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tains of Chumban, in the province of Los Pastos; 

 the bridge of Madre de Dios, called Danto, near 

 Totonilco, in Mexico; the pierced rock near 

 Grandola, in the province of Alentejo, in Por- 

 tugal; are geological phenomena, which bear 

 some resemblance to the bridge of Icononzo: 

 but I doubt whether in any part of the Globe a 

 phenomenon has been discovered so extraordi- 

 nary as that of the three masses of rocks, which 

 support each other by forming a natural arch. 



I sketched the natural bridges of Icononzo 

 from the northern part of the valley, with a side 

 view of the arch. The first proofs of this plate 

 indicate erroneously Mr. Gmelin of Rome as the 

 engraver, instead of M. Bouquet of Paris. 



