The Bavli, Shabas 7 amud 2, has a discussion about holes in walls, where things might land if thrown. Holes on the r'shus-hayachid-facing side of a wall are deemed r'shus hayachid, so tossing something into one from within the r'shus hayachid is permissible. The question arises, though, what holes on a r'shus-harabim-facing side of a wall are considered: r'shus harabim or not.
The next four paragraphs (five including this one) provide detail about the g'mara and basis for my question: skip down to the horizontal rule if you're familiar with the g'mara and Rashi or simply wish to get to the gist of my question.
Rashi (ד״ה לאו כרשות הרבים דמו) says that in the second alternative — that such holes are not r'shus harabim — they'd be considered a separate r'shus: thus (he continues), if they are four tefach square they're a karm'lis and otherwise they're a m'kom p'tur. Note that a four-tefach-square area would normally be a karm'lis only less than ten tefach off the ground: more than ten tefach off the ground, such an area would normally be a r'shua hayachid. This is the first indication (to me) that these holes in walls under halachic discussion may be only those less than ten tefach off the ground.
Let's continue — excusing, if you please, my quasi-stream-of-consciousness post.
The g'mara goes on to cite a mishna that says if you throw something at a wall four amos away, more ten tefach off the ground, you're exempt; but lower than that, you're liable as if the thrown object had landed on the ground. Rabi Yochanan's interpretation of this is given: that the thrown object stuck to the wall. That Rabi Yochanan didn't offer the simpler explanation, that the object landed in a hole in the wall, indicates, the g'mara says, that had it landed in such a hole, lower than ten tefach, the thrower would be exempt — proof that holes in the wall are not considered r'shus harabim. The g'mara counters that the wall in question has no holes, and that that's the reason Rabi Yochanan didn't say that the object landed in a hole in the wall. How do we know it has no holes? Well, from the first case of the mishna: that the object reached the wall above ten tefach. If the wall had holes and the thrown object landed in one, the thrower would be liable, even above ten tefach!
Now, wait a second. (This is me speaking now, not the g'mara.) Why would the thrower be liable then? I'd think that, since the hole is considered r'shus harabim (the hypothesis of this whole series of arguments in the g'mara), he'd be liable for throwing something four amos in a r'shus harabim. Not so, says Rashi: he'd be liable because "הא ה״ל מרה״ר לרה״י דהוה ליה גבוה י׳ ורשות לעצמו / it's [a throw] from r'shus harabim to r'shus hayachid, for [the hole] is ten tefach off the ground and its own r'shus". This explanation is my second indication that the halachic discussion of whether holes in walls are considered r'shus harabim applies only to those less than ten tefach off the ground — and this one's a strong indication in my opinion. Moreover, Rashi's explanation is necessitated by the next step in the g'mara, which also indicates as much — but I'll stop here.
So Rashi and even the g'mara seem to indicate that the holes in walls that may be considered r'shus harabim are only those that are less than ten tefach off the ground.
- Is this explicit anywhere? I inferred it from the argument of the g'mara and the wording of Rashi, but it seems like an important point to omit. (Moreover, maybe I'm wrong, and the holes in walls that may be considered r'shus harabim are even those more than ten tefach up. If so, that'd make a good answer to this subquestion (and then ignore my second subquestion).)
- Does this apply only to the r'shus-harabim side, or are holes on the r'shus-hayachid side of a wall, also, considered r'shus hayachid only up to ten tefach off the ground? I suspect (strongly) that the r'shus-hayachid side may be different, since, generally, r'shus-harabim airspace is not considered r'shus harabim higher than ten tefach, which is not true of r'shus hayachid; but just as I have no explicit source to say the r'shus-harabim-side holes in walls are (possibly) r'shus harabim only up to ten tefach, so do I have no explicit source to say the r'shus-hayachid-side holes in walls are r'shus hayachid even higher than ten tefach.