An excerpt from the book, An Account of the Slave Trade on the Coast of Africa, published in 1788.
During the voyages I made, I was frequently witness to the fatal effects of this exclusion of fresh air. I will give one instance, as it serves to convey some idea, though a very faint one, of their terrible sufferings…. Some wet and blowing weather having occasioned the port-holes to be shut and the grating to be covered, fluxes and fevers among the Negroes ensued. While they were in this situation, I frequently went down among them till at length their room became so extremely hot as to be only bearable for a very short time. But the excessive heat was not the only thing that rendered their situation intolerable. The deck, that is the floor of their rooms, was so covered with the blood and mucus which had proceeded from them in consequence of the flux, that it resembled a slaughter-house. It is not in the power of the human imagination to picture a situation more dreadful or disgusting. Numbers of the slaves having fainted, they were carried upon deck where several of them died and the rest with great difficulty were restored….
As very few of the Negroes can so far brook the loss of their liberty and the hardships they endure, they are ever on the watch to take advantage of the least negligence in their oppressors. Insurrections are frequently the consequence; which are seldom expressed without much bloodshed. Sometimes these are successful and the whole ship’s company is cut off. They are likewise always ready to seize every opportunity for committing some acts of desperation to free themselves from their miserable state and notwithstanding the restraints which are laid, they often succeed.