exhibited by the Geysers of Iceland. 223 



surrounding the Geyser is filled with volumes of steam, while 

 a column of boiling water shoots like an arrow to the clouds. 

 The heiglit which the water attains is variously estimated 

 from 80 to 200 feet ; the variation no doubt being the result 

 of a difference in the intensity of the eruption. Successive 

 jets of water continue to be projected from the Geyser for 

 some minutes, after which the pipe or tube becomes empty 

 of water, and the eruption terminates by an immense volume 

 of steam, being emitted with tremendous force and a thun- 

 dering noise. 



In endeavouring to account for the cause of the phenomena 

 in question, I assume that there exists in connection with 

 the Geyser, a subterranean chamber of large size, and of an 

 oblong shape ; the floor of which is of a roundish form, and 

 at a temperature of not less than 340° F. At or near the 

 roof there are fissures communicating with reservoirs, by 

 which water may be allowed to flow into the caverns. The 

 tube which passes from this cavity to the surface of the earth 

 takes its rise from the side of the chamber, and very near 

 the lowest part. Without entering into details, I assume 

 this tube (as other writers on Geysers have done), to be 

 an inverted syphon, the shorter limb of which communi- 

 cates with the chamber, whilst the longer limb forms the 

 exit or emission-tube of the Geyser. In the course of events, 

 water finds access by the fissures into the cavity, where, from 

 the high temperature of the matter it falls upon, it is im- 

 mediately compelled to assume the spheroidal condition, its 

 temperature while in that state being 205*7° F. The water 

 gradually accumulates, till at last so much has entered the 

 cavity, that the mineral floor can no longer keep the liquid 

 in the spheroidal state, the water in consequence touches the 

 metallic surface ; its temperature is almost instantly raised 

 to 212° F. ; and large volumes of steam are generated, pro- 

 ducing a force quite competent to press the boiling water 

 up through the opening prepared by Nature for it. Shortly 

 thereafter, when the whole of the water, or at least a consi- 

 derable portion of it, has been discharged through the con- 

 duit, and the propelling agent has thus cleared a path for 

 itself, the steam escapes in large volumes, with a rushing 

 sound more or less violent. The quantity of steam generated 



