A little work with a soft toothbrush and some warm water and I discovered that this was made by the Prairie du Chien Tool Company. The history of this company as available on line is a bit unclear. Their corporate history states that they have been manufacturing tools since 1920, but it also says that Prairie Tool Company was acquired in 1920. No mention of when the name was changed. Anyway, there is a 1925 patent date on this particular model and since Uncle Ernst was born in 1921 I think it's safe to assume that he didn't acquire it until later than 1925.
I've never seen one of these before and am not quite sure how to use it since a grinding wheel always requires me to have two hand on the item being sharpened, but I am going to make an effort to figure it out, just because. I am thinking that the slow speed of the wheel will keep the blade from being grabbed by the stone so less force would be needed to hold everything together. I know that the advantage of a slow speed wheel is that it doesn't generate the heat that a high speed grinder does, meaning less loss of temper in the blade being sharpened. That whole sentence has a weird tense but I think it makes sense.
Second interesting item, my grandfather's pitchfork. How do we know it is his? Just check out the initials carved into the handle.
Howard Sherman A. Totally cool, it is a short fork with big flat metal tines. I probably won't use it much but what a great piece of family history to have. Sad to see my dad's generation getting older and slowing down, but I'm pretty pleased (as they seem to be) to keep some of this history in the family and maybe have an opportunity to some day pass it on to another generation.