Means of Transportation 
155 
I 
Ellsworth Huntington 
Fig. 123. The earliest form of cart had solid wheels, and the solid-wheeled cart is seen today in 
Turkey. Persia, China, and other parts of Asia. 
The horse is largely limited to the temperate zone, not only because 
brisk commerce and active agriculture require him there, but because 
in tropical regions he readily contracts diseases, and his thin skin makes 
the insect pests especially annoying. Of the hundred and ten million 
horses in the world, the United States has nearly one fourth and Eu- 
rope about one half. Asiatic Russia has ten times as many as Africa, 
although its area is much smaller and the population only a sixth as 
great. What few horses there are in Africa live largely in the more 
temperate regions of the Mediterranean coast and South Africa. 
Some cities where animals are important. Although race horses 
bring the highest prices, some having been sold for much more than 
one hundred thousand dollars, the most useful animals are the heavier 
horses used for hauling loads and for farm work. Moscow was for- 
merly noted for huge, sleek animals, which, though spirited, are also 
gentle. Equally fine horses are seen in Glasgow and in some of our own 
cities, like Chicago. In the northern United States the horse is the 
only animal commonly used for transportation in our cities; but in 
the South the mule team is common. 
More interesting, because less familiar, are the caravans of donkeys 
or camels that crowd the narrow streets of oriental cities, like Damas- 
cus, Bagdad, Algiers, and Tashkent. When a caravan of camels from