As recorded in the Torah, it is forbidden to access the Mizbeyach with steps. For this reason, a large ramp was built on the southern side of the Mizbeyach which measured 32 amos long, 16 amos wide, and 9 amos tall. While all ramps in the Beis Hamikdash conformed to a ratio of 3 amos in length for every amah of height, the slope of the Mizbeyach ramp was slightly shallower, with a ratio of 3½ amos + 1⅓ fingerbreadths of length for every amah of height.This was done to make it easier for the Kohanim to carry the heavy pieces of meat up its smooth surface. The Kohanim used to race up this ramp to decide who would perform terumas hadeshen — until someone got hurt and the Sages decided that this procedure was too dangerous. Even though the ramp had a lip along either side which kept the Kohanim from slipping off the edge, it did not protect someone who was purposely pushed off.
All of the sacrificial parts which were burned on the Mizbeyach had to be thrown onto the Mizbeyach from the ramp, and part of this requirement was that there be a recognizable gap of airspace between the ramp and the Mizbeyach. Thus, the ramp did not touch the Mizbeyach.
On the western half of the ramp this gap was one amah wide and provided access to the Shissin (the cavity where the wine and water libations collected) at the southwest corner of the Mizbeyach. On the ground in the vicinity of that same corner was the access hole for the Shis (the pipe that carried blood from the Yesod to the stream of water beneath the floor).
Set into the top surface of the ramp was a square receptacle measuring one amah to a side and as deep as an arm’s length. Bird chatas-offerings which became unfit would be placed here overnight.
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