James Macqueen was a Scottish enslaver and advocate for British colonisation of the interior of Central West Africa. Formerly a manager of a sugar plantation in Grenada on which he enslaved 400 Africans, Macqueen returned to Scotland in 1810 and took an interest in the geography of Africa and voiced his support for the continuation of enslavement in the Caribbean, the abolition of which pro-slavery campaigners argued would have severely damaged the British economy. Following Britain’s abolition of the slave trade in 1807, Macqueen took a particular interest in the course of the River Niger, which he argued had its mouth in the Atlantic Ocean. In this book, he pushed for British colonisation of the interior of West Africa along the river’s course. This, he believed, would allow the country to stem the flow of enslaved Africans to coastal ports and thus prevent American and other European powers from accessing that market, thereby preserving the Britain’s economic advantage over its rivals.
Macqueen never travelled to Africa but his maps proved, as later expeditions confirmed, that the Niger did indeed have its mouth in the Atlantic. According to David Lambert’s history of Macqueen’s works (Mastering the Niger, Chicago, 2013), much of the geographical information Macqueen used when compiling his geographies came from testimonies by Hausa and Mande-speaking people he had enslaved in Grenada.
Despite disagreeing with Macqueen's beliefs concerning the enslavement of others, the abolitionist Sir Thomas Fowell Buxton consulted the maps when planning for the 1841 Niger Expedition, stating that Macqueen knew more of the region 'than the whole Admiralty'.