(Mishnah): We measure with a rope 50 Amos long, no more and no less. It must be held next to the heart;

If along the way there is a canyon or wall [that fell, and the resulting rock pile is an incline that can be traversed], we 'swallow' it (people hold the ends of the rope from opposite sides. For a wall, they hold it up on poles. It counts like 50 Amos, even though the 'walking' distance along the incline is much greater);

[If it cannot be swallowed (it is too wide), he goes to the side, where it is narrower, swallows it there,] and resumes measuring, as long as he does not leave the Techum. (See Perush Chai diagram, Perek 5 number 70, in the English Charts section.)

R. Dostai bei R. Yanai says in the name of R. Meir, I heard that if for a mountain [that cannot be swallowed, we do not measure with the 50 Amah rope along the slope. Rather,] we are Mekader. (We measure in a way, explained below, that reduces or cancels out the vertical component of the distance. it is as if we drilled through the hill to measure the horizontal distance).

(Gemara): How much is the measure of the Techum? It is 40 rope lengths;

A shorter [rope] is not [allowed, for] it is stretched, and he gains (makes the Techum too big). A longer [rope] is not allowed, for] it sags, and he loses (decreases the Techum).

Some teach that he measures with a linen rope, and some teach with an [iron] chain;

R. Yehoshua says, the only true measure is an [iron] chain (it cannot be stretched), but what can I do? It says in Nevi'im [that we use] ropes ("uv'Yado Chevel Midah'' (Zecharyah 2:5) and sticks) - "u'Fesil Pishtan b'Yado u'Kene ha'Midah''! (We explained this like PNEI MOSHE.)

If there were [at most] 75 Amos between [the measurer] and [the further side of] a Nachal (river or canyon), two Amora'im argued about this;

Note: He is less than 50 Amos from the closer side of the Nachal, so he cannot simply measure 50 Amos and then swallow it.

One of them said that he measures with a rope of 50 Amos, and goes back 25 Amos (to measure this, he brings one end of the rope back to the other. From there, he swallows the Nachal, for it is totally within 50.)

Note: We explained this like SEFER NIR. The other Meforshim explain that he is 75 from the closer end. He goes forward 50, back 25 and forward 50. I cannot explain why he does not simply go forward 50 and 25!

The other said that he measures with a rope of 50 Amos, and the rest he measures with a rope of four Amos. (I.e. he measures with a rope of four Amos the minimal amount to times needed to enable him to swallow the Nachal within 50.)

If the Nachal was narrow below and wide above, if [the width above] is up to 50 Amos, you view it as if it were full of earth and pebbles [and we 'swallow' it]. If not, he climbs up and climbs down (ROKE'ACH) [to be Mekader].

Note: Usually, "Nachal'' is a river, and so most Meforshim explain here. It is difficult for them below "and so he does on the mountain.'' Also, why does it say "view it as if it were full of earth and pebbles''? It should say "view it like dry land''! PNEI MOSHE explains that the Yerushalmi uses it to denote a canyon, which our Mishnah discussed.

If the Nachal was bent (in places it descends on a mild slope, and in places it is very steep), Rav Chisdai said that he looks through a tube and gauges with his eyes the horizontal distance (where the slope is mild), and returns and does so in the mountain (where the slope is steep).

(R. Acha citing R. Chinena citing R. Yirmeyah citing R. Shmuel bar Rav Yitzchak): (The Mishnah says that we are Mekader for mountains.) This is if a plumb line is displaced four Tefachim, which is an [important] space. (If not, we measure only the horizontal distance, and ignore the slope. We explained this like SHA'AREI TORAS ERETZ YISRAEL.)

(R. Yosah citing R. Avunah citing Rav Yehudah, and R. Yudan leaned to say in the name of Rav): If the Elyon (the one on top, holds the rope) at [the height of] his feet, and the Tachton (the one on bottom, holds it) at his head (and then the rope is horizontal), all agree that we are Mekader;

[Even] if the Elyon [holds it] at his loins, and the Tachton at his head (and then it is horizontal), all agree that we are Mekader;

When [do R. Meir and Chachamim] argue? If he holds it at his heart. R. Meir says that we are Mekader, and Chachamim say that we are not Mekader. (We explained this like YEFEI EINAYIM.)

Note: It seems that this is whether the Elyon holds it at his heart and the Tachton holds it at his head, or the Elyon holds it at his loins and the Tachton holds it at his heart. Chachamim hold that since it is a small difference, we are not Mekader.

(R. Ba citing Rav Yehudah, and R. Ze'ira citing Mar Ukva): We are Mekader only with a rope five Amos long. Some teach, with a rope of four Amos. (We explained this like SHA'AREI TORAS ERETZ YISRAEL.)

(R. Ze'ira citing Rav Chisdai): We are not Mekader [when measuring] cities of Leviyim, and not for Eglah Arufah.

Observation: (A verse says that we measure 2000 Amos around Levite cities, and another verse says 1000 Amos.) This is fine for the opinion that 1000 Amos are Migrash (vacant areas) and [past that, until] 2000 Amos are fields and vineyards. (We do not learn Techum Shabbos from their cities.)

Question: However, according to the opinion 1000 Amos are Migrash and 2000 is the Techum Shabbos, do we not learn Techum Shabbos from their cities?! For what is primary (the cities) we are not Mekader, and for what is secondary (Techum Shabbos), we are Mekader?! (We explained this like HA'GAON RAV C. KANIEVSKY, SHLITA.)

Question: What is the source that they did not bury people in the Techum of the Levite cities?

Answer (R. Avahu citing R. Yosi ben Chaninah): "U'Migresheihem Yihyu li'Vhemtam... ul'Chol Chayasam'' - they were give for life, and not for graves.