¶ THE LONG (S) IS A RELIC FROM THE PAST. Although sometimes used in historical productions. Otherwise the long (s) has fallen into disuse. The setting shown here is in the original Caslon Oldstyle. It is printed by placing the type forme on a stone, inking the type surface with a brayer (evolution of the sheep's foot), laying (floating) paper onto the inked forme, placing a proof planer on top, and then striking with a mallet.
A proof planer is identical to a type planer but with a felted platen. Proofing planers were a crude and efficient method allowing for quick alterations including correction of typographical errors.
In short, it is an early pre-press technique.