QUESTION: The Mishnah (32b) states that although an Eruv placed in a tree at a height of ten Tefachim or more is not valid, an Eruv placed in a tree at a height of less than ten Tefachim is valid. The Gemara explains that the Mishnah refers to a branch that extends beyond four Amos from the tree. When the Mishnah discusses an Eruv placed "above" or "below" ten Tefachim, it means that the branch starts at a point below ten Tefachim from the ground and then curves upward and rises above ten Tefachim. The Mishnah is not discussing two different branches, one starting above ten Tefachim and one below, but rather two sections of one branch. The Gemara proves this from the words "above" and "below," which always refer to the higher or lower section of a single object (in this case, a branch).

The Gemara in Shabbos (8b) quotes a Beraisa which states that there is a difference between an object placed in a pit "above" ten Tefachim from the bottom of the pit and one placed "below" ten Tefachim. The Gemara asks that since the pit is deeper than ten Tefachim, the object should be considered in a Reshus ha'Yachid regardless of where in the pit the object is placed. The Gemara answers that the Beraisa refers to two different pits, one which is less than ten Tefachim deep and one which is ten Tefachim or more deep. This Beraisa raises two questions:

(a) The Gemara here implies that the height at which an object is placed in a tree does make a difference. Why does the height at which the object is placed in a pit not make a difference?

(b) When the Mishnah here says "above" or "below" ten Tefachim, the Gemara says that it must refer to different heights on a single object (here, the branch). The Gemara in Shabbos, though, says that the same terminology may refer to two different objects altogether, and it does not necessarily refer to two different heights on one object (there, the pit).

(a) There is a difference between a deep pit and a tall tree. When the Mishnah discusses an object placed on a branch of a tree at a height of less than ten Tefachim, it is referring to a large branch that looks like the curved arm of a Menorah. In the vertical part of the Menorah-like branch, less than ten Tefachim from the ground, there is a four Tefachim deep niche which is four Tefachim wide. The object inside that niche is considered to be within the Reshus ha'Rabim. Above that niche the branch continues upwards. The upper surface of the branch, which is above ten Tefachim from the ground and four Tefachim long by four Tefachim wide, is considered a Reshus ha'Yachid.

Since the niche is below the rest of the branch, it is not viewed as part of the Reshus ha'Yachid at the top of the branch (that is, the entire branch is not viewed as one large Reshus ha'Yachid), even though the Halachic Mechitzos of the Reshus ha'Yachid at the top of the branch (the Mechitzos formed through Gud Achis by the outer surfaces of the branch) extend downward and surround the niche as well. The reason for this is that there is no space on the surface of this niche that can be used with the Reshus ha'Yachid, because the solid branch cuts it off and separates it from the Reshus ha'Yachid on its upper surface. A similar situation is mentioned in Shabbos (7a) with regard to a house, the inner space of which has a height of nine Tefachim while the surface of the roof is ten Tefachim above the ground. Since the inside of the house does not have a usable height of ten Tefachim, it is not considered a Reshus ha'Yachid. The inside of the house is not considered part of the Reshus ha'Yachid formed by the roof because the inside of the house is cut off from the surface on top of the roof by the roof itself.

A pit is different. Since the pit is entirely open, the Mechitzos on the bottom are the same as the Mechitzos on the top (above ten Tefachim) which enclose a Reshus ha'Yachid. Any indentations in the walls of the pit are "Chorei Reshus ha'Yachid." (See also TOSFOS HA'ROSH 34a, DH Niskaven.)

(b) To answer the second question, one may suggest that while it is common to find a tree with many carved-out indentations, in a pit there is generally only one surface (the bottom of the pit). Therefore, when the terms "above" and "below" are used with regard to a pit, it is acceptable for those terms to refer to two different pits. When the words "above" and "below" are used with regard to a tree, they refer to the same tree, since it is common to have several surfaces at different points on the tree. (M. KORNFELD)

QUESTION: Rebbi Yirmeyah says that an Eruv inside a basket hung from a tree above ten Tefachim is valid because one can bend the basket down to below ten Tefachim, so that he and the Eruv are in one Reshus.

Why does this act make the Eruv valid? When one bends the basket, he transfers the basket and the Eruv inside it from a Reshus ha'Yachid to a Reshus ha'Rabim, which is an Isur d'Oraisa.

(a) TOSFOS (DH Ho'il) in the name of the RASHBAM says that Rebbi Yirmeyah is of the opinion that "Eged Kli Shemei Eged." That is, if the basket lies partially in a Reshus ha'Rabim and partially in a Reshus ha'Yachid, then the food inside the basket is also considered to be partially in a Reshus ha'Rabim and partially in a Reshus ha'Yachid. The basket itself has not been transferred from one Reshus to another Reshus, because it sits atop the border of two Reshuyos (Shabbos 91b). The food inside, therefore, is also not considered to have been transferred from one Reshus to another.

(b) TOSFOS adds that even if Rebbi Yirmeyah does not agree that "Eged Kli Shemei Eged," there still is no Isur d'Oraisa transgressed when one bends the basket down to below ten Tefachim. When he brings the basket from above ten Tefachim to within ten Tefachim, he turns it into a Karmelis and not a Reshus ha'Yachid. Consequently, the food inside it rests in a Karmelis and not in a Reshus ha'Yachid. When one bends the basket in this manner, he transgresses only an Isur d'Rabanan (which, for the sake of Eruvei Techumin, is permitted during Bein ha'Shemashos).

It seems that the Rashbam does not find this answer acceptable because he maintains that a utensil, such as a basket, cannot be a Karmelis ("Ein Karmelis b'Kelim"). Therefore, the basket is considered at rest in a Reshus ha'Rabim once it is pulled down to less than ten Tefachim. (The principle of "Ein Karmelis b'Kelim" is discussed by Tosfos in Shabbos 5a and 156a, and Rashi in Shabbos 8a.)

(c) The RITVA says that when the basket is tilted, the bottom of the basket rests against the vertical surface of the tree (that is, the basket itself lies sideways), or at least the food in the basket rests on a tilted surface. In order to be liable for the transfer of an object from a Reshus ha'Yachid into a Reshus ha'Rabim, the object must come to rest on a horizontal surface of a "Makom Chashuv," which is defined as a surface with an area of at least four by four Tefachim. Since the tilted basket, or food, rests on a vertical surface and not on a horizontal one, it is not considered as if it rests on a four-by-four-Tefach surface of a Reshus ha'Rabim.

(This answer needs further elucidation, because the Gemara in Shabbos (7a) says that if something is thrown four Amos in a Reshus ha'Rabim and comes to rest laterally on the vertical side of a brick, he is liable for carrying four Amos in a Reshus ha'Rabim. If the brick has a thickness of at least four by four Tefachim, then the object is on a Makom Chashuv. See Ritva there.)