Horsey latitudes or Subtropical High are subtropic latitudes between 30 and 35 degrees both north and south. This region, under a ridge of high pressure called the subtropical ridge, is an area which receives little precipitation and has variable winds mixed with calm.
A common misconception is that the name derives from the apocryphal 17th century practice of throwing a ship's horses overboard during a prolonged calm in order to conserve water. This is unlikely; fresh horse meat would have been highly desirable compared to ship's rations (usually salted meat) and eating any livestock onboard instead of rations would actually help conserve water, as fresh water was needed to make the salt pork or beef (ironically referred to as "salt horse") edible.
The term probably came from the "dead horse" ritual, a practice in which the seaman would parade a straw-stuffed effigy of a horse around the deck before throwing it overboard. Seamen were often paid partly in advance before a long voyage (see Beating a dead horse), and the "dead horse" was this period of time (usually a month or two). The ceremony was to celebrate having worked off the "dead horse" debt. As European west bound shipping would reach the subtropics at about the time the "dead horse" was worked off, the region became associated with the ceremony.
The consistently warm, dry conditions of the horse latitudes also contribute to the existence of temperate deserts, such as the Sahara Desert in Africa, the southwestern United States and northern Mexico, and parts of the Middle East in the Northern Hemisphere, and the Atacama Desert, the Kalahari Desert, and the Australian Desert in the Southern Hemisphere.