How did they thickness the boards before the advent of machines

[Fergie 307]

Saw pits were often used to cut off and thickness boards from larger pieces of timber before the age of mechanisation. They had to be fairly accurate in their cuts too so as not to expend energy with other tools finishing to the required thickness.
Not a job I would have enjoyed but it was done nonetheless.

This is where the terms top dog and underdog originated. The poor guy in the bottom of the pit, who got all the sawdust was the underdog. I think the dog reference is presumably because the saw was dog toothed.

 

[Fergie 307]

Or I should say one of its origins, of course the term also has clear links in our very civilised old "sport" of dog fighting.