Rashi and Rambam hold that a pillar, in order to be r'shus harabim must be exactly 9 tefachim (as you wrote). May we understand from this that from 9 plus until 10 (makom patur), such a pillar would be a carmelis? If so, what is their reasoning? Shouldn't it be a reshus harabim since if people use it at 9 tefachim they will be even more likely to make use of it between 9 and 10 tefachim?
Chaya Passow, Yerushalayim
Sholom Rav,
The Gemara explains that a pillar of nine Tefachim is considered R'shus ha'Rabim because people tend place their loads on it - rendering it part of the R'shus ha'Rabim. Less than that it is either a Karm'lis or a Makom P'tur (depending on its area), because It is not convenient to place one's load on it.
Rashi and the Rambam are now saying that nine Tefachim is specific, because if it is more than nine, then, like less than nine, it is inconvenient to use for resting one's load.
Be'Virchas Kol Tuv
Rabbi Chrysler