Most of the dragsaws I’ve managed to find online seem to be from years in the range of 1910 to 1920, and feature a mechanical movement similar to, but the reverse of a locomotive’s drive wheel and connecting rod. Instead of a steam-driven piston driving a circular wheel, an engine-driven wheel drives a reciprocating piston, which is attached to a large cross-cutting saw. There are all manner of models on YouTube in every state of restoration or disrepair, but I particularly like the following example. It shows the motion well, including the finishing stroke. Most other videos give up far before that. I think I need one of these, connected to an exercise bike ;)
This one in particular makes me feel the power that one of these things can hold, and I worry especially for the man’s legs and feet!
UPDATE: Don’t forget to check out the dragsaws littering Google Images Those things could buck some pretty big logs! Perhaps the most incredible thing about the following image is that the historical site whence it comes claims that the man pictured – one John Shambolt, c. 1917 – is using the dragsaw to turn that tree into stove wood! What a waste of such enormous lumber! Makes me long for a time when – and a place where – resources were functionally infinite. Of course, I’d miss the internet ;)
-- Gary, Los Angeles, video game animator