[469] There are extensive ranges of dunes on various parts of the coasts of the British Islands, but I find no estimate of their area. Pannewitz (_Anleitung zam Anbau der Sandflachen_), as cited by Andresen (_Om Klitformationen_, p. 45), states that the drifting sands of Europe, including, of course, sand plains as well as dunes, cover an extent of 21,000 square miles. This is, perhaps, an exaggeration, though there is, undoubtedly, much more desert land of this description on the European continent than has been generally supposed. There is no question that most of this waste is capable of reclamation by simple planting, and no mode of physical improvement is better worth the attention of civilized Governments than this.

There are often serious objections to extensive forest planting on soils capable of being otherwise made productive, but they do not apply to sand wastes, which, until covered by woods, are not only a useless inc.u.mbrance, but a source of serious danger to all human improvements in the neighborhood of them.

[470] BOITEL, _Mise en valeur des Terres pauvres par le Pin maritime_, pp. 212, 218.

[471] See _Appendix_, No. .

[472] For details, consult ANDRESEN, _Om Klitformationen_, pp. 223, 236.

[473] When the deposit is not very deep, and the adjacent land lying to the leeward of the prevailing winds is covered with water, or otherwise worthless, the surface is sometimes freed from the drifts by repeated harrowings, which loosen the sand, so that the wind takes it up and transports it to grounds where acc.u.mulations of it are less injurious.

[474] _Travels and Researches in Chaldaea_, chap. ix.

[475] _etudes Forestieres_, p. 253.

[476] LAVERGNE, _economie Rurale de la France_, p. 300, estimates the area of the Landes of Gascony at 700,000 hectares, or about 1,700,000 acres. The same author states (p. 304), that when the Moors were driven from Spain by the blind cupidity and brutal intolerance of the age, they demanded permission to establish themselves in this desert; but political and religious prejudices prevented the granting of this liberty. At this period the Moors were a far more cultivated people than their Christian persecutors, and they had carried many arts, that of agriculture especially, to a higher pitch than any other European nation. But France was not wise enough to accept what Spain had cast out, and the Landes remained a waste for three centuries longer. See _Appendix_, No. 64.

The forest of Fontainebleau, which contains above 40,000 acres, is not a plain, but its soil is composed almost wholly of sand, interspersed with ledges of rock. The sand forms not less than ninety-eight per cent. of the earth, and, as it is almost without water, it would be a drifting desert but for the artificial propagation of forest trees upon it.

[477] _economie Rurale de la Belgique, par_ EMILE DE LAVELEYE, _Revue des Deux Mondes_, Juin, 1861, pp. 617-644.

[478] _Geognosie_, ii, p. 1173.

[479] According to HOHENSTEIN, _Der Wald_, pp. 228, 229, an extensive plantation of pines--a tree new to Southern Russia--was commenced in 1842, on the barren and sandy banks of the Ingula, near Elisabethgrod, and has met with very flattering success. Other experiments in sylviculture at different points on the steppes promise valuable results.

[480] "Sixteen years ago," says an Odessa landholder, "I attempted to fix the sand of the steppes, which covers the rocky ground to the depth of a foot, and forms moving hillocks with every change of wind. I tried acacias and pines in vain; nothing would grow in such a soil. At length I planted the varnish tree, or _ailanthus_, which succeeded completely in binding the sand." This result encouraged the proprietor to extend his plantations over both dunes and sand steppes, and in the course of sixteen years this rapidly growing tree had formed real forests. Other landowners have imitated his example with great advantage.--RENTSCH, _Der Wald_, p. 44, 45.

[481] _Souvenirs d'un Naturaliste_, i, pp. 204 _et seqq._

[482] "If we suppose the narrow isthmus of Central America to be sunk in the ocean, the warm equatorial current would no longer follow its circuitous route around the Gulf of Mexico, but pour itself through the new opening directly into the Pacific. We should then lose the warmth of the Gulf Stream, and cold polar currents flowing farther southward would take its place and be driven upon our coasts by the western winds. The North Sea would resemble Hudson's Bay, and its harbors be free from ice at best only in summer. The power and prosperity of its coasts would shrivel under the breath of winter, as a medusa thrown on sh.o.r.e shrinks to an insignificant film under the influence of the destructive atmosphere. Commerce, industry, fertility of soil, population, would disappear, and the vast waste--a new Labrador--would become a worthless appendage of some clime more favored by nature."--HARTWIG, _Das Leben des Meeres_, p. 70.

