By turning it further you may make the blood start from the ends of them.

By taking the key away, as at E, you leave the tortured person in agony, without any means of extricating himself, or of being extricated by others.

This screw, as I was then informed, was applied by way of punishment, in case of obstinacy in the slaves, or for any other reputed offence, at the discretion of the captain.
At the same place I bought another instrument which I saw.

It was called a speculum oris.

The dotted lines in the figure on the right hand of the screw represent it when shut, the black lines when open.