Why did one library book have several catalog cards?

One book could be found through more than one question: Who wrote it? What was it called? What was it about? Catalog entries under different headings gave readers different routes to the same work. The extra entries were useful because a reader who remembered the title might not know the author, while someone researching a subject might know neither. Counting cards, therefore, was not the same as counting books.^[1][2]

Charles A. Cutter put those three starting points near the beginning of his 1891 Rules for a Dictionary Catalogue. He also wanted a catalog to show what a library held by an author or about a subject, and help readers choose an edition. His opening discussion distinguished shorter finding lists from fuller descriptions, recognizing that different libraries needed different amounts of detail.^[2]

A different heading changed the route

Imagine three readers approaching the same gardening book. One remembers its writer, another remembers its title, and the third wants advice about roses. The diagram shows their possible starting points. This is a hypothetical example, not a reconstruction of an actual catalog record. It illustrates why additional entries mattered without implying that every book received exactly three cards, or that every library used identical rules.^[1][2]

At the Library of Congress, author, title and subject cards were interfiled alphabetically. They were not necessarily three separate cabinets. The heading told the reader where to start looking. Subject searches also depended on the catalog’s chosen vocabulary: its guide explains that older cooking material appears under Cookery. Knowing an everyday word did not always mean knowing the heading that would lead to the desired books.^[1]

An extra card could do another job

The photographed University of Michigan card below adds an important wrinkle. It names Jacques Derrida and the 1976 American edition of Of Grammatology, then identifies itself as Card 2. Its printed instructions concern additional copies in other libraries. Under Undergraduate Library appears a call number. This is a continuation of location information, not evidence that the card was a second title or subject entry.^[3]

Read that card from top to bottom and its jobs separate clearly: identify the work and edition, explain why the extra card exists, then record a library and number. The visible instructions say numbers are supplied when they differ from the first card. A numeral on a card consequently needs context; it cannot tell you, by itself, how many search headings or physical copies existed.^[3]

A shopping catalog helped you choose something to order; these drawers helped you find something a library held. That difference changes how to read the entries. Start with the heading to understand the search route, then inspect the edition, location and any continuation instructions. The card’s position and its contents work together, rather than each piece of cardboard representing one separate book.^[1][2][3]

Do you remember searching by an author, a title, or a subject?