Warren in Lancaster, PA
Here are Roubo's stones for sharpening moulding planes.

These are water stone slips that are wedged into slots. There is a well in the center of the board for water. Roubo used water stones for coarse work, oil stones for polishing. Slips that are fixed to the bench like this are more efficient.

There are lots of instances like this, of people who have little experience with traditional work assuming that they know all about it. I read a fellow this morning who said cauls have been used on panel gluing for thousands of years. It did not occur to him that they used hot hide glue and would not have had time for the elaborate set up he imagined.