Middot, Chapter Three, Mishnah Five
This mishnah describes the set-up used to slaughter the sacrifices. Some of this mishnah was also found in Tamid 3:5 (coincidental, I think, that the number of the mishnah is the same).
1) There were rings to the north of the altar, six rows of four each. And some say, four rows of six each.
a) Upon them they used to slaughter the sacrificial animals.
2) The slaughter house was to the north of the altar, and on it were eight small pillars on top of which were blocks of cedar wood, in which were fixed hooks of iron, three rows in each, upon which they would hang [the sacrifice] and they would strip its hide on tables of marble that stood between the pillars.
Section one: There were twenty-four rings on the north side of the altar, either in six rows of four, or four rows of six. They would put the animals head in the ring to slaughter it.
Section two: The mishnah describes the slaughterhouse, especially the hooks on which they would hang the meat after the sacrifice was slaughtered. It is also describes the tables upon which the meat would be washed.