid-1943, great Central Arc he preferred the connection made the value of pendulum observations for the or spheroid and its orientation at origin were worked printing was in operation with three large high-speed at Cape Comorin in 1809. From this he brought up determination of variations of and out in piecemeal manner in various campaigns. machines. At the time of Independence (1947) his height by vertical angles from station to station. introduced the theory of compensation or isostacy. In the year 1937, another adjustment was mapping of about 60 per cent of the country had been At that time surveyors in India had no professional attempted, incorporating the new triangulation completed on the primary scale of 1 inch to 1 mile. interest in the measurement of the vertical rise and DEVELOPMENT OF THE GREAT ARC series observed after 1880: the Laplace stations to fall of tides along the coast except to find the level of The measurement of the Great Arc from Cape control directions and new baselines measured with PRESENT SCENARIO the sea from which to calculate their land heights. Comorin to the Himalayas was completed by 1843. invar wires between the year 1930 to 1934 to control After Independence, there was an immense increase Lambton followed the practice of his time by The grid-iron system consists of meridional chains the scale of the triangulation series. In this in developmental activities and this drive continues calculating his heights from low water. It was only in of triangle tied together at upper and lower ends by adjustment, instead of resolving the simultaneous till today. It was only the Survey of India, as the 1837 that the mean between high and low tide longitudinal chains. This ambitious scheme of normal equations formed after incorporating new premier organization engaged in surveying and observations for at least half a month were proved to triangulation commenced with the Great Arc Series, data, the graphical technique of adjustment was mapping, which could take up survey work for match closely between one place and another. Self based at Dehra Dun in the north and Sironj in employed. However, this technique was not developmental schemes, because of which normal registering tide gauges had been invented during central India as the southern end. The Northwestern considered appropriate and the adjustment found to topographic surveys became secondary. 1830-33 and were established at the Colaba Himalayan series was further extended from the be of no practical use. During the First and Second Five Year Plans, the observatory, Bombay in 1842. Tide gauges at various Dehra Dun base while from Sironj the Calcutta The adjustment of 1880 has remained the basis department was faced with demands for survey other places were also connected through spirit level longitudinal series was extended up to a base at of Indian triangulation and mapping except for a which required far more survey infrastructure than it during 1851 to 1860. Karachi. In 1887, the series was started as constant change of -(2’27”.18) in longitude. This had. During the First Five Year Plan (1951-6), nearly Levelling was initiated on scientific lines in an extension of the Northwestern Himalayan series. change was essential as the longitude of the Madras 70 per cent of the department was employed in 1858. It was General Walker who was the founder of The height of stations averaged 17,000 ft in this observatory was revised in 1905. developmental surveys and in the Second Five Year this activity and initiated the field work. series. The second highest peak, next to Mount Early mapping activities of the Survey were Plan about 60 per cent was directed towards this Waugh took over in 1843 from Everest and Everest, was found during this triangulation to be scientifically executed and based on the triangulation purpose. The department had diverted the work load during the seventeen years of his administration, the 28,290 ft high and this was named . series adjusted in 1880. Most of the maps were on the with the switching over to the metric system in 1956

