"Did I Miss Something?"
(Illustration courtesy of The Temple Institute)
Bob Miller commenting on Engineering Questions From A Non-Engineer:
I hope someone can explain Rashi's Chumash comments on Shemos 26:28 (actually the Rashi on this is under 26:26):
A simple reading of this seems to say that each of the 3 walls has its own central rod from end to end. I see no indication here that all 3 really make up the same rod. Why no indication, or did I miss something?
If I as an ordinary engineer wanted one continuous center rod without miraculous help, I might do it like this:
1. Make two long rods slightly longer than the long walls, and one short rod slightly longer than the short wall.
2. Slightly narrow and then thread one end of each long rod (male threads).
3. Drill and tap the short rod to make two threaded holes in the same side of this rod, one hole near each end, to line up with the center holes in the long walls.
4. Once all the vertical boards (with their center holes) were in position and held in place by the assembly crew, put the short rod through the short wall with this rod's threaded holes facing the holes in the long wall.
5. Insert each of the two long rods into its long wall from the open end, threaded end first.
6. Rotate the long rods to screw their threaded ends into the threaded holes in the short rod. Rotating rods this long would not be easy, because of friction and their length, but some kind of giant Vise-Grip pliers could help the crew do this.
So this is difficult but seems doable. The problem is how to keep the whole assembly together in heavy winds, etc. So even here, some type of miracle might be needed to hold it all together reliably, unless some other bracing that we don't know about was allowed.
A Simple Jew comments:
Bob: I appreciate your astute engineering feedback on this and I too read Rashi the way that you did which led me to ask the question in the first place. Perhaps, however, this just brings our discussion on emuna peshuta full circle. How does the rational mind accept or explain the miraculous story concerning the middle rod? Is anyone able to find a commentary with an explanation of this that does not rely on a miracle story? It certainly does not appear so.
I just noticed that this week's Torah Tots Midrash Maven included this story which Yitz also mentioned in his comment:
Then there's the 103-foot (72 amah) wooden beam. Ever heard of "A Tree Grows In Brooklyn?" Well, here's "A Tree Grows In Be'er Sheva". Actually, that tree had an important cameo in Jewish history that goes all the way back to Avrohom Avinu. He planted the original seed and, throughout his years, prayed and served his guests beneath the shade of its towering trunk. As the Bnei Yisroel crossed the Yam Suf, the Malachim chopped down the tree and dropped the giant trunk on the sea bed before them. The people understood that this huge relic was destined for greatness, so they took it along with them. Indeed, the giant tree trunk became the middle beam in the Mishkan.
(Illustration courtesy of Torah Tots)
UPDATE: Dixie Yid comments:
I looked this up in the sefer Shaarei Aharon this morning and found this very interesting pshat.
It is actually a machlokes. The opinion Yitz originally quoted is from the Gemara Shabbos Daf 98, which said that there was one 70 (or 72) Amah long briach hatichon that went through all three sides curving miraculously at the corners.
However Shaarei Aharon quotes the Malbim who quotes "Braisa D'Meleches Hamishkan," which says that there actually were 3 brichim tichonim; two that were 30 amos long for the sides and one that's 12 amos long for the back minus two at the corners. According to this there was no miracle necessary for the briach hatichon.
Shaarei Aharon points out that the Gemara Shabbos clearly disagrees with this Braisa regarding whether there were 3 brichim tichonim (according to the Braisa D'meleches Hamishkan), or 1 Briach Hatichon that miraculously curved, made from either the makal of Yaakov Avinu or the Aishel Avraham.