ഒരു സർവ്വേ കഥ...!!!

 A survey story ... !!!

 One day in 1819. Lt. George Everest with a large group of 150 people is trapped in a jungle between the Krishna and Godavari rivers. Here you will find spiders as large as small birds, rattlesnakes, wild boar and even tigers. Monsoon clouds are rolling in the sky outside. It can rain at any time. It's not too late. Heavy rain. The trees fell down. The venomous animals lost their nests and started crawling all over the place. The ration of the group which was supposed to come to Musinadi (a tributary of Krishna river) was interrupted. So the food was lost.

 Everest can be reached on the same day near the hill called Sarangapalli opposite the river Krishna. But the accompanying elephants carrying the surveyors do not dare to cross the river. Yet Everest, the team leader, did not give up. He crossed the river in a bamboo boat with 12 of his faithful men. By the time he got there it was well past dark. The rain did not subside at all. And frightening thunder and lightning. Everyone in the group had no food that day and was starving and in the pouring rain. Soon everyone was infected with malaria.

 The event described above is one of the most memorable events in world history. That is the story of Indian mapping known as The Great Trigonometric Survey. As a result of the Fourth Mysore War with Tipu Sultan in 1799, the Kingdom of Mysore came under the control of the East India Company. With that, three-quarters of India itself fell into the hands of the British. Maj. William Lamton, a warlord and surveyor who participated in the war, suggested to the then Governor-General, Lord Wellesley, that a land survey was needed to establish dominance over the occupied territories and to levy taxes. . For that, Lamton came up with a new idea. But at that time no one knew that it was an idea that would change the history of the Indian Empire itself.

 According to this, the survey will not be based solely on the traditional methods of astronomy. Rather, it will be an innovative technology that has been successfully tested in countries such as France and Spain. He assumed that the survey based on the planets would be less accurate and longer in duration. But everyone questioned the impracticality of conducting a survey in an area that stretches from Kanyakumari in the south to the Himalayas in the north, as India is low-lying with many mountains, valleys, craters and forests. But Lamton was optimistic. He did not succumb to opposition. Lord Wellesley also stood by him.

 Triangulation means nothing else. The same trigonometry we learned in schools (sign theta, cos theta). By measuring the distance between two areas (baseline) and understanding the angles from them to a third region, one can find the dimensions of the other angle and sides of the triangle that make it up. For example, we know that the dimensions of a triangle of 45,45,90 degrees are 1: 1: 2. . Thus, considering only one baseline, a chain of many triangles can be formed.

 The area of ​​the triangle thus formed can be calculated by calculating the area of ​​that area. Thus Major Lamton marked the beginning of the triganometric survey on April 10, 1802, calculating a baseline from St. Thomas Mount in Madras to Perumbauk Hill. A baseline measuring 100 feet (30. 5 m) long and 40 links was used to measure the baseline. Also important was the theodelite device. It's nothing more than a large telescope and scalable scales. It used to measure vertical and horizontal angles. . It weighed about half a ton (508kg) and was carried by 12 giants. The group of about 150 consisted of 4 elephants to carry the chiefs of the surveyors, 20 cavalry for security, and 42 camels to carry other survey materials (in the South Indian survey, oxen were used instead of camels).

 The survey, which started on April 10 in Madras, ended on May 22. It took so long to find a baseline that was just 7.5 (12km) miles. . From that, the readers realized how difficult the survey was. However, the survey was conducted with great accuracy. It was also estimated that the survey chain was expanding at a rate of 0. 0007 per degree in the heat of India. In addition, they realized that the total sum of the angles of a triangle would be more than 180 degrees because the earth's surface is round. On top of all this, the survey revealed that for the first time in the world, the equator is larger than other regions and the Earth's celestial shape.

 Let us now return to the beginning of the article. Lt. George Everest, who contracted malaria and was trapped between the Krishna and Godavari rivers at that time, took a complete rest for 2 years due to illness. After Major Lamton's death in 1823, he took over as the new Surveyor General. But again his health deteriorated and he sailed for England in 1825 for treatment. He stayed there for about 5 years. All this time he had not wasted his time. He thought about how to alleviate the difficulties experienced by the survey team.

  The first lightweight and compact theodolite was built in England. In addition, blocks called expansion bars were arranged to reduce the expansion of the metal. Upon his return from England in 1830, Everest thus remedied the deficiencies and introduced a number of reforms. One of them is the gridiron system, which uses a series of triangles to find the surface area. Accordingly, the survey routes from one end of India to the other and converging at 90 degrees were completed. By 1843, a survey of all parts of India had been completed. It covers an area of ​​56997 miles (91728 km) extending from Kanyakumari in the south to Mussoorie in the north of Uttarakhand. In the same year he retired from the Everest service and was replaced by Major Andrew Scott Waugh as Surveyor General.

 One day in 1852, Radhanath Sikder, Scott's chief accountant (then the chief computer - not our modern computer, but a human computer, did the calculations in the survey), appeared before Scott and said, "Sir we have discovered the highest mountain in the world." Today we call that mountain Everest. In 1865, Scott renamed Mount Everest after its old name, Peak 15, in honor of Lt. Everest.

 (Tail piece: The great trigonomteric survey lasted for more than 60 years. There were several casualties in this survey of about 30,000 people.

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