Other States

Of trigonometry and towers — and two centuries of history

Measuring tool: Bhola GTS tower near Singur is among those covered by a special project. Photo: Special Arrangement  

Often believed by locals and passersby to be abandoned churches or lighthouses, these lofty towers built of fired bricks can be spotted in and around Kolkata.

Not many are aware that these structures, rising 20 m above the ground, were built to undertake one of the greatest surveys in the 19th century — the Great Trigonometrical Survey (GTS) — aimed at measuring the entire terrain of the Indian subcontinent and the great Himalayan mountain peaks including Mount Everest.

Almost 200 years after the GTS was undertaken, a group of geographers and archaeologists have surveyed 15 such towers spread around 50 km radius of Kolkata under the project, “Legacies of the GTS in West Bengal.”

Keith Lilley, professor of historical geography at Queen’s University Belfast and the principal investigator of the project, said that some towers have survived while some others are soon to be lost forever.

“Restoration of these towers is possible and is also important. What is required is an assessment and consolidation of these structures. These structures have been built on firm ground and have survived almost 200 years,” Prof. Lilley told The Hindu.

Referring to one such tower located in the southern fringes of Kolkata — the Samalia GTS — he said the tower has nearly collapsed. Half of the tower, run over by vegetation, fell in 2011. Researchers who carried out the fieldwork said the locals believe that the tower was a batighar or lighthouse, erected during the colonial period to keep an eye on the countryside.

The Bhola GTS tower near Singur in Hooghly district is thought of as a church by locals. Some locals, however, believe that Nawab Siraj-ud-Daulah built the structure to look out for the Marathas, who plundered parts of Bengal in the 18th century.

M. Satish Kumar, another professor from the Queens University, said multiple narratives centring around these towers were an equally important part of culture as the towers.

“In the earlier times these structures were seen as an imposition of the British Empire on the landscape and were even opposed,” he said, referring to the towers located around Kolkata.

Prof. Satish Kumar, however, added that there was not much opposition for such structures in the Madras Presidency where the population “had better understanding about science” and knew what these structures aimed at.

Bishnupriya Basak , assistant professor in the Department of Archaeology of Calcutta University, who has also been associated with the project, said that mapping was an essential part of colonial rule but it was through this project that the culture of surveying has been documented in such detail. “It is like surveying the surveyors,” she remarked.

There are other fascinating stories about the GTS towers.

Mount Everest, the highest peak in the world, was named George Everest, the first Surveyor General of India who had described the GTS as “perhaps of itself the most herculean undertaking on which any Government ever embarked.”

“George Everest was particularly pleased with the towers erected in the north of the city, now on the Barrackpore Trunk Road, which was referred as Calcutta Baseline for the survey. Interestingly, these towers were built under the guidance of Radhanath Sikdar, a city-based mathematician who played an important role in the survey,” said Rajat Sanyal, also an assistant professor in the Department of Archaeology.

In an attempt to highlight the cultural significance of the heritage, an exhibition titled “Legacies of the GTS in West Bengal” will be organised by the National Library, Kolkata, later this month.

“There are hundreds of thousands of such towers and trigonometrical stations across the sub-continent and a detailed study can bring more awareness about the collective value of these towers and the significance which GTS has not only for India but for the world,” Prof. Lilley said.

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Printable version | Sep 18, 2021 3:46:44 AM | https://www.thehindu.com/news/national/other-states/kolkatas-great-trigonometrical-survey-link-of-trigonometry-and-towers/article21616151.ece

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