612 SCIENTIFIC RECORD FOR 1885. 



damage. The lava produced was basaltic and vefy uneven. Some 

 craters emitted bombs with a close surface and a cellular mold. In 

 July, 1876, a temperature of from 130° to 200°, and even 300° C, was 

 observed in the cracks of the lava. In the grass-covered si)ots which 

 the lava overflowed, crystals of chlorhydrate of ammonia have separ- 

 ated. The eruption of Dyngjufjall, of the 29th of March, had some 

 very severe consequences for the fertile regions of the east of Iceland. 

 Hundreds of farms had to be abandoned, but one also rapidly re- 

 covered from the evil effects by removing the light layers of ashes and 

 X)umice stone, and the damage will not be as serious as was feared. 

 This eruption, from the fact that its products were purely trachytic, 

 stands isolated and unique in Iceland in modern times. 



1879. On the 27th of February an eruption in one of the chains run- 

 ning northeast from the Hecla. It lasted to the month of May, with- 

 out doing much harm, the lava not reaching the inhabited regions. 



1879. Tenth submarine explosion southwest of Eeykjanes, on the 30th 

 and 31st of May. 



The following eruptions mentioned in several old lists are charged to 

 the wrong volcanoes: Hecla, 1004, 1029, 1113, 1374, 1583, 1625, 1727. 

 KatJa, 1717, 1727. Trdlladyngja, 1475. Herdhubreidh, 1341, 1510. 

 8idhvjd]cuU, 1728. OraefajdJmll, 1332, 1336, 1720. BreidJiamerkrjdkull, 

 1362. HofsJUkull et Baldjokull, 1710. Everfjall {or Sandfell), 1748, 1752. 

 BaudJmkamhar, 1311. ThSrsmork, 1310, 1350. 3Iosfell, 1340. Breidhi- 

 fjordr {near Snaefellsnes), 1219, 1345. Thingvallahraun, 1587. As to 

 Helgafell, on the island of Westraanna, no positive data exist regard- 

 ing eruptions within historic times. 



Within historic times eruptions have taken place at about 20 differ- 

 ent places in Iceland. Generally speaking the volcanoes are small and 

 only one eruption is on record. Among the large volcanoes, Hecla oc- 

 cupies the first place with 21 eruptions; next comes the Katla with 

 12 or 13, then the Eldej-jar, near Reykjanes, with 10, the TroUad.f ngja 

 with 6 eruptions. The largest current of lava was produced in 1783. 

 The ice-covered volcanoes in the south of Iceland never emit currents 

 of lava, but only ashes; they are above all to be dreaded on account of 

 the " Jokellob" which they produce when the eruption breaks up the 

 covering of ice. The largest number of eruptions have taken place in 

 the fourteenth century (13), and in the eighteenth century (14). In 

 studying the list of eruptions it will be observed that in each period 

 they are concentrated in one certain section and that, in their succes- 

 sion, they rarely made large jumps. The earthquakes are in direct 

 connection with the eruptions, they occurring nearly all in Olfus, 

 Grimsnes, Floi, and at Fj61shlidh, in the vicinity of the Hecla, or at 

 Thingeyjarsysla, the hearth of the volcanoes of the north. 