[483] I know nothing of Captain Allen's work but its t.i.tle and its subject. Very probably he may have antic.i.p.ated many of the following speculations, and thrown light on points upon which I am ignorant.

[484] "Some haue writt[=e], that by certain kings inhabiting aboue, the _Nilus_ should there be stopped; & at a time prefixt, let loose vpon a certaine tribute payd them by the _Aegyptians_. The error springing perhaps fr[=o] a truth (as all wandring reports for the most part doe) in that the _Sultan_ doth pay a certaine annuall summe to the _Abissin_ Emperour for not diuerting the course of the Riuer, which (they say) he may, or impouerish it at the least."--GEORGE SANDYS, _A Relation of a Journey, etc._, p. 98.

[485] The Recca, a river with a considerable current, has been satisfactorily identified with a stream flowing through the cave of Trebich, and with the Timavo--the Timavus of Virgil and the ancient geographers--which empties through several mouths into the Adriatic between Trieste and Aquileia. The distance from Trieste to a suitable point in the grotto of Trebich is thought to be less than three miles, and the difficulties in the way of constructing a tunnel do not seem formidable. The works of Schmidl, _Die Hohlen des Karstes_, and _Der unterirdische Lauf der Recca_, are not common out of Germany, but the reader will find many interesting facts derived from them in two articles ent.i.tled _Der unterirdische Lauf der Recca_, in _Aus der Natur_, xx, pp. 250-254, 263-266.

[486] BARTH, _Wanderungen durch die Kusten des Mittelmeeres_, i, p. 353.

In a note on page 380, of the same volume, Barth cites Strabo as a.s.serting that a similar practice prevailed in Iapygia; but it may be questioned whether the epithet [Greek: tracheia], applied by Strabo to the original surface, necessarily implies that it was covered with a continuous stratum of rock.

[487] PARTHEY, _Wanderungen durch Sicilien und die Levante_, i, p. 404.

[488] _Geognostische Studien am Meeres Ufer_, LEONHARD und BRONN, _Jahrbuch_, 1841, pp. 25, 26.

[489] KOHL, _Schleswig-Holstein_, ii, p. 45.

[490] _Wanderungen durch Sicilien und die Levante_, i, p. 406.

[491] LANDGREBE, _Naturgeschichte der Vulkane_, ii, pp. 19, 20.

[492] Soon after the current issues from the volcano, it is covered above and at its sides, and finally in front, with scoriae, formed by the cooling of the exposed surface, which bury and conceal the fluid ma.s.s.

The stream rolls on under the coating, and between the walls of scoriae, and it was the lateral crust which was broken through by the workmen mentioned in the text.

The distance to which lava flows, before its surface begins to solidify, depends on its volume, its composition, its temperature and that of the air, the force with which it is ejected, and the inclination of the declivity over which it runs. In most cases it is difficult to approach the current at points where it is still entirely fluid, and hence opportunities of observing it in that condition are not very frequent.

In the eruption of February, 1850, on the east side of Vesuvius, I went quite up to one of the outlets. The lava shot out of the orifice upward with great velocity, like the water from a spring, in a stream eight or ten feet in diameter, throwing up occasionally volcanic bombs, but it immediately spread out on the declivity down which it flowed, to the width of several yards. It continued red hot in broad daylight, and without a particle of scoriae on its surface, for a course of at least one hundred yards. At this distance, the suffocating, sulphurous vapors became so dense that I could follow the current no farther. The undulations of the surface were like those of a brook swollen by rain. I estimated the height of the waves at five or six inches by a breadth of eighteen or twenty. To the eye, the fluidity of the lava seemed as perfect as that of water, but ma.s.ses of cold lava weighing ten or fifteen pounds floated upon it like cork.

