"Arabian hourglasses"
This reference is obscure. Bradbury may be referring to the fact that sand dunes in certain locations (such as the Dunes of Oman, on the Arabian coast), actually produce sounds known as “singing” or “booming,” when slides occur or when wind passes over the crest of the dune, and combining it with the notion of sand sliding back up to the top of an hourglass as an analogous image of time running backward the way it is doing when Cooger rides the carousel in reverse.