Who has spread out the heaven like an arch, and founded it upon the waters: This verse refers to Gen 1.6-7 (compare also Job 9.8; Isa 44.24). Ancient people thought of the sky as a round dome (arch) coming down and touching the waters that surrounded the land. Once again the word who introduces a statement, not a question. Good News Bible provides a helpful model for this verse, and so does Contemporary English Version, which says:

• He stretched out the sky like a dome and made sure it stays above the ocean.

Quoted with permission from Bullard, Roger A. and Hatton, Howard A. A Handbook on 1-2 Esdras. (UBS Helps for Translators). Miami: UBS, 2019. For this and other handbooks for translators see here.