INFLUENCE OF THE FOREST ON SPRINGS. 291 
“ At the time of Humboldt’s visit to the valley of Aragua, 
the inhabitants were struck by the gradual diminution which 
the lake had been undergoing for thirty years. In fact, by 
comparing the descriptions given by historians with its actual 
condition, even making large allowance for exaggeration, it 
was easy to see that the level was considerably depressed. The 
facts spoke for themselves. Oviedo, who, toward the close of 
the sixteenth century, had often traversed the valley of Ara- 
gua, says positively that New Valencia was founded, in 1555, 
at half a league from the Lake of Tacarigua; in 1800, Hum- 
boldt found this city 5,260 metres [= 34 English miles] from 
the shore. 
“The aspect of the soil furnished new proofs. Many hil- 
locks on the plain retain the name of islands, which they more 
justly bore when they were surrounded by water. The ground 
laid bare by the retreat of the lake was converted into admi- 
rable plantations ; and buildings erected near the lake showed 
the sinking of the water from year to year. In 1796, new 
islands made their appearance. <A fortress built in 1740 on 
the island of Cabrera, was now on a peninsula; and, finally, 
on two granitic islands, those of Cura and Cabo Blanco, Hum- 
boldt observed among the shrubs, some metres above the 
water, fine sand filled with helicites. 
“These clear and positive facts suggested numerous expla- 
nations, all assuming a subterranean outlet, which permitted 
the discharge of the water to the ocean. Humboldt disposed 
of these hypotheses, and did not hesitate to ascribe the dimi- 
nution of the waters of the lake to the numerous clearings 
which had been made in the valley of Aragua within half a 
century.” 
Twenty-two years later, Boussingault explored the valley 
of Aragua. For some years previous, the inhabitants had ob- 
served that the waters of the lake were no longer retiring, but, 
on the contrary, were sensibly rising. Grounds, not long 
before occupied by plantations, were submerged. The islands 
of Nuevas Aparecidas, which appeared above the surface in 
