The names of theorems, formulas and numbers are a part of notation that almost nobody questions. We write “Pascal’s triangle”, “Pell’s equation”, “L’Hôpital’s rule” as if the name were a neutral label. It is not: the name records who was read, by whom and in what language. A law that confirms itself In 1980 the American statistician Stephen Stigler published a paper with a provocative law: no scientific discovery is named after its original discoverer. And, to round it off, he attributed the law to the sociologist Robert K. Merton, who had already studied the phenomenon. Stigler’s law of eponymy is therefore an example of itself. It exaggerates, but it is right with uncomfortable frequency.
In 1793, at the height of the French Revolution, the National Convention decided that time too would be decimal. The day would have 10 hours, each hour 100 minutes and each minute 100 seconds. Clockmakers made new dials, some with both scales side by side so that people would get used to them. A paper dial presented by the clockmaker Hanin to the National Convention, with the new hours in Arabic numerals and the old ones in Roman numerals, for comparison: “relation of the new hours to the old, adopted by the National Convention”.Hanin · Wikimedia Commons · public domain Decimal time became compulsory at the end of 1794 and was suspended in April 1795, seventeen months after it was decreed. Nobody wanted to change their household clock, church clocks went on striking twelve, and the new time had no practical advantage to make up for the bother. The Republican calendar, with months of 30 days divided into three “decades” of 10, lasted a little longer: Napoleon abolished it at the start of 1806.
The way we write numbers today seems natural because it is the only one we learned. But other cultures solved the same problem, writing quantities and calculating with them, in different ways, and each solution left its mark on what those cultures were able to think. Chinese counting rods For almost two thousand years, Chinese mathematicians calculated with rods: little sticks of bamboo, bone or metal laid out on a board divided into columns. Each column was a decimal place, and a digit from 1 to 5 was made with the same number of rods; from 6 to 9, with one rod worth five plus a few more. So that neighbouring columns would not be confused, the rods alternated position: upright in the units, lying down in the tens, upright again in the hundreds.