Two courtyards one behind the other — if the inner made an eruv but the outer did not, the inner is permitted while the outer is prohibited; the outer, but not the inner, both are prohibited; each courtyard made its own eruv, [then] each is individually permitted. R’ Akiva prohibits the outer, because the right of passage restricts it. But the Sages say: The right of passage does not restrict it.

If one [resident] of the outer forgot to contribute to the eruv, the inner is permitted while the outer is prohibited. If one from the inner [forgot], both are prohibited. If they placed their eruv in one place, and one [resident] of either the inner or the outer forgot to contribute to the eruv, both are prohibited. But if they were inhabited by individuals, they need not make an eruv.

A window between two courtyards — [if it is] four by four [fists] within ten, they may make two eruvin, or, if they wish, they may make one eruv; less than four by four or higher than ten, they may make two eruvin, but may not make one eruv.

If a wall between two courtyards is ten [fists] high and four wide, they may make two eruvin, but may not make one eruv. If there was fruit on top of it, these ascend from here and eat, and those ascend from there and eat, provided they do not bring down. If the wall was breached — up to ten cubits, they may make two eruvin, or, if they wish, one eruv, because it is like an entrance; greater than that, they may make one eruv, but may not make two eruvin.