xvi 



river Magdalena, founded on my astrono- 

 mical observations, together with several 

 hundred plants, are engraved and ready 

 to appear. I shall not leave Europe to 

 undertake an expedition into Asia, till I 

 have laid before the public the whole result 

 of my travels in the New Continent. 



In the memoirs in which we have in- 

 vestigated the various objects of our re- 

 marks, we have considered each pheno- 

 menon under different aspects, and classed 

 our observations according Jo the relations 

 which they bear to each other. To give a 

 just idea of the method we have followed, 

 I shall here add a succint enumeration of 

 the materials, with which we were furnished 

 for describing the volcanoes of Antisana 

 and Pichincha, as well as that of Jorullo, 

 which in the night of the 20th of September 

 1759 5 rose from the earth one thousand 

 five hundred and seventy-eight French feet 

 above the surrounding plains of Mexico. 

 The positions of these singular mountains in 

 longitude and latitude was ascertained by 

 astronomical observations. We took the 

 heights of the different parts by the aid of 

 the barometer, and determined the dip 



