The Gemara answers: This is referring to a case where the shard does not have the sufficient measure for ritual impurity, and is therefore considered insignificant. As we learned in a mishna (Shabbat 82a): One who carries a shard of earthenware on Shabbat is liable only if it is equivalent in size to that which is used to place between one pillar and another when they are piled on the ground, to strengthen the pillars.

The baraita teaches: An earthenware vessel reduces the dimensions of a window. The Gemara challenges: But it is fit for one to use; therefore, it is likely to be removed from the window. The Gemara answers: This is referring to a case where the earthenware is dirty. The Gemara challenges: Even so, it is fit for a bloodletter to collect the blood. It would not matter to him if the earthenware were dirty. The Gemara answers: It is referring to a case where it is perforated and therefore unfit for that use.

The baraita teaches: A Torah scroll reduces the dimensions of a window. The Gemara challenges: But it is fit for reading; therefore, it might be removed. The Gemara answers: This is referring to a Torah scroll that is worn out and unfit for reading. The Gemara challenges: But one is required to place the Torah scroll in a repository for unusable sacred books; therefore, he will certainly remove it to be stored away. The Gemara answers: This is referring to one who determines that its repository will be there. In other words, it was placed in the window with the intent of storing it there in its worn-out state.

§ With regard to the halakha of the baraita referring to salt, the Gemara cites that which Rav says: One can construct a barrier to delineate a private domain on Shabbat or to block the spreading of ritual impurity with anything except for salt and fat, as salt crumbles and fat melts in the heat. And Shmuel says: Even salt can be used as a barrier. Rav Pappa said: And they do not disagree, as this ruling of Shmuel is referring to Sodomite salt, which is like stone and can be used as a barrier, and that ruling of Rav is referring to isterokanit salt, which is taken from the sea and is composed of grains.

The Gemara adds: And now that Rabba said: If a person makes two piles of salt at the opening to an alleyway and places a cross beam on top of them, so that the salt supports the cross beam and the cross beam supports the salt by weighing it down and compressing it, he can use this beam to render it permitted to carry in the alleyway on Shabbat, one can say that even isterokanit salt can be used as a barrier. And even so, Rav and Shmuel do not disagree: This ruling of Shmuel is referring to a case where there is a cross beam to weigh the salt down, and that ruling of Rava is referring to a case where there is no cross beam.

§ The mishna teaches that one must distance a mill from a neighbor’s wall by a distance of three handbreadths from the lower stone of the mill, which is four handbreadths from the upper stone of the mill. The Gemara asks: What is the reason that one must distance a mill from the property of his neighbor? It is due to the vibrations it causes. The Gemara asks: But isn’t it taught in a baraita: And the measure for distancing a mill on a base is three handbreadths from the lower millstone [ha’isterobil], which is four handbreadths from the mouth [hakelet], where the wheat is fed in? But there, what vibrations are there? Rather, the reason for the distancing is due to the noise generated by the mill.

The mishna teaches: And there must be a distance of three handbreadths from the protruding base of an oven until the wall, which is four handbreadths from the narrow upper rim of the oven. Abaye said: Learn from the mishna that the base of an oven is a handbreadth wider than its rim. The practical difference of this observation is with respect to buying and selling, i.e., a buyer should know that this is the proper ratio for the dimensions of an oven.

MISHNA: A person may not set up an oven inside a house unless there is a space four cubits high above it, i.e., between the top of the oven and the ceiling, to avoid burning the ceiling, which serves as the floor of the residence above. If one was setting up an oven in the upper story, there must be a plaster floor beneath it, which serves as the ceiling of the lower story, at least three handbreadths thick, so that the ceiling below does not burn. And in the case of a stove the plaster floor must be at least one handbreadth thick.

And if he causes damage in any case, he pays compensation for that which he damaged. Rabbi Shimon says: They said all of these measurements to teach only that if he causes damage he is exempt from paying, as he took all reasonable precautions.

