Adjusting the buntlines of the upper topsail.  Joining all the buntlines together into one rope requires that they all be the same length.  This enures that they all bunch the sail tightly together the same amount when they are hauled in.  Since the bottom edge of the sail is curved getting these lines all the same length is a little tricky.  The wood bar (green arrow), clamped to the sail, makes it easier.