THE 



AMERICAN JOURNAL OF SCIENCE 



[FOURTH SERIES.] 



Art. XLI. — Some Conditions affecting Geyser Eruption; 

 by T. A. Jaggar, Jr., Cambridge, Mass. 



1. Introduction: the influence of hydrostatic pressure. 



Both field observation and experiment have contributed to 

 our present knowledge of the physical causes of geyser erup- 

 tion. The natural history of geyser regions has been sum- 

 marized by Weed,* and the experimental work by Andrese.f 

 Weed concludes that geysers occur only in acid volcanic rocks, 

 and along natural drainage lines where meteoric waters accu- 

 mulate for discharge. The source of heat is conceived to be 

 escaping hot vapors from slowly cooling lavas, the only known 

 geysers occurring in regions of recent volcanic activity. New 

 geysers originate by the opening of new waterways along fis- 

 sure planes in the^rock, and such new orifices of overflow are 

 continually forming to compensate the diminution in activity 

 of older vents. The cause of the intermittent spouting which 

 distinguishes the typical geyser was originally stated by 

 Bunsenij; ; the boiling point of water rises with increased pres- 

 sure, hence decreases from the lower end of a water-tilled tube 

 upward. If water of a lower stratum, nearly, but not quite, 

 at the boiling point, be lifted by the entrance of steam from 

 below to a level of less pressure and lower boiling point, " the 

 heat which it possesses is in excess of that necessary to make it 

 boil. This excess of heat is instantly applied to the generation 

 of steam : the column is lifted higher and the water below is 

 further relieved. More steam is generated, and from the 

 middle downwards the mass suddenly bursts into ebullition. 

 The water above, mixed with steam-clouds, is projected into 

 the atmosphere. . . ."§ 



* School of Mines Quarterly, New York, 1890, vol. xi, No. 4, p. 289. 

 fNeues Jahrbuch fur Min. Geol. und Pal., 1893, Bd. ii, p. 1. 

 iTyndall: Heat as a Mode of Motion; Appleton, 1888, p. 168. 

 §Tyndall. 1. c, pp. 169-170. 

 Am. Jour. Sci.— Fourth Series, Yol. Y, No. 29.— May, 1898. 

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