Eiruvin 11a: Let us bring proof to Rav Yosef, who held that according to Rav, one may not carry in a courtyard whose openings total more than its solid wall, even if those openings have tzuras hapesachs. “If the walls of the courtyard have many doors and windows, it is good as long as the solid is more than the open.” Rav Kahana responded: That is no proof, because it is referring to openings that are in ruins. Rav Rechumei and Rav Yosef: one explained that “in ruins” means they have no doorposts, and the other explained that it means they have no lintel.
עירובין יא ע”א: לימא מסייע ליה: דפנות הללו שרובן פתחים וחלונות ־ מותר, ובלבד שיהא עומד מרובה על הפרוץ. שרובן סלקא דעתך? אלא אימא: שריבה בהן פתחים וחלונות, ובלבד שיהא עומד מרובה על הפרוץ. ־ אמר רב כהנאֹ כי תניא ההיא ־ בפיתחי שימאי. מאי פיתחי שימאי? פליגי בה רב רחומי ורב יוסףֹ חד אמר: דלית להו שקפי, וחד אמר: דלית להו תיקרה.
The original eiruv of Antwerp did not include the southern neighborhood of Berchem. In 1972, some from the Berchem community came to complain to the rav, Rabbi Chaim Kreiswirth, who appointed Reb Pinchus Kornfeld to survey the area and see if an eiruv was possible. After the survey, Reb Pinchus went over his questions and proposals with Harav Kreiswirth, who took into account the needs of young women with babies to get out of the house on hot summer Shabbosim. He inspected it at the beginning of Nissan so that it would be ready for Pesach.
The eiruv was based on the mesorah Rav Kreiswirth had: to rely on the Shaarei Tzion (siman 3), who permitted the eiruv of Warsaw based on the argument that you can place one lechi at one end of the telegraph line and one at the other, and you need not place one at every pole in between, because although the wire zigzags, the lintel of the tzuras hapesach is allowed to be crooked. The main posek opposing the Shaarei Tzion was the Mishkenos Yaakov.
The eiruv in the main part of Antwerp, on the other hand, was on a higher level of stringency, not making use of the Shaarei Tzion’s kula.
The Shaarei Tzion brings proof from a diyuk in Rashi on the above Gemara in Eiruvin 11a. On the opinion that defines “a ruined door” as one without doorposts, Rashi explains it means the sides are uneven, with some bricks missing and some jutting out. On the opinion that defines it as a door without a lintel, Rashi explains that it has no lintel at all. Why didn’t Rashi say the lintel is crooked, as he explained the doorposts? Clearly, Rashi held that a lintel is allowed to be crooked.
The Mishkenos Yaakov brings a counterproof from a Gemara on the same blatt (Eiruvin 11b) which proves that the lintel of a tzuras hapesach does not have touch the two doorposts, based on the case of an arched doorway, where the two doorposts are vertical for at least 10 tefachim and then start to curve. The curved part separates the doorposts from the lintel, yet it is considered a door requiring a mezuzah. But if a crooked lintel counts, what is the Gemara’s proof? Here the whole arch is a crooked lintel and is contiguous with the doorposts!
The Shaarei Tzion responds that Rashi would answer this based on another position of his (l’shitaso). On the halacha about an arched doorway and mezuzah (Yoreh Deah 287:2), the Taz says that according to Rashi, the two doorposts do not actually have to be vertical for 10 tefachim. They can start curving from the ground up, as long as by 10 tefachim in height they still have 4 tefachim of horizontal space between them. Thus Rashi holds the arch is actually part of the doorposts until that point. Then it becomes the lintel. But this lintel is not kosher, since by that point it is less than 4 tefachim wide! So we must use the horizontal bricks or beam above the arch, which is not contiguous with the doorposts, as our lintel; hence the proof that the top of a tzuras hapesach does not have to touch the sides.
Some time later, a talmid chacham came to visit Antwerp, and decided on his own to inspect the new Berchem eiruv. He began to challenge Reb Pinchus Kornfeld, saying that the eiruv was posul according to the Mishkenos Yaakov. What right did Harav Kreiswirth have to adopt the Shaarei Tzion’s kula? Reb Pinchus retorted with a posuk (Tehillim 87:2), אוהב ה’ שערי ציון מכל משכנות יעקב – “Hashem loves the Shaarei Tzion more than all the Mishkenos Yaakov!”
Source: Mayim Chaim p. 141
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