Eruvin 78 - Ditch

If two courtyards are separated by a ditch that is at least ten hand-breadths deep and four hand-breadths wide, then - since it is not convenient to step over such ditch - it separates the two courtyards into two, and they need to make a separate eruv (common food). This eruv will allow the residents of each courtyard to carry in it, but not into the other courtyard. Even if they fill the ditch with stubble or straw, it still separates them, because those materials will not remain there but will likely be removed. If, however, they fill the ditch with earth or pebbles, then - since those materials will likely stay n there - the ditch has been effectively closed, and they can make only one eruv for all of them.

If they put a board of at least four hand-breadths wide over the ditch, then now they have a choice. If they want, then can look at this board as a connector that allows them to join in a mutual eruv. Or, they can view this board as merely a bridge but not a connector, and create individual eruv for each of the two courtyards.

Art: Clearing a Ditch, 1839 by John Frederick Herring Snr 1795 - 1865

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