40000th

Updated: May 23, 2025

A speck, only 1/25th of an inch in diameter, has, at ten inches from the eye, the same apparent size as an object 1/10000th of an inch in diameter, when magnified 400 times; but forms of living matter abound, the diameter of which is not more than 1/40000th of an inch.

Thomas Henry Huxley - Discourses: Biological and Geological Essays