The British came to India in 1808 for starting the "Great Trigonometric Survey" in order to find out the name and geographic location of the tallest mountains in the world. They began in southern regions of India, and the teams which came for survey slowly proceeded towards northern regions of India using elephantine 1,100 lb transits (which required 12 men for carrying each of them) for calculating the heights in a perfect way. They were able to reach the foothills of the Himalayan Mountains during 1830. Nepal was reluctant to permit British people to get into their country since they were suspicious about the political hostility and potential appropriation by them.

So, the British were constrained to pursue their survey from Terai which is a region that is parallel to Himalayas Mountains and south of Nepal. However, the British crusaded on and commenced elaborate survey of Himalayan mountain peaks from the observation centers up to one hundred and fifty miles far. During 1847, in the month of November, the acting surveyor general in India, Andrew Waugh recorded number of findings from Sawajpore center for observation which was present in the eastern regions of the Himalayan mountain ranges. During that time, the highest peak of earth was considered to be Kanchenjunga and due to curiosity, he observed a peak that was behind it at a distance of one hundred and forty miles. One of the officials of Andrew Waugh, John Armstrong, also located to peak in western side and named it as peak'b'. Waugh discharged James Nicolson to that region in 1849. Nicolson made two findings from Jirol which was one hundred and twenty miles away. Nicolson, was then carried the worlds biggest transit and moved towards east, found another thirty observations from 5 various spots, with the nearest one being at a distance of one hundred and eight miles from the peak.

Nicolson moved back to Patna on Ganges in order to make the required computations based on his finding. His rough data handed an average altitude of 9,200 meters (30,000 feet) for peak 'b'. The refraction of light which can distort the height was not considered for this calculation. The measure precisely showed that peak 'b' was definitely taller than Kanchenjunga. Regrettably, Nicolson suffered from malaria and was pressed to come back home, with the computation incomplete. One of the assistants of Waugh, Michael Hennessy had already started denominating the mountain peaks by using Roman numbers, with Kanchenjunga given a name as Peak IX and peak 'b' was designated as Peak XV.

Mount Everest was recognized as the tallest peak by a Mathematician from India, Radhanth Sikdar along with a Bengal surveyor in 1852, at the headquarters of Survey located in Dehradun. The announcement officially that Peak XV is the tallest was detained for few years as the computations were re-checked again and again. Waugh started to work on the data gathered by Nicolson in 1854, and his employees worked with him for nearly two years on the computations, with issues related to light interaction, temperature, barometric pressure over wide range of findings. Eventually, he declared his observations in a letter to his assistant in Kolkata.

Kanchenjunga was announced to have a height of 28,156 feet (8,582 meters), and Peak XV was having an altitude of 29,002 feet (8,840 meters). Waugh resolved that Peak XV was the tallest mountain peak in the world.