The mishna continues: A person may not open a bakery or a dye shop beneath the storeroom of another, and he may not establish a cattle barn there, as these produce heat, smoke, and odors, which rise and damage the items in the storeroom. The mishna comments: In truth, the halakha is that in the case of a storeroom of wine the Sages rendered it permitted to set up a bakery and a dye shop beneath, as the heat that rises does not damage the wine. But they did not render it permitted to establish a cattle barn, because its odor damages the wine.

GEMARA: The Gemara asks: But isn’t it taught in a baraita that in the case of an oven the plaster floor must be four handbreadths thick, and with regard to a stove it must be three? By contrast, the mishna says that the plaster floor beneath and oven and a stove must be three handbreadths and one handbreadth thick, respectively. Abaye said: When that baraita is taught it is with regard to ovens and stoves of bakers. Since they bake all day long, their implements get very hot. The oven discussed in our mishna is similar to a baker’s stove, which is why in both cases a distance of three handbreadths is required.

The mishna teaches that one may not open a bakery or a dye shop beneath the storeroom of another, and he may not establish a cattle barn there. A Sage taught: If the cattle barn preceded the storeroom it is permitted, i.e., the barn owner is not required to move it. With regard to this point, Abaye raises a dilemma: If he cleaned and sprinkled the area, i.e., he prepared it for use as a storeroom but he has not yet filled it, what is the halakha? Is it considered a storeroom already, and therefore others may no longer put a cattle barn beneath it, or perhaps the halakha is that as long as it is empty he cannot prevent others from establishing a cattle barn?

Similarly, if he added windows for ventilation, which demonstrates his intention to use it as a storeroom, what is the halakha? Likewise, if he establishes an enclosed veranda beneath the storeroom, what is the halakha? If he built an upper room on top of his house for storage, what is the halakha? None of these questions are answered, and the Gemara declares that they shall stand unresolved. The Gemara cites a similar question: Rav Huna, son of Rav Yehoshua, raises a dilemma: If he placed dates and pomegranates there, what is the halakha? Is this considered the start of its use as a storeroom or not? No answer was found to this question either, and the Gemara declares: The dilemma shall stand [teiku] unresolved.

§ The mishna teaches that in truth, it is permitted in the case of wine but not in the case of a cattle barn. The Gemara states that a Sage taught: They permitted it in the case of wine because the heat and the smoke improve the wine. But they did not permit one to establish a cattle barn, because a barn creates a bad odor. Rav Yosef said: This wine of ours spoils quickly, and therefore even the smoke of a candle also damages it. Rav Sheshet said: And alfalfa [ve’aspasta] is considered like a cattle barn in this regard, because it rots over time and creates a foul odor.

MISHNA: If a resident wants to open a store in his courtyard, his neighbor can protest to prevent him from doing so and say to him: I am unable to sleep due to the sound of people entering the store and the sound of people exiting. But one may fashion utensils in his house and go out and sell them in the market, despite the fact that he is not allowed to set up a store in the courtyard, and the neighbor cannot protest against him doing so and say to him: I am unable to sleep due to the sound of the hammer you use to fashion utensils, nor can he say: I cannot sleep due to the sound of the mill that you use to grind, nor can he say: I cannot sleep due to the sound of the children. It is permitted for one to make reasonable use of his own home.

GEMARA: The Gemara asks: What is different in the first clause of the mishna, which states that one can prevent his neighbor from opening a store in the courtyard because the noise keeps him awake, and what is different in the latter clause, which states that one cannot protest when his neighbor performs labor that is noisy? Abaye said: In the latter clause we arrive at the case of one who operates in another courtyard, i.e., one cannot prevent activity in a separate courtyard that is connected to the alleyway in which he lives. Rava said to him: If so, let it teach that in a different courtyard it is permitted. Why does the mishna not specify that it is referring to a different courtyard? Rather, Rava said: