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XXVIII.— Guano. By James F. W. Johnston, F.R.S., 

 Sic, Hon. Mem. of the Royal English Agricultural Society. 



§ 1. Of the Natural Occurrence of Guano. 



GuanO;, according to Humboldt, is the European pronunciation 

 of the word huanu/' which in the language of the Incas means 

 dung or manure. The substance long known by this name occurs 

 at various points along the coast of Peru, between the i3th and 

 21st degrees of south latitude, both on the main land and on the 

 numerous islands and rocks which are sprinkled along this part 

 of the shores of South America. It forms irregular and limited 

 deposits, which at times attain a depth of 50 or 60 feet (Hum- 

 boldt), and are excavated like mines of iron ochre. It is not 

 known to exist in any quantity north of 13° or south of 21°; 

 though the flocks of cormorants, flamingoes, cranes, and other 

 sea-fowl (from the droppings of which it has been derived), ap- 

 pear to be equally numerous along both the more southerly coast 

 of Atacama and the more northerly shores of Arequipa. 



Mr. Winterfeldt, who appears to have more recently visited tlie 

 west coast of South America, has published the following addi- 

 tional information in Bell's Weekly Messenger of the 11th of 

 September, 1841 : — 



" There are three varieties of guano — the red, the dark-grey, and the 

 white. The first two are met with in the isles of Chincha near Pisco, at 

 Iquique, and on the hill of Pica. The term ' guano of Iquique ' is 

 sometimes used from its having been first procured from the island of 

 that name. This island is situated about 400 yards from the port of 

 Iquique. It is about half a mile long, and about 200 yards broad ; and 

 furnished large quantities of guano for 25 years, when it became ex- 

 hausted. The hill of Pica is very high, and is covered with guano down 

 to the water's edge ; while that side which does not face the sea is of 

 sand and gravel. In this hill or rock I am informed that a silver-mine 

 was formerly worked, but that no trace of guano was found during the 

 excavation. The adjoining hills on either side are of sand, which is car- 

 ried by the winds, and covers up the guano ; to remove which the sand 

 is first taken away, and deep excavations are made ; the guano extend- 

 ing nearly a quarter of a league in length, and 300 yards in depth.* 

 It is likewise found at St. Lobos, about three leagues to the south of 

 Pica; butj as the anchorage is dangerous, little business is done here." 



§ 2. Origin of the Guano. 

 The extraordinary thickness and extent of these deposits of 

 guano seem at first sight to throw discredit on the statement that 



* Mr. Winterfeldt can scarcely mean that the layer of guano is actually 

 900 feet in thickness : it probably climbs up the mountain side so high. 

 Pica and Iquique are both within the latitude of 21° S., the limit assigned 

 by Humboldt. 



