In 1787 the Society for Effecting the Abolition of the Slave Trade was formed and Thomas Clarkson records that Richard Sharp was elected onto this famous Committee along with David Hartley. The Committee produced prints showing the cramped layout on a typical slave ship (the "Brookes"), which had a profound effect on all who saw it, significantly helping to change public opinion regarding the slave trade. The print showed each slave being allocated less than 2 metres height and .5-metre width for a lengthy sea voyage that could last for 6 months or more, such figures being calculated on the assumption that there were about 400 slaves on a ship when in fact it was known that there were sometimes more than 600.