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and the basic map scale having been changed to 2° (about 200 km) apart and upgradation of the geodetic work, Frost, Worden, Lacoste Romberg and considerable extent. The first plotting instrument was 1/50,000 from 1 inch to 1 mile. It was during the existing series classified as ‘secondary’ has been taken Automated (CG-3M) gravimeters for gravity installed in 1950. Since then rapid strides have been Second Five Year Plan that various advanced up by the Survey of India. There has been measurements and QHM (quartz horizontal made in the field of photogrammetric survey. After techniques of mapping became available and there tremendous growth in the field of space geodesy in magnetometer), BM (zero balance magnetometer), 1955, with the acquisition of analogue instruments of were pressing demands for maps needed for the last couple of decades. Proton magnetometer for geomagnetic observations, high precision, photogrammetric and plotting development work. Since that time, the Survey of The TRANSIT system was adopted by the Survey all are in use for geodetic and geophysical surveys. machines from stereo models were adopted and India has kept pace with modern technologies of of India in the seventies to establish geodetic control. Computers are extensively used for better and more became the standard procedure for topographical surveying and mapping and continues to adopt A more rigorous system called NAVSTAR GPS homogenous adjustments and data processing. large-scale mapping in the department. The Survey various activities in the field of geodesy and (navigation satellite with time and ranging global of India now has analytical/digital photogrammetric geophysics, topography, photogrammetry, positioning system), or simply GPS,a satellite based TOPOGRAPHICAL MAPPING instruments which are being used for map-making cartography and printing, manpower development, radio navigation system providing three-dimensional After establishing the ground control points either and for generating digital data. and so on. positions, navigation and time information to by conventional ground method or by space-based In the Survey of India the process of map- suitably equipped users all over the at any techniques, the subsequent steps include: survey of making with aerial photographs starts with the GEODETIC AND GEOPHYSICAL SURVEYS point of time, was introduced in the year 1980. The ground details and verification, annotation and planning of the aerial photograph. The Ground The responsibility of establishing geodetic and GPS technique was adopted in the Survey of India introduction of names of rivers, roads, villages, Control Points (GCPs) at selected locations are geophysical control in India lies with a separate around the year 1990 and enormous work has since towns, etc, and depiction of topographic features by connected with existing geodetic control by field directorate known as the Geodetic Research Branch. been done in this area. Electronic distance measuring contour and other suitable symbols. The SPOT, IRS and survey and their positions are captured. With With the introduction of modern instruments in devices have been introduced since 1962 and a Landsat imagery for topographical mapping on small photographs and minimal ground control and their improving the precision and accuracy of all geodetic number of bases have been added to the principal scale are also used. Digitally generated data is used to position identified, the stage is set for undertaking and geophysical surveys, the activities of this branch Indian triangulation system. create a cartographic database in various scales, Independent Model Photogrammetric Triangulation have been diversified and today it is engaged in a There is a growing realization that Indian namely, 1:250,000 and 1:25,000. In addition to this and subsequent computation provides requisite number of research and developmental programmes. geodetic datum needs to be redefined and Indian data base for district planning a map series on scale control points in each model. The models, properly Theodolites used in the past were replaced by triangulation readjusted afresh. This is because of the 1:250,000 is being carried out. Digital terrain model oriented, are then used for generating cartographic glass arc theodolites in the late forties of the 20th inherent weakness in the geodetic datum and (DTM) is being generated for developmental activities data which is verified on the ground before preparing century, which made it possible to read directly to an triangulation adjustment of 1880. These inherent in the country. the final map. accuracy of 0.2 second of arc. Geodetic bases of weaknesses are: ill fitting of the ellipsoid, inadequate With the completion of the 1:50,000 Topo- length 10-12 km, established during the period bases and non application of various geodetic graphical Survey of the entire country by 1982 and DIGITAL CARTOGRAPHY 1831-82, have been measured with Iridia 10 ft bars, corrections like deflections, skew normal, geodesics, mapping by 1985, India has joined a select group of As a part of its activities to keep abreast with the while modern baselines were measured with invar etc, in the observed directions. Enormous amounts of countries which have completed map cover on the latest technologies in the science of map-making, wires. In order to check the scale of Indian data have been collected after the first adjustment of national scale. The department now has an ambitious the Survey of India adopted the digital mapping triangulation, these baselines have been measured 1880, namely, baselines, Laplace stations and several programme of covering the whole of India by maps programme in the early eighties. It adopted the with great care. Accuracy of baselines was of the new triangulation series in the Great Trigonometrical on 1:25,000 scale. The country covers 394 maps on Computer Assisted Cartography (CAC) system, the order of 3 part per millennium (3 mm per km) or Survey.After incorporation of this data in the Indian scale 1:250,000 and 5,106 sheets on scale 1:50,000. ‘Automap’ in 1981. In this system geographical and better. Astrono-mical azimuths have also been triangulation net, simultaneous adjustment of the other data are stored in digital form and processed measured at a few stations to keep a check on the primary and secondary series has been taken up to PHOTOGRAMMETRY on demand to draw the required map output by orientation of the triangulation series. In order to redefine the Indian Geodetic Datum. Aerial photographs made their appearance in the using a computer operated drafting table. The Survey provide first order control by a chain of primary and Various geodetic and geophysical modern early years of World War 1 when sephotographs were of India took a giant leap forward in 1986 when secondary series every 4° (about 400 km) apart the instrumentations are being put in use for geodetic, extensively used for preparation of large-scale maps integrated digital map production systems were triangulation network was completed by the year gravity and geomagnetic observations. Glass arc in India. The introduction of photogrammetry installed at three locations: (a) Modern Cartographic 1956. The work for densifications to bring control at theodolites, astrolab, chronograph, crystal clocks for simplified the work of ground surveyors to a Centre (MCC), Dehra Dun, (b) Digital Mapping

