Study Eruvin folio 10B with parallel Hebrew-English text, traditional commentary, and modern study tools. Free access to Babylonian Talmud online.
One prepares a board 10 handbreadths high with a length of 4 cubits and stands it lengthwise down the middle of the alleyway, and thereby forms two small alleyways at the entrance to the alleyway, neither of which is more than 10 cubits wide.
Alternatively, one can act in accordance with the opinion of Rav Yehuda, as Rav Yehuda said: If an alleyway is 15 cubits wide, how does one reduce its width? He distances himself two cubits from one of the walls of the alleyway and prepares a board 3 cubits wide, thereby leaving an opening of on
The Talmud asks: And why must one reduce the width in this manner? One could also prepare a board 1½ cubits wide, and distance himself two cubits, and then prepare another board 1½ cubits wide, leaving the alleyway with an opening of only 10 cubits. Apparently, one may conclude from the fact that Ra
The Talmud rejects this: Actually, I would say to you that ordinarily it is considered as standing even when one must combine the standing segments on the two sides of the breach. However, it is different here, as the air, i.e., the two cubit opening, of this one side of the far board and the air,
The Talmud suggests: And one could instead prepare a board one cubit wide and distance himself one cubit, and prepare another board of a cubit and distance himself one cubit, and prepare a third board of one cubit, thus ensuring that the open space is not greater than the standing segment on both s