As we have seen, by squaring the city, we add space in the corners to the teĥum. However, the Sages pointed out that sometimes we cannot draw straight lines to square the whole city, because the resulting square would include uninhabited areas that are too large to be considered subsumed by the city. Examples of this would be cities that are shaped like a bow or like an L. The operative principle is that if there are 4,000 amot between the two ends of the shape, that part of the city cannot be squared.
. Rambam and SA 388:4 state, in disagreement with this diagram, that the 2,000 amot are measured from the edges of the inhabited homes. The resulting teĥum follows the curve of the bow. However, the diagram follows the opinion of Tosafot (55b, s.v. “ve-im lav”), Rosh, most Rishonim, and Rema that for the inside of the bow, where the arc narrows to less than 4,000 amot, we draw a “bowstring” from one end of the arc to the other and measure the teĥum as 2,000 amot from that straight line (see diagram). The halakha follows the majority of poskim, especially since the laws of teĥumin are rabbinic, so the halakha follows the lenient position. Although Tur has an even more lenient opinion, the rest of the poskim disagree, as detailed in BHL s.v. “ve-yesh omrim.” Uncertainty still remains regarding how to measure the teĥum for the rest of the bow, where the arc widens to 4,000 amot and greater. It would seem that we can follow the position of Rambam and SA that the teĥum follows the curve, as displayed in the diagram. Ĥazon Ish maintains this as well (OĤ 110:10). See Harĥavot.