308 JOURNEY TO CENTRAL AFRICA.

Frank may travel in comparative safety, from Cairo to the borders of Dar-Fur and Abyssinia, while the White Nile and its tributaries afford avenues to the very heart of the unexplored regions beyond. The climate is the greatest obstacle in the way of discovery, and the traveller whose temperament is best adapted for the heats of the inter-tropical zone, possesses the best chance of success.