What are horse latitudes and how did they get the name?

There are two sub-tropical high-pressure belts extending approximately between latitudes 15 and 30 degrees to the north and south of the Equator. Horse latitudes are generally areas of high pressure marked by calm, subsiding air that gets heated during descent. It is said that Spanish sailors ferrying horses to the West Indies were usually stuck for months in these calm waters and had to throw their horses into the water to conserve drinking water for themselves. This led to the term ‘horse latitudes’.