Doris Baron with Manometer tape. Before the development of electronic computers, the term "computer" referred to people, not machines. It was a job title, designating someone who performed mathematical equations and calculations by hand. The majority of computing work involved three components: reading film, running calculations, and plotting data. During wind tunnel tests, manometer boards measured pressure changes using liquid-filled tubes. Computers "read" photographic films of the manometer readings, and recorded the data on worksheets. Working one on one for an engineer, or collectively in a computing section, computers then ran different types of calculations to analyze the data, and plotted the results on graph paper. All this work was done by hand, using slide rules, curves, magnifying glasses and basic calculating machines. Once completed, the calculations, graphs and other information were checked for accuracy and sent back to the engineers to design the next tests.