At one of the workshops I went to, John Carter who is in charge of this collection said he thought he understood it till the computor enhancements became possible. As I study this collection in my spare time I see all kinds of things that could drive one crazy.
Actually for me one of the best things the "Supper" picture shows is the differance in the amount of fat on an 1880's ham and one from our modern improved leaner pig. But thats for a post I'm going to do in Cosie's Corner.
Until very recent times left handed people were forced to be right handed and the term for lefthanded, sinister, also came to mean someone kind of evil. I've never seen a left handed muzzle-loader either.
The nails, it don't matter except that I learned that what I thought was right isn't always so, because the round-headed wire nails were starting to be made, I sure thought they dated later, but again that depends on the source we belive.