Yaddayim chapter 1

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Extra Material

• Discussions
• Additional Ideas

  One hundred pairs of hands?

  According to the smaller measure for a quarter-Log (7⅓ cubic finger-breadths), sufficient water exists to wash two pairs of hands held closely together. Doubling this to a half-Log (14⅔ cubic finger-breadths) suffices for four pairs of hands, reflecting a linear progression in water usage. A full Log could then wash eight pairs of hands and, in practice, extend to ten pairs, as residual water accumulates after each washing.

  However, the Mishnah’s claim that a Log could suffice for one hundred pairs of hands is impractical. Even with the larger measure of a quarter-Log (10.8 cubic finger-breadths, yielding 43.2 cubic finger-breadths for a Log), the water available per pair of hands—each typically comprising ten fingers—is less than half a cubic finger-breadth (approximately 0.432 cubic finger-breadths per pair, or 0.0432 per finger). This amount is insufficient for effective washing beyond a limited number of people. Thus, the Mishna’s reference to “one hundred” is hyperbolic, indicating that a Log can suffice for the hand-washing of many people, but not much more than ten.

  The number of pairs of hands a Log of water can wash depends on hand size relative to the average finger-breadth, the efficiency of water pouring, and whether washing extends to the knuckles or wrists. Using Shmuel’s calculation or Rav Chisda’s, a Log comprises 29⅓ or 43.2 cubic finger-breadths, respectively. For hands of typical size washed to the knuckles, with efficient pouring and hands held close together or lined up in a row to maximize efficiency, a Log typically suffices for 10–11 pairs. For larger hands, scaled to a proportionally larger finger-breadth, 14 to 17 pairs can be washed with an optimal technique, as the required water volume increases with finger-breadth size.

• Points to Ponder

  Can we determine the exact nature of the Machatz by considering why someone might turn it upside down to pour water with it? Does it hold more water in this position? Is there a reason it cannot be used to pour water when right-side up? Or does this Halacha simply provide an example of an item unsuitable for ritual hand-washing?

• Further Reading

  • Mishnayoth Khati - Order of Taharoth vol ii.
  • Mishnayoth HaRambam - Mossad HaRav Kook - Orders of Kodashim/Taharoth.