Nineteenth-century periodicals significantly outnumber books from that era, and present historians with an immensely valuable set of sources, but their use is constrained by the difficulty of identifying relevant material. For many periodicals, contents pages and volume indexes have been the only guide, and the few subject indexes that exist usually provide only an indication of the subjects mentioned in the article titles. By contrast, the Science in the Nineteenth-Century Periodical project (SciPer) indexed the science content of general-interest periodicals by skim-reading the entire text. The project’s approach to indexing is described and the relative merits of indexing and digitization in aiding researchers to locate relevant material are discussed. The article concludes that, notwithstanding the more sophisticated search interfaces of more recent retrodigitization projects, human indexing still has an important role to play in providing access to the content of historic periodicals and in mapping their data structure
