Centres of the slave trade in East Africa patrolled by the Royal Navy. Wood engraving, 1875.

"The exposure by Dr. Livingstone, in the letters sent home not long before his death, of the cruelties of the slave trade on the Eastern side of Africa, was not Ieft entirely without effect. Sir Bartle Frere, appointed by Her Majesty's GovernmentSpecial Envoy to the Arab Sultan of Zanzibar, conducted a series of negociations for the suppression of that iniquitous traffic with fair diplomatic success. A small British naval squadron on the coast has for some time been employed in checking the operations of the Arab dealers who convey frequent miserable cargoes of captive negroes to the ports of the Red Sea and Persian Gulf. These unhappy people are brought down to the coast from districts far in the interior, especially from the shores of the great inland lakes, Tanganyika, Victoria Nyanza, and others lying beyond them. 'The Arab traders, whose caravans have long been accustomed to traverse that region at convenient seasons of the year, encourage certain tribes to make continual predatory raids upon their neighbours for the purpose of kidnapping children or young persons and women, to be sold in the slave-markets of Arabia and Persia. Zanzibar … has been the local head-quarters of this abominable commerce. ... We have on a former occasion given some views, from sketches made by a son of Sir Bartle Frere and by several officers of his suite or of HMS Enchantress, showing the places on the coast to the south of Zanzibar, such as Quiloa or Kilwa, the Rovuma and Angoxa rivers, and the Comoro Isles, in the Mozambique Channel. Captain Stratford Tuke, R.N., commanding H.M.S. RifIeman, has favoured us with other sketches, giving views of the principal places to the north of Zanzibar. Mombasa and Melinde, situated about three or four degrees south of the Equator, are the most important. … "--Illustrated London news, loc. cit.