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Centre (DMC), Dehra Dun, and (c) Digital Mapping SURVEY TRAINING mapping organization in the country bears a special placed on IT driven ‘transparent’ e-governance. Centre (DMC), . Having overcome the Over the years, officers and staff of the Survey of responsibility to ensure that the country’s vast The nation has been generating voluminous field/ initial difficulties of new technology induction in the India have ventured into unmapped territory for territory is explored and mapped suitably to provide digital data, that is, information through systematic early nineties, the department aimed to achieve others to follow and record as they surveyed the base maps for the expeditious and integrated topographical surveys, geological surveys, soil flexibility in satisfying users’ demands by establishing deepest forests, deserts and swamps, the lowest development of the nation. In the process, the Survey surveys, cadastral surveys, etc. Access and availability a structured Nations Cartographic Data Base (NCDB) coastal belts and highest mountains. All this has of India has been producing all purpose of such information to the citizen, private enterprises and Geographic Information System (GIS). In the year been possible because of the basic training they topographical and various other series maps required and government are of immense importance. As a 2000 the Survey of India brought out a digital received, either on the job or through for the purpose by defence, by civil administration, internal security, part of this vision, NSDI,a national system, is being cartographic data base on 1:250,000 scale for the of carrying out specialized survey tasks. for developmental needs, irrigation, watershed involved through a partnership approach among entire country. Digitization on scale 1:50,000 and India’s colonial rulers had established a centre at management, resource management and various various data generating agencies to facilitate 1:25,000 is in progress. This activity is likely to take Abbotabad (now in Pakistan) for the training of types of engineering projects. It is also responsible for integration, easy access and networking of databases some time as the volume of work is high. officers and surveyors of other ranks. Immediately establishing precise planimetric control, heights with the power of IT.This enables information after Independence, a training directorate was above MSL,gravity,geomagnetic and tidal prediction support for decision making in government, PRINTING established at Dehra Dun for the officers and staff of as prerequisites for mapping activities and other industry, academia and other organizations and Conventional map printing activity is a fairly the Survey of India. The training directorate was scientific applications. The department is committed serves the needs of the public. cumbersome process in which map manuscripts are subsequently shifted to Hyderabad in 1962. With to provide technical expertise to other countries in The strategy and action plans of NSDI have colour separated and press plates are prepared advances in the field of computers, electronics, satellite the fields of geodesy, surveying, cartography and been formulated through a multi-institutional through a chain of intricate reprographic processes. techniques and remote sensing, the technology of survey education. approach involving the Department of Science & The final printing is carried out on rotary offset surveying has undergone a qualitative change With the introduction of digital technology in Technology (DST), Survey of India (SOI), Indian Space multicolour printing machines. Map printing necessary to catch up with modern trends. With the the department, a digital topographical database for Research Organization (ISRO), Geological Survey of activities started in the Survey of India when the assistance of the UNDP, the training directorate was the entire country is being created in various India (GSI), and National Atlas & Thematic Mapping printing machine at Calcutta became fully operational reorganized as the Survey Training Institute (STI) and planning processes and for creating GIS.Its Organization (NATMO), etc. in 1852. One of the tasks of this new office was the came into existence in 1970. This institute, apart specialized directorates such as the Geodetic and In order that maps in analogue and digital printing of postage stamps of India. The first stamp from catering for internal training needs, also Research Branch, Research and Development form are available to users all over India for the was printed on 4 May, 1854. By 1865 another imparts training to other organizations in India and Directorate and Survey Training Institute have been sustainable development of the country, a new series printing press had been established in Dehra Dun. also to students from developing countries. With the further strengthened to meet the growing of maps on WGS 84 datum is planned and the work The requirement for more printing machines introduction of sophisticated hardware and software, requirements of users. The department has also been on various components involved in this proposal has increased considerably during 1940 and a full-fledged staff members have been trained in collaboration contributing immensely to a number of multi- already begun. printing press was now installed at Dehra Dun which with the International Institute of Aerospace Survey institutional scientific programmes related to the In over two and half centuries the Great started functioning by the middle of 1943. and Earth Sciences (ITC) in the Netherlands. field of geophysics, remote sensing, glaciology, study Trigonometrical Survey of India has collected Reproduction techniques have undergone Being a premier institute in survey education in of seismicity and seismotectonics. scientific invaluable information and its resources continue to revolutionary changes over the years. With the Asia, the Survey Training Institute is geared to meet expeditions to Antarctica and digital data transfer. be utilized in the development of the nation. availability of information from digital cartographic the sophisticated training needs commensurate with The Survey of India has taken up a major Geodetic and geophysical information such as data bases it became imperative for the organization fast changing technologies required not only by programme related to technological development in planimetric and height control, gravity, geomagnetic to install compatible printing machines and the students from within the country but from the field of mapping activities with the initiatives of and sea level data are being continuously collected Survey of India now has five printing groups located neighbouring countries as well. the Department of Science & Technology. Under this with the aim of serving humanity by forewarning at (Calcutta), Dehra Dun, Hyderabad and programme the National Spatial Data Infrastructure them about natural disasters and by making Delhi with the latest map publishing system and RESPONSIBILITIES AND CHALLENGES (NSDI) and a new series of maps have been initiated. information and resources available to earth machines, making them compatible with digital data In its assigned role as a national mapping agency, the fast moving into an information and scientists. and capable of producing the highest quality. Survey of India, as the premier national survey and knowledge based society. Emphasis is increasingly

