Menachos Chapter 11, Mishnah 6. This mishnah describes how the Table in the Sanctuary functioned, the vessel upon which the lechem hapanim (showbread) was placed. The arrangement is a rather complex mechanism, and it is highly recommended to look at a picture or a diagram of the structure, since a verbal description is no match for seeing it with one's own eyes. Nevertheless, we will try to describe it in order.
The basic structure:
The Table was made of gold, and the loaves of the lechem hapanim were arranged on it in two rows - two stacks - of six loaves each. So that the loaves would not become moldy, a space of air had to be left between them by means of 'reeds': hollow tubes cut lengthwise in half, shaped like an upside-down U, which separated one loaf from the next. Not all the loaves rested on reeds - the two bottom loaves (one in each stack) lay directly on the Table itself with no space beneath them, while the five loaves above them in each stack were raised one above the other by means of those reeds.
The count of the reeds:
Altogether there were twenty-eight reeds, fourteen in each stack. At first glance this is a puzzling number - how do we arrive at it?
The bottom loaf rested on the Table itself, and therefore only five gaps remained in each stack: between the first and the second, between the second and the third, between the third and the fourth, between the fourth and the fifth, and between the fifth and the sixth.
In the four lower gaps, three reeds were placed in each gap - three times four, which is twelve.
In the top gap, which bears a lighter weight and needs less support, only two reeds were placed.
Twelve plus two - fourteen in each stack, and multiplied by two: twenty-eight.
The senifim - support from the sides:
The loaves also needed support from the sides, so that they would not fall off the edge and would not break - for if even one loaf broke, all of them were disqualified. These supports are called 'senifim', and they are supporting posts standing at the side.
There is a difference of opinion as to their exact form, and Rashi describes how they looked: possibly they were like the two sides of a shelf - vertical golden posts holding the stack from both of its sides; or possibly they were like three vertical golden posts serving as support from the sides. Either way, the result is the same: the loaves are braced and pressed from the sides, against the faces of the loaves that face one another. The senifim stood on the floor, pressed upward against the Table, and their upper ends reached the height of the top of the sixth loaf in each of the two stacks.
The words of the mishnah:
"Arba'ah senifin shel zahav hayu sham" - four golden supports were there, leaning against the Table, to hold the bread in its place and in its shape. "U'mefutzalin b'rasheihen" - they had notches and grooves at their upper part. "She'hayu somchin bahen, shenayim l'seder zeh u'shenayim l'seder zeh" - like two pairs of bookends: two supported the stack of six loaves of one row, and two supported the stack of six loaves of the second row, so that they would stay in place.
"V'esrim u'shemonah kanim" - 'kaneh' means a reed stalk, and also a tube, and from it comes the name 'kaneh' for the windpipe. Here it refers to tubes that were cut lengthwise into halves, shaped like a U, and laid upside down - in the words of the mishnah: "ka'chatzi kaneh chalul" - like half a hollow tube. These twenty-eight reeds served to support the loaves, according to the count detailed above: three between the first loaf and the second, three between the second and the third, three between the third and the fourth, three between the fourth and the fifth, and two between the fifth and the sixth. "Arba'ah asar l'seder zeh v'arba'ah asar l'seder zeh" - in each of the two stacks there were fourteen reeds, and altogether twenty-eight.
"Lo siddur kanim v'lo netilatan docheh es haShabbos" - neither the arranging of the rods nor their removal overrides Shabbos:
The rods are not inserted on Shabbos, nor are they removed on Shabbos, because by rabbinic law this looks like building and dismantling a vessel - assembling the separate parts of this composite structure and taking them apart. True, this is not permanent building but merely part of a vessel, so the prohibition is only rabbinic, yet that makes no difference here: since there is no need to do it specifically on Shabbos in order for the order of the service to be carried out, it is not done on Shabbos. This is the principle we have already seen earlier in the chapter, the principle of Rabbi Akiva: whatever can be done before Shabbos does not override Shabbos.
"Ella nichnas me'erev Shabbos v'shomtan v'nosnan l'orko shel shulchan" - on Friday afternoon the kohen enters the Sanctuary and slips out the twenty-eight rods, so that he will not have to remove and dismantle them on Shabbos when the loaves are taken out, and so that they should not fall. He then places them along the length of the Table: according to most opinions on the floor next to the legs of the Table, and possibly on the Table itself if there is room there. "Along its length" means in the direction of the Table's length - its two cubits of length run from east to west, and therefore the rods too are aligned from east to west.
"V'chol hakeilim shehayu baMikdash arkan l'orko shel bayis" - and all the vessels that were in the Temple, their length ran along the length of the House:
All the vessels of the Temple are positioned so that their long side runs from east to west:
The Table: its length is aligned east to west.
The Menorah: its seven branches extend lengthwise, from east to west.
The Ark: the two staves that protrude from it as far as the Curtain also extend from west to east.