עירובין ח׳:ז׳ - ח׳:ח׳

אמת המים – even in the private domain, it is a Karmelit (i.e., an intermediate domain between a private domain and a public domain, established by the Sages. The Sages extended the prohibition against carrying on Shabbat from a private domain to a public domain or carerying within the public domain to include certain areas which resemble a public domain. Any open area larger than four square handbreadths that is not a public thoroughfare is in the category of a Karmelit, i.e., fields, seas, rivers, alleyways and lanes. On Shabbat it is prohibited to caerry four cubits within a karmelit or to transfer from a private or public domain to a karmelit and vice versa).

עשו לה מחיצה – with the rim over the face of its width which is recognized that it was made for the water.

מעשה באמה של אבל – the name of a city, that would pass within the courtyards and they would fill from it in the courtyards for the partitions of the wall of the courtyard that were suspended upon it were beneficial. Bug Rabbi Yehuda, according to his reasoning who argued also regarding a cistern, but the Halakha is not according to him.

שלא היה בה שיעור – A Karmelit, that was not ten [handbreadths] deep or was not four [handbreadths] wide, where the waters are not made into a domain into themselves to be considered a Karmelit unless it is ten [handbreadths] deep and four [handbreadths] wide. If they made it at the entrance but not at the exit, it does not benefit at all, for it connected to the water that is outside of the courtyard in its departure, and it all becomes a Karmelit; [but, if they made it – (i.e., the partition) at the exit but not at the entrance it also does not benefit, for it is connected to the water that is above outside of this courtyard. But if they made it at its entrance and at its exit, it benefits, that it appears] as if they begin in this courtyard.

גזוזטרא (balcony)- it is similar to board/plank or a place of its source that juts out from the private domain and protrudes over the water.

אא"כ עשו מחיצה – all around he balcony or around the perforation four [handbreadths] by four [handbreadths] that is hollowed out in its idle, for we state “imagine that the partition continued downward (see again Talmud Eruvin 87a).

בין מלמעלה – above from the the perforation of the balcony.

בין מלמטה – attached to the balcony from below it But Maimonides explained that from below on he water corresponding to the perforation of the balcony, as we stated, “imagine that the partition continued upward [prolonged to reach the ceiling” (Talmud Eruvin 89a and Sukkah 4b), as if the partition reached to the perforation that is in the balcony that we fill [water] from it.

זו למעלה מזו – and the perforation that we fill fro at the top is directed opposite the lower perforation.

עשו לעליונה – that the members of he lower area made a partnership with those who lived in the upper area to make a partition in the upper area, but not in the lower area.

שתיהן אסורות עד שיערבו – for since those who dwelled below are partners in this partition of the upper level, it forbids them. But if they made [a partition] for the lower section, but not make one for the upper area, even though for the upper area there was no partnership in the partition of the lower area, both of them are prohibited. The upper area is prohibited for they have no partition, and the lower araa, even that there is a path to the upper area through it, for it too fills waer from there, it forbids it until they make an Eruv with it. But these words, that the two balconies are removed from each other when it is ten handbreadths high or more between one and the other, but if both of them are within ten [handbreadths] even if both of them made a partition, they will alwas forbid one on the other until they make an Eruv.