3 . ▁Cla pp erton ▁and ▁Den ham ▁re group ed ▁near ▁the ▁Mand ara ▁Mountains ▁and ▁returned ▁to ▁England ▁in ▁ 1 8 2 5 . ▁They ▁published ▁their ▁advent ures ▁in ▁ 1 8 2 6 ▁as ▁N arr ative ▁of ▁Tra vel s ▁and ▁Disc over ies ▁in ▁Northern ▁and ▁Central ▁Africa , ▁ 1 8 2 2 , ▁ 1 8 2 3 , ▁ 1 8 2 4 . ▁ ▁James ▁Richard son ▁led ▁a ▁British ▁expedition ▁to ▁the ▁Ch ad ▁Bas in ▁in ▁ 1 8 5 1 . ▁He ▁was ▁accompanied ▁by ▁Germ ans ▁Heinrich ▁Bar th ▁and ▁H erman ▁Over weg . ▁Their ▁goal ▁was ▁to ▁explore ▁the ▁land ▁south ▁of ▁Lake ▁Ch ad . ▁Richard son ▁died ▁at ▁Lake ▁Ch ad ▁in ▁ 1 8 5 1 . ▁The ▁others ▁arrived ▁at ▁the ▁Mand ara ▁Mountains ▁and ▁then ▁expl ored ▁U ba , ▁the ▁northern most ▁Ful ani ▁settlement ▁in ▁the ▁Adam awa ▁Em ir ate ▁then ▁continued ▁on ▁to ▁Y ola . ▁Over weg ▁died ▁in ▁ 1 8 5 2 , ▁but ▁by ▁ 1 8 5 5 , ▁Bar th ▁was ▁back ▁in ▁England , ▁where ▁he ▁published ▁Tra vel s ▁and ▁Disc over ies ▁in ▁North ▁and ▁Central ▁Africa . ▁ ▁In ▁ 1 8 6 5 ▁to ▁ 1 8 6 7 , ▁two ▁German ▁exped itions ▁under ▁Ger hard ▁R olf s ▁and ▁Gustav ▁Nach t ig al ▁expl ored ▁the ▁Ch ad ▁Bas in ▁and ▁the ▁Mand