Mani with Hjuki and Bil

In Scandinavian mythology the wagon that drags the moon across the sky is driven by Mani. On the wagon the children Hjuki and Bil also is traveling. Their job is to cover up the moon partly or completely so we get the lunar cycles.

Hjuki and Bil are possibly remembered in the rhyme that starts "Jack and Gil went up a hill to fetch a pail of water"

Compare to the story as Snorri Sturluson tells it in Gylfaginning

Máni stýrir göngu tungls ok ræðr nýjum ok niðum. Hann tók tvau börn af jörðunni, er svá heita, Bil ok Hjúki, er þau gengu frá brunni þeim er, Byrgir heitir, ok báru á öxlum sér sá, er heitir Sægr, en stöngin Simul. Viðfinnr er nefndr faðir þeira. Þessi börn fylgja Mána, svá sem sjá má af jörðu.

Moon steers the course of the moon, and determines its waxing and waning. He took from the earth two children, called Bil and Hjúki, they that went from the well called Byrgir, bearing on their shoulders the bucket called Sægr, and the pole Simul. Their father is named Vidfinnr. These children follow Mani, as may be seen from the earth.