The Outer Altar served as the focal point of the sacrificial service. [The smaller, Inner Altar â located within the Sanctuary Building â was used for offering incense.] After an animal offering was slaughtered, its blood was applied to the walls of the Altar and certain parts of the animal were then burned on the fires located on the Altar’s top.
The Altar was a three-tiered structure made of stones held together with cement and coated with plaster. The first tier was called the Yesod, or foundation, and measured 32 cubits (48 feet) square and 1 cubit (1½ feet) high. It only protruded from the body of the Altar on the west and north. Above the Yesod was the Sovev, or surround [since, unlike the Yesod, it protruded from the body of the Altar on all four sides], measuring 30 cubits (45 feet) square and 5 cubits (7½ feet) high. Above the Sovev was the top level, called the Altar, measuring 28 cubits (42 feet) square and 3 cubits (4½ feet) high. On the four corners of the Altar were extensions called Keranos (sing., Keren), meaning horns [since they protruded upward like the horn from the head of an animal] which were hollow and open on top, 1 cubit square and 1 cubit high (1½ feet per side).
On the top of the Altar, starting near the outer edge, the first 2 cubits (3 feet) were depressed into the top, leaving a small lip around the edge of the Altar to prevent the Kohanim from falling off (there was a similar feature around the edge of the Sovev). The Kohanim would walk within this channel as they performed their various tasks on the top of the Altar.
Near the southwest Keren on the top of the Altar were two silver bowls. These bowls were receptacles for the libations which were offered on the Altar: water libations were poured into the western bowl and wine libations into the eastern one. Water libations, offered only on Succos, were brought together with the wine libations and both were poured into their respective bowls simultaneously. In order for them to empty at the same rate, the drain in the wine bowl was made slightly wider than the drain in the water bowl to account for the difference in viscosity. The drains of both bowls led down through the Altar to a deep subterranean hollow under the southwest Keren of the Altar.
The Torah requires that the Kohanim ascend the Altar via a ramp, as opposed to steps. The main access ramp of the Altar was centered on its southern side and measured 32 cubits (48 feet) long, 16 cubits (24 feet) wide, and 9 cubits (13½ feet) tall. The main ramp was flanked by two smaller ramps. On the eastern side was a ramp to the Sovev and on the western side a ramp to the Yesod.
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