and, as has been shown in another place, of the
principal revenue of the crown derived from Amer-
ica. ¹ Their number and productiveness steadily
increased with the advance in methods and the
additions to the number of mines worked. Hum-
boldt estimated the average annual production
from the discovery of America as follows:

The total yield from 1493 to 1803 he put at five
billion seven hundred and six million seven hun-
dred thousand pesos. ³ At the beginning of the
nineteenth century the total annual production he
calculated to be forty-three million five hundred
thousand, or about ten times the known produc-
tion of the rest of the world. ⁴

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