Parts of the diary are quoted in The Mission to Uganda, edited by Rennell Rodd and published in 1894, after Portal's death.

Entries record the voyage in HMS Philomel to Mombasa, the journey of the caravan, arrival at Kampala on 17 Mar, the course of Portal's investigations, the return march to the coast via the River Tana (to discover whether an alternative route to the coast was practicable), and the arrival in Zanzibar on 22 Oct.

The four preliminary pages contain a 'Shooting record', 5 Jan-9 May, noting the place and game, and by whom they were shot; at the end of the volume is a continuation of this record, as well as of letters sent, and miscellaneous notes.