Four slaves in East Africa chained at the neck carrying brushwood fuel; other slaves chained at the neck working in rice fields. Wood engraving or process print after J.B. Zwecker after J.A. Grant.

Licence: Public Domain Mark

Credit: Four slaves in East Africa chained at the neck carrying brushwood fuel; other slaves chained at the neck working in rice fields. Wood engraving or process print after J.B. Zwecker after J.A. Grant. Wellcome Collection. Source: Wellcome Collection.