Today, a story about wool weaving and computers. The University of Houston's College of Engineering presents this series about the machines that make our civilization run, and the people whose ingenuity created them.
Weaving a pattern into cloth is no easy matter. Different shuttles, carrying the weft strands, have to be threaded through the warp strands in a precise order to give the weave its pattern. In 1805 a French engineer named Jacquard invented means for automating that process. He passed a chain of cards, with holes punched in them, in front of a mechanism. The mechanism reached through wherever a hole let it, and picked up a thread. We've used the Jacquard loom principle in textile mills ever since.
Five years later, in 1810, the young Englishman Charles Babbage went to Cambridge to study math and mechanics. In 1816, when he was only 25, he was made a fellow of the Royal Society for his work on calculating-machines and methods. In 1834 he conceived a machine that could be told how to carry out a sequence of calculations. He conceived of programmable computation. He never completed this "analytical engine," as he called it, but he set down all the essential principles of today's digital computers.
Now, back to Jacquard's loom. The key to operating any computer lies in transmitting sequences of on-off commands. Babbage used Jacquard-style punched cards. The presence or absence of a hole communicated a simple on-off command to the machine.
But Babbage's idea went fallow for a long time. Meanwhile, another bright young man, Herman Hollerith, joined the Census Office -- a world of endless copying and tallying. Suppose someone asked, "What percent of our population are Irish immigrants?" How do you get an answer from millions of data sheets?
One person had tried making ink marks on a continuous paper roll. Then Hollerith thought of punching holes in the paper, like a player-piano roll. Holes registered each piece of data mechanically, the way a player piano sounds notes. But that lost the identity of individual records and opened the door to nasty errors.
One day a friend said to Hollerith, "There should be a way to use separate cards with notched edges to keep track of data." Bingo! Hollerith saw it. He developed a system for punching all the data for each person into a single card. If you were a citizen, and literate, one hole went in column 7, row 9. He had a full system working in time for the 1890 census.
If you took up the computer before the 1980s, you too worked with Hollerith cards -- the same size as an 1890 dollar bill. You typed each Fortran command on its own card. Hollerith eventually left the Census Office to form his own company. And today that company bears the name International Business Machines, IBM. It's wondrous to see how ideas turn and change and flow -- Jacquard to Babbage to Hollerith, and Hollerith's company, at length, building fully evolved Babbage engines -- for us all to use.
I'm John Lienhard, at the University of Houston, where we're interested in the way inventive minds work.
Cardwell, D.S.L., Turning Points in Western Technology. Canton, MA: Science History Publications/USA, 1972, pp. 119-121.
Reid-Green, K.S., The History of Census Tabulation. Scientific American, February 1989, pp. 98-103.
From Appleton's Cyclopaedia of Applied Mechanics, 1892