Figure 11  Detail of an engraving, from Thomas Clarkson’s History of the Abolition of the African Slave Trade, London, 1807. Influential figures such as Thomas Clarkson were given the responsibility of collecting information to support the abolition of the slave trade. This included interviewing 20,000 sailors and obtaining equipment used on the slave ships such as iron handcuffs, leg-shackles, thumb screws, instruments for forcing open slaves’ jaws, and branding irons. In 1787 he published his pamphlet, A Summary View of the Slave Trade and of the Probable Consequences of Its Abolition. After the abolishment of the British slave trade in 1807, Clarkson published his book History of the Abolition of the African Slave Trade.