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India welcomes you to the eternal quest of humankind THE EXHIBIT 15

In a time long gone, about 3000 years strengthened by the Indian tradition of the , was considered sacred. But these were subjective depictions; they before the birth of Christ, somewhere in oral learning and communication of The moon was next in importance and incorporated the culture and beliefs of the sweeping expanse of land known knowledge as sutras. its cycle provided the basis for a working the observers, just as much as the today as India, Man stood beneath the A sutra is the encoding of thoughts into . The length of the year was known scientific tradition of the subcontinent vast emptiness of the sky and gave shape compact word-capsules or formulae that and calculated as also the lunar month. did. In the 19th century, subjectivity PRELUDE The to the infinity of the cosmos. contain a very high density of expression In all seven were identified - had no place within a new ‘rational’ And so was born the concept of sunya - and is often set to metre. the Sun, Moon, , , , empirical science the West was in itself nothing, a void, but having Between the 6th and the 4th century , and . Records of celestial awakening to. infinite potential. BC, the grammarian Panini put down a phenomenon are found in the Vedic Later, much later, in the 7th century AD, sophisticated language theory - a Samhitas, Vedanga Jyotisa and Surya Bramagupta became the first person to masterly achievement of logic, analysis , dated between 2500 BC Right: Buddhist concept of integrate this concept into mathematics and classification. and 400 BC. by treating the sunya as a number. An epigrammatic sutra on the rising of , author of the earliest the In this cosmographic conception, When sunya is added to or subtracted the planets: in the 6th century preserved work dealing with Mount Meru is shown as the centre from a number, the number remains astronomical treatise Pancasiddhantika, mathematics and astronomy dated to the of the Universe. unchanged; when multiplied by sunya it Varahamihara uses consonants to define a 5th century, has given a systematic becomes sunya;when a quantity is added simple numeral value and a vowel to give treatment of the position of the planets Below: The City of Bunarus to sunya the result is that which is added. the place value. in space. He calculated the circumference The city plan of Varanasi surveyed by Mathematicians in India were already “From the R anomaly of of the earth. The axial rotation of the James Princep in 1832. working with a base 10 system that had conjunction of Jupiter, Mars and Venus earth, radius of the planetary orbits in unique symbols for the numbers one subtract one fourth of itself. From that of terms of rotation around the sun, through nine and a place value notation. the rest, (viz. Mercury and Saturn) add elliptical orbits of the planets and the As early as 2500 BC, the Harappan an eight. Add both algebraically and note causes of eclipses of the sun and moon, civilisation had adopted a uniform system the direction, north of south. Multiply all have been considered. of weights and measures that were this by R (i.e. 120’) and divide by the A cyclic concept of time, rooted in n decimal in nature. Both weights and scales hypotenuse got in the last step. The the idea of a or cycle, was the basis have been discovered, and measurements latitude is got, its direction being that of of Indian astronomy. A mahayug was of excavated ruins reveals that these units the noted direction.” identified as a period at the beginning of of measurement were used in the The sciences, including mathematics, which all the planetary bodies are in planning and construction of that of Vedic times were closely related to conjunction. It ends when each of these extraordinary city. philosophy and religion. The complicated planets has completed an integral The introduction of sunya perfected geometry that was developed in 800 BC in number of revolution and they are in the writing of numbers in decimal Baudhyana’s Sulbashastras for instance, conjunction again. arithmetic, and, thus, were made simpler related to the rules for measuring and The number of revolutions made in this infinite calculations of reality. constructing the sacrificial fire altars. They period by the planets was also calculated. Known in different places at different are religious works, but extraordinary in The sun, it was worked out, would make times as sifr, zephirum, tziphra, zenero, terms of mathematical content - the 43,20,000 revolutions and the moon, zero, sunya gradually came to be problem is stated in geometric terms, the 5,77, 53,336 revolutions in one period assimilated by the and solution given in a combination of of the mahayuga. from there, over four geometry and algebra. also referred to the centuries, into western The use of Pi, the ratio of the sphericity of the earth in his treatise mathematics. circumference of the circle and its Pancasiddhantika,which plots the ancient At that time diameter resolved difficulties arising of view of the world. knowledge, whether the need to circle a square or the square a This located Mount Meru, the highest in science or circle. Also laid down by Baudhyana as point on earth on the North Pole. technology, dealt the means to identify the perpendicular Surrounding it are four island continents primarily with the (north-south) direction in the east-west aligned to the four points of the . abstract and line of altar settings, was the logic better Four rivers flow down from the mount. carried, therefore, a recognised today as Pythagoras’s theorem. The southern island is Jambudvipa where strong essence of The belief that cosmic energy sources humans reside. timelessness. are the procreators of the entire manifest Thus, from a time in the distant past This was further world was central to Vedic philosophy. when our understanding of the universe Sages studied the sky and tracked the seamlessly integrated both the physical movement of heavenly bodies to define, and the metaphysical, the subcontinent Early Indian Globe within the logic of infinity, a point in has been bound in the North by This 18th Century globe shows the earth in two time and space. mountains from which the waters that parts. The upper half are the The sun was regarded as being the most nourished life flowed all the way down heavens and the lower the earth. important heavenly object and its path, to the sea.

