The story
Various theories; probably from a sailors' ritual of parading a straw-stuffed effigy of a horse around the deck before throwing it overboard.
Etymology from Wiktionary, CC BY-SA 4.0.
horse latitudes
Today it means: The warm, subtropical bands which encircle the globe between approximately 30 and 35 degrees both north and south of the Equator, characterized by high atmospheric pressure and dry variable winds ranging from calm to light. Full definition →