When the wooden shoe maker is going to saw a tree trunk into logs, he knows what size of wooden shoes he's going to make.

When he has selected a suitable tree trunk, the trunk is measured.

He takes the diameter of every log with a slide caliper (fig 1). He holds this caliper across the trunk.

By the shape of the trunk, either being round or oval, you can tell which type of wooden shoes the wooden shoe maker is able to create: high, low, large or small wooden shoes (fig 2).



As the tree trunk tapers off, the wood can be used efficiently by letting the size of the wooden shoes to be made, depend on the diameter of the log as sketched in fig 3.