Skidder on flatcar

The skidder shown below appears to be a home built affair, probably incorporating a commercially available donkey engine for hoisting.

The flat car is from the Wisconsin Central, a predecessor to the Soo line.  Lumber and logging was a significant business for that line around the turn of the century (1899/1900).  The only visible means of holding the skidder to the flat (other than gravity) are some chins at the rear.