66 VULCANISM ITS NATURE AND FUNCTION. 



is a study as it were but of yesterday.* Till substantial 

 progress has been made in this direction, and sufficient facts 

 for generalisation collected, it were idle to speculate, and 

 waste of time to surmise. 



Such is a brief, and we trust not unintelligible sketch of 

 that Vulcanicity or internal heat-force which is incessantly 

 reacting upon the rocky crust we inhabit. Than the earth- 

 quake, volcano, and great crust-pulsation, we have no higher 

 manifestations of natural force ; no phenomena before whose 

 power man's weakness becomes more apparent. There are, 

 no doubt, other terrific agencies in nature the ocean when 

 lashed into fury by storms, the flooded and headlong river, 

 the hurricane, and the thunderstorm. Man, however, learns 

 to brave and battle with these. The hardy islander dares 

 the ocean-storm in his little skiff; civilised nations build 

 their piers and breakwaters that their fleets and navies 

 may ride behind them in defiance of the storm. Man dams 

 and diverts the river-current, restrains it within bounds, 

 or even turns it to account as the moving power of his 

 machinery. By strength and weight of material he can re- 

 sist the fiercest sweep of the wind-blast ; or if need be, can 

 yoke it to his wheels submissive and serviceable. He even 

 toys with the thunder, and brings the lightning down from 

 the storm-cloud. But before the shock of the earthquake 

 and the throes of the volcano, man savage or civilised 

 shrinks altogether abject and helpless. With them, how- 

 ever frequently they may occur, he never becomes familiar. 

 The earth, with which all his ideas of stability are associated, 

 rocks and reels beneath him his proudest cities become 

 an instantaneous mass of ruin and rubbish ; himself falls 

 prostrate, or if he flees, he flees only to accelerate his fate. 



* See the ' Seismology/ and ' Seismographic Maps/ of the Messrs Mal- 

 let, of Dublin. 1861. 



