The compass of the altar - A shelf or projecting ledge, of convenient width, carried round the altar half way between the top and the base. It was supported all round its outer edge by a vertical net-like grating of bronze that rested on the ground.

And thou shalt put it under the compass of the altar beneath,.... That is, the grate was to be put within the square compass of the altar, in the hollow part of it, for the wood and sacrifice to be laid upon it:

that the net may be even to the midst of the altar; and as the altar was three cubits high, this net or grate was let down by chains to its rings a cubit and a half, and being of such a depth was capable of containing a great deal.

And thou shalt put it under the compass of the altar beneath, that the net may be even to the midst of the altar.

5. put it under the compass of the altar beneath-that is, the grating in which they were carried to a clean place (Le 4:12).

27:1-8 In the court before the tabernacle, where the people attended, was an altar, to which they must bring their sacrifices, and on which their priests must offer them to God. It was of wood overlaid with brass. A grate of brass was let into the hollow of the altar, about the middle of which the fire was kept, and the sacrifice burnt. It was made of net-work like a sieve, and hung hollow, that the ashes might fall through. This brazen altar was a type of Christ dying to make atonement for our sins. The wood had been consumed by the fire from heaven, if it had not been secured by the brass: nor could the human nature of Christ have borne the wrath of God, if it had not been supported by Divine power.