Siman - Eruvin Daf 78
- A peg in a post
Rav Huna said, עמוד ברשות הרבים גבוה עשרה ורחב ארבעה – if a post that is ten tefachim high and four tefachim wide, thereby constituting a reshus hayachid, stands in a reshus harabim ונעץ בו יתד כל שהוא מיעטו – and one wedged a peg of any size into the top of the post, the peg reduces some of the top’s surface area rendering it a makom petur.
The Gemara presents three interpretations of Rav Huna’s ruling: Rav Ada bar Ahavah said, ובגבוה שלשה – and the peg must be three tefachim high. Rashi explains that if it is not three tefachim it is considered part of the top’s surface. Abaye and Rava both said, אף על פי שאין גבוה שלשה – even though the peg is not three tefachim high, it still renders the top of the post a makom petur since that part of the surface where the peg was put is not usable. Rav Ashi disagreed with both interpretations and said, אפילו שגבוה שלשה טפחים – even if the peg is three tefachim high it does not render the top of the post a makom petur because it is possible to hang something onto the peg. Rashi explains that since the peg performs a function of the post, it is considered as part of the post and not something that detracts from it.
- Straw rungs between two narrow ladders
Rav Yosef asked Rabbah what the halachah is if one placed two ladders against the wall, each one less than two tefachim wide, and he put straw in the middle, which Rashi explains to mean that he pressed the straw into the shape of rungs and connected them to each ladder. Do we regard the ladders as having the requisite width of four tefachim? Rabbah answered, אין כף הרגל עולה בהן – the ball of the foot cannot go up on them, since one usually steps on the middle of part of the rung. Therefore, the straw rungs are not a valid extension.
Rav Yosef then asked what the halachah is if one affixed straw rungs on either side of a narrow ladder and Rabbah responded, כף הרגל עולה בהן – the ball of the foot can go up on them, and therefore the straw rungs are a valid extension.
- Using an ordinary tree or an asheirah tree as a סולם
Rav Yosef asked, עשאו לאילן סולם מהו – what is the halachah if one made a tree into a ladder? Is the tree considered a pesach which allows the two chatzeiros to join in a mutual eruv even though one may not climb a tree on Shabbos? He then asked that if we rule that an ordinary tree can indeed serve as a ladder to be an eruv, עשאו לאשירה סולם מהו– what is the halachah if one made an asheirah tree into a ladder? Since one gets הנאה from the eruv chatzeiros, would it be permissible to use it?
Rabbah answered that the tree is mutar and the asheirah is assur. The Ritva explains that since it is permitted to use the tree as pesach during the week, we view the Shabbos challenge as incidental and it does not affect the tree’s legal status as a pesach. Rebbe Yochanan said, and there are those that say that Rebbe Elazar said, כל שאיסור שבת גורם לו אסור - the tree which cannot be climbed because of hilchos Shabbos is assur, but the asheirah which cannot be used for a non-Shabbos related reason is mutar. Rav Nachman bar Yitzchak presents a third answer.
