[ 92 J 
VI. On the boiling Springs of Iceland. By Mr. Joun Murray.* 
Tx reading the description of the boiling springs or geysers of 
Iceland, as given to us by Stanley, Hooker, Mackenzie, and by 
Henderson, I found it difficult to account for the zntermission 
of the jets, supposing the subterranean fire to continue wnifurm 
in temperature. 
] caused an apparatus to be con- 
structed, which tended to explain the 
phenomena of the intermission of the 
jet and recession from the basin into 
the central pipe. A section of that 
simple apparatus is on the margin, 
and its phenomena clearly and satis- 
factorily prove that the circumstances 
adverted to, are ascribable to the 
cooling of the water from the united 
influences of radiation and evapo- x 
ration. Radiation, from the sur- () 
face of the water in the basin into ob 
which it rises ; and Evaporation, from ep, 
that dispersed into the atmosphere SF ee 
in the play of the geyser. 
The apparatus consists of a cylindrical tin case surmonnted 
by a concave basin, into which the water rises through a central 
pipe (representative of the siliceous stalactitic pipe obtaining in 
the geysers, the consequence of deposition of siliceous matter 
from the water containing silica and soda in solution), and which 
descends nearly to the bottom of the cylinder. 
The apparatus being supplied with water, and a spirit lamp 
introduced, the water ‘will, in a short time, be perceived slowly 
ascending into the basin. The steam finally bursts through the 
water and forms an irregular jet; and so soon as the water ts 
cooled by the causes adverted to, it retires from the basin into 
the pipe, and the same phenomena are reiterated at intervals. 
The experiment is a very beautiful one, and alwavs gratifying. 
Dr. Heuderson has stated a curious fact with respect to these 
wondrous phzenemena; and though it has been rudely ques- 
tioned, it is one, surely, that may be conceived a necessary re- 
sult. ‘L advert to the circumstance of the play of the geysers 
being more promptly determined by casting stones into the 
pipe. This is easily explaiied by supposing the pipe at its 
lower extremity curved (a phenomenon which I myself have 
* This paper was transmitted to the Wernerian Society of Edinburgh. 
witnessed 
