1)

(a)'Ribah le'Echad, u'Mi'at le'Echad' - is speaking, not when a discrepancy occured in two different spots, but when it occurred on the same spot. There too, we assume that it is the person who measured the shorter distance who erred.

(b)Even if the discrepancy was so great that it was not possible to ascribe it to the fact that one who measured the shorter distance was not careful to pull the rope taut, it is still possible to ascribe it to the fact that he was not aware of the Din of adding the diagonal to the square. But if the discrepancy is even greater than that, then we must assume that it is not the shorter one who erred, but the longer one - and we accept the shorter measurement (though it is not clear why, in this case too, we should not still apply the principle of going Lehakel by Eruvin).

(c)'Lo Amru Chachamim es ha'Davar Lehakel Ela Lehachmir' - means that whatever Chazal decreed in connection with Techumin is all Lehachmir on Divrei Torah; there is nothing Lehakel (since Techumin is purely de'Rabbanan). That is why our Mishnah adds that, since Techumin is purely de'Rabbanan, wherever possible, we are lenient.

2)

(a)The criterion for including the whole town in the one Eruv - is that it was initially a private town. Therefore it is not similar to the camp of Yisrael in the desert, and is like a Reshus ha'Yachid.

(b)Whenever an Eruv incorporates the whole town - the individual Mavo'os do not require separate Eruvin.

(c)We are speaking here, about a town which has no real Reshus ha'Rabim - if it does, its Din will be described later in the Sugya.

(d)One cannot be Me'arev an Ir shel Rabim ve'Na'asah shel Yachid - because it may revert to its original status as an Ir shel Rabim, in which case an Eruv will not help (and the people unaware of this, will continue to rely on the Eruv, as they did before).

3)

(a)An Ir shel Rabim ve'Na'asah shel Yachid is permitted to make a communal Eruv - if they leave a small section on the towwn's outskirts outside the Eruv, who subsequently make their own Eruv. That small section must consist of fifty residents (according to Rebbi Yehudah), or three Chatzeros each consisting of two houses (according to Rebbi Shimon).

4)

(a)The Gemara initially thought that an Ir shel Yachid ve'Na'asah shel Rabim must have previously belonged specifically to the Resh Galusa - because then, the entire town would fall under his jurisdiction (with regard to obtaining permission to judge, to permit blemished Bechoros and to give Semichah). Consequently, the crowds would always meet at the Resh Gelusa's residence, and would remind each other not to carry without new individual Eruvin - even after it became a public town.

(b)If that is so, asks the Gemara - they would also meet in Shul every Shabbos morning (to hear the Derashah) - even by an a town that was initially a public one, and they too, would remind each other not to carry without individual Eruvin.

(c)If a Reshus ha'Rabim passes through an Ir shel Yachid ve'Na'aseh shel Rabim - one places a Lechi or a Koreh at both ends and one is permitted to carry.

(d)One cannot however, do the same with an Ir shel Rabim which was always an Ir shel Rabim - because there, since there is nothing to remind them that this is not a real Reshus ha'Rabim, all the Mavo'os which resemble a Reshus ha'Rabim, require individual Tikunim.

5)

(a)One can be Me'arev an Ir shel Yachid ve'Na'aseh shel Rabim - either by being Me'arev the entire town with one Eruv, or by being Me'arev it Mavoy by Mavoy. It is not possible to make one Eruv for half the town, and the other half Mavoy by Mavoy - because, since the town was originally a private one, each Mavoy will forbid the other Mavo'os, if it does not combine in the communal Eruv (like a Mavoy where one of the Chatzeros did not join in the other Chatzeros' Eruv).

(b)An Ir shel Rabim that was always an Ir shel Rabim may combine the whole town in one Eruv - if there is only one entrance to the town (i.e. the main street does not pass from the gate at one end of the town to the gate at the other (in which case, it does not resemble the Camp of Yisrael in the desert).

(c)The author of the Beraisa, who permits making an Eruv in a Reshus ha'Rabim - is Rebbi Yehudah, whom we quoted a number of times in the first Perek.

(d)An Ir shel Yachid ve'Na'asis shel Rabim is not permitted to divide into two, to make two separate Eruvin - because, since it was initially an Ir shel Yachid, it is like the case of the residents of a Chatzer who made an Eruv, where if one resident forgot to participate in the Eruv, he forbids all the other residents to carry from their houses to the Chatzer.

