Ezekiel 43:13 - Matthew Poole's English Annotations on the Holy Bible

Of the altar of burnt-offerings; for the altar of incense was within the temple, and is called the golden altar, but this in this verse is the brazen altar, and stood in the court of the house. The cubit is a cubit and an hand breadth; the great or sacred cubit, three inches longer than the common cubit. The bottom, the ledge or settle, or as a little bench fastened to the altar on all sides at the bottom, shall be a cubit in height. The breadth, from the edge of this settle or bench on the outside, to the edge where it joined the body of the altar, a cubit; and this breadth, twenty-one inches, broad enough for the priests to walk on round the altar, as they had occasion. The border, a ledge going round on all the squares, on the outer edge of this settle, a span high, about nine inches, which was to prevent the priests. that they slipped not down in walking on this settle. This shall be the higher place of the altar: this seems somewhat harshly translated; the French hath it, this shall be the back of the altar; as the back bears burdens, so this should bear the weight of the whole altar; this the basis or bottom, as called before, which was one cubit in each square broader than the next square frame or settle.