50 
Proceedings of the Royal Society 
to Iierbubreib, the deepest drifts measuring some eight feet, being 
north-east of Vabalda to five miles south of the “Broad-shouldered.” 
The explorer’s chief work was about the Askja or southern 
Dyngjufjoll — I must warn my readers not to confound these 
“ Chamber hills” with the “ Trolladyngja (sing.), perhaps better 
known as Skjaldbreib, the “Broad shield. As Mr Watts intends 
to publish his discoveries, I must not abuse the liberality with 
which he gave his information. He would break up the fanciful 
horseshoe of the great map, which in these parts is a mere field- 
sketch, into a heart-shaped series of hills, mounds, and cones, here 
connected, there separated, by “ Gils ” and broad passes : on the 
western side the Odaba lava has penetrated into the enceinte , and 
a latitudinal bar of heights traverses the southern quarter. By 
walking over the eastern hills Mr Watts came in sight of the centre 
i 
of eruption ; the aneroid stood at 25'05 ( = 5000 feet in round num- 
bers, whilst the northern plain is about 1000 feet lower. Various 
angles to Herbubreib (80° to 40° for mag. var., west = 40), and 
the Skjaldbreib (170° to (04° = 130°) placed the Gja-site inside the 
horseshoe in N. lat. 64 45' and about W. long, (f.) 17 
The centre of the eruption, which we will call the OskjugjA, 
was a mere fissure, an acute-angled triangle with the apex to S.S.W.; 
stepping the base gave a little more than a mile, and the 
circumference would be about five. The three arms were deep 
and perpendicular crevasses opened in the hills by the eruption, 
and the lips readily fell in. The heights around it, especially 
those to the east, were strewn with thick strata of pumice, ejected 
wet, and decomposing under atmospheric action ; they also showed 
that surface-streams of water had lately flowed over the new matter. 
The most curious part of this 
Gja is that it contains a triangle 
within a triangle, both similar in 
all their accidents ; moreover, 
there is a series of smaller fissures 
extending from the centre to the 
apex, and to the two other angles, 
north-western and north-eastern. 
At the eastern arm, a deep pit 
about a quarter of a mile in circumference discharges volumes of 
The Oskjuyja 
