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IMAGINARY CHANGES OF CLIMATE.
(Pall Mall Gazette.)
THREE consecutive years of drought, while they have stimulated the inventive resources of practical agriculturists, have had the natural effect of calling forth a plentiful crop of specu- lation from weather prophets and projectors, and half-instructed meteorologists, and all the philosophic tribe of Laputa in general, to whom the periodical press now affords such fatal facilities. We have often noticed that in the tabular statements of those compilers of weather records who write to the Times, useful and welcome as their communications are, every season is sure to be "extraordinary," almost every month one of the driest or wettest, or windiest, coldest or hottest, ever known. Much observation, which ought to correct a tendency to exaggerate, seems in some minds to have rather a tendency to increase it. And many seem now to regard three dry hot years in succession as betokening some general change of climate, as if it was not perfectly certain, in the wide range of the table of what we call chances, that with our existing conditions
of climate such a combination must every now and then recur. We know an ingenious theorist who would fain persuade us that a cycle of six hundred unfavorable years has just reached its termination, and that English agriculturists, who left off making wine about A.D. 1250 because their grapes ceased to ripen, will soon be making it again, and continue to do so for an equivalent number of centuries. Others speculating quite as conjecturally and even more absurdly, seem to attubute the impending change of climate -of which they assume the reality -to the operation of men. They fancy that by extended drainage and the cutting down of trees the amount of rainfall may have been diminished. As to drainage, it may suffice to remember that our rain is derived from the evaporation of the Atlantic, and is not likely to be affected by the diminution of that which proceeds from a few swamps. As to the effects of cutting down trees, the subject has been made so much of in recent times that it requires to be treated more respectfully. Yet there are two consider- ations which militate against the theory, the first relative to its application to England, the second to the doctrine in general. As to the first, it may be greatly questioned whether there has been for some generations past any diminution of our tree covered surface. There is a balance of gain and loss. Some woods have been felled. Some districts, once rich in hedge-row timber, have been partially stripped for reasons of scientific agriculture. But, on the other hand, the Englishman's passion for plant- ing and for preserving timber has been steadily at work in the contrary direction. Take the neighborhood of London for an instance ; any of us who are old enough may remember how scarcely more than a generation ago, the specta- tor from any height commanding an extensive prospect would note great bare tracts of heath, of cultivated but unenclosed land, and of re-
cently enclosed common with low treeless hedges. All this is altered now. Go where you will for a view in the "home counties," a sea of leaves seems to extend around on every side. And we believe that most people, if they consult their experience, will make the same report of the parts of the kingdom with which they are acquainted. The local authorities who have been lately bestirring themselves to pre- vent disforesting of the New Forest, on the ground of apprehending deficiency of rain, are certainly indulging in very imaginative apprehensions.
But in the next place, what real ground is there for connecting together, in temperate climates at all events, the presence of forests and the frequency of rain as cause and effect ? The assertion is so commonly made that to doubt its truth seems almost like contradict- ing a received physical fact. And yet it will be found on examination that it really rests on no solid foundation either of reasoning or experience. The question is a procès jugé et pas plaidé. As for the reason of the supposi-
tion, none whatever has been assigned, so far as we are aware, except that a surface shaded with woods is somewhat cooler than one de- nuded of it, and therefore likelier to attract the passing shower. How far this may be true it would be difficult to verify, or whether a hun- dred acres covered with wood really present a cooler area than if covered with turnips or other vegetation ; but the effect of such a cause as this must be very limited at any time, and (which is more important) it can apply only at the warm season of the year. In winter, when a full half of our rainfall takes place, the "open" is notoriously cooler than the shaded surface, and therefore should, by the supposition,
attract more moisture. In cold countries-Can-
ada, for instance -the woodman can ply his trade in the sheltered interior of the forest when out of door work is completely suspen- ded in the cleared land by reason of extremity of cold. Supposing, therefore, the precipitation from the air to be in any degree affected by the presence or absence of forest covering, one- half of the year ought to balance the other.
In France the prevalence of the theory that the clearing of woodlands diminished rain was such, a few years ago, as almost to produce a panic among philosophers ; and in France the question could be tried experimentally with greater ease than here, because the surface of that country is more markedly divided between thick wood and bare fields than is the case with ours. Something meriting the name of obser- vation was, therefore, applied to the problem, and we believe we are right in saying that the result hitherto arrived at is altogether adverse to any connection between the alleged cause and effect. Rainfall cannot be shown to have diminished generally in France through the removal of forests, which in the last hundred years has been very extensive, nor can it be shown locally that rain has diminished where forests have been cut down. One experimen- talist compared for some years the meteoro- logy of two adjoining valleys in Burgundy, the one covered with wood, the other entirely bare, and found that less rain fell in the former. But observation of this kind must no doubt be far more extensive and more prolonged to be really valuable, and none such has been applied since this question began to be agitated.
