242 
is volcanic, do’ not appear to confirm this 
reasoning ; for they there found the se- 
cond’s pendulum to be 39.01717 inches 
long: whereas, the mest probable ellipsoid 
figure of the earth, when all the best geo- 
detical and pendulum measurements, and 
some astronomic phenomena, have been 
taken into the account, by Count Laplace, 
has a flattening of s5¢ 75 and the calcu- 
lated length of a pendulum thereon, in 
lat. 0° 32’ 19”, would be 39.01170 inches : 
but on Abingdon Island it is found .00547 
inches longer; indicating an increased, in- 
stead of a diminished, gravitating force 
there; answering, when compared with 
Captain Kater’s London observation, to a 
flattening of ss}.05, and when compared 
with Captain Sabine’s Melville Island ob- 
servations, of gs 1%, Which are flatten- 
ings considerably larger than is, with pro- 
bability, due to the latitude of Abingdon 
Island ; and.shewing, that a greater num- 
ber of equatorial pendulum. observations, 
where volcanic caverns cannot be supposed 
to affect the results, are still wanting, to 
infer therefrom any thing satisfactory as 
to the exact figure of the earth. But, 
after all, is the mass of Abingdon Island 
really volcanic? or has merely the wild 
theory of Hutton, as to basaltic and other 
rocks, been resorted to, in fixing its deno- 
mination ? 
Whether Strata of Basalt have, in any in- 
stances, been formed of the ejected Matters 
from Volcanoes, has been much doubted by 
many geclogists, sice ascertaining that the 
basaltic, or toad-stone strata of the Derby- 
shire Peak Hundreds, and of several other 
districts, interlay regular strata, abounding 
in subaqueous zoophites, and have no pre- 
tensions to the volcanic character which 
had been assigned to them: but a dis- 
covery lately made in Auvergne, by Count 
de Luizer, between two rivers which bear 
the name of Coreze, seems, undoubtedly, 
to shew that the basalt there has been 
ejected from a volcano, in the present 
state of our planet; because, the volcanic 
sand and tuffa, on which it rests, contains 
the bones of several kinds of large dry- 
land quadrupeds, which it is impossible to 
confound with the remains of the sub- 
aqueous animals found in the regular stra- 
tification, without any admixture of dry- 
land beings. A race of animals antece- 
dent to the existence of man, and part of 
those which, in other situations, are found 
imbedded in diluvial matters, upon the 
regular strata; such are here found, nearly 
similarly imbedded and preserved with the 
animals of Pompei and Herculaneum, ex- 
cept that they have undergone a more com- 
plete mineralization, and that, upon the 
tufaceous matters which contain them, vast 
strata of basalt have been formed. 
‘The cause -of increased Temperature in 
decp Mines, the experiments and argu- 
ments upon which, as applies to Cornwall, 
Spirit of Philosophical Discovery. 
[April 1, 
we have noticed in our 55th yol. p. 121] 
and 531, and in vol. 56, p. 314, has, we 
think, obtained a final elucidation from Mr. 
M. P. Moyle, in No. 48 of the “ Annals 
of Philosophy.” This gentleman, after ad- 
mitting a chief cause of this heat to be 
the lengthened column of the atmosphere in 
the bottoms of very deep mines (which 
principle Dr. T. Cooper, in America, and 
Mr. Matthew Miller, in England, were 
the first, we believe, toadvance), shews that 
the vainly-imagined central heat of the Plu- 
tonic faction in geology, has nothing to do 
in the matter. The temperature of the 
air in Oatfield engine shaft, at the depth of 
364 yards beneath the surface, was, a few 
years ago, 77° of Fahrenheit, whilst the air, 
circulated through that part of the mine, 
and the mining operations were in full 
activity ; but now, since the mine is dis- 
used, and become full of water, and the 
atmosphere has been some time excluded, 
a selt-registering thermometer, let down 
through the water to the same place in the 
shaft, which before shewed 77°, indi- 
cates no greater heat than 54°! this being 
the nearly uniform temperature of the 
water from top to bottom of this deep 
shaft. On the contrary, in Herland en- 
gine shaft, when full of water a few years 
ago, the register thermometer shewed the 
temperature of the water therein, to the 
depth of 200 yards, to be uniformly 54° ; 
but lately, on emptying this mine of water, 
the air, in the same shaft, at 200 yards 
deep, was found to be 66°; at the same 
time that the thermometer, let down 
twenty yards deeper into the stagnant 
water, shewed the temperature there still 
to remain 54°! These results were con- 
fidently foretold by Mr. Moyle, before the 
late filling of one, and the emptying of the 
other, of these deep mines, took place ; and, 
surely, no greater proofs can be offered, 
that the cause of increased temperature in 
a deep mine lies in the external atmo- 
sphere, and not in any internal source of 
heat. 
A cause for the constant Setting-in of a 
Current through the Straight of Gibraltar, 
has lately been attempted to be assigned 
by Mr. Smyth, who, by a series of experi- 
ments with Six’s self-registering thermo- 
meters, around the island of Sicily, at 
twenty to forty yards deep, found the heat 
of the sea-water there to be 73° to 76° of 
Fahrenheit, at the same time that the heat 
of the water, outside of the Straight, was 
only 63° to 64°; and he thence argues, 
that increased evaporation, owing to this 
excess of heat, causes a constant lowering 
of the surface of the Mediterranean Sea. 
However the fact may be, as to an excess 
of evaporation, aboye the quantities of 
water supplied by the surrounding rivers of | 
this sea, it is evident that the subterranean 
heat of Sicily is far feo local, and lies too 
near to the surface, to affect, in any sensible 
manner, the whole of the Mero or 7 
‘ . The 
