« PreviousContinue »
destroyed for a season, would forthwith obey the gravitating forces on a revolving sphere, would assume the spheroidal figure of rotation, and remain universally circumfused with water, as under the primordial abyss. But a partial and successive series of disruptions of the crust will cause only a partial approximation to that ultimate figure, accompanied with a transient deluge of greater or less extent over the surface. When the explosive commotions cease, the ocean undulations will subside, the sea will flow back into larger but shallower basins, and the dry land will again appear, furrowed, and strewed over with the detritus of the storm. This view of a diluvial transition, in my apprehension, can hardly be deemed hypothetical, resting as it does on the joint bases of geological facts and physical laws.”
“We have therefore every physical reason to conclude that each great antediluvian convulsion of the earth extended the empire of the sea, and abridged the boundaries of the land by a permanent submersion of some of its regions; mechanical effects involving commensurate physical changes of climate; 1. by the thickening deposits of the ocean; 2. by the increase of the cooling or aqueous surface of the globe ; and 3. by the decrease of the heating or terrene, as will be fully developed in treating of the deluge in the fifth chapter.”
These novel views are resumed, with additional explanations, when the phenomena of the deluge are described.
“ The bouleversement involved in these propositions, and deducible from the phenomena on which they rest, must, by the established laws of physics, as we have already shown, have materially increased the area of the ocean, and diminished that of the land. To what degree this change of proportion amounted, we have no precise data to determine.
" On Mr. Penn's principles, the ratio of land to water was inverted by the deluge; for he assumes that our actual seas correspond in surface to the antediluvian lands, and our actual lands to the antediluvian seas. But the researches of Professor Buckland on the Kirkland and Franconia caves, as well as those of Baron Cuvier on the grotto of Oiselles, concur to prove that these were dens inhabited by antediluvian quadrupeds; and therefore must have formed a portion of its dry land. - Moreover, most of our coal districts, and primitive schistose mountains, in Scotland, for example, bear no good evidence of having lain under the sea during the long antediluvian period. A few sheils may no doubt be found scattered over their surface, relics of the deluge; but these marine exuviæ
do not constitute regular testaceous strata in their body, as would undoubtedly have happened during a long residence in the hosom of the ocean. Our coal-measures, indeed, are most probably the basins of antediluvian lakes and marshes.
“ With Mr. Penn's proportion of land and water, I conceive the terraqueous globe would not have been habitable by man and his companion animals. It would have possessed nearly three parts of earthy surface to one of aqueous; whereas there is now fully three of aqueous surface to one of earthy. Or, since dry ground is the heating surface, and water is the cooling, the heating faculty of that ancient globe would have been three times greater than the present, and its cooling faculty three times less; making a nine-fold difference in calorific constitution between the two, without taking into account the proper heat of the antediluvian seas. Under such circumstances of heat and aridity, vegetation must have pined, or most probably expired, except in a few narrow bands of soil along the margin of the sea; as is now exemplified on the Barbary shores. If we suppose that only one half of the primeval land perished at the deluge, and that half possibly a great continent, (corresponding to the Pacific Ocean,) which might form the whole world to the antediluvians, unversed as they evidently were in navigation, then the area of their dry land would have been equal to that of their seas; and the general climate of their globe, as far as depended on the constitution of its surface, would have been three times warmer and drier than the present. This by no means implies, however, thermometric and hygrometric degrees three times higher than the present. Besides, the hotter surface of the land would be compensated by a greater radiation of heat into space, and the hotter surface of the seas by a more copious evaporation of water into the air. Still that incontestable physical principle will perfectly account, to a certain extent, for the higher temperature which prevailed in our latitudes in antediluvian times, and for the sudden and vast refrigeration induced by the deluge. I do not presume to define the numerical proportions of land and water on that ancient globe; but I maintain that such a mighty diluvian catastrophe, as it suffered, could not be accomplished by any powers of nature which the laws of inductive logic authorise us to employ, namely, general explosive and disruptive forces of volcanic origin, without increasing the area of the sea, at the expense of the land. We must moreover keep in view the increasing obstruction of the central heat after each successive catastrophe." The specimens now exhibited of Dr. Ure's work will recommend it more effectually to the notice and patronage of our readers than the most elaborate eulogium which a critic could indite. The wood-cuts and plates represent a well-selected variety of mineral sections and organic remains. In five copper-plates are figured seventy fossil shells, characteristic of the several great strata from the mountain limestone up to the London clay. There is an exquisite lithographic impression of the petrified stem and leaves of a cactus cylindricus-a fossil which appears to occur very plentifully in a coal sandstone in Ayrshire.
The popularity of Dr. Ure's work will be deservedly enhanced by the consideration that he has triumphantly confuted every cavil of the least consequence, which geological sciolists have urged against sacred history. And all this is done in a truly philosophical spirit without the slightest air of religious intolerance. On the whole, we regard this new system of geology, as one of the most valuable accessions lately made to the scientific literature of our country.
