32 PRACTICAL ARBORICULTURE 
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When an explosion occurs the clouds of vapor rise to a great height, making 
a very beautiful appearance. 
At a distance of a few miles no danger is apprehended, yet the Indians who 
occupy the villages upon the mountain slope abandoned their homes temporarily 
when the volcano gave evidence of continuous eruption. 
IRRIGATION. 
From the time of the Conquest Mexico has practiced irrigation. The long 
aqueducts of masonry, the arches of brick, to carry streams of water over broad 
and deep valleys are still in good preservation, although constructed three centu- 
ries ago. Dams of cut stone, with pressers or reservoirs of great extent, and dis- 
tributing canals, convey water from the canyons to the fields far away. 
Rude as may be the implements, and fixed in ancient habits as are the people, 
yet they are adepts in the art of irrigation. 
Mountains have been pierced with tunnels to bring the precious fluid from 
distant valleys, for on the elevated lands agriculture is dependent upon irrigation 
to extend the season of plant growth beyond the rainy period. 
The dry and rainy seasons are more marked in Central Mexico than in the 
Eastern United States, although in California similar periodic rains occur, and 
during the rainless months water must be supplied. 
There are great agricultural valleys throughout the tablelands of Mexico, 
where corn, cotton, sugar cane, alfalfa and small grains are grown, while the 
Maguey is one of the principal products, pulque being as much a national drink 
among the poorer classes as beer is in Germany, wine in France and whisky in 
the United States. 
Upon the lowlands near the seacoast, where the air is more moist irrigation is 
unnecessary. 
There are places where, on rough, rocky hills, bare of soil, have been built 
large cities. Here, in excavations in the rocks, filled with soil from a distance, 
are growing fine shade trees. Walls of masonry have been erected, four or five 
feet square, two feet high, about these trees, in which water is poured to irrigate 
them. This also protects the trees from careless people and stray stock. 
Some of the great trees, as the one which we illustrate, the cypress of Mon- 
tezuma, at Chapultepec, have been religiously cared for during more than 400 
years. 
TEMPERATURE. 
During July and August the telegraph brought reports of very high tem- 
perature throughout the United States, the thermometer being reported to register 
105 degrees at times. In Central Mexico, at the same time, the weather was 
extremely pleasant, with but 70 to 75 degrees Fahrenheit. Towards the close of 
each day a dark cloud would usually appear, and suddenly a rain of brief duration 
indicated the rainy season. Frequently these rains occurred at night. 
This equable temperature makes the table lands of Mexico a more pleasant 
region for summer residence or travel. At no time was it unpleasantly warm, 
while at night blankets were always acceptable. 
