A Tour of the South
Charles Grandison Parsons (1807-1864), a physician from Windham, Maine, travelled through the southern states in 1852 and 1853. He then lectured on his experiences and turned his journal into this published volume to promote abolition.
In one of Parsons' observations, "When we have called a man a slave, we shall probably find, if we analyze our thoughts, that we have degraded him below the level of manhood, in our practical estimation, and the wrongs he suffers seem to lose a great measure of the enormity we should attach to them if inflicted on a man. Our sympathies are moved when the slave is starved, scourged, tortured; but it is not so much because his manhood is degraded as because the animal is suffering. Such being the influence upon ourselves, it is not strange that those who have been trained in the midst of the corrupting system, and taught to regard the slave as a mere chattel, without personal rights, should exercise little sympathy for his wrongs."
Note that the introduction was contributed by Harriet Beecher Stowe, author of Uncle Tom's Cabin (1852).
The full-text of this item is available through the Internet Archive here.
C. G. Parsons stated, "I will, however, give a brief description of the instruments of torture which are in common use in the South. In this department the slaveholders exhibit more mechanical skill, and power of invention, than in their implements of husbandry." In addition to the thumb screw, Parsons describes the stocks, a gag, and a chain gang.