The seven-segment LED display is ubiquitous. But how old do you think the fundamental idea behind it is? You nixie tube fans will be thinking of the vacuum-tube era, but a reader sent us this ...

We’ve been displaying numbers using segmented displays for almost 120 years now, an invention that predates the LEDs that usually power the ubiquitous devices by a half-dozen decades or so.

A common display found on digital watches and readouts that looks like a series of 8s. Each digit is formed by selective illumination of from one to seven separately addressable segments.