This week, I am kicking off by sharing a story I didn’t learn about until I had worked in the software industry for 20 years: how computing came about. Many of us know the story of Bill Gates and Paul Allen creating Microsoft or Steve Jobs licensing Xerox Parc’s technology to bring GUI to the masses. Too few of us know about their distant forerunners: Nevil Maskelyne, Charles Babbage, Claude Shannon, Alan Turing, or John von Neumann.
The Original Computers
Before electronic computers, Computer was a job title held by humans.
There is a rich history of humans as computers dating back to at least Mesopotamia in 3000 BC. Donald Knuth, who is famous for The Art of Computer Programming, chronicles the story in his research paper Ancient Babylonian Algorithms. We know the Babylonians were working with algorithms, because they wrote them down on tablets. Knuth writes, “they represented each formula by a step-by-step list of rules for its evaluation. In effect, they worked with a ‘machine language’ representation of formulas instead of a symbolic language. The calculations described in Babylonian tablets are not merely the solutions to specific individual problems: they actually are general procedures for solving a whole class of problems.”
The Babylonians gave example numbers in their calculations, a lineage we can give thanks to anytime we use a REPL. The Babylonians did not explore all possible avenues; Knuth found no usage of control flow or iteration. It would take time for algorithms and computation to develop more fully.
Organizing Human Computers
Computing would have to become more crucial and more expensive before humans would be motivated enough to outsource computation as a job. The seeds were planted centuries ago.
Dating back to 1497, sailors were calculating their latitude from the North Star, but calculating longitude required delicate timekeeping devices that would be damaged on a ship rocking at sea. The British government enacted The Longitude Act of 1714, encouraging entrepreneurs and scientists to devise a means for calculating longitude.
Nevil Maskelyne, an astronomer and also an appointee to England’s Board of Longitude, wrote the volume pictured here: The British Mariner’s Guide. It laid out how you could calculate longitude by lunar distance. The problem then became knowing where the moon was on any given day. Thanks to Kepler and Newton this was largely a matter of math.
Tabulating the Heavens tells the story: “The Nautical Almanac and Astronomical Ephemeris, was to be published annually giving data relating to a particular year. It contained tables of lunar distances tabulated for every three hours of every day. It also contained other astronomical data of use to both the navigator and the astronomer.”
Maskelyne organized a network of at least 35 human computers each working from their homes on their own timetable throughout England. Computing started as a literal cottage industry. Maskelyne did not send all the equations that underpinned the almanac to each computer, but rather sent them a list of steps to extract data from several tables. A typical calculation would involve 12 table lookups and about 14 arithmetic operations on eight digit numbers. Each month’s table involved up to 1,365 cells to be calculated.
The almanac was used by several famous explorers, including Captain Cook during his voyage to New Zealand in 1768 and again in 1772.
The work of Isaac Newton, Nevil Maskelyne and Halley (not discussed here, but also a pioneering computer) was not without its critics. The famous book Gulliver’s Travels is actually a critical satire of the perceived arrogance of these computers.
The French Angle
The story of distributing computation across humans doesn’t stop with Maskelyne’s almanac. He would encounter and influence another crucial computing pioneer. That story picks up on the other side of the English Channel, in revolutionary France. In 1791, the new regime wanted to shed all memory of “old” way of doing things, and the Académie des Sciences decided to create a new system of weights and measures. The new units were all based on the metric principle: they would be related through a measure of ten: 10 centimeters in a decimeter, 10 decimeters in a meter and so on. One of the units that needed addressing was angle measurement. Under the new system, a right angle would no longer have 90 degrees. Instead, it would be split into exactly a hundred of new units, called grades.
If the new angle units were to be successful, someone had to publish trigonometric tables in book form. The Académie des Sciences wanted the work done and the job fell on the shoulders of Gaspard de Prony, the director of the Bureau of Land Management.
De Prony quickly realized that a single person wouldn’t even come close to completing the work before the deadline. Fortunately, he had met Maskelyne and was aware of his work.
Moreover, as was common among his social circle at the time, de Prony was a big fan of Adam Smith and his “On Wealth of Nations”. De Prony bragged he “could manufacture logarithms as easily as one manufactures pins”: a nod to Adam Smith’s division of labor theory.
The computation was organized in 3 levels:
The first level consisted of 5-6 high-ranking mathematicians, including such paragons as Adrien-Marie Legendre (of the Legendre polynomial and Legendre transform fame) and Lazare-Nicolas-Marguerite Carnot. This group had nothing to do with the actual computations, their job was to oversee the process and to choose the analytical approximation formulas. The resulting equations only contained additions, subtractions and multiplications. That meant that even people with rudimentary arithmetic skills could master them.
The second level had 6-8 lesser mathematicians, whom de Prony called “planners”. Planners had two jobs. First, they used the formulas, devised by the high-ranking mathematicians, to create worksheets. The sheets had exact instructions for a simple computation on one side, and a table of input values on the other, followed by the blanks to be computed and filled in. The second job, called “differencing”, involved looking at the differences between the adjacent values of any given function. As all trigonometric functions are continuous, subsequent values in the table should be close to each other. This allowed planners to check the result of a computation, without redoing it.
The third group, the actual computers, up to 90 in their number, were the ones filling the worksheets prepared for them by the planners. As the computations were trivial, anyone with a basic knowledge of arithmetic and decent mechanical skills could be a computer. In fact, most de Prony’s computers were… out-of-work hairdressers! As the result of the revolution, the demand on powder wigs had collapsed, and many well educated coiffeurs were looking for something new to do.
There is an interesting parallel here: the de Prony’s planners were basically translating mathematical equations into the instructions for “computers”. In a way, this represents the work of a modern programmer. One coder-friend jokingly remarked, ‘my job is translating research papers into computer code.’ Not unlike a planner of 1792 indeed.
Du Prony was still operating the computing enterprise until 1801. By then, saddled by high inflation, the revolutionary government did not have the funds to publish the tables. However, the work would catch the eye of Charles Babbage, most likely when he visited Paris in 1819, but also because De Prony had reached out to several English physicians who Babbage was connected to.
Read issue 2, which picks up where we left off: the story of Charles Babbage and how computation went from a job for humans to a job for mechanical computers. As time goes forward human computers fade by volume, but the intertwined nature of humans and computing lives on to this day. For example, every time you fill out a CAPTCHA you are a human computer providing gold data back to electronic computers.
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Credits and More Reading
My friend Max Grigorev was instrumental in encouraging me to work on engineering topics, and helped with the writing of this issue.
Our research was greatly aided by Jame Gleick’s The Information. If you want to learn more about the history of computation and information theory, I cannot think of a better place to start. When Computers Were Human was also heavily cited for this issue. We only covered a fraction of human computer history. This book is an incredible read if you want to explore deeper.
Special thanks to Jimmy Soni, author of A Mind at Play: How Claude Shannon Invented the Information Age, for encouraging my choice of format and pacing. I am also grateful to Maran Nelson, Fawaz Al-Matrouk, and several others for providing early feedback on drafts. Any mistakes or omissions are my fault, not theirs.
Also if you love it, please let your friends know. In later weeks, I’ll be working on original research outside the history of computation (problem solving, debugging, static analysis, and more). If you have suggestions write us at email@example.com.
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