27 G THYSICAL GEOGRAPHY OF THE SEA, AND ITS METEOROLOGY. 



air above and occupy tlie space it held. Nor is this all. This 

 austral vapour, rising up, is cooled and condensed. Thus a vast 

 amount of heat is liberated in the upper regions, which goes to 

 heat the air there, expand it, and thus, by altering the level, 

 causing it to flow ofi'. This unequal distribution of atmosphere 

 between the two halves of the globe is imperfectly represented in 

 harometric profile on Plate I. (§ 215) — the shading around the 

 periphery of the circle being intended to represent the relative 

 height, and the scales standing up in it, the barometric column. 



-513. Influence of Antarctic icebergs in expelling the air from 

 austral regions. — This part of the southern ocean where the 

 barometer shows diminished pressure is frequented by icebergs, 

 many of them very large and high, and some of them sending up 

 towers, minarets, and steeples, which give them the appearance 

 in the distance of beautiful cities afloat. Each one of them is a 

 centie of condensation. • Could an eye from aloft look down upon 

 the scene, the upper side of the cloud stratum would present 

 somewhat the appearance of an immense caldron, boiling, and 

 bubbling, and intumescing in the upper air. These huge bergs 

 condense the vapour, and the liberated heat causes the air above 

 them to swell out, and to stand like so many curiouslj^-shaped 

 fungi above the general cloud level. And thus, where the 

 icebergs are thick, the clouds are formed low down. Icebergs, 

 like islands, facilitate the formation of clouds and promote 

 precipitation. 



514. The horse latitudes — the doldrums. — Turn we now to the 

 equatorial cloud-ring. Seafaring people have, as if by common 

 consent, divided the ocean off into regions, and characterized 

 them according to the winds ; e.g., there are the "trade-wind 

 regions," the "variables," the "horse latitudes," the " doldrums," 

 .etc. The " horse latitudes" are the belts of calms and light airs 

 .(§ 210) which border the polar edge of the north-east trades. 

 They were so called from the circumstance that vessels forfnerly 

 bound from iS'ew England to the West Indies, with a deck-load of 

 horses, were often so delayed in this calm belt of Cancer, that for 

 the want of water for their animals, they were compelled to 

 throw a portion of them overboard. The " equatorial doldrums " 

 is another of these calm places (§ 212). Besides being a region 

 of calms and baffling winds, it is a region noted for its rains and 

 clouds, which make it one of the most oppressive and disagreeable 

 places at sea. The emigrant ships from Europe for Australia 



