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time, and to which I wish to apply my deductions. Guano 
is usually considered as the excrement of the sea-fowl, which 
has accumulated during a long period of time, so long that 
attempts have been made to calculate its age from its thick- 
ness. Thus Humboldt, who first made this substance known 
to the Eastern Hemisphere, in 1840, states that on the Chincha 
Islands it has a depth of 50 to 60 feet and that the accum- 
ulation of the preceding 800 years had formed only a few 
lines of this thickness. The facts brought forward by Mr. 
Squier show how difficult it is to arrive at any certain 
knowledge on this point, and in fact show that we have no 
means of ascertaining the age of the Guano deposits, even if 
we accept the theory of their origin from the source usually 
ascribed to them. Itisa remarkable fact that in a curious 
old book entitled, “The First Book of the Art of Metals, 
written in Spanish by Albano Alonzo Barba, Master of Art, 
born in the Town of Lepe in Andalusia, Curate of St. 
Barnard’s Parish in the Imperial City of Potosi, in the 
Kingdom of Peru in the W. I. in the year 1640. T'rans- 
lated into English in the year 1669: London, 1670,” we 
find the following passage. Speaking of the substance we 
are considering, the author says, “It is called Guano 
(ze. dung; ) not because it is the dung of sea-fowls, (as many 
would have it,) but because of its admirable virtue in mak- 
ing ploughed ground fertile,” and both Mr. Squier and Dr. 
Habel inform me that the name Guano (correctly written and 
and pronounced Whuanno) does not necessarily mean dung, 
but something that, like dung, causes the plantstto grow; being 
derived from the verb to grow. Then we find that Guano 
is not confined to islands only, but occurs in large quantities 
on the contiguous headlands, and many ravines extending 
into the interior of the country contain Guano in smaller and 
larger quantities. Thus the ravines of Lobo, Culata, Sacra- 
mento, Animas, Morillo, Guajes, Colorado, Chucumata and 
Pica are reported to contain pure Guano deposits, covered by 
a thick coating of sand. Neither is it found in rainless 
districts only, for as [ have said it is found on the islands 
off the California coast, which is by no means rainless, and 