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A spectacular land mass that can reveal the true shape of the earth THE EXHIBIT 17

The plan determining the positions of the principal The survey plan is quite audacious. Maps are power knowledge of the Indian princely states is A plan to survey the subcontinent of geographic points… ascertaining the great It seeks to explore the territories of The British Army is still smarting under a not for sharing. Most maps are guarded, Hindoostan, ascending the 78th meridian… geographical features… upon correct Tipu Sultan in Mysore, the Nizam of defeat with Tipu Sultan, misled by a map safe from an envious neighbour or would- This is the story of a scientific endeavour mathematical principles…” Hyderabad in the Deccan, the Maratha that had shrunk the land and changed the be conqueror. of Herculean proportions to be launched George Everest is the brilliant executor of confederacy of the Peshwa, Holkar, topography. The General’s Even the most assiduous surveys till PLAN The on the vast expanses of Hindoostan. Lambton’s scientific legacy. He will join the Scindia, Bhonsle and Gaekwad brother, Arthur Wellesley (better known now have resulted in maps more The enormous peninsula will be Survey when it reaches central India and stretching from the Deccan to Delhi, later as Duke of Wellington), therefore enthusiastic than accurate. Large areas are surveyed on the most precise and “correct take the Great Arc forward to its conclusion the Nawab of Awadh... supports Lambton’s grand proposal. An left blank or detailed imprecisely. To the mathematical principles” by Brigade- at the foothills of the Himalayas. A scientist, In its agenda, it is much like a astute strategist, he understands dismay of the powers, the widely Major William Lambton, an officer in engineer and astronomer and above all, a military campaign. However, the potency of an accurate acclaimed Map of Hindoostan by His Majesty’s 33rd Regiment. man of indomitable will and character, he Lambton, who has proved his map in a military James Rennell will soon be revealed to The venture has the full support of the will raise the accuracy of the Survey to the soldierly qualities in the last campaign. have gross errors, with all principal places Company who sees the Indian highest possible level. Restless experiments battle of Seringapatam, is Maps merit great ”considerably out of position”,and “an subcontinent as a highly desirable territory. and innovations will earn him the epithet interested in nothing except attention, specially as error of no less a quantity than 40 miles in For Lambton, however, this is a great of “Neverrest”. his scientific dream. the geographical the breadth of the Peninsula”. space for geodetic investigation. The subcontinent is a large, curved surface of the earth close to the equator, a continuous Coat of Arms of George Everest global detail, that can be accessed, mapped the East India A worthy successor to Lambton who made the Arc his life’s work. The loftiest peak in the Himalayas and mathematically computed. Company and, consequently, in the world, was given his name: Lambton is a mild-mannered man of an acknowledgement of the painstaking scientific extraordinary scientific passion. A self- endeavour that crawled through the subcontinent’s vast taught astronomer, geographer and burning expanse to mak possible the measurement of the mathematician, it is his “desideratum snow-capped Himalayas. most sublime…to determine by actual measurement the magnitude and figure of William Lambton the earth, an object of the utmost Initiated into higher mathematics importance in the higher branches of early in life; joins the British army as an mechanics and physical astronomy.” ensign in the 33rd Regiment; moves A man of his times, Lambton to Canada, enlisted as a surveyor; spends 13 years in shares the 19th century Park Estate in Hathipaon near Mussorie wilderness applying himself to obsession with the figure of The Estate was bought by Everest in 1829. surveying and mathematics - the earth. His imagination is Here he set up both home and office and many and foregoing promotions; fired by similar investi- of the operations of The Great Arc were finally moves with his conducted from here. gations in Lapland and Peru. regiment to India, aged Lambton joins the British almost 50 years. army as an ensign in the 33rd Regiment and is sent to Canada. Enlisted as a surveyor, he spends 13 years in the wilderness applying himself to surveying and mathematics - and foregoing promotions. He finally moves with his regiment to India, almost 50 years of age. “The presence in India of a man of Rennel's map of Hindoostan Lambton’s genius and character, knowledge of mathematics and interest in Lambton’s Proposal geodesy, was entirely fortuitous…” The original letter dated 10th February 1800, The proposal : politically correct, from W. Lambton to geographically precise and the Secretary to the scientifically sublime Governor of Madras James Rennel forwarding his proposal The first Surveyor General, was Lambton’s Plan of a Mathematical and for a mathemathical Geographical Survey talks about “the great commissioned by Lord Clive in and Geographical 1760 to survey the country. advantage to general geography that Survey to be extended would be derived from extending a survey across the presidency. across the Peninsula of India for…

