DISCOVERIES IN THE CELESTIAL SPACES. 347 



•^tions by the beautiful researches of Boussingault and Dumas 

 13 one of the brilliant points of modern meteorology. 



The.extension of physical and chemical knowledge, which 

 we have here briefly sketched, could not fail to exercise an 

 influence on the earliest development of geognosy. A great 

 number of the geognostic questions, with the solution of which 

 our own age has been occupied, were put forth by a man 

 of the most comprehensive acquirements, the great Danish 

 anatomist, Nicolaus Steno (Stenson), in the service of the 

 Grand-duke of Tuscany, Ferdinand II. ; by another physi- 

 cian, Martin Lister, an Englishman, and by Robert Hooke, 

 the " worthy rival" of Newton.* Of Steno's services in the 

 geognosy of position I have treated more circumstantially in 

 another work.f Leonardo da Vinci, toward the close of the 

 fifteenth century (probably when he w^as planning the canals 

 in Lombardy which intersect the alluvial and tertiary forma- 

 tions), Fracastoro in 1517, on the occasion of the accidental 

 exposure of rocky strata, containing fossil fishes, at Monte 

 Bolca, near Verona, and Bernard Palissy, in his investiga- 

 tions regarding fountains in 1563, had indeed recognized the 

 existence of traces of an earlier oceanic animal world. Leo- 

 nardo, as if with a presentiment of a more philosophical classi- 

 fication of animal forms, terms conchylia "■ ayiimali die hanno 

 Vossa di fuora.'' Steno, in his work on the substances con 

 tained in rocks (De Solido intra Solidum naturaliter Contento), 

 distinguishes (1669) between (primitive ?) rocky strata which 

 have become solidified before the creation of plants and ani- 

 mals, and therefore contain no organic remains, and sediment- 

 ary strata (turbidi maris sedimenta sibi invicem imposita) 

 which alternate with one another, and cover the first-named 

 strata. All fossiliferous strata were originally deposited in 

 horizontal beds. This inclination (or fall) has been occasion- 

 ed partly by the eruption of subterranean vapors, generated 

 , by central heat (ignis in medio terra3), and partly by the giv- 

 mg way of the feebly-supported lower strata. $ The valleys 

 are the result of this falling in." 



Steno's theory of the formation of valleys is that of De Luc, 

 while Leonardo da Vinci, like Cuvier, regards the valleys as 



* Sir John Herschel, Discourse on the Study of Natural Philosophy, 

 K 116. 



t Humboldt, Essai Gfognostique snr le Gisemcnt des Roches daiu lei 

 ieux Himispheres, 18'23, p. 38. 



X Steno, De Solido intva Solidum natiiTaliter Contento, 1G69 p. 2. 17 

 28, 63, and 69 (fig. 20-25). 



