# The Solution of Erathostenes

- Author:
- Ku, Yin Bon (Albert)

**Eratosthenes of Cyrene**(276 - 194 BC) was a Greek scholar who made remarkable discoveries in many different fields. His work on prime numbers, such as

**the sieve of Eratosthenes**, is still important in modern number theory. He also made a surprisingly accurate measurement of the Earth's circumference. Here we are going to present his mechanical solution to double mean proportionals problem: The two red parallel bars are