and in some places became thick and turbid. Lake Ontario also felt its effects, and the sea round the Eastern Antilles, Antigua, and its neighbouring islands; and, although the tide is not known to rise more than 18 inches, it suddenly rose 20 feet.

The atmospheric and other phenomena which usually accompany earthquake, and consequently precede eruption, are, an unnatural calmness of the air, a violent and remarkable agitation of the sea, the sudden bursting forth of sulphureous springs, deep rumbling sounds, and violent explosions, resembling the discharge of artillery. The phenomena which precede subaqueous activity are precisely similar to these, except as they may be affected by the mass of water which covers the vent.

(To be continued.)

ART. XII. On the Effects produced by the Precession of the Equinoxes. By Sir JOHN BYERLEY, F.R.S.L.

Sir,

(Continued from Vol. IV. p. 316.)

In advancing a new theory, I had not the ridiculous pretensions of imagining that it would at once attain universal, or even general, assent. The astronomical system of Ptolemy and the vortices of Descartes have still their partisans, who look down with pity on Copernicus and Newton. Even whole scientific academies have adopted errors which a schoolboy of the present day would blush for. To cite only two relative to my subject:-In 1693, the French Academy of Sciences decided that it was preposterous to suppose that the sea and land on the globe did not present an equal extent of surface. Sir Isaac Newton had determined, by theory, the earth to be an oblate spheroid; but, strange to say, the measurement of a degree of the meridian, by the French mathematicians, which ought to have confirmed Sir Isaac's theory, led the French Academy of Sciences to an opposite conclusion; and for forty years they taught the world to believe the earth to be a prolate spheroid; or sharpened, instead of flattened, at the poles.

As to theories of the earth, they are innumerable; all beautiful, all poetical; from Burnet and Whiston down to Buffon and Delisle de Sales; the latter of whom supposes the solar system to consist of about 17,000,000 of planets and comets.

They are all advocates of a central fire, which they probably caught from Newton; who, in one of his few aberrations in science, had calculated that the comet of 1680 was, at its perihelion, 2000 times hotter than red-hot iron. Chemistry was then in the infancy in which Boyle had left it, and no one asked himself the question whether comets possessed such a capacity for caloric, or whether the solar rays were really hot. It is very poetical to talk of "The golden orb, pouring forth floods of light through boundless space:" we now know that planetary space is neither warmed nor illumined by the solar rays; all is cold dark night, save within the atmospheres of the planets; there, the solar rays, acting on the atmosphere, produce combustion, from which light and heat are evolved. This is one argument against a central fire: but before I develope the whole of the new theory, I wish the truth of its basis to be brought to the test of actual experiment.

I have advanced that the ecliptic is a real circle on the earth; that, by the precession of the equinoxes (arising from the earth's figure) the equator cuts it in a different point every year, returning to the same point in 25,920 years (according to De Lambre). By this motion, the poles of the equator revolve round the poles of the ecliptic on a radius of 23° 28', or about 1400 geographical miles. Thus far astronomers agree with me; and here, I am sorry to say, we part company. They do not admit that this can produce any changes on the earth's surface; whereas I attribute nearly the whole of them to it, and I will even appeal to them, and them alone, to decide the question.

Now, if, as I assume, the pole of the equator revolves in the circumference of a circle of 2800 miles in diameter, all churches and buildings erected due north and south, even only one hundred years since, are no longer so; that no sundial erected the same length of time is at present correct; that no meridian, traced with care at such a period, is at present true; that all latitudes and longitudes, determined with the utmost care 50 to 100 years since, differ from those taken by recent observers; and that it is easy to state beforehand not only on what side the supposed errors lie, but their

amount.

I do not wish to prejudge the question; as I have already stated, the astronomers shall decide it: but I may be per

The late Baron Fourier, perpetual Secretary to the Royal Academy of Sciences of Paris, calculated planetary space to be 90 degrees below the freezing point of Fahrenheit.

mitted to state a few historical facts in support of the theory I advance.

Tycho Brahé traced a meridian at his observatory, at Uranienburg, which M. Picart found incorrect, and declining to the west. Cassini traced one in the cathedral of Milan, in which the same error is found.* All who have recently determined, by astronomical observation, latitudes and longitudes suppose their predecessors to have not taken due care, or to have had defective instruments; and M. de Pouqueville, in his excellent History of Greece, informs us that the Venetians laid down all the Greek coasts falsely in their charts, in order that the vessels of other nations might be stranded: a hard sentence on the husbands of the Adriatic, which we may probably be able to reverse.

