Many prisoners routinely spent a part of their sentence in solitary confinement in the "dark cell". This cell had no window or lighting and once inside, with the door tightly shut, it would have been almost impossible to tell if it was day or night.

If a prisoner committed a serious offence - such as hitting an officer or trying to escape - he might also be put into the dark cell as a punishment. Prisoners could spend days or even weeks in solitary and dark confinement and many went mad.