I have a French UI set up, and GIMP is in French too. Looking here, inches are – pouces. Turns out in French an inch is a pouce, which translates as thumb, the phalanx of the thumb. In Spanish — pulgada. It’s purported to stem from Latin, with the same root as the French.
I decided to see what an inch is in Russian. Turns out, it’s also thumb, but from Dutch, from where the word thumb originates as well.
It is commonly believed that an inch was originally defined as the length of the phalanx of the thumb. According to other legends, an inch was defined as 1/36 of a yard, which in turn was set as the distance between the tip of the nose and the thumb of an outstretched arm of King Henry I of England (there’s also a version that the yard was the length of his sword).
The funny thing is, in the USA, where inches are most commonly used worldwide, a completely different word is used, inch, which comes from uncia, 1/12 part, in this case — of a foot. Meanwhile, the French word pouce resembles the Greek word pous, which means “foot,” but the etymology of the French clearly connects pouce with the Latin pollicis, meaning related to the thumb.
But that’s not all. Feet are different for everyone. Clearly, only one type is in use now, but there was once the Viennese inch (26.340278mm), the Spanish inch deemed to be 23.2166mm, and a whole bunch more. The Spanish inches were demarcated between continental Spain (23.2166mm) and Mexico (23.278mm). In Germany, nearly every region had its own inch. For instance, in Baden it was 3 cm, and in Saxony 2.36 cm. In Canadian Quebec, the French inch was used, but since 1985 (recently!) its value changed to 2.707005 cm. In the USA since 1958, the American inch has been equated with 2.54 cm.
The British inch, which stabilized in 1958 and became the basis for the internationally recognized standard, changed five times. Perhaps feet were growing. For example, in 1819 it was 1000000/393694 cm ≈ 2.5400438 cm, and then slightly reduced it was adjusted four more times in the sixth digit after the decimal point.
Also, interestingly, for the French inch, which is pouce, there is a formula – 75000/27706 mm, which gives approximately 2.706995.
Also interestingly, if you see pipes by GOST standards marked 1/2″, they would be 21.3mm in millimeters, and a 5″ pipe — 140mm. Attempting to calculate the conversion coefficient reveals that “pipe inches” vary for different pipe diameters and are moreover larger than the standard inch value of 25.4mm.
So, in the homeland of inches, an inch is defined as part of the foot, and outside the homeland of inches — as part of the hand 🙂
Hi, I'm Rauf Aliev. 