Of course, this scepticism of ours does not in any degree touch the real and provable utility of forests in agricultural economy. It has not been shown that they increase the rainfall, nor any good reason given for supposing it, but they are of the greatest service in economising it. They preserve the fallen water, both by the percolation which takes place more readily on the soil shaded by them than on exposed sur- faces, and also by obstructing evaporation. They are most useful accessories both against flood and against drought. But under our English climate there is a contingency perhaps more injurious in the long run both to human health and the fruits of the earth than even flood or drought. This is the prevalence of damp, cold, sunless weather. Some suppose that an over- abundance of trees has a tendency to aggravate this particular evil. Certain it is that in the vicin- ity of that very New Forest, of which the main- tenance is now so strongly urged by some climatologers, a large number of the inhabit- ants who can afford it are apt to migrate in what they deem the unhealthy season -the fall of the leaf -and resort to a more bracing
and invigorating air.
Not only the effect of forest but the effect of modern field drainage requires to be established on far more accurate evidence than has as yet been obtained. We do not mean its effects on climate in the general sense, which we believe to be none at all, but on the preservation and distribution of water, on the permanent pro- ductiveness of the soil, and on human and animal health. These are questions of which we shall have to leave the scientific investiga- tion to those who may come after us ; for the present we seem likely to content ourselves with deductions from very narrow experience with very large conjecture and very confident assertion.
According to a note in the American Natura- list, the name " White Mountain" is naturally applied to the highest mountains in all coun- tries that being the signification of the names Himalaya, Mont Blanc, Hoemus, Sierra Nevada, Ben Nevis, Snowdon, Lebanon, Chimborazo, Illimani, and White Mountains.
Another Sensational Balloon Journey. -The Gazette, of Cambray, gives an account of the arrival at that place of the balloon Washington, and of the journey of the aero- nauts from Paris. The Washington left Paris at 7 o'clock on the morning of the 12th. It was under the care of the aeronaut Bertant, and also carried M. Lefaivre, an envoy, with despatches to Vienna, and M. Van Roose- bitche, a Belgian, whose specialty it is to rear and manage carrier pigeons. When the balloon ascended at Paris it stopped at 500 meters. At this elevation there was danger from the Prus- sian rifles, and soon, indeed, bullets were whistling past the ears of the travellers. Some even lodged in the balloon, which, causing it to sink lower, by no means diminished the danger. It was necessary to have recourse to extreme measures. All the sacks of ballast were thrown out, and the car rapidly rose from 1200 to 1500 metres. It then set at defiance the bull- ets, which fell short of it. But it was not yet out of reach of the balls sent after it. The wind rose and all danger seemed at an end. It was not so, however, for half an hour afterwards the ball- oon sank again. It hung over a town evidently occupied by the enemy for three-quarters of an hour, and was exposed to a continuous fire of musketry. Soon, however, a high wind from the south rose, and the balloon, whirl- ing about in a wild manner, was carried far out of reach of the enemy. It sank at last to within reach of the ground. This was near the railway station at Cambray. The aeronaut thought the moment favorable to throw out his grappling iron with its 400 metres of cable. While a high gale was blowing he un- wound rapidly the rope. The grappling iron was about to catch the ground, and had it done so the journey would have ended. But, no! The aeronaut was caught in the folds of the rope, which had got tangled, and he was dragged out of the car. He fell, and his death seemed certain, but by an incredible piece of good fortune he was entangled in the cable. He fell nearly 20 metres, yet strange to say, he had only a few slight bruises. The balloon, left to the direction of the two other travellers, con- tinued its course. The grappling irons caught the ground, and threw to one side both car and balloon. They continued on their course, striking against trees, which they broke in a shock against the ground. Another of the travellers, M. Lefaivre, was pitched out of the car. It remained occupied by the pigeon trainer only, who exhibited, however, the greatest coolness. Making use of the ropes which connected the car with the balloon, he climbed up to the latter and opened it with a knife. He pulled away large shreds from it, and at last it shrank and fell. Country people to the number of 200 then carne up, and it was stopped. The Belgian had not, how- ever, got to the end of his troubles. The peas- ants mistook him for a Prussian, and threaten- ed him with summary punishment. "Do with me whatever you like," he said, "but help, in the first instance, to save the despatches which I bring from Paris." These words were spoken in a tone which put an end to all alarm. Three- quarters of an hour afterwards all the three travellers were dining, and they were able to reach Cambray three hours later and convey to the Post-office the five enormous bags of despatches which they brought from Paris, weighing about 400 kilogrammes. The place at which this balloon came to the. ground was Avesnes, eight kilometres from Cambray.