Complete Works of Robert Louis Stevenson (Illustrated) (878 page)

To recapitulate:

1st. We find that single trees appear to act simply as bad conductors.

2nd. We find that woods, regarded as solids, are, on the whole, slightly lower in temperature than the free air which they have displaced, and that they tend slowly to adapt themselves to the various thermal changes that take place without them.

3rd. We find forests regarded as surfaces acting like any other part of the earth’s surface, probably with more or less difference in amount and progression, which we still lack the information necessary to estimate.

All this done, I am afraid that there can be little doubt that the more general climatic investigations will be long and vexatious. Even in South America, with extremely favourable conditions, the result is far from being definite. Glancing over the table published by M. Becquerel in his book on climates, from the observations of Humboldt, 235 Hall, Boussingault, and others, it becomes evident, I think, that nothing can be founded upon the comparisons therein instituted; that all reasoning, in the present state of our information, is premature and unreliable. Strong statements have certainly been made; and particular cases lend themselves to the formation of hasty judgments. “From the Bay of Cupica to the Gulf of Guayaquil,” says M. Boussingault, “the country is covered with immense forest and traversed by numerous rivers; it rains there almost ceaselessly; and the mean temperature of this moist district scarcely reaches 78.8° F.... At Payta commence the sandy deserts of Priura and Sechura; to the constant humidity of Choco succeeds almost at once an extreme of dryness; and the mean temperature of the coast increases at the same time by 1.8° F.” Even in this selected favourable instance it might be argued that the part performed in the change by the presence or absence of forest was comparatively small; there seems to have been, at the same time, an entire change of soil; and, in our present ignorance, it would be difficult to say by how much this of itself is able to affect the climate. Moreover, it is possible that the humidity of the one district is due to other causes besides the presence of wood, or even that the presence of wood is itself only an effect of some more general difference or combination of differences. Be that as it may, however, we have only to look a little longer at the table before referred to, to see how little weight can be laid on such special instances. Let us take five stations, all in this very district of Choco. Hacquita is eight hundred and twenty feet above Novita, and their mean temperatures are the same. Alto de Mombu, again, is five hundred feet higher than Hacquita, and the mean temperature has here fallen nearly two degrees. Go up another five hundred feet to Tambo de la Orquita, and again we find no fall in the mean temperature. Go up some five hundred further to Chami, and there is a fall in the mean temperature of nearly 236 six degrees. Such numbers are evidently quite untrustworthy; and hence we may judge how much confidence can be placed in any generalisation from these South American mean temperatures.

The question is probably considered too simply — too much to the neglect of concurrent influences. Until we know, for example, somewhat more of the comparative radiant powers of different soils, we cannot expect any very definite result. A change of temperature would certainly be effected by the plantation of such a marshy district as the Sologne, because, if nothing else were done, the roots might pierce the impenetrable subsoil, allow the surface-water to drain itself off, and thus dry the country. But might not the change be quite different if the soil planted were a shifting sand, which,
fixed
by the roots of the trees, would become gradually covered with a vegetable earth, and be thus changed from dry to wet? Again, the complication and conflict of effects arises, not only from the soil, vegetation, and geographical position of the place of the experiment itself, but from the distribution of similar or different conditions in its immediate neighbourhood, and probably to great distances on every side. A forest, for example, as we know from Herr Rivoli’s comparison, would exercise a perfectly different influence in a cold country subject to warm winds, and in a warm country subject to cold winds; so that our question might meet with different solutions even on the east and west coasts of Great Britain.

The consideration of such a complexity points more and more to the plantation of Malta as an occasion of special importance; its insular position and the unity of its geological structure both tend to simplify the question. There are certain points about the existing climate, moreover, which seem specially calculated to throw the influence of woods into a strong relief. Thus, during four summer months, there is practically no rainfall. Thus, again, the northerly winds when stormy, and especially in winter, tend to depress the temperature very suddenly; and thus, 237 too, the southerly and south-westerly winds, which raise the temperature during their prevalence to from eighty-eight to ninety-eight degrees, seldom last longer than a few hours; insomuch that “their disagreeable heat and dryness may be escaped by carefully closing the windows and doors of apartments at their onset.” Such sudden and short variations seem just what is wanted to accentuate the differences in question. Accordingly, the opportunity seems one not lightly to be lost, and the British Association or this Society itself might take the matter up and establish a series of observations, to be continued during the next few years. Such a combination of favourable circumstances may not occur again for years; and when the whole subject is at a standstill for want of facts, the present occasion ought not to go past unimproved.

