The publication of Hamman Yaji's diary through the combined effort of J. H. Vaughan and A. H. M. Kirk-Greene is a rare and remarkable contribution that deserves commendation from all those interested in West African studies. An important merit of the publication is that the diary, which sheds light on various aspects of West African history, is now at the fingertips of a wider readership. The diary is a catalogue of events which Hamman Yaji (District Head of Madagali, northeastern Adamawa, 1902–27) regarded as important for the period 1912–27. Apart from numerous slave raids on the neighbouring non-Muslim communities, trade, religious observances, reciprocity, obligations and Hamman Yaji's relations with his Muslim neighbours and Europeans are recorded in detail.