Satapatha Brahmana Part V (SBE44), Julius Eggeling tr. [1900], at sacred-texts.com
11:8:2:11. Verily, there are four kinds of fire,--the one laid down, the one taken out, the one taken forward, and the one spread (over the three hearths). Now, that which is laid down is this very (terrestrial) world; that which is taken out is the air-world, that which is taken forward is the sky, and that which is spread is the regions. And that which is laid down is Agni, that which is taken out is Vâyu (the wind), that which is taken forward is Âditya (the sun), and that which is spread is Kandramas (the moon). And that which is laid down is the Gârhapatya, that which is taken out is the Âhavanîya, that which is taken forward is the (fire) they lead forth eastwards from the Âhavanîya; and that which is spread is the one they take northwards for the cooking of the victim, and that (used) for the by-offerings 1: let him therefore perform the animal sacrifice on a fire taken forward.
127:1 See III, 8, 3, 18; 8, 4, 9, with note.