From ancient times until the 19th century, the same unit of measurement could have different meanings not only in different countries, but also in different cities of the same country! Thus, in Austria in the 15th century, almost every city and even every significant market had its own measures. In Germany, attempts to streamline the system of measures began in the early Middle Ages, but did not lead to anything until the end of the 19th century. In France in the 14th century, an attempt to introduce identical measures throughout the state failed due to the resistance of the ruling princes and bishops. Neither Louis XI in the 15th century, nor Louis XVI at the end of the 18th century were also able to bring measures to uniformity... Only in 1875, an international agreement was finally signed in Paris - the “metric convention” to ensure international uniformity of measurements and improve the metric system of measures . Sometimes, reading books or articles on the Internet, we come across units of measurement from different countries and times that we do not understand. The curious immediately have questions: The pirate drank a pint of beer - how much is this in liters? Thumbelina got her name from the word “inch,” so how tall was this fairy-tale little girl? Bigfoot - Bigfoot got its name for the huge size of its feet, but what is it, a simple foot? How is a nautical mile different from a land mile? How much is it - an oblique fathom in the shoulders? How does it differ from the flywheel fathom? How much does it take to eat a pound of salt? And a bunch of other questions about measurements, to which you will find answers in this book.