244 General Notes. [ April, 
must, therefore, believe that the propelling power in the geyser acts 
temporarily and suddenly, while in the common hot spring, quiet, boiling, 
or eruptive, constant or periodical, the force is evolved with considerable 
regularity. The idea which the writer desires to convey will be rendered 
more evident by the comparison of Figures 14and 15. Figure 14 shows 
the supposed section of a common eruptive spring ; and it will readily be 
seen that jets may even occur in cold springs of this structure, provided 
a quantity of carbonic acid or other gas is struggling to free itself from 
beneath the ledge at o. In Figure 15, which is intended to represent the 
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wr N \ fe 
M1 
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WRAY 
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q 
a 
(Fie. 15.) IDEAL SECTION OF AN INTERMITTENT GEYSER. 
Laermer the phenomena of eruption during the escape of vapor, prior to the ejection of hot 
grees the water in the bent passage ¢ becomes heated, and evolves vapor 
also, as in o. After a time, the expansion of the vapor in b is able to 
overcome the combined pressure of the water and vapor in ¢ and o, when 
the latter is forced out, followed by a portion of the water in the reset 
