Charley, as you no doubt know, the stuff is few and far between! Incidentally, I took a little tour of Mobile once -- who knows what I thought I'd find, ha ha! The run-down waterfront...where I closed my eyes and tried to imagine...something! They have a museum there, in which I kept thinking around the next corner an exhibit of cotton screwing would pop up! :) The only thing of note was a little model of the ALABAMA, where nearby you could push a button and hear the chantey.

Anyway, my meager findings are:

Two patents for ~improving~ the cotton screws.

The first one is from 1878

In the diagram, I ~think~ B and C represent traditional jackscrews.

The second one is from 1881

It seems like 'J' in that one is supposed to be the traditional jackscrew.

I also found this photo (!) of one. Don't get too excited; it's not being used, and really hard to see. Go to page 34 of this thesis

Through my previous reading (OK, browsing) I've learned two things. 1) The screw gangs were usually segregated into black or white crews. 2) Cotton screwing was one of the best paid kinds of labor, and also considered quite specialized, and screwmen were thus viewed as an elite class of dock laborers.

Gibb