22. Διὰ τί ἐν τοῖς ὑψηλοῖς τῶν οἴκων ὁ ἀὴρ διευριπίζει, καὶ μάλιστα ταῖς εὐδίαις; ἢ διότι ὁ ἀὴρ πολύκενός 5τίς | ἐστι τὴν σύγκρισιν; ὅταν οὖν ἄρξηται εἴσω ῥεῖν, συγχωρεῖ ὁ ἐν τῷ οἰκήματι ἀὴρ καὶ συστέλλεται. τούτου δὲ συμπίπτοντος τῷ χρόνῳ πολυκενώτερος γίνεται ὁ ἔξωθεν, καὶ χώραν πολλὴν ἴσχει. εἰς ταύτην οὖν τὴν χώραν πίπτει ὁ ἐκ τοῦ οἰκήματος ἀήρ, ὢν 10πλησίον, καὶ φέρεται εἰς ταύτην | τὴν χώραν διὰ τὸ κρέμασθαι καὶ τὴν τοῦ κενοῦ φύσιν μὴ δύνασθαι ἀντιστηρίζειν. κατὰ πολλὰ δὲ αὐτοῦ μέρη τούτου συμβαίνοντος, ἕπεται αὐτῷ ὁ πλησίον διὰ τὴν πρόωσιν·17 εἶτα πολλοῦ ἔξωθεν φερομένου ὁ μὲν ἔσω τόπος πολύκενος γίνεται, ὁ δὲ ἔξω πυκνότερος, καὶ 15πάλιν ἔξωθεν εἴσω φέρεται. | καὶ ταῦτα ἀλλάσσονται.
22.30 Why in lofty rooms does the air ebb and flow throughout,31 and especially in fair weather? Is it because the air, with respect to its composition, is something with a lot of empty space? So when (the air outside) begins to flow in, the air in the room gives way and is compressed. Now when the air collects together, in time the outside air becomes emptier, and so contains much space. Into this space, therefore, the air from the room falls, and it travels into this space because it is suspended and the nature of the void is not able to resist it. And when this happens in many parts of it, the nearby air follows it because of the forward thrust; then, when much air travels outside, the place inside comes to have a lot of empty space, whereas the outside air becomes denser, and so it travels back inside from the outside. And these32 continue to interchange.