Part 42 (2/2)
No. 28 (page 231, _note_). In a remarkable pamphlet, to which I shall have occasion to refer more than once hereafter, ent.i.tled _Avant-projet pour la creation d'un sol fertile a la surface des Landes de Gascogne_, Duponchel argues with much force, that the fertilizing properties of river-slime are generally due much more to its mineral than to its vegetable const.i.tuents.
No. 29 (page 265, _note_). Even the denser silicious stones are penetrable by fluids and the coloring matter they contain, to such an extent that agates and other forms of silex may be artificially stained through their substance. This art was known to and practised by the ancient lapidaries, and it has been revived in recent times.
No. 30 (page 268). There is good reason for thinking that many of the earth and rock slides in the Alps occurred at an earlier period than the origin of the forest vegetation which, in later ages, covered the flanks of those mountains. See _Bericht uber die Untersuchung der Schweizerischen Hochgebirgswaldungen_. 1862. P. 61.
Where more recent slides have been again clothed with woods, the trees, shrubs, and smaller plants which spontaneously grow upon them are usually of different species from those observed upon soil displaced at remote periods. This difference is so marked that the site of a slide can often be recognized at a great distance by the general color of the foliage of its vegetation.
No. 31 (page 286, _note_). It should have been observed that the venomous principle of poisonous mushrooms is not decomposed and rendered innocent by the process described in the _note_. It is merely extracted by the acidulated or saline water employed for soaking the plants, and care should be taken that this water be thrown away out of the reach of mischief.
No. 32 (page 293, _note_). Gaudry estimates the ties employed in the railways of France at thirty millions, to supply which not less than two millions of large trees have been felled. These ties have been, upon the average, at least once renewed, and hence we must double the number of ties and of trees required to furnish them.--_Revue des Deux Mondes_, 15 July, 1863, p. 425.
No. 33 (page 294, _second paragraph of note_). After all, the present consumption of wood and timber for fuel and other domestic and rural purposes, in many parts of Europe, seems incredibly small to an American. In rural Switzerland, the whole supply of firewood, fuel for small smitheries, dairies, breweries, brick and lime kilns, distilleries, fences, furniture, tools, and even house building--exclusive of the small quant.i.ty derived from the tr.i.m.m.i.n.gs of fruit trees, grape vines and hedges, and from decayed fences and buildings--does not exceed an average of _two hundred and thirty cubic feet_, or less than two cords, a year per household. The average consumption of wood in New England for domestic fuel alone, is from five to ten times as much as Swiss families require for all the uses above enumerated. But the existing habitations of Switzerland are sufficient for a population which increases but slowly, and in the peasants' houses but a single room is usually heated. See _Bericht uber die Untersuchung der Schweiz. Hochgebirgswaldungen_, pp. 85-89.
No. 34 (page 304). Among more recent manuals may be mentioned: _Les etudes de Maitre Pierre._ Paris, 1864. 12mo; BAZELAIRE, _Traite de Rebois.e.m.e.nt_. 2d edition, Paris, 1864; and, in Italian, SIEMONI, _Manuale teorico-pratico d'arte Forestale_. Firenze, 1864. 8vo. A very important work has lately been published in France by Viscount de Courval, which is known to me only by a German translation published at Berlin, in 1864, under the t.i.tle, _Das Aufasten der Waldbaume_. The princ.i.p.al feature of De Courval's very successful system of sylviculture, is a mode of tr.i.m.m.i.n.g which compels the tree to develop the stem by reducing the lateral ramification. Beginning with young trees, the buds are rubbed off from the stems, and superfluous lateral shoots are pruned down to the trunk. When large trees are taken in hand, branches which can be spared, and whose removal is necessary to obtain a proper length of stem, are very smoothly cut off quite close to the trunk, and the exposed surface is _immediately_ brushed over with mineral-coal tar. When thus treated, it is said that the healing of the wound is perfect, and without any decay of the tree.