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The first step of the greatest geodetic measurement ever undertaken THE EXHIBIT 19

Inch by inch, over grains of sand, to Astronomical observations are taken to fix The foundation A triumph of precision crystals of snow the latitudinal positions at each end of the At Madras, Lambton fusses over the Measurements and observations of the Slowly, and with great deliberation, the baseline. baseline operations, supervising every chain, the angles, the stars, are taken Survey will journey in a great arc from the detail as the 100 foot measuring chain is twice, thrice, four times. This systematic sands of Marina Beach in Madras to the 27 September 1802 to 13 April 1803: stretched 400 times to cover the distance check-countercheck precision will

IS TRIANGLE FIRST The 1 towering Himalayas, taking half a century The penant at St Thomas’ Mount is of 7 ⁄2 miles (12 km). Each time it is spread become the hallmark of the Great to reach its goal. From start to finish, it is observed from each end of the baseline, in its special housing, levelled, aligned Trigonometrical Survey. the scientific determination of the first thereby forming the first triangle. with elevating screws, and anchored step that will steer the Survey in a The penant at Perambauk Hill is against the high winds. Because metals relentless pursuit of precision. observed from each end of the baseline, expand, a new chain is kept as a standard The flag-off is the measurement of the forming another triangle. and elaborate expansion and tests are baseline at Madras, on grounds Lambton The hypotenuse of the second triangle conducted regularly. has chosen carefully “the country best becomes a base for the next triangle. suited for this measurement…St Thomas’ In this way the triangulation moves No scope for error Mount…an entire flat, without any hilltop to hilltop, over 36 stations. The Great Theodolite, the main Early Triangulation Map impediment for nearly eight miles, Lambton reports that the work has instrument with which the angles are On April 10 1802, Lambton began his first triangulation, starting at the Marina Beach commencing at the race ground and “been conducted with every possible observed, receives special attention. Each in Madras. He carefully laid the baseline for extending southerly”. attention”. and every aspect is tested: the semicircle; the measurement of the length of a degree The region selected is politically line of collimation; values of revolutions; of latitude along a longitude in the middle friendly and supportive of the endeavour: divisions on the micrometer in the of peninsular India, at St Thomas’ Mount Fort St George in Madras has been a eyepiece of the . in Madras. British base since 1640. The surrounding countryside is perfect for the exercise, dotted with droogs (hills) that offer convenient vantage points so essential for triangulation. The Brihadeshwara Temple, Tanjore The Survey will begin by determining Moving down the coast to the Kaveri river, the survey the length of a degree, between two runs out of mountains. However, Lambton discovers and two longitudes - measuring another type of rock formation: the magnificent north-south and east-west. domes of carved rock temples, which tower over Two seas will be connected by actual endless waves of coconut palms. Winches, hoists measurement, the Bay of Bengal in the and ropes come into play. The sensitive, delicate Great Theodolite, which weighs half a tonne without east and the Arabian Sea in the west. packing, is exalted to a supreme position on the Triangle by triangle, a mathematical temple gopuram, with the blessings of the priests. mesh will cover the entire subcontinent. As many as ten magnificent temples lend their This will become the base for all other gopurams to the Great Theodolite. Then, at the surveys, which can then be accurately Brihadeswara Temple, the holding rope breaks. extended in any direction and to any The Theodolite slams against the rock and its finely distance. Fort St. George Madras calibrated circle is destroyed. Lambton picks up The earliest British settlement in India the pieces. Retreating to a tent in the ordnance The first triangles: “as perfect a thing establishment at Trichinopoly and forbidding entry of the kind as has yet been executed…” to all except technical assistants, he reinstates the theodolite in six weeks, restoring all its former accuracy. 