The object of the SciPer Index is to provide a subject index to the scientific, medical, and technical references within periodical articles. While there are already in existence several important indexes to the titles of articles in nineteenth-century periodicals, approached both on a periodical-oriented and on a subject-oriented basis, there are few subject-based indexes of the content of articles. There are obvious reasons for this - most notably that such a venture could easily become prohibitively time-consuming, but also that excessive detail could overwhelm the user with unhelpfully indiscriminate search hits. In this electronic age, the solution to the former might seem to be to digitize the texts of periodical articles. However, digitization cannot solve, and if anything exacerbates, the latter problem. As digitial publishers themselves recognize, only a scholarly reader can reliably identify and index those references in a periodical text which are likely to be of relevance to scholars.
Mindful of these practical difficulties, the SciPer Index is based on an approach to the indexing of scientific material which was at once thorough and selective. In order to identify relevant references, members of the research team read each periodical run in its entirety, however unlikely it seemed to be that any given article would contain pertinent material. The subject area was also conceived as broadly as possible, since one of the objects was to explore both the boundaries of science, technology, and medicine, and the interpenetration of literary and scientific discourse.
The indexers sought to identify and index all material relating to natural knowledge and its applications, and to nature in general, which was deemed to be of particular relevance to the scientific enterprise in the period - whether as illuminating its wider context, or as more especially highlighting the contested form of the enterprise itself. However, generalized descriptions of natural productions, of other races, of health and medicine, of agriculture and landscape, and of the use of technology were generally excluded if they were not considered to have some more particular relevance to science, technology, or medicine, or to have an explicitly scientific frame.
One main criterion for inclusion of material in the SciPer Index was its relevance to the current interests of historians of science and of cultural and literary historians. The object of the index is in part to provide historians with primary source material from the general periodicals which is relevant to their current work. In addition, however, the index is intended to enable scholars to move beyond existing historiographical mores, by providing access to primary source material of types currently unexplored in the literature. For this reason, an alternative criterion for inclusion of material is its relevance to science as it was conceived in its original historical context.
While longer references of scientific relevance were indexed however conventional their contents, more selectivity was applied in indexing brief or passing references. Thus, where a passing reference of scientific relevance was similar in content to many much longer references of the same period and journal, it was omitted from the catalogue, while a passing reference of a more unusual or novel nature was generally included.