OPINIONS: Rav Huna discusses how to measure the Techum of a city situated on the edge of a river. If there is a "Dakah" of at least four Amos that separates the river from the city, then the Techum is measured from the river. If there is no "Dakah," then the Techum is measured from the houses.

What is a "Dakah" and why does it allow the city's Techum to be measured from the river?

(a) RASHI explains as follows. The people in the city face a constant threat due to the proximity of the river. The river might overflow and destroy their homes and fields, and the people who live next to the river are at risk of falling in and drowning. When there is a wall four Amos high along the edge of the river, they no longer feel threatened, because when the river overflows it usually does not swell more than four Amos, and the people no longer have reason to fear they will fall into the river. Therefore, it is considered a more permanently settled area and its Techum is measured like the Techum of any normal city, from the edge of the city (which, in this case, is the river).

If, however, there is no wall four Amos high between the river and the houses, the city is considered a temporary settlement. It is not considered a city at all and each resident measures his Techum from his own house.

(b) The RITVA cites the RIF and the RAMBAM (Hilchos Shabbos 28:9) who explain that the measurement of the Techum depends on whether the river becomes part of the city or not. If there is a Dakah -- that is, a platform four Amos wide -- at the edge of the river, then when the river dries up they will be able to use the river bed by standing on the platform. Since the river is usable, it is considered part of the city and the Techum is measured from the outer edge of the river and not from the bank next to the city. If there is no Dakah and thus the people cannot use the riverbed when the river dries up, then the river is not considered to be part of the city and the Techum of the city is measured from the last houses, near the inner edge of the river. When the Gemara says that when there is no Dakah the Techum is measured from "Pesach Beiso," it does not mean "the entrance of his house," but rather "the entrance of its house," referring to the city's outermost house (or the house which serves as the entrance to the rest of the houses of the city).

QUESTION: The Gemara cites a Beraisa that records a ruling which Rebbi made concerning two cities on a hillside, Chamsan and Geder. Rebbi ruled that the people of Geder, at the top of the hill, were allowed to go down to Chamsan, but the people of Chamsan, at the bottom of the hill, were not allowed to go up to Geder. The Gemara gives a number of explanations why the residents of one city could go to the other city, while the residents of the other city could not go to the first. The last two explanations are those of Rav Safra and Rav Dimi. Rav Safra says that one of the two cities was in the shape of a bow, and its unique shape was the cause for the different rulings for the two cities. Rav Dimi says that one of the cities (Geder) was a large city, and the other city (Chamsan) was a small city.

Rav Dimi's explanation is clear. If Geder was a large city, then the people of Geder could walk down to Chamsan, because the opposite edge of Chamsan was still within the 2000-Amah Techum of Geder. The Techum of Chamsan, though, ended in the middle of Geder, and thus the residents of Chamsan were not allowed to walk throughout the city of Geder.

What, though, does Rav Safra mean when he says that "it was a city in the shape of a bow"? Which city was similar to a bow? Furthermore, how does his explanation differ from that of Rav Dimi, who explains that one city was larger than the other?

(a) RASHI explains that Chamsan was in the shape of a bow. The side of the "bowstring" (the line between the two tips of the city) was on the side that faced Geder (and the curve of the bow faced towards the bottom of the mountain). The tips of the city were more than 4000 Amos apart, and thus the Techum for people living in the middle of Chamsan's bow was measured from the boundary of the actual city (from where the houses ended) and not from the bowstring. Consequently, the people in the open part of the bow of the city were not able to walk all the way into the city of Geder. The people who lived in Geder, though were allowed to walk into and throughout Chamsan, because Geder's Techum was measured from the edge of the city, from which point 2000 Amos reached the opposite edge of Chamsan. From that point in Chamsan, though, 2000 Amos reached only the edge of Geder, or a little within Geder, but certainly not the far side of Geder.

