The use of metaphor in popular science is widespread to aid readers’ conceptions of the scientific concepts under discussion. Almost all research in this area has been done by careful close reading of the text(s) in question, but this article describes—for the first time—a digital ‘distant reading’ analysis of popular science, using a system created by a team from Glasgow and Lancaster. This team, as part of the SAMUELS project, has developed semantic tagging software which is based upon the UCREL Semantic Analysis System developed by Lancaster University’s University Centre for Computer Corpus Research on Language, but using the uniquely comprehensive Historical Thesaurus of English (published in 2009 as The Historical Thesaurus of the Oxford English Dictionary) as its knowledge base, in order to provide fine-grained meaning distinctions for use in word-sense disambiguation. In addition to analyzing metaphors in highly abstract book-length popular science texts from physics and mathematics, this article describes the technical underpinning to the system and the methods employed to hone the word-sense disambiguation procedure.