Eruvin 58a (נח.) — the Talmud in English

And likewise, if

he reached a mountain—

he spans it and returns to his measure!

provided that he does not go beyond the Shabbat limit

in order to span the valley.

Rashi brought two interpretations:

The first is that the width of the valley opposite the city extends beyond the limit, but the width of the valley gradually narrows at a point that is not opposite the city itself, although that point is within the city’s limit.

The surveyor has two options for measuring where the city’s limit ends within the valley:

a. He may proceed toward the city, to the place where the valley narrows, all of which is within the city’s limit, and span it there, at the place where it is narrower [by measuring the horizontal distance above it], and continue the measurement from its other edge until the limit has been completed.

From there he will look toward the point where the city’s limit lies within the widened valley, opposite the city itself.

b. He may proceed from the side of the city, beyond the limit, to the place where the valley ends, and measure there the distance to the point opposite the valley’s other edge, which faces the city, in order to determine by how many cubits that edge of the valley extends beyond the limit. He then goes to the edge of the valley opposite the city and measures the difference within the valley, by looking back toward the city into the valley, counting the number of cubits that exceed the limit, and marking the location of the limit in the valley.

The Mishna says that he should perform the measurement according to the first option, since it is unnecessary for him to go beyond the limit during the measurement, and he should not measure according to the second option, in which he must go beyond the limit and measure there.

And even though the measurement is performed on a weekday and not on Shabbat, we must be concerned that perhaps someone who sees him measuring beyond the limit will conclude that this place is within the Shabbat limit.

The second interpretation is that the valley is very long. Although its width is within the limit, it is more than fifty cubits wide there, and it is impossible to span it opposite the city unless one goes outside, to the sides of the city beyond the Shabbat limit, where the valley narrows and it is possible to span it there.

The Mishna thereby teaches that one should not measure the width of the valley there, lest observers say that this place, at the sides of the city, is within the Shabbat limit.

If he cannot span it—

in this case [as opposed to other measurements associated with a mitzva, such as eglah arufah]

excluding other measurements performed for a mitzva, such as the measurement for a heifer whose neck is broken]

Rabbi Dostai bar Yannai said in the name of Rabbi Meir: I heard that one measures by making indentations

piercing

through the mountains.

That is, the measurement is treated as though there were a hole through the mountain through which the measuring rope could be passed.

For one does not measure the slopes of the mountains as they are. Rather, one takes a rope only four cubits long, and the measurement is carried out by two surveyors:

One stands holding the rope opposite his heart, while the other, standing four cubits away at the height of the slope, places it at his feet. In this manner they proceed, measuring the distance horizontally rather than vertically.

Gemara:

We raise a question concerning this:

From where are these matters

that the measurement must be carried out with a rope fifty cubits long

derived? Rav Yehuda said that Rav said: As the verse states [Exodus 27], concerning the courtyard of the Tabernacle:

[the verse concerning the courtyard of the Tabernacle]

“The length of the courtyard shall be one hundred cubits

and the width fifty by fifty.”

The Torah said:

From the fact that the Torah said, “the width fifty by fifty,” the Torah taught:

With a rope of fifty cubits—

measure.

And we challenge this: But

this

verse

is needed

to teach us the size of the open square in the courtyard of the Tabernacle, which must be seventy cubits and some remainder by seventy cubits and some remainder, since this is what the Torah said:

Take fifty

cubits,

and encircle

with them a square of

fifty

by fifty!?

And we answer:

If so,

that the verse comes only with regard to the size of the open square of the courtyard of the Tabernacle,

let the verse say, “And the width of the courtyard is

fifty

fifty.”

What is the meaning of

“fifty by fifty,”

as the verse states?

You may infer two things from it.

We learned in the Mishna:

Neither less nor more.

The tanna

taught in a beraita:

The measuring rope must be

no less

than fifty cubits,

because

a short rope stretches, and thereby

increases

the measurement.

Nor more—

because

the weight of the rope prevents it from being stretched properly, and thereby it

decreases

the measurement.

Rabbi Asi said: One measures only with a rope of afaskima.

And we explain:

What is afaskima?

Rabbi Abba said: Nargila.

What is nargila?

Rabbi Yaakov said: A palm branch with a single fiber ["Fiber" is a strand that grows and winds around the palm tree].