10 April to 22 May 1802: The base of the first triangle is measured - 1 a stretch of 7 ⁄2 miles (12 km). Page from The Trignometrical Survey Lambton's notebook The Chain of the Peninsula of India pertaining to the The 100 ft chain that was used by Lambton, under the Supertendence measurement of the to measure the first baseline. This British-made of Major W Lambton baseline at Tanjore. chain was intended for the Emperor of China, 33rd Regiment foot. but by circumstance, ended up in the possession of Dr. Dinwiddie, who then sold it to Lambton.

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So dear to Lambton, no one else may handle it. THE EXHIBIT 21

Specially commissioned by Lambton from and the ship carrying it is captured by a top of the Brihadeswara temple, Tanjore. of order from continual use”, and it is Cary of England, instrument makers par French frigate but released, “in the Lambton restores it to its original accuracy. badly in need of rest and repair. The excellence, the 36” theodolite is a machine interests of science”. The second is a sudden storm that sends grand old instrument is sent for of many enthralling parts. It is fitted with The Great Theodolite is a giant, the tent crashing down on the instrument. renovation to the workshop in Calcutta. a 36” horizontal circle, 18” vertical circle weighing half a tonne. When Lambton In its 28th year, Everest finds “the delicate And put back on the field for principal THEODOLITE The great and 5 verniers. The readings are so fine, takes delivery of the equipment at screws of the levels are all more or less out triangulation for another three decades. they have to be read through microscopes Pondicherry in, he needs more than 12 fitted on each circle. coolies to port it. Levelling Instuements “A very noble piece of workmanship” An illustrious history Incorporating a spirit level and telescope, were used for the The circle of the theodolite is divided with The theodolite suffers two measuring the rise and fall of the great accuracy. In almost all respects it is a accidents. The first accident ground along the baseline. replica of the instrument made by is a fall as it breaks its Distances could be roughly measured Ramsden for the famous holding rope while by pushing a perambulator equipped of Great Britain. being hoisted to the with a milometer. The theodolite is shipped to India at a time when England and France are competing for territory in the East Lambton’s Great Theodolite Built by William Cary, a noted English manufacturer weighs half a ton. It was shipped from England, but the ship was captured by the French. However when the french authorities realised what it was, it was repacked and forwarded to India.

Theodolite designed by Everest The legend on this drawing reads: Drawings illustrative of the 3 feet Theodolite designed by Lieut. Colonel Everest and constructed under his superintedence by Messers H. Barrow for the G. T. Survey of India.

Astronomical Circle The Stop was constructed Three Feet Theodolite by Moshin Khan, in a tiny Drawings illustrative of workshop in the back the three feet Theodolite streets of Calcutta. constructed for the H. E. Company by Messers Houghton & Simms.

Three Feet Theodolite Drawings illustrative of the three feet Theodolite constructed for the H. E. Company by Messers Houghton & Simms.

