As we have seen (section 2), we square a person’s mekom shevita to determine his teĥum. If he is in a field (i.e., not in a city or town), his mekom shevita is a square with four-ama sides; if he is in a city, we inscribe the city in a square. From this square we measure 2,000 amot in each direction.
Let us add now that when we square the city, we do so based on the four cardinal directions (SA 398:3). If the city already has corners that lend themselves to squaring in a way that does not follow the four cardinal directions, the squaring is done accordingly (SA 398:1).
Examples of squaring based on the four cardinal directions:
Examples in which it is agreed that the squaring does not follow the four cardinal directions:
When a city’s shape lends itself to squaring that does not correspond to the four cardinal directions, the poskim disagree how to square it. Some maintain that only when there is a compelling reason not to follow the four cardinal directions may one follow the layout of the city (SAH 398:3; Ĥayei Adam 76:14). However, most poskim maintain that if the shape of a city clearly lends itself to squaring in a certain way, we follow this squaring even though it does not correspond to the four cardinal directions (see n. 7). In cases of doubt, the local rabbinate or rabbinic authority should make the decision.
Examples of such intermediate cases in which a city’s shape clearly lends itself to squaring in a direction other than the four cardinal directions include cases where one side of the city is straight from one end of the city to the other (figure 1) and cases where the perimeter of the city contains a right angle (figure 2, in which case we follow the directions of the right angle and not the four cardinal directions).
It is important to note that if one is spending Shabbat outside a city and his mekom shevita is limited to four amot square, he may choose to square his mekom shevita in whatever direction he wishes, and this will also determine how his 2,000-amateĥum is squared (see section 12 below).
. The city’s residents may not decide to square the city in a way that does not follow the four cardinal directions just because they would like to add space in the corners in the direction they wish to go. This is because the law is unequivocal: the city must be squared in accordance with the four cardinal directions. This is based upon the procedure described for the Levite cities: “You shall measure off two thousand amot outside the city wall all around. You shall measure off two thousand amot outside the city on the east side, two thousand on the south side, two thousand on the west side, and two thousand on the north side, with the city in the center” (Bamidbar 35:5). We see that the verse follows the four cardinal directions. This understanding is implied in MT 28:7 and SA 398:3, and is also followed by MB 398:7 and Ĥazon Ish 110:23. Some maintain that the city’s residents do have the right to decide to square their city in a way that does not correspond with the four cardinal directions. In such a case, every individual is bound by the group’s decision (Rabbeinu Yehonatan, Eruvin 16a, s.v. “im”; Perisha 398:1; Mirkevet Ha-Mishneh, Shabbat 27:2; Noda Bi-Yehuda, Mahadura Tinyana, OĤ 51).. In the city featured in figure 1, most Rishonim and Aĥaronim rule that it is squared based on the right angle (as is the case with a city that is shaped like an L, according to Rashba, Ran, Ritva, and Me’iri). In the city featured in figure 2, one side of the entire city is a straight line. The law in such a case can be derived from the case of a city that is shaped like a bow (section 7), where it is squared based on this straight line, or “bowstring” (Me’iri, Eruvin 55a). Ĥazon Ish states this as well in OĤ 80 and 110. Some maintain that in both the above cases, the city must be squared based on the four cardinal directions (SAH 388:3; Ĥayei Adam 76:14). Others maintain that in all doubtful cases, the city is squared in whichever way will add the least area to the city (Ĥazon Ish 110:23). The halakha follows the first opinion, that of the majority of poskim, and the figures above reflect this opinion. Nevertheless, when it is not clear if the perimeter of a city contains a right angle, the local rabbinate or rabbinic authority may decide to rely on those who rule that such a city should be squared based on the four cardinal directions.