|The Outer Altar of the Temple|
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 base, 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 ledge [since it formed a ledge upon which the Kohanim would walk], 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.
Three different fires were kept burning on the Altar every day. The largest one was located on the eastern side and everything brought to the top of the Altar to be burned was placed on this fire. Each morning this fire would be rebuilt by laying down two logs, parallel to each other, and then stacking two more logs on top, perpendicular to the first two, to form a square. A few more layers were added to make it very large.
The second fire provided the coals used in offering the incense. The size of the incense fire was large enough to produce 5 se’ah (1.5 cubic feet) of coals per day and 8 se’ah (2.3 cubic feet) of coals on the Sabbath.
The third fire was a maintenance fire, the pilot light of the Altar whose purpose was to fulfill the requirement of maintaining a “constant flame” (Leviticus 6:6) on the Altar. If the main fire would go out they would relight it from this small fire.
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.
On the southwest corner of the Yesod were two round depressions with small holes at the bottom which served as drains. Both drains were located towards the southern edge of that corner with the eastern drain being further south than the western drain. Blood poured on the western Yesod flowed along the top of the Yesod via a channel which directed it to the western drain. Blood poured on the southern Yesod (i.e. directly on the southwest corner) flowed into the eastern drain. This eastern drain also had a channel leading to it since the drains themselves were very small and it would be impossible to pour the blood directly into such a small hole.
In the Courtyard was a channel of flowing water called the Amah [“cubit”] — 1 cubit wide and 1 cubit deep, hence the name. This channel started near the southwest corner of the Altar and ran due south to the Water Gate. When the Kohanim wished to clean the floor of the Courtyard they would block the pipe of the Amah at the Water Gate, causing the water to back up and flood the Courtyard. The pipe was then reopened and all the refuse would be carried away with the water. Directly under the southwest corner of the Yesod was a small hollow, called the Shis, which was connected underground to the nearby Amah. All the blood poured on the Altar would run down the two drainage holes into the Shis and from there into the Amah. This blood-enriched water would be carried out to the Kidron Valley where it was sold to farmers as fertilizer with the proceeds going to the Temple.
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.