for computing the age of any given land or formation can be obtained from upheavals.

I need not refer to the slow upheavals along the coast of Greenland, Norway, and Sweden, as they are neither uniform nor continuous in their movements. Lands often rise gradually for a certain time, then remain stationary at the same elevation above the sea, and again subside. No computations can be founded on such irregular and uncertain mutations. I alluded to the upheavals in Australia in my former paper, to which I beg reference. I shall next refer to another movement of the earth which has not been duly attended to, although it is the most important of all the changes; viz., the movement northward, which produces climatal and geographical changes. The evidence of the lands having not only upheaved, but also moved en masse from the tropics to the Arctic region, is as strong and conclusive as the proofs of their having been raised from the deep.

Before proceeding to consider in detail the northerly movement of the lands, I shall give a brief description of the currents of the ocean, and endeavour to show that terrestrial matter generally is subject to the same law of movement from pole to pole. The currents of the ocean are well described in Captain Maury's Physical Geography of the Seas, to which I beg reference for details. These currents commence in the Antarctic region, and after flowing along the various configurations of the coasts in the Indian, Pacific, and the Atlantic Oceans, terminate in the Arctic Circle, and become absorbed therein. These oceanic streams carry with them the vegetable forms of the southern climes into the Arctic basin, by means of the Gulf-stream in the Atlantic, and the Japanese stream in the Pacific.

The northerly actions of the "Gulf" and the "Japanese streams are so well known as not to require further comment on this occasion. The actual rate at which the ocean moves, as a whole, from south to north, is not yet ascertained; but there are strong reasons for believing that the entire ocean changes place in less than seven years.

A bottle thrown into the sea off Cape Horn in 1837 was afterwards. picked up on the coast of Ireland a few years

This northerly action of the ocean alone causes very important geological changes, inasmuch as it not only carries the débris of the vegetation of different climes to the northern hemisphere, which become deposited in high latitudes, but it also conveys a large amount of fine sand and mud, held in suspension, from the mouths of great rivers (like the Amazon

B 2

and the Orinoco) northward, or in the direction of the local bends of the oceanic streams.

Had the vegetable tropical remains, which are found in the formations of the northern hemisphere, consisted simply of broken fragments and mere débris, their occurrence at high latitudes might easily be accounted for by the northerly action of the ocean; but as we also find tropical fossil trees standing with their roots still attached to the soil in which they grew, surrounded with their fallen leaves and the remains of reptiles, we cannot come to any other conclusion than that the lands themselves have moved bodily in that direction.

The oceanic streams radiate from the south pole as the fountain-head, and carry with them the sands, gravels, and the icebergs of the Antarctic region to very low latitudes, sometimes approaching the boundary of the southern tropic. Hence this part of the globe is a scene of desolation and barrenness to the parallel of about 50° latitude south. A very different appearance is seen in the north. The streams of the ocean flowing through the tropics enter into the Arctic basin comparatively warm, with floating vegetation from all climes, and become absorbed therein. The crust, or the crystalline film of the earth, has a similar action, but at a much slower rate of movement.

In Greenland, Spitzbergen, Iceland, Northern Canada, and Nova Scotia, we have excellent examples of fossil trees, in upright positions, with their roots still attached to the soil in which they grew; thus furnishing most incontestable proofs of their having flourished and died on the very same lands as those in which they are now found. At Atanekerdluk, in lat. 70°, trunks of trees are seen standing upright in their native soil. This fossil forest grew on the ground on which the plants are now found fossilized. The fossil plants of North Greenland prove that the land had been favoured with a climate at least 30° Fahrenheit warmer than it is at present, as it is quite certain that they never could have borne a low temperature. If we look at those species which we may consider as possessing living representatives, we shall find that, on an average, the highest limit attainable by them, even under artificial culture, lies about 14° to the southward. In Spitzbergen, lat. 78° N., we find the beech, hazel-nut, and some other species, identical with those from Greenland. The extreme northern limit of the growth of such plants as the fossil trees of Greenland is lat. 53° N. The conclusions drawn from the general appearance of the fossil forests of Greenland, are, that the country was, some years ago, truly a green land, on which vegetation flourished as abundantly as we now see in California. According to the Ice

landic histories, Greenland had a large population in the year 982, with whom Hamburg as well as Norway merchants had a commercial intercourse. The communication continued till the year 1418, when, from the increased severity of the climate, and other causes, such as the black death, &c., the country and its inhabitants became forgotten, and almost disappeared from history.

The contents of all the European deposits indicate that in past ages the lands which are now in the northern hemisphere were once in a much warmer climate, and of so uniform and mild a temperature, that the surface was clothed with coniferous trees, arborescent ferns, and palms. The shores also teemed with turtles and various amphibious reptiles.

The Malay Archipelago is about the size of Europe from the North Cape to the Mediterranean, and from Britain to Russia, and therefore equals all the geological formations which have been examined by geologists with any degree of accuracy. This Archipelago, with its numerous large islands, contains the representatives of nearly all the organic remains found in the formations of Europe. I have seen sharks near Java upwards of twelve feet long, and chambered shells of large dimensions; also elephants of gigantic size in Ceylon and Malacca. The temperature of the sea is high; the nautilus and spirule Peronii, like the ammonites, and various mollusca, abound on the shores, and the corals grow in luxuriant clusters to great magnitude on the reefs, and the bottom of the shallow channels.

