  This research explores temporal concept drift and temporal alignment in
knowledge organization systems (KOS). A comparative analysis is pursued using
the 1910 Library of Congress Subject Headings, 2020 FAST Topical, and automatic
indexing. The use case involves a sample of 90 nineteenth-century Encyclopedia
Britannica entries. The entries were indexed using two approaches: 1) full-text
indexing; 2) Named Entity Recognition was performed upon the entries with
Stanza, Stanford's NLP toolkit, and entities were automatically indexed with
the Helping Interdisciplinary Vocabulary application (HIVE), using both 1910
LCSH and FAST Topical. The analysis focused on three goals: 1) identifying
results that were exclusive to the 1910 LCSH output; 2) identifying terms in
the exclusive set that have been deprecated from the contemporary LCSH,
demonstrating temporal concept drift; and 3) exploring the historical
significance of these deprecated terms. Results confirm that historical
vocabularies can be used to generate anachronistic subject headings
representing conceptual drift across time in KOS and historical resources. A
methodological contribution is made demonstrating how to study changes in KOS
over time and improve the contextualization of historical humanities resources.
