text:  In the upper and middle parts of its course the longitudes were erroneous having adopted Major Rennell's delineation of Western Africa as a guide; but in 1839 the whole of that quarter of Africa was narrowly examined and the courses of the western rivers reduced to their proper positions as delineated in my large map of Africa constructed in that year to which with the "Geographical Survey of Africa " for which it was made the reader is referred for further and particular information on all these subjects