GEOLOGY. 223 



i 



more prevalent and violent in winter than during summer. Taking 

 the whole of Europe, the preponderance of earthquakes during winter 

 is very marked ; the earthquake catalogue to which we have alluded 

 shows that during fifteen centuries and a half 857 earthquakes occurred 

 during spring and summer, and 1157 during autumn and winter. And 

 with respect to Italy it is recorded that generally but little alarm has 

 been felt in summer when signs portended coming earthquakes, where- 

 as those in winter have always inspired the greatest terror. 



Mr. Mallet arrived on the scene of the catastrophe in February, 

 1 858, and although the weather was very inclement, he worked on 

 steadily until he had examined the entire area. This was about 200 

 miles long by 160 miles broad, and embraced the peninsula of Calabria 

 Ultra, south, of a line from Cape Suvero to Cape Colonna. The 

 seismic force greatly varied throughout the region. 



The general direction of the earth-waves, southeast of Naples, ap- 

 pears to have been from north to south, crossed, however, not unfre- 

 queutly, by other waves from east to west. In both cases the waves 

 recoiled, producing the terrible replica, or return shock, which whelms 

 every object within its influence in immediate ruin. Sapouara, a town 

 of eight thousand inhabitants, was absolutely reduced to ruins in a few 

 minutes, its destruction being so absolute that it is not at all probable 

 that it will ever be rebuilt. Beneath its ruins hundreds of human be- 

 ings and animals lie entombed, with fragments of every household 

 utensil, personal and domestic ornaments, and innumerable records of 

 human art ; yet such is the vitalizing property of the Italian climate 

 that in a few years verdure and luxurious vegetation will mantle the 

 heaps where once stood a city, and after but a few generations the ter- 

 rible fate of its inhabitants, nay, its very site, will have become a tra- 

 dition as dim as that of the neighboring Grumentum. 



Although the earthquake was not felt sensibly at Rome, the disturb- 

 ance evinced by several delicate instruments in the observatory of that 

 city led the director of that establishment to conclude that a faint 

 earthquake wave passed beneath that city. Mr. Mallet traced it dis- 

 tinctly north of Naples, until the effects of it became lost in the allu- 

 vium near Terracina. 



Having next ascertained the locality of the greatest seismic force, he 

 proceeded to investigate its depth from the earth's surface. This he 

 found to be about five geographical miles, and he believes that the 

 greatest probable depth of origin of any earthquake impulse occurring 

 in our planet is limited to 30.64 geographical miles, and therefore only 

 just touches the depth which, upon received notions as to the movement 

 of hypogeal temperature, is supposed to form the upper surface of the 

 imaginary ocean of liquid lava of the earth's interior. Mr. Mallet, we 

 observe, doubts the existence of a general increment of temperature as 

 we descend from the surface of the earth. His speculations on volcanic 

 heat in connection with this subject are very interesting : 



" When on Vesuvius, on the occasion of this report, I feel satisfied 

 that I could have so measured the temperature of the minor mouth, 

 then in powerful action, to the depth of several hundred feet, had I 

 possessed the instrumental means at hand. To this smaller mouth it 

 was then possible, by wrapping the face in a wet cloth, to approach so 

 near upon the hard and sharply-defined (though thin and dangerous) 



