77® B A S A 
coaft-oi Africa. To which it may be added, that it is 
found throughout all the volcanifed parts of Italy, though 
not any where immediately in the neighbourhood of Ve- 
fuviue. Sir William Hamilton, however, informs us, that 
in 1779 “picked up fome fragments of large and regu¬ 
lar cryftals of clofe-grained lava or bafalt; the diameter 
of which, when the prifms are complete, might have been 
eight or nine inches.” He obferves, that Vefuvius does 
not exhibit any lavas regularly cryftallized, and forming 
what are called giants caufeways, except a lava that ran in¬ 
to the fea, near Torre del Grteco, in the year 1631, which 
has a fmall degree of fuch an appearance. As the frag¬ 
ments of bafaltes which he found on this mountain, how¬ 
ever, had been evidently thrown out of the crater in their 
proper form, he puts the queftion, “ May not lavas be 
more ready to cryflallize within the bowels of a volcano 
than after their emiffion ? And may not many of the gi¬ 
ants caufeways already difeovered be the nuclei of volca¬ 
nic mountains, whofe lighter and lefs folid parts may Itave 
been worn away by the hand of time ?” M. Faujais de St. 
Fond gives an- example of bafalt columns .placed deep 
within the crater of an extinguifhed volcano. 12. It is 
well afeertained by experience, that there are vaft beds of 
pyrites difperfed through the interior parts of the earth at 
all depths; and it Is alfo a certain faft, that this compound 
fubftance may be decompounded by the accidental effufion 
of water, in fuch a manner as to become hot, and at lalt 
to burn with great fury. This accellion of pyrites is by 
many fuppofed to be the true origin of the volcanic fire ; 
and an argument for this is, that the prefent volcanoes do 
pour forth great quantities of the component parts of py¬ 
rites, particularly fulphur, iron, and clay. Now, among 
the fuperinduced fubftances of the countv of Antrim, and 
the fame may probably be faid of every other bafaltic coun¬ 
try, it is cerfain that the quantity of iron and clay diffufed 
through almofl every fpecies of fofiil, amounts to more 
than one-half of the whole material; fo that two of the 
principal elements of the pyrites are Hill found there, re¬ 
duced in many infiances to a flag or fcoria. The third prin¬ 
ciple, viz. the fulphur, cannot be expefted to remain ; be- 
caufe. fulphur is totally confumed by combuftion; and 
what might perhaps efcape and be fublimed would no 
doubt have fince periflied by decompofition, in confequenee 
of being expofed to the air. Another argument, which 
to Sir William Hamilton appears very convincing is, that 
glafs fometimes takes on the appearance of prifms, orcryf- 
tallizes in cooling. He received fome fpecimens of this 
kind from Mr. Parker of Fleet-ftreet, who informed him 
that a quantity of his glafs had been rendered unfervice- 
able by taking fuch a form. Some of thefe were in lami¬ 
na: which may be eafily feparated, and others refemble 
bafaltic columns in miniature, having regular faces. “Ma¬ 
ny of the rocks of lava in the ifland of Ponza (fays he) 
are, with refpeft to their configurations, ftrikingly like 
the fpecimens of Mr. Parker’s glafs above-mentioned ; 
none being very regularly-formed bafaltes, but all having 
a tendency towards it. Mr. Parker could not account for 
the accident that occafioned his glafs to take the bafaltic 
form ; but I have remarked, both in Naples and Sicily, 
that fuch lavas as have run into the fea are either formed 
into regular bafaltes, or have a great tendency towards 
inch a form. The lavas of mount Etna, which ran into 
the fea near Jacic, are perfect bafaltes; and a lava that 
ran into the fea from Vefuvius, near Torre del Graeco, in 
1631, has an evident tendency to the bafaltic form.” 
