IF ONE CAN THROW AND THE OTHER CAN LOWER
Question (against Rav - Mishnah): If Bnei Chatzer forgot to be Me'arev with Bnei Mirpeses, anything 10 Tefachim tall is to the Bnei Mirpeses. Anything less is to the Bnei Chatzer.
We are thinking that the Bnei Mirpeses live in an Aliyah (a second story 10 Tefachim above the Mirpeses, which is 10 Tefachim above the ground). They are called Bnei Mirpeses because they get to their apartments via the Mirpeses;
(Anything 10 Tefachim above the ground is 10 below the Bnei Mirpeses.) The Bnei Chatzer can throw and the Bnei Mirpeses can lower, yet the Bnei Mirpeses are permitted [like Shmuel]!
Answer: Rav Huna answered [elsewhere], it is permitted to Bnei Mirpeses who live [in apartments whose openings are directly to] the Mirpeses. The same answer applies here. (They are only 10 above the ground. Anything this tall is convenient for them to use.)
Question (Seifa): Anything less is [permitted] to the Bnei Chatzer.
It is convenient for (i.e. less than 10 from) both of them. Both should be forbidden!
Answer: Indeed, it means that it is also [accessible] to the Bnei Chatzer, therefore it is forbidden to both.
Support (Seifa): This is if these are near the Mirpeses. If they are far away, even if they are 10 tall, they are to the Bnei Chatzer;
Question: What is the meaning of 'they are to the Bnei Chatzer'?
It cannot mean 'they are permitted to the Bnei Chatzer', for they are inconvenient for both of them!
Answer: It means that they are also [accessible with difficulty] to the Bnei Chatzer, therefore they are forbidden to both.
Also in the Reisha it means that it is also to the Bnei Chatzer, therefore it is forbidden to both!
Question (Mishnah): If a rock or Chulyah of a pit is 10 Tefachim tall, it is permitted to the Bnei Mirpeses. If it is less, it is permitted to the Bnei Chatzer.
[We are thinking that the Bnei Mirpeses live on the second story. They can lower and the Bnei Chatzer can throw, yet the Bnei Mirpeses are permitted [like Shmuel]!
Answer (Rav Huna): They are permitted to Bnei Mirpeses who live on the Mirpeses.
Question: This answers regarding a rock (it is convenient for Bnei Mirpeses). However, [people draw from the bottom of a pit;] even Bnei Mirpeses use a pit [with difficulty, i.e.] by lowering!
Answer #1 (R. Yitzchak brei d'Rav Yehudah): The case is, it is full of water. (They draw from the top, which is within 10 of them.)
Question: Once they draw some water, it is no longer full, and they use it by lowering!
Answer: Since it is permitted when it is full, it is permitted even when it is not full.
Rejection: No! Since it is forbidden when it is not full, it should be forbidden even when it is full [lest people take the water]!
Answer #2 (Abaye): Rather, it is full of produce.
Question: Once some are removed, it is not full!
Answer: The produce is Tevel. (One may not move it on Shabbos.)
Support: The pit is taught together with a rock. (It does not get diminished.)
Question: Why must the Mishnah teach about a pit and a rock?
Answer: Had it taught only about a rock, which is never diminished, one might have thought that we decree to forbid a pit [even full of Tevel] due to a pit that can be diminished, e.g. it is full of Chulin.
QUESTIONS AGAINST SHMUEL
Question (against Shmuel - Beraisa): If Bnei Chatzer forgot to be Me'arev [together] with Bnei Aliyah, the Bnei Chatzer may use the bottom 10 Tefachim of the wall [of the house facing the Chatzer]. The Bnei Aliyah may use the top 10 Tefachim;
If a ledge juts out from the wall below 10 Tefachim, the Bnei Chatzer may use it;
If it is above [the height that is] 10 Tefachim [below the Aliyah], the Bnei Aliyah may use it.
Inference: (We are thinking that the Aliyah is more than 20 Tefachim tall.) If the ledge is in between (more than 10 Tefachim above the ground, and more than 10 Tefachim below the Aliyah), it is forbidden to both [even though the Bnei Chatzer use through throwing and the Bnei Aliyah by lowering. This is like Rav!]
Answer (Rav Nachman): No, the wall is only 19 tall. It is convenient for one and inconvenient for the other. (Indeed, the middle Tefach is convenient for both, so both are forbidden. Rashi - we do not establish it to be 20 tall, for then the above inference would apply to the exact middle.)
Question (against Shmuel - Mishnah): [If a balcony is above water, if one makes a hole in the balcony and a Mechitzah 10 Tefachim above or below the balcony, he may draw water on Shabbos.] If two balconies are one above the other, and a Mechitzah was made only for the top one, both of them are forbidden unless they are Me'arev together. (The bottom one must throw [the bucket to the top balcony and lower it], and the upper one merely lowers, yet both are forbidden!)
Answer #1 (Rav Ada bar Ahavah): The case is, the people on bottom go up [a ladder] to the top balcony to draw water.
Answer #2 (Abaye): The case is, the upper balcony is less than 10 above the lower one. The Mishnah teaches a bigger Chidush:
It is a small Chidush to forbid both when a Mechitzah was made only for the bottom one. Since they are within 10 of each other, [they are like one Reshus, so] they forbid each other;
Rather, this is even when a Mechitzah was made only for the top one. One might have thought that since it is convenient for them and inconvenient for the bottom one, we give it to the top ones. The Mishnah teaches that this is not so.
This is like Rav Nachman taught;
(Rav Nachman citing Shmuel): If a roof borders Reshus ha'Rabim, it is permitted only if there is a fixed ladder (Tosfos - from the Chatzer; Rashi - from a balcony) [to the roof];
Question: A movable ladder is not enough. What is the reason?
Answer #1: Because they are within 10 of each other, [they are like one Reshus,] they forbid each other;
Rejection (and Answer #2 - Rav Papa): Perhaps Rabim rest their hats and turbans on the roof [or balcony (Rashi). Even if it is above 10, it is convenient for light things, in particular things worn on the head!]