TRUE VOLCANOES. 451 



consider invaluable, some sheets with remarks on the volcanic 

 products of the elevated plateaux of Quito and Mexico, which 

 the great geologist communicated to me for my information 

 more than 46 years ago. Travellers, as I have elsewhere 17 

 said, being merely the bearers of the imperfect knowledge of 



I find beautiful drusic cavities, the walls of which are covered with 

 crystals of iron-glance. Through the whole length of the Puy, cones 

 of dornite alternate with cones of cinders." The second volume of 

 the Travels, containing the letters from Auvergne, was printed in 1806, 

 but not published till 1809, so that the publication of the name of 

 domite properly belongs to the latter year. It is singular that four 

 years later, in Leopold von Buch's treatise on the trap-porphyry, 

 domite is not even mentioned. In referring to a drawing of the pro- 

 file of the Cordilleras, contained in the journal of my travels in the 

 month of July 1802, and included between the 4th degree north and 

 4th degree south latitude under the inscription " Affinite' entre le feu 

 volcanique et les porphyres," my only object was to mention that this 

 profile, which represents the three breakings through of the volcanic 

 groups of Popayan, Los Pastos and Quito, as well as the eruption of 

 the trap-porphyry in the granite and mica-slate of the Paramo de 

 Assuay (on the great road from Cadlud, at a height of 15,526 feet), 

 led Leopold von Buch, too kindly and too distinctly, to ascribe to 

 me the merit of having first noticed " that all the volcanoes of the 

 chain of the Andes have their foundation in a porphyry which is a 

 peculiar kind of rock and belongs essentially to the volcanic forma- 

 tions" (Abhandlungen der ATchademie der Wissenscli. zu Berlin, aus den 

 Jahren, 18121813, s. 131, 151 and 153). I may indeed have noticed 

 the phenomenon in a general way, but it had already, as early as 1789, 

 been remarked by Nose, whose merits have long been too little appre- 

 ciated, in his Orographical Letters, that the volcanic rock of the Sie- 

 bengebirge is "a peculiarly Rhenish kind of porphyry, closely allied 

 to basalt and porphyritic schist." He says '* that this formation i.s 

 especially characterised by glassy felspar," which he proposes should 

 be called sanidine, and that it belongs, judging from the age of its 

 formation, to the middle floetz-rocks (Niederrheinische Rdse, Th. i, 

 s. 26, 28 and 47 ; Th. ii, s. 428). I do not find any grounds for 

 Leopold von Buch's conjecture that Nose considered this porphyry- 

 formation, which he not very happily terms granite-porphyry, as 

 well as the basalts, to be of later date than the most recent floetz- 

 rocks. " The whole of this rock," says the great geologist, so early 

 removed from among us, " should be named after the glassy felspars 

 (therefore sanidine-porphyry) had it not already received the name of 

 trap-porphyry" (Abh. der Berl. AJcad. aus den J. 181213, s. 134). 

 The history of the systematic nomenclature of a science is so far of 

 importance as the succession of prevalent opinions is found reflected 

 in it. 



67 Humboldt, Kldnere ScJiriftcn, Bd. i, Vorrede, s. iii. v, 



2G2 