In oppofition to thefe arguments it is urged, that, in 
many of the countries where bafaltes moll abound, there 
are none of the charafteriftics of volcanic mountains. They 
affect, therefore, that the bafaltes is a fofiil, very exten- 
iively fpread over the furfaceof the earth ; and that, where 
it is found in the neighbourhood of volcanic mountains, 
we ought to fuppofe thefe to be accidentally raifed on a 
bafaltic foil rather than to have created it. But the ad¬ 
vocates for the volcanic fyfiem are not much embarraffed 
with this argument. According to them, the bafaltes lias 
L T E S. ’ 
been formed under the earth itfelf, and within the bowefs 
of thefe very mountains; where it could never have beers 
expofed to view until, by length of time or fome violent 
fhoclc of nature, the incumbent rnafs mull have undergone 
a very conliderable alteration, fuch as fliould go near -to 
deftroy every exterior volcanic feature. In fupport of this 
it may alfo be obferved, that the promontories of Antrim 
do bear evident marks of fome very violent convullion, 
which has left them in their prefent fituatjon; and that 
the ifland of Ragherry, and fome of the Weftern lfles of 
Scotland, do really appear like the furviving fragments of 
a country, great part of which might have been buried in- 
the ocean. It is farther added, that though the exterior 
volcanic charafter be in great meafure loft in the bafaltic 
countries; yet this negative evidence can beef little weight, 
when we confider, that the few infiances where the fea¬ 
tures have been preferved afford a fufficient anfwer to this 
objeftion. Thus the Montagne de la Coupe in France 
Hill bears the marks of its having been formerly a volca¬ 
no; and this mountain is obferved to (land on a bafe of 
bafaltic pillars, not difpofed in the tumultuary heap into 
which they muft have been tliroum by the furious aftiora 
of a volcanic eruption, tearing up the natural foil of the 
countiy ; but arranged in all the regularity of a giant’s 
caufeway, fuch as might be fuppofed to refult from the 
cryftallization of a bed of melted lava, where reft and a 
gradual refrigeration contributed to render the phenome¬ 
non as perfeft as poflible. To thefe obferva.tions we may 
add another from Mr. Ferber, viz. That at the time he 
went from Rome to Oftia they were paving the road with 
a fpecies of black lava. In fome of the broken pieces he 
obferved little empty boles, of the bignefs of a walnut, 
incruftated all around their fides by white or amethyftinc 
femipellucid, pointed, or truncated, pyramidal cryftalliza- 
tions, entirely refembling the agate nodules or geodes, 
which are commonly filled with quartz cryftallizations. 
There was no crack or fiffure in the ambient compaft 
lava; the cryftal fherls were pretty hard, and might 
rather be called quartz. Some fine brovvnifli duft lay in 
the reft of the holes, as impalpable and light as afhes. Me 
tells 11s alfo, that, in the greatefi part of the Paduan, Ve- 
ronefe, and Vicentine, lavas, we meet with an infinite 
quantity of white polygonal fherl cryftallizations; whofe 
figure is as regular, and more polygonal, than the bafaltes, 
Thefe are the principal arguments that have been ad¬ 
duced on the theory of bafaltes; and upon which the late 
celebrated Mr. Bergman exprefl’es himfelf to the following 
purpofe: “ Ten years ago it was a general opinion, that 
the furface of the earth, together with the mountains, had 
been produced by moifture. It is true that fome declared 
fire to be the firft original caufe, but the greater number 
paid little attention to this opinion. Now, on the contra¬ 
ry, the opinion that fubterraneous fire bad been the prin¬ 
cipal agent gains ground daily ; and every thing is fuppo¬ 
fed to have been melted, even to the granite. My own 
opinion is, that both the fire and water have contributed- 
their (hare in this operation; though in fuch a propor¬ 
tion, that the force, of the former extends much farther 
than the latter ; and, on the contrary, that the fire has on¬ 
ly worked in fome parts of the furface of the earth. It 
cannot be doubted- that there has been fome conneftion 
betwixt the bafaltic pillars and fubterraneous fire; as they 
are found in places where the marks of fire are yet vifible ; 
and as they are even found mixed with lava, tophus, and 
other fubftances produced by fire. As far as we know, 
nature makes ufe of three methods to produce regular 
forms in the mineral kingdom. 1. That of cryftallization 
or precipitation ; 2. The crufting or fettling of the exter¬ 
nal furface of a liquid mafs while it is cooling; and, 3. 
The burfting of a moift fubftance while it is drying. The 
firft: method is the mod common ; but, to all appearance, 
nature lias not made ufe of it in the prefent cafe. Cryf¬ 
tals are feldom or never found in any quantity running in 
the fame direftion ; but either inclining from one another, 
or, what is Hill more common, placed towards ene ano¬ 
ther 
