Poking around Google Books (formerly Google Print) this morning and discovered an interesting "oddity".
In old English texts, the lower-case letter ‘s’ when appearing at the start or within a word was written as a sort-of ‘f’ character – more specifically, ſ
Turns out that Google Books can’t cope with this – it reads these as the letter ‘f’, so when searching old texts be sure to accommodate this – for example, searching for impoffible will work and highlight the correct words, but impossible won’t.
It’s hardly an earth-shattering bug, but it’s an interesting note to Google and other would-be book search services to check their OCR software is compatible with 18th century texts!