I think I figured out one thing finally. The northwest chimney, which was removed a number of years ago, must have extended up through the roof. Now that you can see where that was, the sheathing is continuous across the break. That means the sheathing is at least as new as when the chimney was removed. The sheathing is made of old planks with rough edges – bark on the sides. Since old, non-milled material was used in the sheathing when the chimney was removed, it makes sense that hand-split lathe was used on the closets. Meanwhile, since machine-lathe was used on the bathroom… it means the chimney was removed and the closets added at a different time than the bathroom. Therefore - there was a second major renovation – one between when the house was built and when the bathroom was added in 1924. (Oh – got a good date on adding the bathroom – they found a newspaper stuffed behind the soap holder used as a spacer with a June 1924 date on it.)
Some new material has started to appear upstairs – they removed the ceiling joists and installed new ones. I guess it’s easier to hang drywall from a flat surface. Who woulda thunk that.
Oh - some rather impressive trenches have been dug in the front yard for the geothermal heat exchange piping. Six feet deep, four trenches, each about 150 feet long.