i wasn't there, but would have considered binding both trees; so that each falls as 1 and doesn't split into 2 or more shifting plates complicating fold internally.
The first one was so dry, with cracks, could have come apart. 2nd, didn't look split thru after cracking open, but would have inspected more before cut.
Would always stop and inspect facecut like a carpenter on a very find sliding and folding mechanic/perfect matching, nothing less.
'measure' 3 times/3 dimensions; cut once
Another 50% of your answers may be on the butt side of fallen tree/that matches stump.
Was the extra man capable of pulling with rope?
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If tree pulls to left, i plot my control/steering/trigger wood to right rear.
In hinge compressed wood side pushes up/across to other side; stretch hinge side, pulls back and across.
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The trees laid down, where the mechanics brought them (of course);
the saw engineered/carved mechanical commands engineered the steering/could have overcome the Natural loading/fall.
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The first tree: the face is 'dirty'/has an obstruction in the fold operating as a step dutchman, can be dangerous, and hear pushed to opposite side.
Also, the facecuts bypass/ are not carpenter machined to engineer proper hings, this gives face within a face, 2 closes, another type of dutchman
dutchmans can always be dangerous.
The upper face cut seems to be the bypass, so pushes across bend axis of fibre, to not as bad as if lower facecut bypasses and then mechanical instruction is not across flex axis, but up the stout roman column of the spar's strength, so would be less forgiving/ can seize up midway; even barberchair and kill.
www.mytreelessons.com/barberchair%201.swf
http://mytreelessons.com/rl/content/Hinging-Full.swf
extreme usage examples for discussion only, but should just not mess with dutchmans:
http://www.mytreelessons.com/Drawings Archive-Dutchmans.htm
Steering is depending on rear side of hinge, opposite lean side, to be young, flexible, stretchable fibre to pull, not snap.
The dry, dead wood is obviously anything but elastic, and so more care is needed.
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2nd tree
We see younger, more flexible wood; the high stretched fiber on right/circled pulled to this side
Almost like opposing side rear fibre was cut thru
i would have maintained holding wood where saw tip swirls on left, and whittled that control away to folding