Iron wood bench vice

I just bought one for $20, nice and antique and old and rusty, but still very restorable which is what I intend to do. I bought it in lieu of the recent post "won a plane on ebay" which refers to restoring iron from a rusty state via Electrolytic Rust Removal.
This vise is 28 pounds of pure solid cast iron, and was made by American Scale co. KC, MS and is No. 204. The main single screw still moves easily though it is not threaded so it will not twist all the way and close the jaws. These jaws are great, 7" wide and about 3/8" thick and about 4" deep, jaws are open to about 12". This vice will easily restore nicely to a perfectly useable state. It cold be over 100 years old although I would like to know for sure if anyone does know.
I have taken some digital shots @640x480, the-front-of-the-front-vice-jaw has an up and down sliding mechanism within a slide holder, just an up and down peice of metal which has a hole for probably a knob or a handle, the purpose of this I don't know, so if anyone can tell me about it I'd really appreciate it, and I have the images nice and sharp with good contrast, to send through email.
Thanks very much all,
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