The first volume of this pair, The Classification of Bantu Languages, originally published in 1948, investigates the questions arising out of the use of the term Bantu. It establishes and illustrates the criteria used in identifying languages as members of the Bantu family. The technique used in classification is described and its results shown in the form of a series of descriptive classifications of each of the principal areas. As well as the map (not included in the volume due to modern methods of reproduction, but available to view on routledge.com), there is a complete list of languages classified in their groups. The second volume, Bantu Word Division published in the same year, discusses a question which for many years was the subject of protracted controversy, namely the dispute between the conjunctivist and the disjunctivist, with regard to word division. This pamphlet discusses word division from a different angle, and solves the problem in a more conclusive way.

Originally published in 1945, this volume represented the first to classify Bantu languages. This volume does not record all the dialects but makes reference to those in which some grammatical study has been done and classifies them according to mainly geographical zones. Owing to tribal migrations, individual members of a particular zone may be living among members of a different zone (as has been the case with the Ngoni, South-Eastern Zone, who are found among the Eastern Bantu), but the zone label is taken from the habitat of the majority.