No. 35 (page 313). The most gorgeous autumnal coloring I have observed in the vegetation of Europe, has been in the valleys of the Durance and its tributaries in Dauphiny. I must admit that neither in variety nor in purity and brilliancy of tint, does this coloring fall much, if at all, short of that of the New England woods. But there is this difference: in Dauphiny, it is only in small shrubs that this rich painting is seen, while in North America the foliage of large trees is dyed in full splendor. Hence the American woodland has fewer broken lights and more of what painters call breadth of coloring. Besides this, the arrangement of the leaf.a.ge in large globular or conical ma.s.ses, affords a wider scale of light and shade, thus aiding now the gradation, now the contrast of tints, and gives the American October landscape a softer and more harmonious tone than marks the humble shrubbery of the forest hill-sides of Dauphiny.
Th.o.r.eau--who was not, like some very celebrated landscape critics of the present day, an outside spectator of the action and products of natural forces, but, in the old religious sense, an _observer_ of organic nature, living, more than almost any other descriptive writer, among and with her children--has a very eloquent paper on the ”Autumnal Tints” of the New England landscape.--See his _Excursions_, pp. 215 _et seqq._
Few men have personally noticed so many facts in natural history accessible to unscientific observation as Th.o.r.eau, and yet he had never seen that very common and striking spectacle, the phosph.o.r.escence of decaying wood, until, in the latter years of his life, it caught his attention in a bivouac in the forests of Maine. He seems to have been more excited by this phenomenon than by any other described in his works. It must be a capacious eye that takes in all the visible facts in the history of the most familiar natural object.--_The Maine Woods_, p.
184.
”The luminous appearance of bodies projected against the sky adjacent to the rising” or setting sun, so well described in Professor Necker's Letter to Sir David Brewster, is, as Tyndall observes, ”hardly ever seen by either guides or travellers, though it would seem, _prima facie_, that it must be of frequent occurrence.” See TYNDALL, _Glaciers of the Alps_. Part I. Second ascent of Mont Blanc.
Judging from my own observation, however, I should much doubt whether this brilliant phenomenon can be so often seen in perfection as would be expected; for I have frequently sought it in vain at the foot of the Alps, under conditions apparently otherwise identical with those where, in the elevated Alpine valleys, it shows itself in the greatest splendor.
No. 36 (page 314). European poets, whose knowledge of the date palm is not founded on personal observation, often describe its trunk as not only slender, but particularly _straight_. Nothing can be farther from the truth. When the Orientals compare the form of a beautiful girl to the stem of the palm, they do not represent it as rigidly straight, but on the contrary as made up of graceful curves, which seem less like permanent outlines than like flowing motion. In a palm grove, the trunks, so far from standing planted upright like the candles of a chandelier, bend in a vast variety of curves, now leaning towards, now diverging from, now crossing, each other, and among a hundred you will hardly see two whose axes are parallel.
No. 37 (page 316, _first note_). Charles Martin ascribes the power of reproduction by shoots from the stump to the cedar of Mount Atlas, which appears to be identical with the cedar of Lebanon.--_Revue des Deux Mondes_, 15 July, 1864, p. 315.
No. 38 (page 332). In an interesting article on recent internal improvements in England, in the London Quarterly Review for January, 1858, it is related that in a single rock cutting on the Liverpool and Manchester railway, 480,000 cubic yards of stone were removed; that the earth excavated and removed in the construction of English railways up to that date, amounted to a hundred and fifty million cubic yards, and that at the Round Down Cliff, near Dover, a single blast of nineteen thousand pounds of powder blew down a thousand million tons of chalk, and covered fifteen acres of land with the fragments.
No. 39 (page 339). According to Reventlov, whose work is one of the best sources of information on the subject of diking-in tide-washed flats, _Salicornia herbacea_ appears as soon as the flat is raised high enough to be dry for three hours at ordinary ebb tide, or, in other words, where the ordinary flood covers it to a depth of not more than two feet.
