The Tapering Roof and Side Door of Noah's Ark

"And to a cubit you shall finish it from above" (Genesis 6:16). Rabbi Nehemiah says: it was shaped like a vault, and he kept narrowing it as it rose, narrowing it as it rose, until he brought it to a single cubit at the top, as it is said, "And to a cubit you shall finish it from above." (And there are those who report that Rabbi Judah says there were three hundred and thirty compartments in it. He explains: there were four compartments across its width, and four times thirty makes one hundred and twenty compartments. The lowest level had one hundred and twenty, the second had one hundred and twenty, totaling two hundred and forty. The upper third level had only three rows, since it narrowed as it rose and the width of the ark there was only forty cubits, and three rows make ninety; with the other two hundred and forty, that is three hundred and thirty compartments according to Rabbi Judah. According to Rabbi Judah it works out, since the height of the compartments reached up to the roof. And Rabbi Nehemiah holds it was shaped like a vault, sloping and descending like a sloped roof.) "And you shall set the door of the ark in its side" (Genesis 6:16). The Torah taught you proper conduct, that if a person builds a hall ten by ten, he should make its entrance from the side. "With lower, second, and third decks you shall make it" (Genesis 6:16). The lowest deck was for refuse, the second for himself and his sons and the clean animals, and the upper for the unclean. And some reverse it: the lowest for the unclean, the second for himself and his sons and the clean, and the upper for refuse. How did he manage it? He had a kind of trapdoor, and he would open them from the side. "You shall make it" [it shall help itself] - meaning it also helps itself along.