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1)

(a) Rabah bar Rav Huna restricts the use of a suspended Mechitzah over a stream to drawing water *from* it, as opposed to pouring water *into* it. Why should this be any different than an Ukah (a large Uka that can hold two Sa'ah of water) in a small Chatzer, quoted in the next Mishnah, into which pouring water is permitted, desUkae the fact that the water then flows out into the Reshus ha'Rabim.
(b) What does the second Lashon of Rabah bar Rav Huna hold?

(a) Rav establishes our Mishnah (which forbids the owners of both ledges to use the hole in the upper-ledge to draw water, if only the upper owner made a Mechitzah, but not the lower one) when they are within four Tefachim of each other, but not if they are further away than that.
Why the difference?

(b) Will it make any difference if the one is more than ten Tefachim higher than the other? How do we know that that is not what Rav is referring to when it makes a distinction between 'Semuchah' and 'Mufleges'?

(a) 'Yesh Gezel be'Shabbos, ve'Churvah Machzir le'Ba'alav'.
Why does this statement appear contradictory?

(b) How does the Gemara explain it?

(c) But if the Din Gezeilah (i.e. the obligation to return it) applies on Shabbos, then how do we account for the Din in our Mishnah, which forbids the owner of the upper ledge to use his ledge, because the owner of the lower ledge uses it (proving that the person who uses his friend's Reshus *does* acquire certain rights, and forbids the owner to use it)?

(d) In that case, who permits the owner to use his ledge, even if the owner of the lower ledge then makes Mechitzos?

(a) We quoted (in 1a) above, our Mishnah which permits pouring water into a small Chatzer by digging an Uka which contains two Sa'ah of water. The Tana permits this even if the Uka is outside the Chatzer. What is the difference between a Uka which is *inside* the Chatzer and one which is *outside*, and why is that?

(b) Why should the Uka need to hold specifically *two Sa'ah* of water?

(c) Rebbi Eliezer ben Ya'akov permits pouring water into a 'Biv' of four Amos in the Reshus ha'Rabim.
What is a Biv, and why specifically one of four Amos?

(d) Why are we not concerned that the water might not sink into the ground fast enough, and will subsequently spill over the sides into the street?

(a) The Rabbanan disagree with Rebbi Eliezer ben Ya'akov with regard to a Biv. What do they say, and what is their reason?

(b) Does a Chatzer of less than four Amos require an Ukah, if together with the porch, it totals four Amos?

(c) If one of two raised stoeps with steps leading down into a common Chatzer that is less than four square Amos, made an Ukah, and the other did not, may it be used, and if so, who may use it?

6)

(a) *Rabah* explains that a Chatzer of four Amos does not require an Ukah, because, unlike a smaller Chatzer, where one's intention is to pour the water out (and we decree that he might pour it directly into the street), one's intention in pouring the water in the Chatzer, is to settle the dust (so there is no reason to issue a decree).
How does *Rebbi Zeira* explain the distinction between a small Uka and a large one?

(b) What is the difference between the two answers?

(c) How will Rabah explain our Mishnah, which exempts a combined Chatzer and porch of four square Amos from an Ukah?

(a) How does Rebbi Zeira explain the Beraisa, which explicitly requires a square of four by four Amos to exempt from an Uka?
Who then, is the author of our Mishnah?

(b) Rebbi Zeira is forced to learn like this, because our Mishnah says 'Chatzer she'Hi Pechusah me'Arba al Arba'.
What does he infer from there? What should the Mishnah have said otherwise?

(c) But the author of the Seifa is Rebbi Eliezer ben Ya'akov; does that not imply that the author of the Reisha is not?

9)

(a) Why does the Beraisa permit pouring water into the small Uka during the rain season, even when there is *no* Ukah?

(b) Then why do the Chachamim forbid pouring sewage into the drain on the roof, where he also wants it to become absorbed there?

(c) What is the difference, according to Rav Nachman, by an Uka that only holds a Sa'ah, between the rain-season and the dry season, and why the stringency in the dry season?

(d) What leniency does Abaye then add?

(a) According to the initial version of Rava's statement, he maintains that, when our Mishnah forbids the residents of the one raised stoep to use the Ukah of the other (despite the fact that they are sharing the same Chatzer), it is speaking even when they made an Eruv.
Why does the Gemara reject the suggestion that this is because the two courtyards will now be pouring *four* Sa'ah into the Uka, instead of *two*?

(b) What is 1. a Gistera, 2. a Bereichah, and 3. an Arivah, and what is their significance in this context?

(c) What Rava really said was that if they made an Eruv, then both stoeps are permitted to use the Ukah that was made by only one of them.
If they did not, why may the residents of the second stoep not use the Uka?