40 
HOT SPRING. 
of Cornicularia, allied to C. bicolor , but three or 
four times as large, and all over of a grey color. 
I met with only one patch of it, growing inter¬ 
mixed with Trichostomum canescens , in rocky 
places. From these hills, though at a consider¬ 
able distance, I could perceive the steam from 
the hot spring, and, taking a different route 
from what I had done when I made a former 
attempt, I at length, with some difficulty, ar¬ 
rived at it. When full a mile from the spot, 
the superior verdure of the grass, that was within 
the influence of the heat, was very remarkable. 
What struck me as most extraordinary in this 
spring, though I afterwards found it not to be 
uncommon in Iceland, was the circumstance of 
its being actually situated in the middle of a cold 
stream, bubbling up from some little cavities, 
which were formed in a whitish siliceous incrus¬ 
tation, that covered a considerable portion of the 
bed of the river, and extended on one side of it, 
even as far as the shore, where its surface was 
covered with numerous minute mammillae. This 
incrustation is a deposit from the water, and the 
mammillae are probably caused by the irregular 
falling of the water upon it in drops. On dipping 
in the water my little pocket thermometer which 
was graduated to no more than 120° of Fahren¬ 
heit’s scale, but was the only one I had with me at 
the time, the quicksilver instantly rose to the top 
