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 lower.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 grall- 
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 voleanos, a gaseous body, principally aqueous vapor 
We may, therefore, very fairly agree with Krug Von idda, 
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 a 
the respective depths. Hence the constant ebullition of the pe 
manent springs, and their boiling heat. If, on the other hand, 
the vapors be prevented, by the complicated windings of a 
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 Jarge 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 
