Show Notes 2/16/25: Measuring Mountains

In this week's show, we mentioned that the Indian subcontinent was measured and mapped using a tool called Gunter's chain. This was a device invented by a clergyman and mathematician named Edmund Gunter. It's a 66-foot-long measuring device consisting of 100 links. Measurements obtained with this device gave us units like the furlong, mild, and acre. Here is a Gunter's chain.

As we also mentioned, you can't really use measuring chains for mountains. For that you need a tool that measures distances and angles so that you, the surveyor who knows math, can use trigonometry to turn those measurements into heights (fyi the official name of the British mapping effort was called The Great Trigonometrical Survey so they knew what they were getting into). The tool they used is called a theodolite. They're still used today in surveying, but they've gotten much smaller, lighter, and electronic. The ones the British carried around India weighed over 500 pounds. Here's a theodolite schematic and an old example.