Society for the Diffusion of Useful Knowledge (Great Britain)J. & C. Walker (Firm)1 map; 32 x 39 cmengraved by J. & C. Walker ; Scale approximately 1:27,000,000 ; Prime Meridian: Greenwich ; Relief shown by hachures ; 'Published by the Society for the Diffusion of Useful Knowledge 15th Sepr. 1839.' ; London : Society for the Diffusion of Useful Knowledge9940261314202441ark:/81985/n2n011v27Society for the Diffusion of Useful KnowledgePublicAfricaMapsAfrica1839Northwestern University