Exodus 40:6. Thou shalt set the altar of the burnt offering before the door of the tabernacle of the tent of the congregation.
This altar was placed in the court, not far from the entrance to the Tabernacle (Ex. 40:6,29). It was made of acacia wood, and covered with plates of brass. It was five cubits long, five cubits broad, and three cubits high, and had four horns at the four corners. It had brazen rings, and staves covered with brass were provided for moving it. It was hollow, and is supposed to have been filled with earth, thus complying with the command in Exodus 20:24. See also Exodus 38:1-7.
Around the altar, midway from the bottom, was a projecting ledge on which the priest stood while offering sacrifice. This is represented in the word karkob, rendered “compass” in Exodus 27:5 and Exodus 38:4; a word which Gesenius renders margin or border. It is supposed that an inclined plane of earth led to this on one side, probably the south. Thus we may see how Aaron could “come down” from the altar (Lev. 9: 22).
Various views have been entertained in reference to the grating or network spoken of in Exodus 27:4-5 and Exodus 38:4. Some place it at the top of the altar, supposing that the lire and the sacrifice were put upon it; but if the altar was tilled with earth, as we have supposed, there would scarcely have been any need of a grating for such a purpose. Others suppose the altar to have been only half-filled with earth, and that this grating was placed inside of the altar half way to the bottom, for the purpose of holding the earth. Both these theories assume that the grating occupied a horizontal position. Some archaeologists, however, suppose this grating or network to have been perpendicular, and to have dropped from the edge of the karkob, or projecting ledge, to the ground. Thus in Exodus 27:5, it is said, “And thou shalt put it [that is, the “grate of network of brass,” verse 4] under the compass [karkob] of the altar beneath, that the net may be even to the midst of the altar.”
Meyer is very decidedly in favor of this view; indeed we are not sure but he ought to be credited with having first suggested it. After speaking of the karkob, or ledge, he says: “Under the outer edge of this bench was the copper lattice work, which extended from it to the ground on all four sides, just as the body of the chest extended from the inner edge of the bench. It formed, with the bench or the karkob around, an expanding set-oft; by reason of which the under half of the altar, on all sides, appeared wider than the upper. On the karkob, bench, or passage-way, the priest walked in order to attend to the sacrifice, to lay wood upon the altar, or to officiate in other ways....The grating served to preserve the base of the altar from the sprinkled blood of the sacrifices (see Ex. 29:12; Lev. 4:7) and to keep away from the sacred altar men and the beasts to be offered in sacrifice” (Bibeldeutungen, pp. 201-211).