The History of Speed Measurement

Speed and Survival

Humans have always cared about speed — how fast a horse could travel, how quickly a ship could cross an ocean, how fast an arrow flew. But measuring speed precisely required both distance and time measurement, which made it one of the later fields of metrology to be formalized.

The Knot at Sea

Sailors in the 16th and 17th centuries measured ship speed using a 'chip log' — a piece of wood tied to a rope with knots tied at regular intervals. The log was thrown overboard and the number of knots that paid out in 30 seconds was counted. This gave speed in 'knots' (nautical miles per hour), a term still used in aviation and maritime navigation today.

mph and km/h

Miles per hour emerged as a practical unit with the railroad age in the 19th century — the first passenger railway (Liverpool to Manchester, 1830) quoted speeds in mph. Kilometers per hour came with the metric system. The first land speed record was officially set in 1898 by Gaston de Chasseloup-Laubat at 39.24 km/h (24.4 mph) in an electric car.

The Sound Barrier

The speed of sound (~343 m/s at sea level, or Mach 1) became culturally significant in the jet age. Chuck Yeager broke the sound barrier on October 14, 1947, in the Bell X-1 rocket plane. 'Mach' numbers are named after Austrian physicist Ernst Mach, who studied shock waves in the 1870s.

The Speed of Light — The Ultimate Limit

Einstein's 1905 special relativity established the speed of light (299,792,458 m/s) as the universe's absolute speed limit. In 1983, the speed of light became the foundation for defining the meter itself — meaning all speed measurement is now ultimately linked to this cosmic constant.