וְנָתַתָּ֣ה אֹתָ֗הּ תַּ֛חַת כַּרְכֹּ֥ב הַמִּזְבֵּ֖חַ מִלְּמָ֑טָּה וְהָיְתָ֣ה הָרֶ֔שֶׁת עַ֖ד חֲצִ֥י הַמִּזְבֵּֽחַ׃
And thou shalt put it under the ledge round the altar beneath, that the net may reach halfway up the altar.
Read kabbalistic (mystical) interpretation of Exodus 27:5: and classical mystical sources.