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 ICBLAND, 703
tates &
4th : - - eae i
sth - - 2
6th ° - - ia
N° lV. with 7 fides.
rft fide - - Diameter 2 10
ad - - - 2 4
3d . . - 1 TO
4th - - - 2 0
sth - - - fr
6th - - - reno
7th - - . pers
The pillars are all over as fmooth, and as fharp cornered as thofe of the Giant’s
Caufeway ; their colours are generally black, though the external fides fometimes in-
cline to yellow, as their furfaces are bleached by the weather. As to their grain and
fubftance, they entirely refemble, and are moft probably the fame original fub{tance as
the Icelandic agate. AsI have nothing remaining of it, I cannot examine what effect
borax and other alloys, or aqua-fortis, and the like, would have upon it: what is the
nature of its proper gravity, and what polifh it will admit of, it would, notwithftand-
ing, be ufeful to be informed of in order to compare it with fimilar kinds of {tone from
other parts.
But in what manner have thefe regular pillars been produced? It is the received
opinion that the fire has been acceflary to it: you have yourlelf remarked, Sir, that it
mutt either have beena matter which had been melted by fire, and burft afterwards,
and that then a liquid, which we are yet unacquainted with, muft have produced their
regular cry(taline figures ; or elfe it muft have been, as you have likewife obferved, a
kind of earth, which, after having been foftened by the exhalations arifing from a fubter-
raneous fire, its whole mafs was forced out of its fituation, and aflumed this regular
form asit grew dry. I have noticed this diftiné and regular appearance in dried clay,
and even in ftarch when dried ina cup or bafon. For it may be demonftrated that they
are not cryf{tals formed by Nature, by their not being produced as all other cryltals are,
by external appofition (per appofitionem) nor in any other matrix, as is common among
cryftals.
It would be very difficult to determine whether the matter of which thefe prifmatic
pillars confift, burft into the regular forms after it was melted, and was growing cold, or
whilft it was drying, as you feem inclined to believe: I cannot deny that my eyes have
prepoffefled me in favour of the firft opinion, in all thofe places where I have feen any
of thefe pillars ; but as fo many objections may be offered againft this opinion, | am
obliged to leave the matter undetermined. ‘The following may, however, ferve as a
proof, that I did not, without due foundation, believe them to be a kind of lava,
which burft in growing coldand hard. Firft, you find both in the ifland of Staffa and
many other places, that the pillars ftand on lava or tuffa, and are furrounded by this
matter. Secondly, at Staffa, there was a Jarge ftratum above the pillars, in which
there were many pieces of thefe pillars irregularly thrown among one another, which
leaves us to conjecture that they muft have been more in number, and_ higher after an
old eruption of fire, but that a fubfequent eruption had overthrown them, and mixed
them with the whole mafs. ‘Thirdly, we found one of thefe pillars, on breaking it, full
of drops, almoft like a laétile or dripping ftone ; and none furely will pretend a bafalt
tobe of fucha compofition, Fourthly, I have formerly faid, that the pillars in fome
places
<< prev. page << föreg. sida << >> nästa sida >> next page >>
