256 Natural History of Volcanos and Earthquakes. 



other at intervals of from twenty-four to thirty hours ; in these 

 cases, the masses of steam ascended to the clouds, and the water 

 spouted to a height of ninety feet. For two hours after, one of 

 the smaller eruptions, during which time there were no traces of 

 action, and only thin clouds of steam were formed at the surface, 

 the temperature of the water was 194° F., which was reduced 

 still lov/er by the evaporation. After a dull rumbling noise 

 within, the water suddenly began to boil up again, the basin was 

 filled till it flowed over, immense bubbles of steam burst from 

 the funnel-shaped opening, and projected the water to a height 

 of about twenty feet. Immediately after the eruption, when 

 tranquillity was completely restored, the water was at the boiling 

 point, but its temperature soon fell below that degree. 



The Strokr, the eruptions of which almost exceed in gran- 

 deur those of the Great Geyser, has this peculiarity, that it is at 

 the same time a permanent and an intermittent thermal spring. 

 It shows itself to be permanent by its incessant ebullition, and 

 intermittent by the tremendous eruptions which seem to be re- 

 peated at intervals of from, two to three days. 



No doubt can be entertained respecting the nature of the 

 agent by which the waters of the Geyser, the Strokr, and other 

 less considerable springs, are thrown to such an immense height. ^ 

 It is, as in volcanos, a gaseous body, principally aqueous vapor. 

 We may, therefore, very fairly agree with Krug Yon Nidda, 

 and consider volcanos in the same light as intermittent springs, 

 with this difference only, that instead of water they throw out 

 melted matters. 



He takes it for granted that these hot springs derive their tem- 

 perature from aqueous vapors rising from below. When these 

 vapors are able to rise freely in a continued column, the water at 

 the different depths must have a constant temperature, equal to 

 that at which water would boil under the pressure existing at 

 the respective depths. Hence the constant ebullition of the per- 

 manent springs, and their boiling heat. If, on the other hand, 

 the vapors be prevented, by the complicated windings of its 

 channels, from rising to the surface ; if, for example, they be ar- 

 rested in caverns, the temperature in the upper layers of water 

 must necessarily sink, because a large quantity of it is lost by 

 evaporation at the surface, which cannot be replaced from below. 

 And any circulation of the layers of water at different tempera- 



