Recently in this journal (Wilmsen 2003:360-375), I delineated Charles John Andersson's route to the Okavango River based on entries in his diaries and an overlooked map of the route published by Thomas Baines in 1866. noted there that, while the place, Okambombo, where Andersson first stood on the banks of the Okavango was correctly plotted on Baines' map, its geographical coordinates were given only approximately. I also noted that Andersson did not bring along his astronomical instruments on his first excursion to the river, and assumed therefore that no coordinates for the place were obtained. However, in the course of my preparation of Andersson's papers for publication, I have since worked through the 116 unnumbered pages of geographical calculations recorded in volume 10 of the papers and found latitude observations for several points along the route, including Ombongo and Okambombo; his calculations for these latter two places are shown in Figure 1.

Andersson left the river on 29 March 1859 and returned to it on 29 April (CJAP-3.3:169); on 4 May the correct latitude, 17°46′08″S, was determined by astronomical observation. About this, Andersson (CJAP-3.3:172) wrote, “[o]btained a latitude. Between Ombongo & this place (Okambombo) I am only out a mile in latitude.” The latitude for Ombongo was obtained just before this, on 16 April on his way back to the river (CJAP-3.3:165). On Baines' map this latitude is given as 17°37′53″S, but as can be seen, this is just one of Andersson's interim reckonings before the “True Latd 17°39′38″” is calculated (figure 1). Baines (1866:217) gave approximate coordinates for Okambombo in his text, writing “17°30′S. lat. and longitude about 19°E,” but the correct coordinates (17°46′08″S about 18°55′E) are plotted on the map. Both discrepancies are due to the fact that the published map was redrawn by Royal Geographical Society cartographers, who copied one that Andersson made in Cape Town at Galton's urging (GP-UCL 1866) based on “upwards of three thousand prismatic compass triangulations and astronomical observations of latitudes” (found in volume 10), while Baines copied from the letter Andersson wrote from Okambombo to Dr. Norton Shaw, secretary of the Society.