Now, look at the tree from a spot that is 90 degrees around the tree from your first spot, and determine if the tree is leaning, or heavy to your right or left. You have now established quadrants for the tree, and you can safely say which quadrant the tree would fall into if the stem was severed with no hinge, and no wedges to guide it. You also know now if you will need to use wedges to tip the tree in the direction you want it to fall. Some will say this takes too much time, but these easy steps make each tree fall where you want it, and they save you from smashing saws, skidders, and other valuable items, such as houses.
In the YouTube video below, you can easily see a wedge cut out on one side of the stem. Many people think that a tree will magically fall toward this cut, but the opening is actually made to allow a tree to rotate downward on the hinge you should have built right behind it. There is nothing magical about this cut. As you watch the video you will see the cutter severs all the wood holding the tree up, and it falls the way the lean and weight are directed. At least no-one was hurt.
Balanced stems are rather special, and they MUST be pushed or pulled in the right direction, with a good hinge set up to guide them. Simply cutting them loose turns them into unguided missiles, as this smokestack drop demonstrates. After watching the video a few times, it appears to me that the explosives knocked out all the support except in one spot, and the stack fell away from that point. Since I am a forester and not an engineer, I won't give my opinion on how this stack should have been set up to fall, but I do think that the guys who did this ought to spend some time in the woods with a good logger before they do another.
Parts Two and Three: