The laws of Shabbat are derived from the various activities of the Tabernacle. The source for the laws of transporting from one domain to another is the case of loading the beams of the Tabernacle on wagons when it was time for the Children of Israel to move in the desert. This discussion leads to an examination of the beams themselves and their arrangement.
The Sages taught: The Tabernacle beams were one cubit thick at the bottom, and they narrowed to a fingerbreadth as they reached the top, as it is stated: “And they shall match at the bottom, and together they will be ended [tamim] at the top toward a single ring; so shall it be for them both, they shall form the two corners” (Shemot 26:24). And below, when the children of Israel crossed the Jordan River, it says: “And those who went down toward the Sea of Arava at the Dead Sea came to an end [tamu]” (Yehoshua 3:16). Tam means finished or terminated. Here, too, the beams narrowed as they reached the top until they were virtually terminated; this is the statement of Rabbi Yehuda. Rabbi Neḥemya says: Just as they were one cubit thick at the bottom, so too, they were one cubit thick at the top, as it is stated: “Together.”
The Gemara asks: Isn’t it written: Tamim? The Gemara answers: Rabbi Neḥemya explains that this word teaches that they should bring whole beams and they should not bring planks and attach them. The Gemara asks: And according to the other opinion, Rabbi Yehuda’s opinion, isn’t it written: “Together”? The Gemara answers: That comes to teach that they should not be positioned askew from each other; rather, they should be perfectly aligned.
The Gemara asks further: Granted, according to the one who said: Just as they were one cubit thick at the bottom, so too, they were one cubit thick at the top, it is understandable why it is written: “And for the back of the Tabernacle westward you shall make six beams. And you shall make two beams for the corners of the Tabernacle in the back” (Shemot 26:22-23). This means that the width of these beams comes and covers the remaining thickness of those. However, according to the one who said that they were one cubit thick at the bottom and they narrowed to a fingerbreadth as they reached the top, they would not be perfectly aligned, as at the corners this beam goes in and this beam goes out. Part of the beam would protrude out of the Tabernacle. The Gemara answers that it was not only the thickness of the beam that narrowed. One pared the width of the beams as well so they were sloped like mountains and did not protrude.
According to Rabbi Neḥemya, the beams were of equal width for their entire length. When they were then arranged along the length and width of the Tabernacle, two open spaces were created, one at each corner, where additional beams were inserted. According to Rabbi Yehuda, who says that the beams narrowed, there also remained an open space in the corners of the Tabernacle between the length and the width of the structure. It was necessary to insert a specially crafted beam that was slanted on two sides, marked in red, to fill the opening.
According to the Me’iri, the initial assumption was that all of the beams were sloped on both ends. Therefore, it would have been difficult to place an additional beam that would leave the corners of the Tabernacle evenly closed on all sides. The answer of the Gemara is that the beams were sloped like a mountain, i.e., sloped on only one side.