Yerushalmi Eruvin 5:8 ירושלמי עירובין ה׳:ח׳

MISHNAH: Rebbi Aqiba told them, do you not agree with me about one who puts his eruv at the mouth of a cave that he only has 2’000 cubits from the place of his eruv? They told him, when is this? If there are no dwellers in it, but if it is inhabited he walks through all of it²²If the cave is inhabited it becomes a house and the entire cave is counted as 4 cubits. and outside 2’000 cubits. It turns out that the interior is easier than its top²³If somebody puts his eruv on top of a cave where nobody dwells, he only has 2’000 cubits from the place of his eruv.. But for one who measures about whom they talked one gives 2’000 cubits even if his measure reaches its limit inside the cave²⁴As noted before, by making an eruv one reduces his Sabbath domain to a circle of radius 2’000. If the eruv was deposited outside the cave he cannot walk inside the cave to a distance farther than 2’000 cubits from the eruv even though for the cave dwellers the entire cave is only counted as 4 cubits..

HALAKHAH: Paragraph. “Rebbi Aqiba told them, do you not agree with me,” etc. Rebbi Jacob bar Aḥa in the name of Rebbi Eleazar. The one who acquires rest¹⁵⁹It is his place of residence for this Sabbath. in a fore-court has it easier than one who puts his eruv in a fore-court. He who acquires rest in a fore-court walks in its entirety and outside of it 2’000 cubits. He who puts his eruv in a fore-court only has 2’000 cubits from the place of his eruv¹⁶⁰Since anybody who makes an eruv loses all additions to the circular domain of radius 2’000 cubits.. Rebbi Zeˋira asked: If one said, rest should be acquired for me in the fore-court? Rebbi Ḥanania the son of Rebbi Hillel said, this is the disagreement of Rebbi Meïr and Rebbi Jehudah¹⁶¹Chapter 4, Note 83.. Rebbi Meïr is of the opinion, the main point of an eruv is by a loaf. If he puts his eruv in a fore-court he only has 2’000 cubits from the place of his eruv. Rebbi Jehudah said, the main point of an eruv is by his feet. If he said, rest should be acquired for me in the fore-court, he walks in its entirety and outside of it 2’000 cubits.

The roof of a tower is considered [part of] the town. The roof of a cave is considered as fields. What, really dwellers¹⁶²This refers to Mishnah 10. Do we require that a cave be inhabited or only that it should be habitable?? Or maybe just inhabitable? Since Rebbi Isaac bar Naḥman said in the name of Rebbi Ḥanina: one considers it as if filled by water and clay¹⁶³His definition of “uninhabited” is “unhabitable”; therefore for him “inhabited” means “habitable”., this means even inhabitable. Rebbi Isaac ben Rebbi Eleazar said, this implies (a city)¹⁶⁴It seems that for עיר “city” one should read מערה “cave”. which has two exits, if between one and the other there are 3’999 cubits one walks in its entirety and outside it 2’000 cubits, 4’000 cubits he only has 2’000 cubits from the place of his eruv. Rabbi Aḥa said; Rebbi Ze`ira explained it. If he would put his sandal anywhere he could go outside and put it on; and if he would put his sandal anywhere he could go outside and put it on. What is the difference from which side he comes? From one side it is forbidden, from both sides it is permitted⁶⁰A line segment can be the border of the completion of a town only if all of its points are accessible from the town on the Sabbath. Therefore if the radius of the semi-circle is > 2’000, a point distant almost 2’000 from one side is not accessible from the other and the center is not accessible from anywhere. Therefore the chord cannot be the border of the completion; the Sabbath domain only is the set of all points of distance at most 2’000 from any point of the semi-circle. Babli 55a..

Rebbi Aḥa in the name of Rav Ḥinena: If the roof of the cave was 4’000 cubits¹⁶⁵Probably this again should read “4’000 - 1”. he walks in its entirety and outside it 2’000 cubits, on top of a wall it is unlimited. If the roof of the cave was 6’000 cubits he walks in its entirety and outside it 2’000 cubits by the help of nibariot¹⁶⁶Possibly “protuberances”, Arabic نبرة. If the cave below is considered a human dwelling, the roof above it can be made similar to the roof of a house by subdividing it into several roofs by natural outcroppings.. What about tops of roofs? Rebbi Yose in the name of Rebbi Jacob bar Aḥa, Rebbi Aeneas bar Pazi in the name of Rebbi¹⁶⁷Read: “Rav Jehudah”. Jehudah, Rebbi Aḥa brings it in the name of Samuel. On top of the roofs one carries even a kor, even two kor¹⁶⁸Meaning bet kor, a surface area of 30 bet seah (Chapter 1, Note 288).. Rebbi Meïr said, one carries up to two bet se’ah. Rebbi Yose ben Rebbi Abun said, the word of Rav disagrees with him¹⁶⁹With both Samuel as quoted later, and R. Aḥa whose attribution is shown wrong., as we have stated there¹⁷⁰Mishnah 9:1. Even though the houses below define different private domains, the roofs, although divided by walls, form a single domain on which one may carry from one house to the next: “All roofs of a city form a single domain.” Samuel said, up to two bet se’ah. Rav said, one carries there even a kor, even two kor. It is the same for tops of roofs and tops of ships¹⁷¹If ships are tied together in a harbor, one carries from ship to ship as one carries from roof to roof..