"When we introduced the Ngram Viewer, we pointed out some potential pitfalls with the data. For instance, the 'medial s' ( ſ ), an older form of the letter s that looked like an integral sign and appeared in the beginning or middle of words, tends to be classified as an instance of the letter 'f' by the OCR algorithm used to create our version of the data. Andrew West, blogging at Babelstone, found a clever way to exploit this error: using queries like 'husband' and 'hufband' to study the history of medial s typography, he pinned down the precise moment when the medial s disappeared from English (around 1800), French (1780), and Spanish (1760)."
16 August 2011
On historical typography: