water among the hills; some in the form of permanent lakes, and frequently as ponds which are forded with difficulty after heavy rain, but which are dried up in summer. Not unfrequently, the hill tops are free from the spongy substance which covers most of our own, at least the parts that are above the range of cultivation; and the result is such as has often been noticed in Australia. The whole waters of a shower are discharged into the ordinary river beds at once, and there is a destructive flood; whereas, with us much is retained, and trickles out in a supply for weeks or months afterwards. But the important point is, that fallen timber is soon covered up in the rich vegetation which surrounds it; and thus, while our mosses at home afford us frequent examples of the disinterring of trees, we can witness almost daily, in the primitive forest, the previous process of burying them. It is very likely that before the tree becomes completely imbedded, its external layers are rotted off; and that the smaller branches share the same fate. This also would harmonise with our own experience respecting subterranean timber. Near the equator a fallen tree is still more rapidly buried; but timber is there of such rapid growth, and usually so porous, that it soon decays. The roots which remain under ground wholly or partially, in any latitude, sometimes retain their positions long after all traces of vegetation above ground have disappeared.* Thus, the troops of voyagers who cross

The following are extracts from my Diary :

All the valley of Arica, now a sandy desert, sparkling with hexagonal crystals of salt, is described in old Spanish maps as the forest of San Juan de Dios. Perhaps it is now more elevated, and therefore worse watered; or worse watered from any other cause. Trees are occasionally dug up, and converted into charcoal. Growing bushes spread their roots far under the sand, and new tops spring up from this subterranean communication. At Copiapo, cart loads of gigantic tree roots were being drawn through the street. They are found running far underground, following the moisture: though the tops appear to be only low shrubs. The well known law, by which roots and branches follow each other, -the remotest twig letting the drop fall on the spongiole of the root,-does not apply here; perhaps because nature has placed them in a rainless district. Also, many roots are found in the Cordilleras at camping places, where there is no appearance of vegetation.

There was formerly a forest between Tarapaca and Negresos, several

from side to side through the passes of the Andes, find roots of bushes and shrubs in the most sterile places; and muleteers sometimes carry them upwards of ninety miles, that they may serve as fuel to the miners, encamped in some portion of the great desert of Atacama.*

3. Sands.t

The effect of drifting sands on our own coast are as nothing compared with their effects on a coast where sand is the only object visible, except at rare intervals, for nearly 2,000 miles. It is seldom agitated by strong winds; but such as do occur produce sometimes very curious effects. On the wild journey of about ninety miles, from Islay to Arequipa, the sand is rolled up into a series of crescents, the horns of which are turned from the sea; and near Caldera on the railway journey to Copiapo, the prevailing direction of the wind is shown by a tail of fine sand, behind each small stone or each tuft of weeds or roots. Some of the effects are such as are unknown or not sufficiently marked to attract attention at home; yet they are very important as showing us how the prevalence of sand is both a cause and an effect, and what a powerful agent it is.

Tradition, whose records we have no reason to doubt,— and indeed it is confirmed by both historic documents and physical evidence,-informs us, that many places which are now unsightly deserts were once covered with rich vegetation. But the Spaniards, during their rule of nearly two centuries, cut down the trees for fuel in smelting the metals, and the face of the country was at once changed. Rain became less. leagues in length and as many in width; so that a guide was required by any one crossing it. It was surrounded by fire, and wholly burnt down; but the roots of the trees are still procured from the ground. Its destruction commenced about forty years ago, and in fifteen years no vestige of it was left except solitary The wood of the subterranean forest was formerly discovered by piercing, and was used in large quantities for boiling the nitrate: but now the coal of Chile is used, and is preferred to every other kind.

trees.

This was the case at the Rio Salado Mine, near Chañaral in North Chile. + Transactions, vol. xviii, (N. S., vi,) p. 27.

frequent, till at last some of the spots became included in that extensive district of the West Coast, where, (as in a much larger area of the Old Continent,) rain never falls. It is said that not far from Iquique in the extreme south of Peru, there is a skeleton forest to be seen all the trees having been destroyed by the sand which buries several feet of their trunks, yet each still stands on the spot where it grew. One is prepared to believe this, after seeing the tops of the trees which have been sanded up at the Sniggery Wood+ in our own neighbourhood: but the moisture of our climate preserves their vitality, and those whose tops are visible are in full leaf at this moment. The tradition respecting former forests where there are now deserts only, receives further confirmation from the fact that numerous trunks of trees are found beneath the sand. They are detected by iron piercers, just as trees are discovered from time to time in the bogs of this country.

The diminution of rain when the surface has become denuded of trees, is not only a fact of general occurrence, but one of great importance. At this moment Valparaiso is threatened with a want of water, the supply having gradually diminished precisely as building and other operations necessitated the removal of the trees. And the law of change was stated by Mr. Cyril Graham to the Royal Geographical Society,§ in May, 1868. "In all parts of the globe where forests perish, "rain ceases or diminishes in quantity; and desiccation of course follows. Such a change has occurred not only in

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• About twenty leagues off, there is a skeleton forest. It was deprived of water, and the vegetation died out; but there are hundreds, perhaps thousands of the trees still standing with timber undecayed. Some are as thick as a man can embrace, (say six feet in circumference,) but of course no leaf or bud is ever put forth now. Another forest near it is still green. Trees of a more hardy kind can be shown, which have never known water for from ten to fifteen years, except such as falls in the form of dew, or is extracted in moisture from the sand; yet they produce fruit to the present time.-Diary.

+ Transactions, xviii, page 33, No. 6.

§ Journal, xii, 193.

29th July, 1868.

"Sinai, but Central Arabia and Asia,* and many other "regions."

Thus it follows, that in so far as the natural causes correspond with those in our own country, the effects are identical. The doubt which has been entertained respecting the reasons for changes in our own climate, is dispelled by the clearer evidence of other lands. And processes which take place among us so rarely or on so small a scale as to suggest, to the ignorant and sceptical, that they cannot bear the conclusions placed upon them, are of such frequent occurrence or on so large a scale elsewhere, that the inferences assume the form of recognised general laws.

III.-HOUSES.

Heeren assigns as one of the reasons why a greater degree of civilization prevails in Europe, that the climate has compelled the population to live in strong and comfortable houses. This secures to them permanence of locality, and ensures attention to domestic relations. On the contrary, there is comparatively little permanence, and domestic ties are less respected, where houses are rude in appearance and can be rapidly constructed,

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The following was stated by the Rev. H. B. Tristram, at the meeting of the British Association at Norwich :-" There were several points of great importance, connected with exploration in the East, which bore not only upon Jewish history, but upon Assyrian and Persian history as well. One was, the rapid "diminution of population, in the region of Sinai, in consequence of the rapid "diminution of rainfall. There was the clearest possible evidence, that the "rainfall in former times, was much greater and much more certain than it is at "present. With reference to the smelting operations carried on in the district "in former times, we found an enormous number of mines, and vast heaps of "slag spread all over the country; showing that the Egyptians or some other people worked very extensively in iron and copper: and he could conceive "how rapidly the forests would be denuded for the supply of the amount of "wood required for such operations. Again, in southern Judea you would "scarcely meet with a shrub, so completely had the country been denuded of "wood. It was impossible to travel anywhere without coming upon the ruins of "oil presses and wine presses; and now there was not an olive tree nor a vine "to be met with. When we considered the evidence of what the country once "was, we might have some idea of what the population was, and of the abun"dance of the rainfall which they enjoyed. The absence of rain in the present "day was exceptional, due entirely to the cutting down of trees; and the only "way of restoring it was by planting trees afresh,"