To put, therefore, my theory to the test, I earnestly entreat that astronomers and persons possessing exact chronometers, will, at the approaching equinoxes, ascertain whether our cathedrals, churches, abbeys, &c., are now in the meridian, and whether old sundials are not also erroneous. If my theory be true, and that they were, when built, erected correctly to the four cardinal points, they will all, without exception, be now found to decline to the west; and from the quantity of the declination the date of their erection may be ascertained to four or five years: this is a new art de vérifier les dates, which, if founded in truth, will be of great importance in chronology.

The communication of the results to your valuable work I earnestly solicit, whether they be for or against me.

"If right, I'll smile; if wrong, I'll kiss the rod."

London, Feb. 1. 1832.

J. BYERLEY.

*I wrote to our astronomer royal, Mr. Pond, to ask if the meridian which I supposed must have been traced by Flamsteed was now correct. Mr. Pond obligingly informed me that there existed no traces of Flamsteed's meridian at the royal observatory of Greenwich.

REVIEWS.

ART. I. A Manual of the Land and Freshwater Shells of the British Islands, with coloured Plates of every Species. By W. Turton, M.D. Foolscap 8vo. London, Longman, 1831. 10s. 6d.

THIS is a very neat and beautiful little volume; and will be, we doubt not, a very acceptable present to the bulk of British conchologists, since it will enable them to classify their collections of native land and freshwater shells according to the most approved system of the day, and to attach their respective names with facility and with certainty. The descriptions of the species are not merely correct: they are remarkable for elegance, perspicuity, and propriety of language, the technicalities of the science being used only on necessary occasions; while the figures are characteristic, and both engraved and coloured in a very creditable manner.

We know not that we can say more in favour of the book, and it would not have been just to its author to have said less. Its main defect lies in the want of information relative to the anatomy, physiology, and habits of the animals. Müller said, long ago, that we had amused ourselves sufficiently with shells, had expressed enough of wonder about their forms and colours; and that it was time to leave these things to children, and bind ourselves up like men to study the living inmates, their structure, and manners. How the call has been answered on the Continent, it boots us not to enquire: in this country it found no responsive echo; and if at this late hour we begin to feel and acknowledge its justice, it must, nevertheless, be granted, that very few among us (and Dr. Turton is not of the few) even yet cultivate this department of natural science as Müller bade us, and as common sense would dictate. The greater number of our living conchologists care more for rare species, and perfect specimens, and pretty and uncommon varieties, and such similar absurdities, than for the anatomical discoveries of a Lister or a Cuvier, for the high discussions of a Lamarck, or even for the economical observations of a Müller and a Montagu.

The history of conchology in Great Britain during the present century is, indeed, any thing but creditable to the reputation of us who are conchologists. If we except some

few but excellent detached essays in the journals, and, perhaps, Sowerby's Genera of Recent and Fossil Shells (for even in that work the animal plays too subordinate a part), there has not been published, during the thirty-one years which have elapsed, a single work that is worthy of the advanced state of our knowledge, a knowledge contributed almost entirely by foFeigners. The introductions most popular amongst us are bare expositions of a system which in every step runs counter to nature and to sense, with a supplementary explanation of useless terms, or of terms which require no explanation. Other introductions there are, we are quite aware; but even these are merely systematical, and make no pretensions to originality and what are our recent systematic works but repetitions of a twice-told tale, descriptions of things which have been described as well before, without spirit, or life, or variety? On running over these works, one might suppose that the animal was beneath a naturalist's notice, so sedulously is every particular relative to it avoided; and if a chance remark is made, it is done with all caution, and as a by and by affair. There, for example, lies before us the Conchological Dictionary of Dr. Turton, where we see in every page a mark that the author had seen the species in a living state: but he would be a most credulous man who should turn to that volume for any useful knowledge. And this is the more to be regretted, as few have had, or can have, the opportunities of our author in investigating the economy of these animals. Who that is not a mere conchologist who does not envy him, in particular, the possession of his noble Sérpulæ ? and who, that ever saw the tenants of even our common species, does not regret that they had fallen into hands who knew not their value and their curious beauty? Conchologists deem little of the pleasure, the interest, or the nobleness of their study, when they confine themselves to the examination of the outward and inorganic covering.

Dr. Turton himself seems now aware of this. Conchology, he tells us, in the dedication of the present volume,"is scarcely beyond its infancy." And again he says:-"Till the

* The works alluded to are those of Brown, Brooks, and Burrows; of which the latter has reached a second edition: the best proof possible of its popularity. Brown says (1816), of the Linnæan system, that no one has been able to supersede it by a better; and that "its beauties must perpetuate its preeminence." The perpetuity of Captain Brown is, we suppose, a cycle of about ten years; for in his late work, entitled Illustrations of Conchology, this preeminent system has not the precedence, and newly proposed genera are adopted in such numbers as to alarm even our reforming spirit. Brooks and Burrows are no less laudatory of the Linnæan system, and abusive of every other; but they are consistent.