Hello,
There are a few things that can and cannot be inferred from Mr. Schwartz's investigations, and IMO some have been taken out of context for whatever motives certain people have here. It is obvious from the concave bevel that Studley had access to a large wheel waterstone for grinding. However, the method of honing cannot, with any certainty, be assessed. Can we say Studley intended to produce a concave bevel, and preferred to do it that way? No and in all likelyhood, he did not. ( though I too am guessing, I think logically I might by correct) A very slight convexety is more likely due to the fact that humans are not machines and cannot too easily make their arms move in one plane, but will rock a little and produce a rounding without intention. This is not the same as purposely rounding over (under?) the bevel as per Mr. Sellers and his desciples. Using this sort of artifact to give creedence to a methodology is spurious, as is witnessing one example of a phenomena and concluding that most everyone did the same at the time. The concave grind was likely used as a reference on the stone, and the whole bevel sharpened as flat as humanly possible, freehand; just as many woodworkes do these days. In fact, just the same as Krenov did with concave grinds on his tools.
The 'ruler trick' is nothing new, nor was it ever purported to be by David Charlesworth, who currently champions this method of treating the tool's back. It is likely that many craftsmen used a similar short cut to preclude lengthy blade fettling. However, the 'dubbing over' found in the tool chest was just as likely to be caused by stropping both sides of the plane iron, rather than purposly 'sharpening' a back bevel.
I do not see how we can say woodshops had no way of grinding their tools and had to wait for peddlars and the like to visit with grinding wheels. If these relatively poor traveling folk could afford a sandstone water wheel, I am sure that cabinet makers, piano makers etc. would also have such a necessary device, considering their stock in trade was sharp edge tools. In fact, if memory serves, Alan Peters refers to all cabinet shops having large sandstone waterwheels by the door of their shop. Evidently, Studley ground his tools with a similar device.
Mike.