Such observations might include the following: —

The observation of maximum and minimum thermometers in three different classes of situation —
videlicet
, in the areas selected for plantation themselves, at places in the immediate neighbourhood of those areas where the external influence might be expected to reach its maximum, and at places distant from those areas where the influence might be expected to be least.

The observation of rain-gauges and hygrometers at the same three descriptions of locality.

In addition to the ordinary hours of observation, special readings of the thermometers should be made as often as possible at a change of wind and throughout the course of the short hot breezes alluded to already, in order to admit of the recognition and extension of Herr Rivoli’s comparison.

Observation of the periods and forces of the land and sea breezes.

Gauging of the principal springs, both in the neighbourhood of the areas of plantation and at places far removed from those areas.

1873.

 Read before the Royal Society, Edinburgh, 19th May 1873, and reprinted from the
Proceedings
R.S.E.

 
Jour. Scot. Met. Soc.
, New Ser. xxvi. 35.

 Quoted by Mr. Milne Home.

 
Atlas Météorologique de l’Observatoire Impérial
, 1867.

 
Comptes Rendus de l’Académie
, 29th March 1869.

 Professor Balfour’s “Class Book of Botany,” Physiology, chap. xii., .

 
Comptes Rendus
, 1867 and 1869.

 See his paper.

 
Annales de Chimie et de Physique
, xlv., 1830. A more detailed comparison of the climates in question would be a most interesting and important contribution to the subject.

 Reviewed in the
Austrian Meteorological Magazine
, vol. iv.; .

 
Comptes Rendus
, 28th May 1860.

 
Ibid.
, 20th May 1861.

 Becquerel, “Climats,” .

 Scoresby-Jackson’s “Medical Climatology.” 

ESSAYS OF TRAVEL

I

DAVOS IN WINTER

A mountain valley has, at the best, a certain prison-like effect on the imagination, but a mountain valley, an Alpine winter, and an invalid’s weakness make up among them a prison of the most effective kind. The roads indeed are cleared, and at least one footpath dodging up the hill; but to these the health-seeker is rigidly confined. There are for him no cross-cuts over the field, no following of streams, no unguided rambles in the wood. His walks are cut and dry. In five or six different directions he can push as far, and no farther, than his strength permits; never deviating from the line laid down for him and beholding at each repetition the same field of wood and snow from the same corner of the road. This, of itself, would be a little trying to the patience in the course of months; but to this is added, by the heaped mantle of the snow, an almost utter absence of detail and an almost unbroken identity of colour. Snow, it is true, is not merely white. The sun touches it with roseate and golden lights. Its own crushed infinity of crystals, its own richness of tiny sculpture, fills it, when regarded near at hand, with wonderful depths of coloured shadow, and, though wintrily transformed, it is still water, and has watery tones of blue. But, when all is said, these fields of white and blots of crude black forest are but a trite and staring substitute for the infinite variety and pleasantness of the earth’s face. Even a boulder, whose front is too 242 precipitous to have retained the snow, seems, if you come upon it in your walk, a perfect gem of colour, reminds you almost painfully of other places, and brings into your head the delights of more Arcadian days — the path across the meadow, the hazel dell, the lilies on the stream, and the scents, the colours, and the whisper of the woods. And scents here are as rare as colours. Unless you get a gust of kitchen in passing some hotel, you shall smell nothing all day long but the faint and choking odour of frost. Sounds, too, are absent: not a bird pipes, not a bough waves, in the dead, windless atmosphere. If a sleigh goes by, the sleigh-bells ring, and that is all; you work all winter through to no other accompaniment but the crunching of your steps upon the frozen snow.