The heat emitted by lava currents seems extremely small when we consider the temperature required to fuse such materials and the great length of time they take in cooling. I saw at Nicolosi ancient oil jars, holding a hundred gallons or more, which had been dug out from under a stream of old lava above that town. They had been very slightly covered with volcanic ashes before the lava flowed over them, but the lead with which holes in them had been plugged was not melted. The current that buried Mompiliere in 1669 was thirty-five feet thick, but marble statues, in a church over which the lava formed an arch, were found uncalcined and uninjured in 1704. See SCROPE, _Volcanoes_, chap. VI. -- 6.

[493] FERRARA, _Descrizione dell' Etna_, p. 108.

[494] LANGREBE, _Naturgeschichte der Vulkane_, ii, p. 82.

[495] _Physikalische Geographie_, p. 168. Beds of peat, accidentally set on fire, sometimes continue to burn for months. I take the following account of a case of this sort from a recent American journal:

"A CURIOUS PHENOMENON.--When the track of the railroad between Brunswick and Bath was being graded, in crossing a meadow near the populous portion of the latter city, the 'dump' suddenly took on a sinking symptom, and down went the twenty feet fill of gravel, clay, and broken rocks, out of sight, and it was a long, _long_ time before dirt trains could fill the capacious stomach that seemed ready to receive all the solid material that could be turned into it. The difficulty was at length overcome, but all along the side of the sinkage the earth was thrown up, broken into yawning chasms, and the surface was thus elevated above its old watery level. Since that time this ground, thus slightly elevated, has been cultivated, and has yielded enormously of whatever the owner seemed disposed to plant upon it. Some three months ago, by some means unknown to us, the underlying peat took fire, and for weeks, as we had occasion to pa.s.s it, we noticed the smoke arising from the smouldering combustion beneath the surface. Rains fell, but the fire burned, and the smoke continued to arise. Monday we had occasion to pa.s.s the spot, and though nearly a week's rain had been drenching the ground, and though the surface was whitened with snow, and though pools of water were standing upon the surface in the immediate neighborhood, still the everlasting subterranean fire was burning, and the smoke arising through the snow."

[496] One of the sublimest, and at the same time most fearful suggestions that have been prompted by the researches of modern science, was made by Babbage in the ninth chapter of his _Ninth Bridgewater Treatise_. I have not the volume at hand, but the following explanation will recall to the reader, if it does not otherwise make intelligible, the suggestion I refer to.

No atom can be disturbed in place, or undergo any change of temperature, of electrical state, or other material condition, without affecting, by attraction or repulsion or other communication, the surrounding atoms.

These, again, by the same law, transmit the influence to other atoms, and the impulse thus given extends through the whole material universe.

Every human movement, every organic act, every volition, pa.s.sion, or emotion, every intellectual process, is accompanied with atomic disturbance, and hence every such movement, every such act or process affects all the atoms of universal matter. Though action and reaction are equal, yet reaction does not restore disturbed atoms to their former place and condition, and consequently the effects of the least material change are never cancelled, but in some way perpetuated, so that no action can take place in physical, moral, or intellectual nature, without leaving all matter in a different state from what it would have been if such action had not occurred. Hence, to use language which I have employed on another occasion: there exists, not alone in the human conscience or in the omniscience of the Creator, but in external material nature, an ineffaceable, imperishable record, possibly legible even to created intelligence, of every act done, every word uttered, nay, of every wish and purpose and thought conceived by mortal man, from the birth of our first parent to the final extinction of our race; so that the physical traces of our most secret sins shall last until time shall be merged in that eternity of which not science, but religion alone, a.s.sumes to take cognizance.

APPENDIX.

No. 1 (page 19, _note_). It may be said that the cases referred to in the note on p. 19--and indeed all cases of a supposed acclimation consisting in physiological changes--are instances of the origination of new varieties by natural selection, the hardier maize, tomato, and other vegetables of the North, being the progeny of seeds of individuals endowed, exceptionally, with greater power of resisting cold than belongs in general to the species which produced them. But, so far as the evidence of change of climate, from a difference in vegetable growth, is concerned, it is immaterial whether we adopt this view or maintain the older and more familiar doctrine of a local modification of character in the plants in question.

