Releasing June 2025!

India in Triangles: The Incredible Story of How India was Mapped and the Himalayas Measured |

Explore the History and Science Behind The Great Trigonometrical Survey | Ages 11+

Authors: Shruthi Rao and Meera Iyer

Cover art: Mohith O; Cover design: Samir Bansal

Published by: Penguin Random House India

Nineteenth-century India

+ dedicated men

+ simple instruments

+ lots of paper

= One of the greatest scientific undertakings in history.

Step into the boots of fearless surveyors as they trek across forests, mountains and monsoons—facing disease, wild animals and gruelling terrain—to chart the subcontinent with astonishing precision.

This was the Great Trigonometrical Survey, an ambitious mission to map India using triangulation—a brilliant method that helped them measure every inch with accuracy. Along the way, they calculated the height of the world’s tallest mountain and revealed the true shape of the earth.

Packed with adventure, ingenuity, mishaps and the unsung heroes of science, this is the epic true story of mathematics, grit and discovery.