Before powered saw mills, making lumber was much more labor intensive. Now I can flip a switch to crank up the band saw or table saw; or pull the cord to fire up the chainsaw for big work. It’s easy to forget how good we have it. Notice the sturdy little sawhorse holding up the trunk. I suspect this was hot and hard work.
There is much more about this stereo image here.
Preindustrial Craftsmanship 
Of all the pit and other “hand milling” I have done…大鋸 (Oga-big) family of saws are the most brilliant in my view…
Oga-Biki or “big saw” Sawmilling is my favorite and probably the most simplistic of methods found anywhere in the world…前挽大鋸 (maebikioga-“before minced large saw”) and the work of the 木挽 (kobiki-sawyer) can still be found today there, though a much rarer craft today, but with many upcoming enthusiasts.
Great that you shared this!!
Thank you for all the information. I have never pit-sawed anything but thought it was a great and informative image.