540 HISTORY OF GEOLOGY. 



subjects, we may notice the celebrated painter Leo- 

 nardo da Vinci, whom we have already had to refer 

 to as one of the founders of the modern mechanical 

 sciences. He strenuously asserts the contents of 

 the rocks to be real shells, and maintains the reality 

 of the changes of the domain of land and sea 

 which these spoils of the ocean imply. " You will 

 tell me," he says, " that nature and the influence of 

 the stars have formed these shelly forms in the 

 mountains ; then show me a place in the mountains 

 where the stars at the present day make shelly 

 forms of different ages, and of different species in 

 the same place. And how, with that, will you ex- 

 plain the gravel which is hardened in stages at dif- 

 ferent heights in the mountains?" He then mentions 

 several other particulars respecting these evidences 

 that the existing mountains were formerly the bed 

 of the sea. Leonardo died in 1519. At present 

 we refer to geological essays like his, only so far 

 as they are descriptive. Going onwards with this 

 view, we may notice Fracastoro, who wrote con- 

 cerning the petrifactions which were brought to 

 light in the mountains of Verona, when, in 1517, 

 they were excavated for the purpose of repairing 

 the city. Little was done in the way of collection 

 of facts for some time after this. In 1669, Steno, 

 a Dane resident in Italy, put forth his treatise, De 

 Solido intra Solidum naturaliter contento ; and 

 the following year, Augustino Scilla, a Sicilian 

 painter, published a Latin epistle, De Corporibus 



