LEAVES TRIPOLI WITH MR. RICHARDSON AND DR. OVERWEG--SUPPRESSION OF SLAVE TRADE THE CHIEF OBJECT OF THE EXPEDITION--NUMEROUS RUINS SEEN--CROSS THE HAMMADA DESERT--REST AT AN OASIS--REACH MOURZOUK--DR. BARTH'S ADVENTURE--NEARLY PERISHES IN THE DESERT--DIFFICULTIES OF JOURNEY-- FOLLOWED BY TAWAREK FREEBOOTERS--PREPARATIONS FOR AN ATTACK--STRANGE DANCERS--TRIBUTE DEMANDED--CAMP AT NIGHT--EXPECTING AN ATTACK--CONSTANT FIRING KEPT UP--CAMELS STOLEN--PURSUED--DANGEROUS SITUATION--TRAVELLERS EXPECT DEATH--SAVED BY FRIENDLY CHIEF--DR. BARTH VISITS AGADES--A SALT-CARAVAN--THE CARAVAN REACHES TAGELEL. The British Government had, in 1849, appointed Mr Richardson, an experienced traveller in Africa, to the command of an expedition which was to start from Tripoli, on the north coast, and thence endeavour to penetrate to the central part of the continent. By the recommendation of the Chevalier Bunsen Dr Barth, who had spent three years travelling through Barbary and the desert tracts to the westward bordering the shores of the Mediterranean, was allowed, accompanied by another German, Dr Overweg, to join the expedition. A light boat, which was divided into two portions and could be carried on the backs of camels, was provided, and a sailor to navigate her either on Lake Chad or down the Niger. Dr Barth and his countryman at once pushed on for Tripoli, in the neighbourhood of which they made long excursions while waiting for the arrival of Mr Richardson, who had remained in Paris for despatches. One of the principal objects of the expedition was the abolition of the slave trade, which it was known was carried on to a fearful extent in those regions. The principal employment of the Moorish tribes on the borders of the territories inhabited by blacks is still, as it was in the days of Mungo Park and Clapperton, slave-hunting. Villages are attacked for the purpose, when the prisoners captured are carried northward across the desert and sold in Morocco and the other Barbary states. Another object was the opening up a lawful commercial intercourse with the people who might be visited, and the exploration of the country for scientific purposes, as well as to discover the course of the great river which the Landers had seen flowing into the Niger in their adventurous voyage down that stream. On the arrival of Mr Richardson the travellers at length set out from Tripoli, on the 24th of March, 1850. They rode on camels, a considerable number of which were also required to carry their baggage. The boat had unfortunately been divided only into two pieces instead of four, thus causing much trouble.