GEOLOGY. 233 



boiling pools in the bottom of Kilauea show no sympathy in their 

 conditions; one may sink 100 feet, while another is overflowing; the 

 smaller pools may boil at their ordinary level and overflow, when the 

 large lake, 1,000 feet in diameter, has sunk 100 or 150 feet below the 

 bottom plain of Kilauea. 



Again; although the pit Kilauea is 600 to 1,000 feet deep (the 

 depth varying with its different phases), eruptions sometimes take 

 place through the very top of its walls, so that lavas will at times 

 come to the very brink of the pit, and flow back again ; and this, too, 

 while the great pools of lava are open hundreds of feet below, and in 

 constant ebullition. When in 1843 an eruption took place from the 

 summit of Mount Loa, and streams of lava for a whole month flowed 

 out in different directions for a distance of twenty-five miles, Kilauea 

 boiled at its usual rate, without the slightest disturbance or signs of 

 change, or appearance of sympathy. Missionaries who visited it 

 when the crater at its summit was in full activity, report that perfect 

 quiet and undisturbed regularity prevailed in Kilauea. It is a surpris- 

 ing fact, that eruptions should take place at an elevation of 13,760 

 feet, when, on the slopes of the mountain, sixteen miles distant, there 

 is an open vent like Kilauea, more than three miles in length, and 

 10,000 feet lower in elevation. Why is there no relief here for the 

 vast accumulation of pressure ? This pressure, when the central con- 

 duit is filled to the summit, amounts to 17,200 pounds to the square 

 inch. How is it that the wide, open passage, which Kilauea appears 

 to present, affords no escape for the imprisoned lavas ? How is it 

 possible, if the two great conduits, that of the centre of Mount Loa, 

 and that of Kilauea, intercommunicate, how is it possible that the 

 heavy rock fluid stands 10,000 feet higher in one leg of the syphon than 

 in the other ? It is certainly difficult to conceive how the ordinary prin- 

 ciples of hydrostatics can be so set aside. From the quiet character of the 

 eruptions, it is apparent that there was no paroxysmal elevation of the 

 lavas to the summit ; it was a slow and gradual result. 



Whatever mode of solving the difficulty be adopted, one conclusion is 

 evident volcanoes are no safety-halves of the globe, although often so 

 called. Assuredly, if, while a vast gulf is open on the banks of Mount 

 Loa, lavas still rise and are poured out at an elevation of 10,000 feet 

 above it, Kilauea is no safety-valve even to the area covered by the 

 single mountain alone. If lavas may be ejected from the very lip of 

 Kilauea while the pools are .still boiling within it several hundred feet 

 below, Kilauea, notwithstanding its extent, the size of its great lakes of 

 lava, and the freedom of the incessant ebullition, is not a safety-valve 

 that can protect its immediate vicinity. How, then, with so limited a 

 protecting influence, can it relieve from danger a neighbouring island ? 

 How can the narrow conduit of a volcano relieve continents from the 

 great earthquakes that sometimes traverse their whole extent"? 



Volcanoes are in fact indexes of danger ; they point out those por- 

 tions of the globe which are most subject to convulsions. Earth- 

 quakes and eruptions are often allied results of the same general 

 cause. As the volcano becomes more active, the earthquakes of the 

 region become more frequent : and the latter cease when quiet follows 



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