4. De Morgan, Periodicals and Encyclopaedias

Through his many books and publications in various periodicals, Augustus De Morgan was a disseminator of mathematics, particularly to the general public. An active member of the Society for the Diffusion of Useful Knowledge, founded by the same people who established University College London, De Morgan was also a great promoter of mathematics via its publications. The most striking example is his significant involvement as a contributor to the Penny Cyclopaedia (27 vols., 1833-1843), for which he authored more than 700 articles on mathematics and astronomy, some of which are very long.

In this chapter we propose to contextualise these articles by comparing them with the mathematical production in other encyclopedic works of the time, such as the well-known Encyclopaedia Brittanica (with its several editions), Rees’ Encyclopaedia (1802-1820), the Edinburgh Encyclopaedia (1808-1830) and the Encyclopedia Metropolitana (1845). Through this comparative study, we will give an overview of De Morgan’s scholarly and journalistic output, showing the extent of his writings for a general audience, and revealing him to have been one of early Victorian Britain’s most prolific and gifted mathematical expositors.