FROM A CISTERN BETWEEN TWO COURTYARDS NO WATER MAY BE DRAWN ON THE SABBATH UNLESS A PARTITION TEN HANDBREADTHS HIGH HAS BEEN MADE FOR IT EITHER BELOW OR WITHIN ITS RIM. R. SIMEON B. GAMALIEL STATED, BETH SHAMMAI RULED: BELOW, AND BETH HILLEL RULED: ABOVE.
What is this partition and what does “above” and “below” mean?
This is, perhaps, a symbolic partition near the rim, just to indicate that there is a division of the waters. Or it is a real wall that divides the cistern in half and extends from the bottom of the cistern to either just below or just above the waterline.
Even more curious:
R. JUDAH OBSERVED: THE PARTITION COULD NOT BE MORE EFFECTIVE THAN THE INTERVENING WALL.
That is, the wall that divides the two courtyards.
The same thing, the Mishnah continues, with a water channel passing through a courtyard. It must have a partition ten handbreadths high at its entrance and at its exit from the courtyard. R. Judah rules that the existing wall of the courtyard can serve as this partition. Others not.
And if the water channel is less than 3 handbreadths wide (R. Simeon b. Gamaliel rules: less than 4), a bucket can be lowered from a balcony to draw up water – from houses on either side of the channel.
Thus providing “running water.”