4 o8 THE POPULAR SCIENCE MONTHLY. 



forgets that all the lava that flows to the surface comes from the 

 depths of the crust, where its departure leaves a void which cau 

 be compensated for only by the depression of the adjoining ter- 

 ritory to such an extent that the emerged relief really gains noth- 

 ing. More than this volcanic action, which M. Ldotard would 

 make creative, is really, above everything else, destructive. I ask 

 no better proof of this than the great explosions of which the nine- 

 teenth century has been the witness ; that of 1845, at Temboro, 

 which covered the neighboring country and the surface of the sea 

 with a mass of debris estimated at a hundred cubic kilometres ; 

 and the more recent eruption at Krakatoa, which threw into the 

 Strait of Sunda eighteen cubic kilometres of debris and formed 

 an abyss between two and three hundred metres deep, in a place 

 where there had previously stood a volcanic mountain several hun- 

 dred metres high. While I have felt called upon to make this rec- 

 tification, I will add that that does not prevent me from believing, 

 with M. Le'otard, that the final triumph of the dry land is infinite- 

 ly more probable than its submersion ; and that by reason of the 

 considerable movements of the crust and the wrinkles which lat- 

 eral compression in consequence of the progress of cooling can 

 not fail to engender from time to time." 



SKETCH OF LUIGI GALVANI. 



THE experiments of Galvani were the beginning of a new 

 course of development in physical science, the fruits of which 

 promise to be infinite in number and of incalculable magnitude 

 and importance. 



Luigi Galvani was born in Bologna, Italy, September 9, 1737, 

 and died in the same place, December 4, 1798. He exhibited 

 when very young a fervent zeal for the Catholic religion, of 

 which he was exact in observing the most minute rites. He even 

 thought of going into a monastery, but was diverted from his 

 intention, and, while his religious inclinations were still promi- 

 nently marked, he became interested in scientific pursuits. En- 

 tering upon the study of medicine, he gave his attention chiefly 

 to anatomy and physiology human and comparative. Having 

 successfully maintained a thesis on the Bones, their Nature and 

 Formation, he was appointed, in 1762, public lecturer on anatomy 

 at the University of Bologna, where he became known as a skill- 

 ful and accurate teacher, though not eloquent in address. Along 

 with his professorship he gained high repute as a surgeon and 

 childbed doctor. He produced during the earlier period of his 

 professional career a number of memoirs of considerable merit, 