Hoe bude bodas On some Phenomena of Vesuvius.—Extracted from the Journal of, and communicated by Octavius Morgan, Esq.
basi March 25th, 1828.-Vesuvius had all day been sending forth, at very short intervals, immense volumes of dark smoke, or rather dense vapour, charged with ashes and sand, which were carried in an eastward direction, by a strong westerly wind that prevailed all day, and which fell in showers on the opposite side of the mountain, as was plainly discernible from Naples, darkening the air beneath as they passed. We started from Naples at 74 P.m., and in our way to Resina, and afterwards, whilst ascending the mountain, I saw frequent flashes of sheet lightning, some above the volcano, and others in various' directions all around—not seeming to proceed from any particular spot. There was also much hail both on the cone, and down below at Resina. We ascended to the summit without other inconvenience than a very strong wind. On the brink of the crater, the wind was so tremendously powerful that it was utterly impossible to stand; to creep on all fours was our only chance of escaping being precipitated into the
crater. The coldness and impetuosity of the blast, and the quantity of ashes and sand swept by it from the edge of the cone, not to omit a most violent hailstorm, rendered our situ-, ation peculiarly unpleasant. The craterwas by this time nearly half filled with the scoriæ which had been thrown up: from the liquid lava beneath, and floating on its surface had thus accumulated. The surface was funnel-shaped, and from the central depression, the explosions and ejections usually proceeded, the effect of which was, as if a very sudden and violent blast, or disengagement of vapour, rushing up from beneath, carried up with it into the air a quantity of these red-hot masses of scoriæ, raising them to a great height above the crater, as though they had been no heavier than feathers. The appearance of the crater at this time was as an enormous furnace, or a valley of fire, the surface of the scoriæ being nearly black, except at the moments of the explosions, when the whole glowed with the most vivid brightness. The central depression was always at a white heat. Whilst we were sitting on the brink of the crater, a new spot, nearer to us than the old point of discharge, burst forth within the crater with a pro-, dious explosion, the mountain trembling beneath us.
A vast quantity of red-hot scoriæ were hurled to an immense elevation, and scattered about on all sides. The violence of the wind, however, drove them from us. As I sat behind the other persons, Lobserved the following curious phenomenon. On the highest parts of the hats, coats, cloaks, hoods, &c. of all those before me, was a phosphorescence, that is to say, a pale greenish light was visible on the most elevated extremities of all parts of their clothing that were exposed to the wind. A green crape veil, (which I wore to protect my face from the sand and ashes carried by the wind,) when agitated by the blast, appeared to be edged with a fringe of sparks, resembling the light of a glow-worm. When removed from the influence of the wind, the light ceased; but on allowing it again to float in the gale, the light instantly reappeared. The tips of my gloves on being exposed to the wind bore each a spark, like a glow-worm's tail, and seemed communicable from one finger
to the other by contact, yot unlike phosphorus. Lower down the mountain, this appearance was not perceivable, though ex** Oui bairt. ...
posed to the same wind. When we left the crater*, the wind and hail were so violent, that it was impossible to keep our torches alight, and we were obliged to grope our way back to the Hermitage in the most complete darkness, over the broken lava, perhaps the most rugged spot on the face of the globe.
On Radiating ELECTRICITY, by Charles Bonnycastle, Esq.,
Professor of Mathematics in the University of Virginia in the United States of America. Communicated by P.
Barlow, Esq., F.R.S. WHEN Benner first invented that beautiful little instrument, the gold leaf electrometer, he found that a candle placed upon the top of it greatly increased its sensibility; and other experimentalists were not long in observing that a candle possesses the property of depriving all bodies in its neighbourhood of the electricity imparted to them. About a year ago I made some experiments upon this subject, and arrived at what appeared to me an important fact, that electricity radiate, with great velocity when the body upon whose surface it exists is raised to a white heat. I was much struck with this results from its analogy to what I had before witnessed, when assisting Mr. Barlow in his researches on the magnetism of hot iron. We had found the magnetic action to cease entirely at the moment when the temperature became that of white heat, or somewhere about 1000 degrees of Fahrenheit ; and were at a loss to explain the phenomenon, which I have now little doubt arose from a radiation of the magnetic fluid. A similar analogy occurs in galvanism; the brilliant development of light and heat, which takes place when the connecting wires of a powerful battery are armed with charcoal points, does not commence until the charcoal has become intensely white; but it will afterwards be maintained, although the points are removed several inches asunder, and from all the phenomena, is manifestly a case of radiation.
* It was about half-past twelve o'clock. It occurred to me at the time that it was a powerful discharge of electric fluid; but how excited, or by what laws thus discharged, I could not discover.