2 mishnayot! The first one addresses damage caused by something put in the public domain - specifically, one who hides something damaging or makes a fence out of something damaging (like with thorns), when others are damaged, the owner needs to pay full damages. The Gemara narrows the application of the mishnah's more general case quite a lot - how can water do damage on the ground in the public domain? The second mishnah addresses the carting of fertilizer that benefits from the trampling of pedestrians to the public domain. And the concept that the first one to claim an ownerless item becomes the owner. Plus, another mention of Chanukah candles and the liability of a shopkeeper for damage caused by them, depending on their placement.