The answer appears on the sixty-second page of the book.

They cannot be dreamy Daniels, they cannot be spasmodic — gallop one half-hour, and slacken the next.

[…] they also instrumentalize race to reinstate nostalgic, vanguard notions of political activism […]

Methods of applying pain were many and ingenious, in particular the ways of twisting, stretching and manipulating the body out of shape, normally falling under the catch-all term of the rack, or the brakes.