Siman - Shabbos Daf 100

• Difference between a pit filled with water and one with produce

Abaye said that if there was a pit in reshus harabim that was ten tefachim deep and four tefachim wide (meaning, it is a reshus hayachid), full of water, and someone threw an object into it, he is liable. However, if it was full of produce, he is exempt. The Gemara explains that water in the pit does not nullify its mechitzos (partitions), whereas the fruit does.

Rashi explains that in the case of the fruit, it is as if the pit is filled to its top with earth.

• Wind blowing the object

The Mishnah states that if one who was standing in a reshus harabim, threw an object within four amos, but it was propelled by the wind to a point beyond four amos, he is exempt.  If he threw the object beyond four amos, and the wind blew it back to within four amos, he is liable.

The Gemara asks how the thrower, in the second case, could be liable if the object never came to rest outside of four amos. Rebbe Yochanan answers that it rested briefly.  A Baraisa supports Rebbe Yochanan and states that one would be liable even if the wind held the object in midair for a moment (provided the object was within three tefachim of the ground, where the principle of lavud is operative).

• Drawing water onto a boat on Shabbos

There is a machlokes Amoraim regarding how one may draw water from the sea, on board a ship on Shabbos:

• Rav Huna said that one may extend a small rod from the ship and fill a bucket of water and bring it on board.

• Rav Chisda and Rabbah bar Rav Huna said one should make an enclosed area four tefachim wide over the water and fill the bucket through that area.

The Gemara explains that according to Rav Huna, the ten tefachim height of a karmelis at sea is measured from the floor of the sea, therefore the part of the sea that is above those ten tefachim is a makom petur. It is therefore permitted to draw water from the sea, into the boat, which is a reshus hayachid. The rod only serves as hecker, (a reminder) that it is forbidden to transfer from a karmelis to a reshus hayachid. According to Rav Chisda and Rabbah bar Rav Huna, the ten tefachim of a karmelis is measured from the water’s surface, and therefore if one would draw water from the sea to the boat, he is bringing water from a karmelis to a reshus hayachid, which is forbidden. Consequently, water needs to be drawn through a four tefachim wide enclosed area    .