96 HISTORY OF GEOLOGY AND PALEONTOLOGY. 



He opposes the Catastrophal Theory, which taught that from 

 time to time destructive catastrophes had occurred in past 

 ages, and had annihilated the whole or the greater portion of 

 existing forms ; and he lays down principles of the evolution 

 of one from another along continuous lines of descent, but 

 in accordance with definite natural laws of growth and decay. 

 He argues that just as a definite span of life is meted out to 

 each individual, and the time may be longer or shorter accord- 

 ing to the kind of organisation, in the same way each species 

 and each genus possesses a definite energy of existence, and 

 when that has been exhausted, death ensues from natural 

 causes of decay. 



While it is as a palaeontologist that Brocchi's name will be 

 remembered, his first contribution was a mineralogical and 

 chemical treatise on the iron-works of Mella, in Val Trompia; 

 he then studied the porphyrites and basalts of the Fassa valley, 

 and, in agreement with Wernerian doctrines, referred them to 

 an aqueous origin. Later in life, after the publication of his 

 monograph, he returned to the study of volcanic rocks, with 

 the result that he became a Volcanist. 



The volcanoes of South Italy had always proved an attractive 

 study in scientific circles, and yet it was remarkable how few 

 of the scientific works regarding them had been contributed 

 by those resident in the immediate neighbourhood. 



Sir William Hamilton's work on Vesuvius and Etna (p. 45) 

 had prepared an excellent foundation for further research, and 

 a worthy continuation was provided by the Frenchman, Dolo- 

 mieu, 1 in his descriptions of the Lipari and Pontine Isles, and 

 his detailed mineralogical researches on the rocks of these 

 islands and of Etna. 



Dolomieu departed from the usual method of research that 



1 Guy S. Tancrede cle Dolomieu, born 175 a t Dolomieu, in the 

 Dauphine, was an officer in the army; he travelled for several years in 

 Sicily, South and Central Italy, the Pyrenees and Alps; in 1796 he was 

 elected a Professor in the Paris School of Mines, and accompanied the 

 French Expedition to Egypt. While on the return journey he was taken 

 into custody, for political reasons, in Naples, and was imprisoned for two 

 years. After he regained his liberty he became, in 1800, Professor of 

 Mineralogy at the Natural History Museum in Paris, but died in the 

 following year in Paris. His most important works are: Ti'aveis in 

 the Lipari Isles (Paris, 1783); On the Earth-Tremors in Calabria (Rome, 

 1784) ; On the T^pontine Isles ^ and a Catalogue of the Products of Etna 

 (Paris, 1788). 



