THE GUANO ISLANDS. 369 



Balda de la Independencia. — Here is one of the largest 

 deposits not yet opened. 



Isla e islote de Ballesta. — Contains large quantities. 

 Isla Blanca. — Contains large quantities. 

 Isla Mashorca. — Contains large quantities. 

 Islas de Guanape. — These islands contain quite extensive 

 deposits ; they furnish, at present, our main supply. 



Isla de Macabi. — The southern portion of this island is 

 entirly covered with guano, whilst the northern section con- 

 tains isolated or detached deposits. 



Islas de Lobos de Afuera. — The deposits are here thick, 

 extensive and numerous. 



Islas de Lobos de Tierra. — Contain also large, valuable 

 deposits. 



Islas de Chincha. — These three islands have for thirty 

 years past furnished the main supply for exportation ; they 

 contain at present but small quantities. 



As the exact configuration of the grounds which are covered 

 by deep layers of guano must remain, even in case of a care- 

 ful measurement, somewhat uncertain, it is but natural that all 

 numerical valuations hitherto published regarding the amount 

 of guano present have been merely approximations. The 

 actual yield has exceeded, in every instance almost, the 

 amount previously stated. The deposits upon the Chiuchas 

 were stated, in 1853, by Elias, to be only sufficient for a 

 demand of eight years more ; they lasted, however, for 

 eighteen years more. Davis reported, in 1862, the extent of 

 guano deposits upon the Guanape and Macabi islands equal 

 to two and one-fourth millions tons ; their present condition 

 indicates that twice the amount is nearer the truth. It seems 

 thus safe to assume, judging from these results in regard to 

 the remaining localities previously enumerated, that the 

 Peruvian government will be able, for many years to come, 

 to supply its customers, at the present rate of demand, with 

 guano. 



Our prospects in regard to the uniform quality of our future 

 supply of Peruvian guano are less satisfactory. The well- 

 known difference in composition between the former Chincha 

 and the present Guanape guano demonstrates plainly the pos- 

 sibility of serious variations regarding the value, commercial 

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