1911 Encyclopædia Britannica/Horse Latitudes
HORSE LATITUDES, the belts of calms and variable breezes at the polar edge of the N.E. and S.E. trades. According to the New English Dictionary two explanations have been given of the origin of the name: one that the calm kills horses on a sailing ship, the other that the name signifies the unruly and boisterous nature of these winds compared with the pleasant trades. The name is commonly applied to the permanent belt of high atmospheric pressure which encircles the globe in 30° to 35° from the equator.