Shabbat 100: Throwing in Different Contexts on Shabbat

A new Mishna: when one throws an object four cubits into the public domain, if the object hits the wall above ten handbreadths from the ground, an exempt domain, it is as if one threw it in the air, and he is exempt.  If it hits the wall below ten handbreadths from the ground, it is as if one threw it and landed on the ground and one who throws an object four cubits and it lands on the ground is liable.  

This is learned regarding a juicy cake of figs that sticks to the wall.  The rabbis wonder what would happen if a stone was thrown that rested in a hole in a wall less than four cubits tall.  Is a mound the same as a wall?

A second new Mishna teaches that if one threw an object in the public domain meaning that he had no intention of violating the Torah prohibition of carrying, and the object rolled and went beyond four cubits, he is exempt.  But if one threw an object with the intention of it landing beyond four cubits, and the object rolled back within four cubits, he is liable from when he threw the object.  

Another new Mishna tells us that one who throws an object from the sea to dry land for from dry land to the sea, from the seat to a boat or from a boat to the sea, from one boat to another - is exempt, because the sea is like a karmelit.  If boats are tied together, one may carry an object even though they are adjacent, one may not carry from one to the other.