Rif Eruvin 5b {Eruvin 17b continues ... 18a}

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5b

{Eruvin 17b continues}
BEGIN PEREK II - Osin Pasin

MISHNA:
We make strips {of wood - pasin} for wells - 4 dey-omdin {=corner pieces, such that there are two standing pieces at right angles} that have the appearance of 8. These are the words of Rabbi Yehuda.




Rabbi Meir says: 8 strips that have the appearance of 12: 4 being corner pieces and 4 flat strips.

Their height must be {at least} 10 handbreadths, their width 6 {handbreadths}, and their thickness any size whatsoever.

Between them may be as much space as to admit 2 teams of 3 oxen each. These are the words of Rabbi Meir.
Rabbi Yehuda says: Of 4 oxen each, tied together and not loose from one another {which would be more distant}, {with enough space between the two teams for} one entering while the other exits.

It is permitted to bring the strips {fairly} close to the well, provided that a cow's head and majority of its body will be within {the enclosure} when it drinks.
{Eruvin 18a}
And it is permitted to distance the strips from the well any amount whatsoever, so long as you increase the number of strips.