The history behind the units.
Why is a mile 5,280 feet, a US gallon smaller than a British one, and water’s freezing point 32 °F? Short, sourced stories that make conversions easier to remember.
- 5 min readHow the meter and the metric system beganFrom a survey of France in the 1790s to a definition based on the speed of light: the surprising story of the meter, the kilogram and the SI.Read
- 5 min readWhy the US still uses feet, pounds and gallonsThe US legalized the metric system in 1866 and has defined the foot in meters since 1893. So why do road signs still say miles? A short history.Read
- 5 min readWhere the inch, foot, yard and mile came fromBarleycorns, Roman paces and a 1959 agreement that finally fixed the inch at exactly 2.54 cm. The history behind everyday US length units.Read
- 5 min readFahrenheit, Celsius and Kelvin: the story of three scalesWhy water freezes at 32 °F, why Celsius once ran upside down, and how Kelvin found the bottom of the scale. The history of temperature units.Read
- 5 min readThe pound and the kilogram: a history of weightFrom the Roman libra to a metal cylinder in a vault near Paris, and finally to a constant of nature. How the pound and the kilogram were defined.Read
- 4 min readWhy a US gallon is smaller than a British gallonA 1706 wine gallon, an 1824 British reform and a fluid ounce that runs the other way. Why US and imperial volumes differ, and when it matters.Read
- 4 min readAcres and hectares: measuring land through historyAn acre began as a day’s ploughing with oxen; the hectare is a tidy 100 m square. How land was measured, and how the US was laid out in square miles.Read
- 5 min readWhy an hour has 60 minutes and a day 24 hoursEgyptian star clocks, Babylonian base-60 math and atomic clocks: how the hour, the minute and the second came to be, and why leap seconds are ending.Read
- 4 min readKnots and the nautical mile: speed at seaSailors measured speed by counting knots on a rope running out behind the ship. Why ships and aircraft still use knots, and what a nautical mile is.Read