6)

(a)Rav Papa restricts the previous Din to the Mavo'os dividing lengthwise (since the Reshus ha'Rabim that runs past the end of the Mavoy combines both sides of the Mavoy, and there is nothing running down the middle of the Mavoy to divide one side from the other); but to divide widthwise (i.e. for the courtyards at one end of the Mavoy and those at the other end to make independent Eruvin) is permitted. Why? Because it is possible for each half of the Mavoy to separate from the other half by each using a different entrance (one the Reshus ha'Rabim at one end, and the other, the Reshus ha'Rabim at the other end).

(b)Rebbi Akiva holds - that if the members of the inner courtyard did not combine with the members of the outer one (despite the fact that they made their own Eruv, permitting them to carry there), they will forbid the members of the outer courtyard (who also made their own Eruv) to carry, since they inevitably need to pass through the outer courtyard to get to the street.

(c)Rav Papa can hold even like Rebbi Akiva - because, in the case of our Beraisa, there is a Reshus ha'Rabim running past each end of the Mavoy, and the members of the courtyards at one end of the Chatzer are not forced to pass through the section of Mavoy that belongs to the courtyards in the other half. Consequently, even Rebbi Akiva will agree that the residents of the one section of the Mavoy will not forbid those at the other.

(d)Rav Papa in the second Lashon, where he forbids the members of the Mavoy to split up either way, can go even like the Chachamim, who hold 'Reshus ha'Materes bi'Mekomah, Einah Oseres she'Lo bi'Mekomah' - because they speak when the residents of the inner courtyard can close the door in between them and the outer courtyard, and remain independent (in fact, we will even force them to do so because of 'Kofin Osam Al Midas Sedom'); whereas in our case, nobody can deny the fact that a Reshus ha'Rabim runs past the front of the Mavoy, and there is nothing in between the two sections of Mavoy to divide between them.

7)

(a)The Beraisa allows the town to be Me'arev Mavoy by Mavoy - only if they build a Dakah.

(b)A Dakah is a low doorway built at the end of each Mavoy. It serves to demonstrate that they have severed their connections from the other Mavo'os who use the Reshus ha'Rabim.

(c)Rav Chisda says that if the members of a Chatzer build a Dakah at the entrance of their Chatzer to the Mavoy, then they do not forbid the residents of the other Chatzeros of the Mavoy (who made an Eruv) from carrying in the Mavoy.

8)

(a)Rebbi Zeira thought that Rav Chiya bar Asi, who had made an Eruv before him in Rebbi Chiya's town, did so because it was an Ir shel Yachid she'Na'asis Ir shel Rabim - which does not require a Shiyur.

(b)Rebbi Chiya bar Asi's real reason for being Me'arev the town - was because, at that time, there was a trash heap blocking one of the entrances, and we have learnt in the Beraisa, that even an Ir shel Rabim can make an Eruv if it has only one entrance. However, that was no longer applicable in Rebbi Zeira's time, due to the fact that the trash heap had been cleared away.

(c)When Abaye told Rebbi Zeira this, he replied - that he had not been aware of that.

9)

(a)If an Ir shel Rabim has an entrance on one side and a only ladder on the other - then it will depend on what Din the ladder has, as to whether it will be permitted to make a communal Eruv there or not.

(b)According to Rav Nachman, what Rav really said (with regard to a ladder between two towns) - was 'Sulam Toras Mechitzah Alav'.

(c)When it came to a ladder between two courtyards - Rav said 'Toras Pesach Alav' (meaning that they had the option of making a combined Eruv or of making two separate Eruvin).

10)

(a)Rav Nachman rules with regard to a Chatzer and an upstairs (outside) balcony with a ladder leading down to the Chatzer whose residents forgot to to participate in the Eruv - that if there is no Dakah in front of the balcony, at the foot of the ladder, then the residents of the balcony forbid those of the courtyard to carry from their houses into the Chatzer; but if there is, then carrying is permitted .

(b)Rav Nachman here appears to give a ladder between a Chatzer and a balcony the Din of an entrance - whereas he just quoted Rav as saying that a ladder between two courtyards has the Din of a Mechitzah?

(c)The reason that, when there is no Dakah, the residents of the courtyard are not permitted to carry - is not because the ladder is considered an entrance and not a Mechitzah, but because it speaks (according to the Gemara's current contention) when the entire balcony is less than ten Tefachim high.

(d)The Dakah is effective concludes the Gemara - because we are speaking when most of the balcony has a Mechitzah, all except for ten Amos. Now an entrance of ten Amos is Pasul. Consequently, if they build a Dakah there, they will be permitted to carry, because then, it is as if they had disassociated the Chatzer from the balcony; otherwise, they are not.