Hairdressers, Part Two: Personal Computers

       The Secret Life of Hairdressers continues with Part Two today. I'm not any more obsessed with hair than anyone else. Really. Once when we were living in Switzerland, the hairdresser touched my hair and exclaimed in delight about how thick and strong my hair was. This sounds nice, but actually it made me feel like a freak. I could tell she was using the "scientist" tone of voice, which is the mesmerized tone one uses when discovering something interesting. Like, say, a two-headed tadpole or some other mutant beast. A long time ago, in a land far away, I was also once a scientist so I recognized that tone of voice instantly.

        My suspicions were confirmed when she asked if she could take one of my hairs for "testing," reassuring me that it would only take a minute. I said yes. She was as excited as a puppy under a Christmas tree. She took the hair over to a device on the counter. She clamped the two ends of the hair so that it was held taut. There was a magnifying glass and ruler to measure the hair's diameter. The machine slowly and gently stretched the hair until the breaking point, just like a miniature medieval torture rack. She noted down all the data, then turned to me. Her forehead was shining with sweat, her eyes were agleam. She was breathless. "This," she whispered, "is the thickest, strongest hair I have ever measured." Then she asked if she could have another hair, as a souvenir. I said yes. I wondered what her hair collection looked like. My family also appreciates my hair. "Wire hair" they call it, with that affectionate, teasing tone of voice that family members use with each other. But I don't have a complex about my hair. Really.

Gaspard Riche, the Baron de Prony (1755-1839).
French mathematician and hairdresser recruiter.

       The MISPFRUH Award, for the Most Innovative Scheme for Post-French Revolution Unemployed Hairdressers, has to go to the French mathematician Gaspard Riche, also known as the Baron de Prony. He was in charge of calculating mathematical tables for a huge land survey, the Cadastre. The government was keen to have comprehensive tables, for they could be used not only for surveying (and thus taxation), but also for astronomy, engineering, and navigation. Prony was initially daunted by the task of calculating these tables (from the numbers 0 to 100,000 to nineteen decimal places, and the numbers from 100,000 to 200,000 to twenty-four decimal places). It was so immense that even all the mathematicians in France would not be able to complete it. What to do?

       In a flash of inspiration after reading about the idea of "the division of labour" in Adam Smith's book "The Wealth of Nations," Prony saw that the job of compiling these tables could be divided up into two separate tasks: mechanical calculation, which did not necessarily require any previous math background, and verification or supervision, which required the skills of mathematicians. If he could train enough workers to grind out the mechanical calculations, relatively few mathematicians would be necessary to carry out the verification and supervision roles, and the job would be done that much sooner. Where to recruit these workers?

Hairdressers, 

        After the French Revolution, fancy, aristocratic hairstyles (see previous post) were definitely out of fashion. This led to high unemployment among hairdressers, and that is where Prony decided to recruit his "computers". The hairdressers had hardly any knowledge of mathematics (many could only add and subtract), and did not have any special interest in science. However, Prony trained them to methodically and mechanically go through a series of calculating steps, on worksheets with a blank space to fill in at the end of each line. It reminds me of our tax forms, but probably Prony's worksheets were even simpler.

...plus Worksheets...

        The hairdressers could take the worksheets home, and when the work was done, they would bring them in to be checked by mathematicians. This is like the cottage industry of piecework sewing that can be completed at home and then brought in to a central location for inspection. In the book "When Computers Were Human," the author D.A. Grier says these trained computers were "little different from manual workers and could not discern whether they were computing trigonometric functions, logarithms, or the orbit of Halley's comet." This model of labour, armies of trained workers grinding out a product for higher ups, can be found today, not only in factories, but also in university graduate schools.

...equals Calculators...

...and Computers.
Babbage's Difference Engine #2, now at the Science Museum in London

       Charles Babbage (1791-1871) was an English inventor who taught himself algebra, became a Cambridge math professor, married for love, and invented the cowcatcher on the front of steam locomotives. He is probably best known now as the "father of the computer," for he realized that if Prony's hairdressers could churn out mathematical data, then a mechanical machine could do it too. He worked for years on designs for a "Difference Engine" that could calculate results to 31 digits, and on an "Analytical Engine" that could be programmed using punch cards. The next time you use your calculator or computer, thank your hairdresser!