THE RATE OF THE TERRESTRIAL CHANGES DETERMINED UPON ASTRONOMICAL DATA.

At the commencement of the last century our geographical maps were extremely imperfect, therefore we have no reliable data on which to make a correct comparison as to the position of any given place now, and that which it occupied a few centuries ago. Humboldt very justly remarked that the latitudes of even the European observatories in the last century were not correct within twenty minutes of a degree. If this was the case in scientific stations, where correct astronomical data might have been expected, what must be the errors and the uncertainties of the positions of other places? These facts show that there are no grounds whatever on which it can be maintained that the latitudes of the lands do not change.

The only means by which we are able to ascertain the

latitude of any given place with exactitude is by reference to the fixed stars, as it is impossible to make terrestrial measurements from the poles. Even in taking the stars as the fixed points to determine the latitude at any given period, they must be observed when in the zenith, so as to be free from errors. The laws of refraction, even at the present day, are not sufficiently accurate for taking observations to determine small changes many degrees below the zenith; therefore, all computations requiring great exactness are founded on zenith distances.

Bradley, during his astronomical observations between the years 1726 and 1735, found, by comparing the catalogues of stars made by Hipparchus and Tycho Brahe, that a change had taken place in the position of the fixed stars with reference to any given station on earth, equal to 50 seconds of a degree per annum, in the plane of the ecliptic westward. Bradley made his observations by means of a vertical telescope. The star chiefly made use of to determine this change was that marked y in the constellation of Draco. (See Phil. Trans., 1748.) Besides the direct and continuous change of 50′′ per annum, he also detected a small undulating movement, which he attributed to a nutation of the poles. He was under the impression that the land was fixed to the globe, as the maps are on an artificial globe. Hence all changes were attributed to nutations of the axis, or to the earth bodily, and not to any movements of the surface of the globe. These movements, although well known in the time of Pythagoras and Aristotle, appear to have been forgotten, and therefore were totally neglected by modern astronomers, in speculating on the probable cause of the above changes.

Bradley was appointed Astronomer Royal in 1742; but beyond the fact of determining the annual change referred to, he made no further observation with reference to this question.

Had this movement only affected the fixed stars, it might have been urged that it originated from the starry heavens moving slowly towards the south-east, and not the lands towards the north-west. But since it also affects the sun, moon, and planets, such an idea could not have been maintained; therefore astronomers have necessarily concluded that it proceeds from a real motion of the earth. The correctness of Bradley's observations was subsequently verified. This change -which causes the appearance of a recession in the equinoxes, is so well established now as not to require further confirmation. The annual amount of this spiral movement of the surface westward at an angle of about 23° 30′ from

the plane of the equator, is but an extremely minute quantity, viz., 50" in longitude and 20" in latitude; yet its continual action from year to year makes itself very conspicuous, and that in a way highly inconvenient to practical astronomers. It destroys, in the lapse of a moderate number of years, the arrangement of their catalogues of stars, with reference to the stations on earth, and renders it necessary to reconstruct them from time to time.

Since the earliest catalogue on record that made by Hipparchus 2,140 years ago-the stations of reference have moved towards the north-west 30°, and have, in round numbers shifted northward during the same time 12° in latitude. That is equal to the cosine of the angle of the spiral plane (of 23° 30') the direction of the superficial movement. The effect of this change in the aspect of the heavens is to make the southerly stars appear to recede southward, and those situated in the north to approach at the rate of 20" per annum in the meridian. Hence it appears that the superficial film of our globe has been made free to move, like the ocean, from south to north, but in a spiral path: this movement has been determined to a fraction of a second of a degree, and is seven and a half furlongs in longitude W. and three furlongs in latitude N. per annum.

As a further illustration of this terrestrial change, let us, by way of an example, take y Ursa Majoris as a convenient fixed star to determine annually our geographical position. The situation of this star is very favourable for making observations in this latitude, inasmuch as it passes within 3° of the zenith, and therefore is, when in that position, unaffected by refraction on its transit.

In January, 1853, Greenwich was 3° 2′ 5′′ to the south of the transit of γ Ursa Majoris. In January, 1864, the Observatory was 2° 58′ 24" S. of this star. In 435 years hence the Observatory will have arrived at the same parallel as y Ursa Majoris, when the star's transit will be seen in the zenith. It might be urged that such a small movement, which is only detected after the lapse of ages, would not be sufficient to account for the geological changes referred to; but I shall endeavour to show that, small as it is, it is quite sufficient to produce them, and in the exact order in which they are seen. I shall take the Isle of Portland as an example. In the deposits of this island is a petrified tropical forest, proving that that part of England has not only been upheaved, but also exposed to a tropical, or at least, a semi-tropical sun. Many of the fossil trees are still standing erect, with the roots in the yery ground in which they grew. The plants are similar to