Eruvin Chart #6

MEASURING THE "TECHUM SHABBOS"

ACCORDING TO RASHI:
		[RAVA-1ST LASHON]	[RAV HUNA BAR NASAN]
1)	A HILL OR VALLEY THAT COMES TO A HEIGHT OR DEPTH OF 10 TEFACHIM WITHIN *5* AMOS	Medidah Yafah(3)	Mavli'a or Mekader(2) (and if the valley is deeper than 100 or 2000 Amos(4), he is Mekader)
2)	A HILL OR VALLEY THAT COMES TO A HEIGHT OR DEPTH OF 10 TEFACHIM WITHIN *4* AMOS	Mavli'a or Mekader(2) (and if the valley is deeper than 100 or 2000 Amos(4), he is Mekader)	Estimate
3)	AN INCLINE SO STEEP THAT IT IS DIFFICULT TO WALK THERE (IT REACHES A HEIGHT OR DEPTH OF 10 TEFACHIM WITHIN LESS THAN 4 AMOS)	Estimate(5)
4)	THE PLUMB LINE DESCENDS STRAIGHT DOWN (WITH A LEEWAY OF 4 AMOS)(1)	Medidah Yafah(6)
ACCORDING TO RABEINU TAM:
1)	IT IS NOT POSSIBLE TO DESCEND THE INCLINE (RISES 10 TEFACHIM WITHIN 4 AMOS)	Natural slope: Estimate Manmade slope: Mavlia or Mekader
2)	IT IS POSSIBLE TO DESCEND THE INCLINE	<4 Amos; > 2000 Amos(4): Medidah Yafah (even the slope itself) 4-2000 Amos: Mavli'a or Mekader

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FOOTNOTES:
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(1) Whether the depth is great or little.
(2) According to Rav Huna bar Nasan, there are *three* categories of measuring, and not four (Tosfos, DH Aval).
(3) (According to the first explanation of Rashi on 58a (DH v'Im Hayah Gai Me'ukam), this "Medidah Yafah" must mean Mekader.)
(4) Chananyah and the Rabanan argue whether the maximum depth is 100 Amos or 2000 Amos.
(5) This is clear from Rashi (58a, DH b'd'Neicha) and Tosfos (58b, DH Aval). Tosfos (58a, DH Ein) writes that an estimate works only for a hill, but not for a valley, because a valley can be easily measured by being Mavli'a. (The Rosh 5:6 adds that if one cannot be Mavli'a a valley or hill with a rope 50 Amos long, he may still not estimate but rather he must be Mekader, whether it is a valley or a hill, since it is not too hard to be Mekader a slope. Rashi, DH b'd'Nicha, does not seem to agree with this.)
(6) The Rosh (5:6) writes that this applies when the width of the valley is more than fifty Amos (when measured from edge to edge at the top). If it is not more than fifty Amos, we must be Mavli'a the width of the valley and include the breadth of the slope, and we may not rely on a Medidah Yafah of the floor of the valley.