Primary Sources in Science Classrooms: Computer Science and Programming with Punched Cards (Part 2)

This post was written by Trey Smith, the Library of Congress 2015-16 Science Teacher in Residence. It is the second part of a two-part series written for Computer Science Education Week, December 7-13.

At the beginning of the 19^th century, Charles Babbage imagined, but never built, a general purpose computing machine. By the end of the century, American thinker Herman Hollerith ushered in a new era of computing with a mechanical system that could process and organize data from the 1890 U.S. census. The story of the census and Hollerith’s electric tabulating machine offers a rich opportunity to explore the complexities of computational thinking.

Using the Library’s Primary Source Analysis Tool and a set of primary sources, teachers can introduce students to Hollerith’s electric tabulating machine.

• An 1890 newspaper article describes the census and Hollerith’s invention.
• An 1895 article provides diagrams of the system’s components.
• An 1890 cartoon humorously sheds light on the census-taking process.
• A 1915 photograph shows the creation of a punched card.

A closer look at Hollerith’s system using primary sources reveals similarities with modern computers. For instance, the electric tabulating machine allowed staff to sort and collate data at a rate previously unattainable. Further, the final paragraph of the Railroad Gazette article forecasts how industries could use the system to discover patterns in data over various time scales.

Students might note, however, that Hollerith’s invention did not use binary code. Additionally, while circuits are fundamental to the tabulating machine then and microchips today, the purposes and scales of the circuits in each device are dissimilar.

Students can explore a statistical atlas of the U.S. created using 1890 census data to understand computing during Hollerith’s time. Today’s computers and software allow for the creation of graphs and charts—displayed on screens. In contrast, Hollerith’s system did not have the complexity that students may take for granted. The electric tabulating machine speedily summarized data, but people drew data visualizations by hand.

Students can also learn quite a bit about possibilities for data representation from the statistical atlas. Take a look at page 55. What’s being communicated using the census data?

Hollerith’s machine was used for future censuses. A 1901 letter from Alexander Graham Bell to Mabel Hubbard Bell illustrates how the system required a different kind of thinking. Alexander Bell, who is best known for his telephone inventions, was trying to design punched cards that could collect a special set of data during the next census.

On page 4 of the letter Bell explains, “The thing that is wanted last I must consider first and that which is needed almost immediately should be last in my thoughts.” Students might consider:

• What kind of data did Bell hope to collect?
• Why might he have been interested in this data?

Beyond these questions, however, is a larger question in computer science: How does one translate a problem such that it can be understood by a non-human system that can then provide an answer that makes sense to a human at the end of the process?