Who Must Flee as an Accidental Killer

"That the manslayer who kills any person unwittingly may flee there" (Joshua 20:3). We learned there [in the Mishnah]: These are the ones who are exiled — one who kills a person unwittingly. If he was pressing with a roller and it fell upon someone and killed him, [or] he was descending a ladder and fell upon someone and killed him, this one is exiled. But if he was pulling the roller [upward] and it fell upon someone and killed him, [or] he was raising [a vessel] with a pulley and the rope snapped and the barrel fell upon someone and killed him, this one is not exiled. This is the rule: in any case where the death occurred in the course of a downward motion, he is exiled; not in the course of a downward motion, he is not exiled. If the iron [axe-head] slipped from its handle and killed, Rabbi says he is not exiled, and the Sages say he is exiled. [If a chip flew] from the wood being split, Rabbi says he is exiled, and the Sages say he is not exiled.