“Strand” is a fiber that grows and winds around the palm tree].

Some say

that the above was stated in a different formulation:

What is afaskima?

Rabbi Abba said: Nargila.

Rabbi Yaakov said: A palm branch with a single fiber.

It was taught in a beraita: Rabbi Yehoshua ben Ḥananya said: There is no

thing

better suited for precise measurement

than

that which is performed with

measurement by means of

iron chains,

which neither stretch nor slacken.

But what can we do, for the Torah said [as a support from the words of the Prophets] that one must measure with a rope, as it is stated [Zechariah 2]:

a supporting indication from the words of the Prophets] that one must measure with a rope, as it is stated [Zechariah 2]:

“And in his hand was a measuring rope.”

And we challenge this:

But it is written [Ezekiel 40], concerning Ezekiel’s prophecy about the Temple:

[concerning Ezekiel’s prophecy about the Temple]

“And in the man’s hand was a measuring reed.”

A reed is not a rope!?

And we answer:

That

measuring reed is not for measuring distance, but

for

measuring

the gates,

the gates of the Temple described in Ezekiel’s prophecy.

Rav Yosef taught: There are three

types of

ropes:

One made of magag,

rushes,

one made of netzer,

peeled willow branches,

and one made of flax.

A rope

made of magag

is required

for the red heifer

—

as we learned: They tied it

to the red heifer

with a magag rope,

which is not susceptible to ritual impurity,

and placed it upon its pyre. A rope

made

made of netzer for a sota—

as we learned: And afterward he brings an Egyptian rope and ties it above her breasts.

A rope

made of flax—

is for measurement.

We learned in the Mishna:

If he was measuring and reached

a valley or a mountain, he spans it and returns to his measure.

And we infer:

Since you taught me

“he returns to his measure,”

by inference, if he cannot span it

in its place,

the surveyor goes

to the place where he can span it,

spans it, and looks

at the place beyond the span

opposite his measure, and returns

to the place of the measurement and continues measuring there.

And we wonder: But

we already learned this

in a beraita, and if this is the explanation of the Mishna, the beraita would not have needed to repeat it.

As the Sages taught: If he was measuring and the measurement reached a valley, if he can span it with a rope of fifty cubits—

he spans it

there.

And if not—

he goes to the place where he can span it, spans it, looks, and returns to his measure.

If the valley was winding [according to Rashi’s second interpretation, following the version in the Tosefta], so that the valley turned from west toward north, and he could span it only on the northern side of the city,

if he could not span it [according to Rashi’s second interpretation, following the version in the Tosefta], so that the valley turned from west toward north, and he could span it only on the northern side of the city,

the spanning of the valley on the northern side does not help him span it on the western side as well, even though through observation and measurement he could transfer the span made in the north to the west of the city.

Rather, he

makes indentations going up and makes indentations going down

in the valley, on the side where it cannot be spanned.

If he reached a wall

that was slightly sloped,

we do not say

that he should pierce

the

wall

in order to pass the rope through it and measure the width of the wall’s slope [that is, he is not required to erect poles up to the height of the wall on both sides and thereby span the slope of the wall. Tosafot].

Rather, he estimates it

by a rough estimation of the slope, without spanning it from the side,

and goes on his way.

And we challenge this:

But we learned in the Mishna: “He spans it and returns to his measure”!

This proves that he may not suffice with an estimate alone!

And we answer:

There,

in the case of a mountain or valley, which must be spanned and for which an estimate does not suffice,

its use is reasonably convenient,

as it is somewhat convenient to walk upon it; therefore he is required to measure it, whether by spanning it or by making indentations.

But

here,

in the case of a wall,

its use is not reasonably convenient,

as the slope of the wall is not fit for walking; therefore it is not included in the measure, and an estimate is sufficient.

Rav Yehuda said that Shmuel said: They taught

that one must measure the valley by making indentations

only

when its slope is somewhat convenient for walking, such as

when “a plumb line does not descend directly opposite it.”

That is, it is a slope that is not steep: if one lowers a builder’s plumb line toward its depth, the plumb line does not descend directly opposite it, because the slope prevents it from descending.

The meaning is that if he lowers the line to a distance of four cubits from the edge of the valley, the line still does not descend directly opposite it.