Map of Guinea, from William Snelgrave's "A New Account of Some Parts of Guinea, and the Slave Trade", 1734
This map is from William Snelgrave's 'A New Account of some parts of Guinea...' and shows the area in which Snelgrave - a British sea captain - traded in slaves. His area of operations is stated as being about 700 leagues (around 2000 miles) from Sherbarow River (Sherbro channel, Sierra Leone) to Cape Lopez Gonsalves (Cape Lopez, Gabon).