(1) Thomas Clarkson interviewed a sailor who worked on a slave-ship and published the account in his book, Essay on the Slave Trade (1789)

The misery which the slaves endure in consequence of too close a stowage is not easy to describe. I have heard them frequently complaining of heat, and have seen them fainting, almost dying for want of water. Their situation is worse in rainy weather. We do everything for them in our power. In all the vessels in which I have sailed in the slave trade, we never covered the gratings with a tarpawling, but made a tarpawling awning over the booms, but some were still panting for breath.