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Technical Note

Please note that full-text searching for the digitized texts in our collections is based on uncorrected OCR (Optical Character Recognition) results. Any recognition errors can affect your search results. Some older publications are especially difficult for OCR software to read accurately. In particular, texts with the following characteristics are prone to error:

  • Hand-written texts, including engraved script on illustration pages.
  • Texts that contain diacritics.
  • Texts that contain non-Roman characters or ligatures.
  • Texts that contain obsolete characters (including the “long S” [looks like an “f”] commonly used in eighteenth century printing).
  • Texts that are printed in atypical fonts difficult for the software to differentiate.
  • Texts that shift fonts within a page including ornamental initials and some italics, for example).
  • Texts appearing on irregularly discolored paper.
  • Texts exhibiting extreme inking variations on the printed page.

In some cases, accuracy for such texts is so low that we have decided not to attempt to provide full-text searching. Full text is not available for Catesby’sNatural History, Caylus’ Recueil d’antiquities, Halfpenny’s Useful Architecture, and Johnson’s One Hundred and Fifty New Designs. Use the “Display Page Text” option to see the underlying OCR results, if available.