At a flood depth of one foot, the _Salicornia_ dies and is succeeded by various sand plants. These are followed by _Poa distans_ and _Poa maritima_ as the ground is raised by further deposits, and these plants finally by common gra.s.ses. The _Salicornia_ is preceded by _confervae_, growing in deeper water, which spread over the bottom, and when covered by a fresh deposit of slime reappear above it, and thus vegetable and alluvial strata alternate until the flat is raised sufficiently high for the growth of _Salicornia_.--_Om Marskdannelsen paa Vestkysten af Hertugdommet Slesvig_, pp. 7, 8.
No. 40 (page 348, _note_). The drijftil employed for the ring dike of the Lake of Haarlem, was in part cut in sections fifty feet long by six or seven wide, and these were navigated like rafts to the spot where they were sunk to form the dike.--EMILE DE LAVELEYE, _Revue des Deux Mondes_, 15 Sept., 1863, p. 285.
No. 41 (page 352, _last paragraph_). See on the influence of the improvements in question on tidal and other marine currents, Staring, _De Bodem van Nederland_, I. p. 279.
Although the dikes of the Netherlands and the adjacent states have protected a considerable extent of coast from the encroachments of the sea, and have won a large tract of cultivable land from the dominion of the waters, it has been questioned whether a different method of accomplis.h.i.+ng these objects might not have been adopted with advantage.
It has been suggested that a system of inland dikes and ca.n.a.ls, upon the principle of those which, as will be seen in a subsequent part of the chapter on the waters, have been so successfully employed in the Val di Chiana and in Egypt, might have elevated the low grounds above the ocean tides, by spreading over them the sediment brought down by the Rhine, the Maes, and the Scheld. If this process had been introduced in the Middle Ages and constantly pursued to our times, the superficial and coast geography, as well as the hydrography of the countries in question, would undoubtedly have presented an aspect very different from their present condition; and by combining the process with a system of maritime dikes, which would have been necessary, both to resist the advance of the sea and to retain the slime deposited by river overflows, it is possible that the territory of those states would have been as extensive as it now is, and, at the same time, more elevated by several feet. But it must be borne in mind that we do not know the proportions in which the marine deposits that form the polders have been derived from materials brought down by these rivers or from other more remote sources. Much of the river slime has no doubt been transported by marine currents quite beyond the reach of returning streams, and it is uncertain how far this loss has been balanced by earth washed by the sea from distant sh.o.r.es and let fall on the coasts of the Netherlands and other neighboring countries.
We know little or nothing of the quant.i.ty of solid matter brought down by the rivers of Western Europe in early ages, but, as the banks of those rivers are now generally better secured against wash and abrasion than in former centuries, the sediment transported by them must be less than at periods nearer the removal of the primitive forests of their valleys. Kloden states the quant.i.ty of sedimentary matter now annually brought down by the Rhine at Bonn to be sufficient only to cover a square English mile to the depth of a little more than a foot.--_Erdkunde_, I. p. 384.
No. 42 (page 358, _first paragraph_). Meteorological observations have been regularly recorded at Zwanenburg, near the north end of the Lake of Haarlem, for more than a century, and since 1845 a similar register has been kept at the Helder, forty or fifty miles farther north. In comparing these two series of observations, it is found that about the end of the year 1852, when the drawing off of the waters of the Lake of Haarlem was completed, and the preceding summer had dried the grounds laid bare so as greatly to reduce the evaporable surface, a change took place in the relative temperature of the two stations. Taking the mean of every successive period of five days from 1845 to 1852, the temperature at Zwanenburg was thirty-three hundredths of a centigrade degree _lower_ than at the Helder. Since the end of 1852, the thermometer at Zwanenburg has stood, from the 11th of April to the 20th of September inclusive, twenty-two hundredths of a degree _higher_ than at the Helder, but from the 14th of October to the 17th of March, it has averaged one-tenth of a degree _lower_ than its mean between the same dates before 1853.
There is no reasonable doubt that these differences are due to the draining of the lake. There has been less refrigeration from evaporation in summer, and the ground has absorbed more solar heat at the same period, while in the winter it has radiated more warmth then when it was covered with water. Doubtless the quant.i.ty of humidity contained in the atmosphere has also been affected by the same cause, but observations do not appear to have been made on that point. See KRECKE, _Het Klimaat van Nederland_, II. 64.
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