It is the curse of the Alpine valleys to be each one village from one end to the other. Go where you please, houses will still be in sight, before and behind you, and to the right and left. Climb as high as an invalid is able, and it is only to spy new habitations nested in the wood. Nor is that all; for about the health resort the walks are besieged by single people walking rapidly with plaids about their shoulders, by sudden troops of German boys trying to learn to jödel, and by German couples silently and, as you venture to fancy, not quite happily, pursuing love’s young dream. You may perhaps be an invalid who likes to make bad verses as he walks about. Alas! no muse will suffer this imminence of interruption — and at the second stampede of jödellers you find your modest inspiration fled. Or you may only have a taste for solitude; it may try your nerves to have some one always in front whom you are visibly overtaking, and some one always behind who is audibly overtaking you, to say nothing of a score or so who brush past you in an opposite direction. It may annoy you to take your walks and seats in public view. Alas! there is no help for it among the Alps. There are no recesses, as in Gorbio Valley by the oil-mill; no sacred solitude of olive gardens on the Roccabruna-road; 243 no nook upon St. Martin’s Cape, haunted by the voice of breakers, and fragrant with the three-fold sweetness of the rosemary and the sea-pines and the sea.

For this publicity there is no cure, and no alleviation; but the storms of which you will complain so bitterly while they endure, chequer and by their contrast brighten the sameness of the fair-weather scenes. When sun and storm contend together — when the thick clouds are broken up and pierced by arrows of golden daylight — there will be startling rearrangements and transfigurations of the mountain summits. A sun-dazzling spire of alp hangs suspended in mid-sky among awful glooms and blackness; or perhaps the edge of some great mountain shoulder will be designed in living gold, and appear for the duration of a glance bright like a constellation, and alone “in the unapparent.” You may think you know the figure of these hills; but when they are thus revealed, they belong no longer to the things of earth — meteors we should rather call them, appearances of sun and air that endure but for a moment and return no more. Other variations are more lasting, as when, for instance, heavy and wet snow has fallen through some windless hours, and the thin, spiry mountain pine-trees stand each stock-still and loaded with a shining burthen. You may drive through a forest so disguised, the tongue-tied torrent struggling silently in the cleft of the ravine, and all still except the jingle of the sleigh bells, and you shall fancy yourself in some untrodden northern territory — Lapland, Labrador, or Alaska.

Or, possibly, you arise very early in the morning; totter down-stairs in a state of somnambulism; take the simulacrum of a meal by the glimmer of one lamp in the deserted coffee-room; and find yourself by seven o’clock outside in a belated moonlight and a freezing chill. The mail sleigh takes you up and carries you on, and you reach the top of the ascent in the first hour of the day. To trace the fires of the sunrise as they pass from peak to peak, to see the unlit tree-tops stand out soberly against the lighted sky, 244 to be for twenty minutes in a wonderland of clear, fading shadows, disappearing vapours, solemn blooms of dawn, hills half glorified already with the day and still half confounded with the greyness of the western heaven — these will seem to repay you for the discomforts of that early start; but as the hour proceeds, and these enchantments vanish, you will find yourself upon the farther side in yet another Alpine valley, snow white and coal black, with such another long-drawn congeries of hamlets and such another senseless watercourse bickering along the foot. You have had your moment; but you have not changed the scene. The mountains are about you like a trap; you cannot foot it up a hillside and behold the sea as a great plain, but live in holes and corners, and can change only one for another.

II

HEALTH AND MOUNTAINS

There has come a change in medical opinion, and a change has followed in the lives of sick folk. A year or two ago and the wounded soldiery of mankind were all shut up together in some basking angle of the Riviera, walking a dusty promenade or sitting in dusty olive-yards within earshot of the interminable and unchanging surf — idle among spiritless idlers not perhaps dying, yet hardly living either, and aspiring, sometimes fiercely, after livelier weather and some vivifying change. These were certainly beautiful places to live in, and the climate was wooing in its softness. Yet there was a later shiver in the sunshine; you were not certain whether you were being wooed; and these mild shores would sometimes seem to you to be the shores of death. There was a lack of a manly element; the air was not reactive; you might write bits of poetry 245 and practise resignation, but you did not feel that here was a good spot to repair your tissue or regain your nerve. And it appears, after all, that there was something just in these appreciations. The invalid is now asked to lodge on wintry Alps; a ruder air shall medicine him; the demon of cold is no longer to be fled from, but bearded in his den. For even Winter has his “dear domestic cave,” and in those places where he may be said to dwell for ever tempers his austerities.