How Snell measured Earth with a chain of triangles

Snell measured Earth using a chain of 33 triangles

33 triangles

In 1615, Willebrord Snell measured about 70 miles between two Dutch towns using a chain of 33 triangles. The towns were about one degree of latitude apart, so he could use that distance to estimate the size of Earth's full circumference.

Octopuses can walk while pretending to drift

Some octopuses move using only two arms while making themselves look like pieces of drifting plants. This lets them move away from predators while staying hidden instead of simply swimming away.

Andeans developed larger lungs for life at high altitude

Roughly One-Third Greater Lung Capacity

People living high in the Andes adapted to low oxygen in several ways: larger lungs, more blood, more hemoglobin, and more tiny blood vessels. Compared with other humans, Andeans had about two liters more blood and twice as much hemoglobin.

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How Snell measured Earth with a chain of triangles

Snell measured Earth using a chain of 33 triangles

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