- Residents who live on the same level as a mirpeses
This Daf continues with the machlokes between Rav and Shmuel whether שלשול, lowering down is considered easier than זריקה, throwing something up or not, in terms of determining who has rights to use a given area. The Gemara attempts to bring a support to Shmuel that lowering down is easier from the Mishnah. The Mishnah stated that אנשי חצר ואנשי מרפסת ששכחו ולא עירבו – If the residents of a chatzeir and the residents of a mirpeses forgot to make an eruv, כל שגבוה עשרה טפחים למרפסת פחות מכאן לחצר – Whichever area is ten tefachim high above the floor of the chatzeir belongs to the mirpeses, and whichever area is elevated less than this belongs to the chatzeir. This seems to support Shmuel since the residents of the mirpeses actually live in an upper story and make use of the mirpeses by lowering things to it.
The Gemara defends Rav by saying that just as the term mirpeses was used in a different case to mean the residents who live on the same level of the mirpeses and not above it, so too here. In that case, the residents of the mirpeses have access to it directly which is why they can use the area on Shabbos and those in the chatzeir that require throwing up to it cannot.
- A ledge protruding from a nineteen tefach high wall
The Gemara attempts to bring a support to Rav from a Baraisa that states, אנשי חצר ואנשי עלייה ששכחו ולא עירבו – If the residents of a chatzeir and the residents of a second story forgot to make an eruv, the residents of the chatzeir may make use of a ledge that protrudes from the wall if it is below ten tefachim, and the residents in the upper story may make use of the ledge if it is above ten tefachim. This implies that if the ledge were in the middle and ten tefachim away from both, it would be restricted from use since it is equally accessible to both.
Rav Nachman answered, הכא בכותל תשעה עשר עסקינן וזיז יוצא ממנו – Here in the Baraisa we are discussing a nineteen tefachim high wall from which a ledge projects. If the ledge is below ten tefachim from ground level it is accessible to the chatzeir as a pesach, which makes it exclusively theirs. If it is above ten tefachim from the ground it is accessible to the residents of the upper story as a pesach, making it exclusively theirs.
- Two balconies who draw water from the higher balcony
The Gemara brings a support for Rav’s position from a Mishnah on Daf 87b that states, שתי גזוזטראות זו למעלה מזו – Two balconies where one is higher than the other, and the upper balcony has a מחיצה תלויה, a four-by-four tefach hole with a ten tefach partition coming down from it in order to draw water from below. The Gemara later explains that this partition was built in partnership with the residents of the lower balcony, so that they will have דריסת הרגל, the right of passage to use the upper balcony to draw water. Therefore, neither balcony can use the hole without an eruv. Since the upper balcony uses the hole with שלשול and the lower balcony uses it with זריקה and with שלשול, and the Baraisa considers them equals, this seems to support Rav’s position. The Gemara answers that the case is where the residents of the lower balcony go up via steps to the upper balcony to get water, which means they also use it only with שלשול, and even Shmuel agrees it is forbidden for both. Abaye gives a second answer.