Thanks guys! I am a bit surprised no one posted a picture of an Ent as a true 'tree feller'...
George, there are some videos online of original Ransome tree saws being run, looks like they do work well. They were made for decades so there must have been an advantage to them. I'm sure once chain saws came out, they took over really fast! The version of the Ransome saw on the crosscut base, with the saw blade vertical to cut logs into shorter lengths, may well have been more popular since they could be set up in one place to process a stack of logs quickly.