Full resolution (JPEG) - On this page / på denna sida - Pages ...
<< prev. page << föreg. sida << >> nästa sida >> next page >>
Below is the raw OCR text
from the above scanned image.
Do you see an error? Proofread the page now!
Här nedan syns maskintolkade texten från faksimilbilden ovan.
Ser du något fel? Korrekturläs sidan nu!
This page has never been proofread. / Denna sida har aldrig korrekturlästs.
VON TROIL’S LETTERS ON ICELAND: 691
oval, fqnare, or pentagonal forms. The aftronomer, Mr. Ejnar Jonfon, has made ufe
of this black glafs in his tubes, both in Copenhagen and in Iceland, for the obfervation
of the fun, and has found them greatly preferable to the darkened glafs. The green
agate is found rather coarfer and more reddifh, like thick bottle glafs: it is called
hraflinnubrodcon.
Brimftone, which may be confidered as the proper fuel of the fire, is found in great
abundance, pure and mineralized: in the north, principally at Hufewick, and in the
fouth at Kryfewick, there are white brimftone mines which are called Namas. I thalt
referve the bafalts for a particular letter.
LETTER XX.—to proressor BERGMAN.
Of Mount Heckla.
Stockholm, September 7, 1773.
Tue caufe of Heckla (or, as it is called in the country, Heck/a-fiall) having been more
noticed than many other volcanos of as great extent, and no lefs wonderful and in-
ftructive, may partly be afcribed to its having vomited fire fo frequently, and partly to
its fituation, which expofes it to the fight of all the fhips failing to Greenland and North
America: as we confidered it with greater attention than any other volcano on the
ifland, I will give you a defcription of the ftate in which we found it on the twenty-
fourth of September 1772.
After we had feen many tra@s of lava, among which Garde and Wvalupe Hraune
were the moft confiderable, we purfued our journey to the foot of the mountain. We
had a tent pitched here, where we propofed to pafs the night, to enable us to afcend the
mountain with greater {pirits in the morning. The weather was extremely favourable,
and we had the fatisfaction of feeing whatever we wifhed, the eruption only excepted.
The mountain is fituated in the fouthern part of the Ifland, about four miles from
the fea-coaft, and is divided into three points at the top, the higheft of which is that in
the middle, and is, according to an exact obfervation with Ramfden’s barometer, five
thoufand feet higher than the fea. We made ufe of our horfes, but were obliged to
quit them at the firft opening from which the fire had burft. This was a place fur-
rounded with lofty glazed walls, and filled with high glazed cliffs, which I cannot com-
are with any thing I ever faw before.
A little higher up we found a great quantity of grit and ftones, and ftill farther on
another opening, which though not deep, however defcended lower down than that of
the higheft point. We thought we plainly obferved evident marks of hot boiling water
in this place.
Not far from thence the mountains began to be covered with fnow, fome fmall {pots
excepted, which were bare. We could not at firft difcern the caufe of this difference,
but foon found that it proceeded from the vapour which arofe from the mountain. As
we afcended higher, thefe {pots became larger ; and about two hundred yards from the
fummit we found a hole of about one yard and a half in diameter, from which fo hot a
fteam exhaled, that it prevented us from afcertaining the degree of heat with the ther-
mometer.
The cold now began to be very intenfe, as Fahrenheit’s thermometer, which was at
54° at the foot of the mountain, fell to 24°. The wind was alfo become fo violent, that
we were fometimes obliged to lie down to avoid being thrown into the moft dreadful
precipices by its fury.
47:2 We
<< prev. page << föreg. sida << >> nästa sida >> next page >>