However, according to this explanation, Rav Safra's explanation is the same as that of Rav Dimi -- Geder was like a large city, the Techum of which covered all of Chamsan, the smaller city, and Chamsan was a small city, the Techum of which barely reached the inside of Geder! (In other words, the far part of the bow of Chamsan was the small city whose 2000 Amos ended in the middle of Geder, whereas the Techum of Geder ended at the opposite side of Chamsan and included all of Chamsan.) What is the difference between Rav Safra's explanation and Rav Dimi's? What does Rav Safra add by saying that Chamsan was shaped like a bow? Even if Chamsan was not shaped like a bow, its Techum ended in the middle of Geder since it was a smaller city than Geder! (RASHBA; see CHIDUSHEI HA'RAN.)

Perhaps we may answer as follows. Rav Safra and Rav Dimi are arguing about what new law Rebbi intended to teach. The Beraisa relates that Rebbi permitted the people of Geder to go to Chamsan, but he did not permit the people of Chamsan to go to Geder. Rebbi ostensibly was teaching a new law, a Chidush, and not merely telling us facts that we already know from other Mishnayos. What, though, was the Chidush that Rebbi intended to teach?

Rav Safra says that Rebbi's Chidush was that the people of Chamsan -- which was shaped like a bow whose tips were more than 4000 Amos from each other -- had to measure their Techum not from the bowstring but from the outermost houses in their direction of travel. Rebbi was teaching that the people of Chamsan were not allowed to go to Geder, because Chamsan's Techum had to be measured from the city proper and not from the bowstring.

According to Rav Dimi, the Chidush of Rebbi was not only that the people of Geder may go to Chamsan, but that we virtually ignore the entire city of Chamsan when we measure Geder's Techum. The people of Geder may walk beyond Chamsan and count the city of Chamsan as no more than four Amos when they measure their Techum. (This is because of the law that when the Techum of one city ends beyond or at the far end of another city, the second city counts as only four Amos out of the Techum of the first city.) Rebbi did not merely permit the people of Geder to go to Chamsan; he permitted them to walk through all of Chamsan as if it were only four Amos. (From the fact that Rashi makes a point of this in his explanation of Rav Dimi, it is evident that this was Rebbi's Chidush according to Rav Dimi's opinion.)

This is the argument between Rav Safra and Rav Dimi: Was Rebbi teaching that Chamsan is not considered a bow for the sake of measuring the Techum from the bowstring, or that the entire city of Chamsan is considered only four Amos relative to the Techum of Geder? (M. KORNFELD)

(b) Alternatively, the ME'IRI points out that in a case in which some of the people of a city cannot go to a certain place while others can, everyone in the city is prohibited from going there. Consequently, if the far end of Geder was within the Techum for the residents at the two ends of the bow of Chamsan but not for the other residents of Chamsan, then the people in the ends of the bow would be prohibited to enter Geder just like the other residents of Chamsan. Rav Dimi maintains that Rebbi was indeed teaching an original Halachah. Since Chamsan was shaped like a bow (and those who did not live in the ends of the bow could not go to Geder), even the people at the ends of the bow were not allowed to walk into Geder.

(c) TOSFOS explains that, according to Rav Safra, it was Geder that was in the shape of a bow, facing away from Chamsan. It was shaped not like a broad bow, but like one narrow enough that there were fewer than 4000 Amos between the ends of the bow. In such a case, the Techum is measured from the bowstring even for the people living in the bow part of the city (as the Gemara says on 55a).

The people in Chamsan, however, were not permitted to walk to Geder. Chamsan sat on a line directly between the ends of the bowstring of Geder and a little further down the mountain. From the periphery of Chamsan it was more than 2000 Amos to any part of the bow of Geder. The people of Geder, on the other hand, were allowed to walk into Chamsan -- even those Gederites living in the bow part of Geder -- because their Techum began from the bowstring and Chamsan was within 2000 Amos of the bowstring of Geder!

According to this interpretation, how does Rav Safra's answer differ from that of Rav Dimi (that one city was large and the other was small)? As we mentioned above, the argument revolves around what Rebbi intended to teach with his ruling. According to Rav Safra, Rebbi intended to teach that when a city looks like a narrow bow, we measure its Techum from its "bowstring." According to Rav Dimi, Rebbi was teaching that when the 2000 Amos of a Techum includes a neighboring city, the entire city counts as no more than four Amos (as we explained Rav Dimi's explanation above). (M. KORNFELD)