Matthew Poole and continuators on Genesis 1:6

6. ¶ And God said, Let there be a Firmament in the midst of the Waters , and let it divide the Waters from the Waters.

Or, An Extension, or a Space or place Extended, or stretched out, and spread abroad like a Tent, or Curtain.

i. e. Between the Waters, though not exactly in the middle place; as Tyrus is said to sit, or be situated in the midst of the Seas, Ezek. 28. 2. Though it was but a little space within the Sea. But of these things see more in the next verse.

Marginal references: Psal. 136. 6. Jer. 10. 12. & 51. 15.; Heb. expansion.