13 191 



less. No. 15 gave no visible exhalations whilst wc were at the springs. No. 16 has 

 developed into an extremely beanliful spring, with a regular-shaped eone of 

 creaniish-yellow silicious sinter (Plate IV'). In other respects this spring does nol 

 seem to have changed particularly during the last 18 years ; there are now fairly 

 strong gaseous exhalations, and the temperature is 93.5° (previously 89°). On 

 account of the picturesque appearance of this spring, we have called it Fagrihver 

 (the beautiful spring). From Fagrihver we gathered the gas Hveravellir No. 16. 

 Nos. 17 and 18, Brœdrahverir, are still the most active springs in this neighbourhood, 

 although they do not eject the water quite so high as previously. According to 

 [\ Thoroddsen's desci-iption, thej' threw the water to a height of 7 — 10 feet, in 1888; 

 in 1906 we estimated the height of the column at 1.5 m. In No. 17 the thermo- 

 meter showed 81°, and in No. 18 84°. Gamli Sirokkur is now quite extinct; the 

 temperature of the water in the basin was 27°, as against 37° in 1888. Nos. 19 

 and 20 are only slightly altered. Their temperature was 85° and 57°. In No. 19 

 there were no exhalations, and in No. 20 they were very slight. No. 21 is a spring 

 which gushes continuously and actively; we measured its temperature twice; the 

 first time it was 90", but the second time it was only 72°. This can partly be 

 explained by the theory that this spring, like most of the other springs at Hvera- 

 vellir, is periodic; but as there is a stream running near by, which to some extent 

 mixes its waters with the waters of the spring (No. 21), the temperature of the 

 latter must be largely dependent on the volume of cold water which flows from 

 the stream into the spring. It is therefore not impossible that the difference between 

 the two measurements of the temperature can be partly accounted for by this fact. 



Besides the springs already referred to, which have all been mentioned and 

 numbered by {>. Thoroddsen, I append a brief description of the hot springs at 

 this ])lace which have not been dealt with by p. Thoroddsen. 



No. 22 is a basin of considerable size to the south of No. 21, with a temperature 

 of 75°. In the water-course east of No. 21 are the two springs which we have 

 marked Nos. 23 and 24. No. 23 is a little cavity in the silicious sinter, through 

 which hot water is ejected with considerable force. No. 24, which is situated by 

 the northern side of the large dome of silicious sinter, covers a large surface. 

 Vapours issue with such force from the edge of the sinter that the water in the 

 basin of the spring is kept continually rippling. The temperature is 95°. 



Nos. 25 and 26 are two pools situated side by side a little to the north-west 

 of No. 11. Both these pools are filled with clear water, without any silicious 

 deposits; as to outward appearance they therefore much resemble No. 1. There 

 were active exhalations in both these springs. From No. 25, in which the tempera- 

 ture was 81°, we took specimen gases, Hveravellir No. 25; the temperature of 

 No. 26 was 89°. 



The foregoing comparison of the conditions of the springs in 1888 and 1906 

 seems to |)oint out that the thermal activity at Hveravellir was less during our visit, 

 than when [>. Thoroddsen explored them, particularly the springs on the upper 



