Von Nidda on the Mineral Springs of Iceland. 223 



matter, at least three hundred feet in circumference. From the 

 middle of this pool there was erupted, at certain intervals, and 

 with a loud thundering noise, a vast column of the same black 

 liquid, which was enveloped in thick clouds of smoke. From 

 all the circumstances connected with the hollow in which this 

 pool is placed, Henderson, with much probability, regarded it 

 as the shattered remains of the crater of Krabla. The surface 

 of the pool was about 700 feet below what appeared to be the 

 highest peak of Krabla, and about 200 feet below the oppo- 

 site height on which the traveller stood. Henderson descend- 

 ed to the margin of the pool, and found that the neighbour- 

 ing soil was composed of coloured clays and sulphur. Nearly 

 about the centre of the pool was the funnel-shaped descend- 

 ing pipe; the eruptions took place every' five minutes, and 

 lasted two minutes and a half; the jets reached a height of 

 thirty feet. Besides this great opening, there was in the pool 

 another jetter, which also exhibited eruptions, though on a 

 smaller scale, and was evidently connected with it, as there was 

 a continual bubbling in a direct line between them. 



There are, to the north of the Myvatn lake, but nearer the 

 coast, some other points where sulphur springs occur, but these 

 are by no means so considerable as the Namar. 



Among the most remarkable spouting springs (huerer) of 

 this district are those of Reikiadal, situated a few miles to the 

 south of the commercial village of Husevig ; they consist of the 

 Nordurhuer, the Oxahuer, and the Sydsterhuer, which are placed 

 near to one another, in a direct line from north to south. The 

 pure boiling water of these springs contains silica in solution, 

 and thus possesses an encrusting power. The basins and pipes 

 are of a large size ; the eruptions are repeated at short intervals, 

 but are of trifling magnitude. 



Between the two trachytic plateaus of the Eriks and Hofs- 

 Jokul, lie the interesting springs of Huerevalle. In this case 

 also, the water and gas springs occur near one another. Some 

 of the water springs are in a constant state of agitation, others 

 are tranquil, and a third class exhibit periodical eruptions. But 

 the most singular spring of the valley is a gas spring, which 

 issues from the summit of a hillock of clay about four feet in 

 height. The gaseous stream escapes from the opening with in- 