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A non-stop field display of scientific ingenuity and imagination THE EXHIBIT 23

Lambton's genius to rights. When the large theodolite by A view that changes the entire that the atmospheric properties of the temples - and Everest to construct heights. Nothing appears to daunt the survey. Troughton was found at first trial unfit for schedule of operations night are better for vision. The Despite the substantial additional expense, Dramatic solutions and inventions are the work, he rectified its defects. When the Despite innumerable difficulties, Lambton atmosphere is much clearer and, what’s towers are constructed in various sizes order of the day. Lambton’s genius in this cranes were unavailable for…raising large has always insisted on working during the more, light is visible over greater and shapes depending on the terrain and respect has already become folklore - of a theodolites to the summits of the observing rainy season. The rain settles the usual distances, enabling the sighting of availability of materials. At the extremities INSTRUMENTATION Inspired larger-than-life figure who could resurrect towers, he constructed others…” haze of the atmosphere, clearing vision. longer angles. of the Calcutta baseline, towers are built even the Great Theodolite. Everest, the Mohsin’s greatest achievement is But this is also the time for pestilence, From here onwards, Everest prefers the 75 feet high to match the elevations of more flamboyant inventor and innovator, dividing the horizontal circles in 1839, a malarial and deadly. On his first night to day. Taking advantage of the night the telegraph towers which are used for creates and improvises on the field. job refused by Barrow, the Mathematical assignment in the flat treeless Deccan air, the Survey begins to work in the observation. For the flat Gangetic plains, Instrument Maker at Calcutta. A delicate plateau, Everest arrives at a solution that healthier dry season. This means eight Everest deploys his civil engineering The uphill task of ensuring operation, with no alters the entire schedule of operations. months in the field as opposed to the earlier skills to design 14 towers, down to the hairline precision precedent in India, it four. And, a greater chance of survival. smallest detail. The surveyors are passionate about their takes Mohsin two and Surveying by the clear light of night For hoisting the theodolite to the tops instruments as these are ported from a half years to execute. Observing a torch lit at a distant station, Tall orders all over the countryside of towers, Everest designs and fabricates height to height. The instruments must be The results are from a specially constructed 20-feet high The lack of natural elevations leads his own crane. The ones available are not maintained in mint condition, despite totally satisfactory. stone tower, Everest is delighted to find Lambton to use the tops of towering good enough... rocky journeys, by palanquin, bullock cart, camel or elephant back. By 1832, Everest has begun to carry the Chronometer workshop with him, consisting of the Manufactured by A Johannsen “artist” Mohsin Hussain, the carpenter & Co, makers to the admirality of the Indian Government and Royal Navies Ram Dheen and a blacksmith. of Italy, Spain and Portugal, 1894, Minories, . The Everest theodolites Everest modifies and improves theodolites Micrometer continuously. He prevails upon Troughton This was attached to the Colby's compensation and Simms to make a 14 inch theodolite bar to measure fire variation in length. based on his design, a stable and easy to The Compensation Bar was introduced by handle instrument, ideal for revenue George Everest to replace the chain. It was surveys. He also gets 18 inch theodolites developed by Thomas Colby, the Ordanance Crane Survey’s Surveyor General who was entrusted manufactured from London, in addition Drawing descriptive of the with the surveying of Ireland. to the one Mohsin Hussain makes, crane constucted for raising almost wholly with local materials. the Theodolite to the tops of the station towers of the Great The uphill task of ensuring Trignometrical Survey of India. hairline precision The surveyors are passionate about their theodolites, zenith sectors, measuring chains, transits, watchful and protective as these are ported from height to height. No error is tolerated. The instruments must be maintained in mint condition, despite rocky journeys, by palanquin, bullock cart, camel or elephant back.

The indispensable Mathematical Instrument Maker Mohsin Hussain, a watch maker from a jeweller’s shop in Madras, is game for any challenge. Everest is gushing in his praise: Flare “Whenever any portion of the complicated Each Flare was sealed into a Scaffolding base-line apparatus was deranged he put it sheep’s bladder and was made Perspective drawing of locally. The recipe involved scaffolding used in the sulphur, nitre, arsenic and approximate operations Strange’s Zenith Sector No. 1 indigo in a specified ratio. of the Great Arc Series Though similar to the Zenith Sector used A flare weighed upto 3 pounds. in 1833-34. by Everest and Waugh, it is smaller in size. (It was manufactured in 1866.)

THE SURVEY OF INDIA