American Bone chain saw, found via Mental Floss - "This peppy little saw could actually save men from war field amputations. It allowed surgeons to wrap the saw around the bone and cut out only the damaged parts, not the whole limb.
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collecting fishing worms: Drive a stake inches deep into the ground. Remove or disengage the chain from a chain saw. Rest the bottom of the running chainsaw on top of the stake. The worms will be coaxed from the soil by the vibration.