1) THE COW AND THE TROUGH
QUESTION: The Gemara discusses whether an animal must be situated mostly in a Reshus ha'Yachid, together with the owner, while the owner feeds it. The Gemara suggests that when the animal is standing in the Reshus ha'Rabim and the owner is not holding it to prevent it from walking away, he may not feed it directly because we are concerned that the owner might be drawn after the animal and carry the bucket of food into the Reshus ha'Rabim. When most of the animal is in the Reshus ha'Yachid, however, he may feed the animal even if he is not holding it.
The Gemara challenges the assumption that one may feed the animal directly even when he is not holding it as long as it is mostly in a Reshus ha'Yachid. The Gemara quotes a Beraisa that says that one may not feed an animal (which he is not holding) directly, but rather he must pour the food or water in front of the animal and let it eat on its own. The Gemara answers that in the case of the Beraisa, there is a trough in the Reshus ha'Rabim that extends into the Reshus ha'Yachid in which the person is standing, and the animal is eating from the trough. One must pour the water into the trough and let the animal eat from there, and he may not carry the bucket of water over the trough (which is a Reshus ha'Yachid) out of the Pasei Bira'os in order to bring it to the mouth of the animal and feed it directly. The reason why he may not carry the bucket to the animal is because of the concern that he might inadvertently place the bucket down in the Reshus ha'Rabim if he finds something wrong with the trough there.
RASHI (DH Ha Itmar) explains that the Gemara's answer refers to a case in which one end of the trough is within the Pasei Bira'os, and the rest of the trough is in the Reshus ha'Rabim. The animal is standing in a different Reshus ha'Yachid on the other side of the trough as it eats, and it is extending its head into the Reshus ha'Rabim in order to reach the trough (see Bach #2).
TOSFOS (DH Amar Abaye) asks why Rashi explains the case in such a complex way, with the animal standing in a separate Reshus ha'Yachid. He should simply explain that the cow is standing in the Reshus ha'Rabim eating from the trough!
ANSWER: The RASHASH answers that Rashi explains that the animal is standing in another Reshus ha'Yachid for the following reason. The Gemara earlier says that when one is holding the bucket and the animal, there is a doubt whether or not the animal must be mostly in the Reshus ha'Yachid in order for the owner to be allowed to feed it. However, when one is holding only the bucket and not the animal, it is obvious that the animal must be mostly in the Reshus ha'Yachid (so that the owner will not be drawn after it into the Reshus ha'Rabim).
Accordingly, the Beraisa cannot be referring to a case in which the animal is standing in the Reshus ha'Rabim, because it would be prohibited to feed the animal in the Reshus ha'Rabim due to the concern that one will be drawn after the animal to the Reshus ha'Rabim. It must be that the animal is standing in the Reshus ha'Yachid. How, though, can the animal be standing in the Reshus ha'Yachid and eating from a trough in the Reshus ha'Rabim, if it is not standing in the same Reshus ha'Yachid as its owner?
Rashi therefore explains that the animal is standing in a different Reshus ha'Yachid on the other side of the Reshus ha'Rabim, extending its head and eating from the trough. Most of the animal is in a Reshus ha'Yachid, even though it is not the same Reshus ha'Yachid as the Pasei Bira'os.
According to this approach, Rashi's explanation is clear. It is obvious why Rashi explains that the animal is in a different Reshus ha'Yachid and is not in the Reshus ha'Rabim. Now, however, there is a different question: What is Tosfos' difficulty with Rashi's explanation?
Tosfos apparently understands that there are three ways to feed an animal. In the first way, one holds the bucket and feeds the animal. In this case, the animal must be mostly in a Reshus ha'Yachid, especially if one is not holding the animal as it eats from the bucket. In the second way, one pours water in front of the animal and lets it drink by itself, in which case the animal may even be in a Reshus ha'Rabim. In the third way, one takes a bucket of water and places it down on the part of the trough that is in a Reshus ha'Yachid, but he continues to hold the bucket. This last case is the case to which the Gemara refers when it discusses feeding the animal via the trough; the Gemara refers to a case in which one holds on to the bucket after he places it down. Such a manner of feeding is permitted even when the animal is standing mostly in the Reshus ha'Rabim, as long as one does not actually hold the bucket up to the animal while it drinks. In such a case there is no concern that the person feeding the animal will be drawn after the animal into the Reshus ha'Rabim, if not for the fact that the trough itself protrudes into the Reshus ha'Rabim. Since the trough protrudes into the Reshus ha'Rabim, there is a concern that he might carry the bucket in his hands into the Reshus ha'Rabim. (That is, he might decide to put the bucket down at the end of the trough which is in the Reshus ha'Yachid, and then he will notice something wrong on the other side of the trough (the end in the Reshus ha'Rabim), or, according to Tosfos, he will find that he cannot put the bucket down on the side of the trough in the Reshus ha'Yachid because the floor of the trough is uneven. Consequently, he will set the bucket down in the part of the trough that is in the Reshus ha'Rabim.) This seems to be the intention of Tosfos. (M. KORNFELD)