Great pictures and sight I must get to.
As Will noted I run Taylor Mill, a water powered up and down sawmill in Derry NH. I run it ever 2nd and 4th Sat 10:00- 3:00
Memorial Day to Oct.
Plenty of water this year!
My experience is with this mill only.
The marks were very pronounced when I started working at the mill, the set was achieved using a lever set. I notice large variations in the steel when setting the teeth so I made a large saw spider (gage). It now cuts with a smoothness similar to a modern band saw....however the spacing of the marks is much wider. Also most of the mills return the carriage with the blade running so there is another set of marks at a different spacing overlaying the cut marks. As part of our interpretation here at the mill we can point to, hewn timbers, vertically sawn timbers, circular sawn timbers and boards and modern band saw.
There were some mentions about the slight angle of the blade, I have this one set about a 1/4 inch forward at the top to lessen the drag on the blade as it goes up....however the 1/4 advance of the carriage only occurs on the down stroke.
I believe they may have swedged the teeth on earlier saws, thus creating a different look to the blade marks.
If anyone has a spare blade 6'5" blade for a mill I would be happy to do some research and share it at a conference.

Bob