No. 2 (page 24, _note_). The adjectives of direction in _-erly_ are not unfrequently used to indicate, in a loose way, the course of winds blowing from unspecified points between N.E. and S.E.; S.E. and S.W.; S.W. and N.W. or N.W. and N.E. If the employment of these words were understood to be limited to thus expressing a direction nearer to the cardinal point from whose name the adjective is taken than to any other cardinal point, they would be valuable elements of English meteorological nomenclature.

No. 3 (page 31). I find a confirmation of my observations on the habits of the beaver as a geographical agency, in a report of the proceedings of the British a.s.sociation, in the London Athenaeum of October 8, 1864, p. 469. It is there stated that Viscount Milton and Dr. Cheadle, in an expedition across the Rocky Mountains by the Yellow Head, or Leather Pa.s.s, observed that "a great portion of the country to the east of the mountains" had been "completely changed in character by the agency of the beaver, which formerly existed here in enormous numbers. The shallow valleys were formerly traversed by rivers and chains of lakes which, dammed up along their course at numerous points, by the work of those animals, have become a series of marshes in various stages of consolidation. So complete has this change been, that hardly a stream is found for a distance of two hundred miles, with the exception of the large rivers. The animals have thus destroyed, by their own labors, the waters necessary to their own existence."

When the process of "consolidation" shall have been completed, and the forest reestablished upon the marshes, the water now diffused through them will be collected in the lower or more yielding portions, cut new channels for their flow, become running brooks, and thus restore the ancient aspect of the surface.

No. 4 (page 33, _note_). The lignivorous insects that attack living trees almost uniformly confine their ravages to trees already unsound or diseased in growth from the depredations of leaf-eaters, such as caterpillars and the like, or from other causes. The decay of the tree, therefore, is the cause not the consequence of the invasions of the borer. This subject has been discussed by Perris in the _Annales de la Societe Entomologique de la France_, for 1851 (?), and his conclusions are confirmed by the observations of Samanos, who quotes, at some length, the views of Perris. "Having, for fifteen years," says the latter author, "incessantly studied the habits of lignivorous insects in one of the best wooded regions of France, I have observed facts enough to feel myself warranted in expressing my conclusions, which are: that insects in general--I am not speaking of those which confine their voracity to the leaf--do not attack trees in sound health, and they a.s.sail those only whose normal conditions and functions have been by some cause impaired."

See, more fully, Samanos, _Traite de la Culture du Pin Maritime_, Paris, 1864, pp. 140-145.

No. 5 (page 34, _note_). Very interesting observations, on the agency of the squirrel and other small animals in planting and in destroying nuts and other seeds of trees, may be found in a paper on the Succession of Forests in Th.o.r.eau's _Excursions_, pp. 135 _et seqq._

I once saw several quarts of beech-nuts taken from the winter quarters of a family of flying squirrels in a hollow tree. The kernels were neatly stripped of their sh.e.l.ls and carefully stored in a dry cavity.

No. 6 (page 40, _note_). Schroeder van der Kolk, in _Het Verschil tusschen den Psychischen Aanleg van het Dier en van den Mensch_, cites from Burdach and other authorities many interesting facts respecting instincts lost, or newly developed and become hereditary, in the lower animals, and he quotes Aristotle and Pliny as evidence that the common quadrupeds and fowls of our fields and our poultry yards were much less perfectly domesticated in their times than long, long ages of servitude have now made them.

Perhaps the half-wild character ascribed by P. Laestadius and other Swedish writers to the reindeer of Lapland, may be in some degree due to the comparative shortness of the period during which he has been partially tamed. The domestic swine bred in the woods of Hungary and the buffaloes of Southern Italy are so wild and savage as to be very dangerous to all but their keepers. The former have relapsed into their original condition, the latter have not yet been reclaimed from it.

Among other instances of obliterated instincts, Schroeder van der Kolk states that in Holland, where, for centuries, the young of the cow has been usually taken from the dam at birth and fed by hand, calves, even if left with the mother, make no attempt to suck; while in England, where calves are not weaned until several weeks old, they resort to the udder as naturally as the young of wild quadrupeds.--_Ziel en Ligchaam_, p. 128, _n._