Circa 1850

Maintaining accuracy in the tedious calculation of mathematical tables was difficult enough, but proofreading the tables before they were printed or after they were set in type was perhaps even more difficult, and it was possible to introduce errors at each step of the process. The use of flong for producing stereotype printing plates in the 19th century provided a particular advantage for the publication of mathematical tables, as well as other publications, since stereotype plates represented “an immutable form of information capture that offered immunity from the inherent vulnerability of movable type to derangement during printing or storage” (Doron Swade, “The ‘Unerring Certainty of Mechanical Agency’: Machines and Table Making in the Nineteenth Century,” Campbell-Kelly [ed.] *The History of Mathematical Tables *[2003] 148).

With maintaining the accuracy of mathematical tables always in mind, Charles Babbage designed his Difference Engine No. 2 to stamp tables automatically into flong so that the tables could be printed accurately without having to typeset them and inevitably introduce errors during the typesetting and proofreading process.