Excellent map of Africa, published by OW Gray in Philadelphia.
The map includes nice detail in the interior, naming many tribes, deserts, towns, lakes, mountains, etc.
O. W. Gray was a publishing firm based in Philadelphia. Later, they published as O. W. Gray & Son. They published atlases in the late nineteenth century. Gray's National Atlas was one of the most successful commercial ventures of the 1870s and one of the last to employ hand coloring on maps.