Construction (Exodus 27:1–8)
"And thou shalt make an altar of shittim wood, five cubits long, and five cubits broad; the altar shall be foursquare: and the height thereof shall be three cubits."
Five cubits square — about seven and a half feet per side. Three cubits high. Acacia (shittim) wood overlaid not with gold but with bronze. The altar is hollow within (Exodus 27:8) — a wooden shell sheathed in bronze, designed to receive the fire of sacrifice. Four horns at the four corners, all of one piece with the altar itself. A grate of bronze network inside; rings and staves for transport. "As it was shewed thee in the mount, so shall they make it."
The altar was large enough for an entire bull or ram to be lifted onto its grate and consumed by fire. Bronze, not wood, is what stood between the body and the flame.
The fire that never went out (Leviticus 6:12–13)
"And the fire upon the altar shall be burning in it; it shall not be put out: and the priest shall burn wood on it every morning... The fire shall ever be burning upon the altar; it shall never go out."
This is not a maintenance instruction. It is a theological statement. The Aaronic priesthood was not allowed to let the altar fire die between sacrifices. The wood was added every morning. The fire of substitution was kept perpetual. Owen reads this as the unceasing virtue of Christ's blood — the fire of the altar never goes out because the application of the once-for-all sacrifice never ceases.
Position — the gospel order
The Bronze Altar was the first piece of furniture encountered on entering the Outer Court. Before the laver. Before the tent. Before any of the gold furniture. Before everything else, the worshipper met blood and fire. This is not arbitrary — it is the gospel order. Atonement comes before cleansing. Sacrifice comes before service. The first lesson of the Tabernacle, the first sight of any worshipper coming through the east gate, was that approach to God begins with substitutionary death.
The typological argument
The bronze metal is significant. Bronze in Tabernacle theology is consistently the metal of judgment. The bronze altar is where judgment was met head-on, on behalf of the worshipper. The fire that should have consumed the sinner consumes the sacrifice instead. The acacia wood inside represents the incorruptible humanity of the substitute; the bronze outside represents the judgment borne. Christ's incorruptible humanity bore the bronze of God's judgment.
"We have an altar, whereof they have no right to eat which serve the tabernacle" (Hebrews 13:10). The new altar is the cross. "Wherefore Jesus also, that he might sanctify the people with his own blood, suffered without the gate" (Hebrews 13:12). The altar of the Outer Court, where Christ shed his blood, is — typologically — Calvary outside the city wall.
The horns — the fugitive's refuge
The four horns at the corners of the altar were a place of refuge. "Solomon, the king of Israel, hath sworn unto me to day that he will not slay his servant with the sword. And he sent, and they brought him down from the altar" (1 Kings 1:51–53; cf. 1 Kings 2:28). A man fleeing for his life could grasp the horns of the altar and claim sanctuary. The horns were where the blood of the sacrifice was applied (Leviticus 4:7). The fugitive's safety was located at the same point as the blood.
The author of Hebrews compresses the imagery: "Who have fled for refuge to lay hold upon the hope set before us" (Hebrews 6:18). Believers are spiritual fugitives gripping the bloodied horns of the only altar that saves.
Commentary
Jamieson, Fausset, and Brown, Commentary Critical and Explanatory on the Whole Bible (1871, PD): the bronze altar is the type of the cross of Christ; its position, materials, and perpetual fire all witness to the once-and-always-effective sacrifice. Charles Spurgeon, sermon "The Brazen Altar" (1864, PD): the altar is for the sinner — not for the perfect. Approach it as you are; the fire is still burning.
→ Cross-link: The Bronze Laver (cleansing follows sacrifice) • The Mercy Seat (the altar's blood ends here) • Bronze Serpent (bronze as judgment-borne).