Jan. 27, 1888.] 



SCIENTIFIC NE^A/S. 



THE USE OF FORESTS. 



SOME time back the world was of opinion that trees 

 were of value merely as supplies of timber, and 

 that where building materials could be easily imported a 

 country might, without any disadvantage, be laid en- 

 tirely bare. To be sure, a few far-seeing individuals, 

 such as Bernard Palissy, were aware of the influence 

 of woodlands as regulators of climate. Similar views 

 were taken in antiquity by Critias, who spoke vaguely of 

 the " sickness of the country in consequence of deforest- 

 ation," and in 1540 by Fernando Colon, who declared 

 that the rains in Madeira, the Azores, and the Canaries 

 had become rarer since the trees had been cut down. 



But, in spite of these warnings, the process of " clear- 

 ing " was carried on in most countries with reckless 

 haste. This havoc was not arrested until its conse- 

 quences were pointed out by Humboldt, Boussingault, 

 and Becquerel, and by a still more authoritative teacher, 

 experience, who on this occasion seems to have charged 

 unusually high school-fees. 



One of the most important effects of woods upon a 

 climate is that they promote rain. The theory of this 

 process is not perfectly understood, but the facts them- 

 selves are matters of experience. There are districts on 

 the Continent where the chief rivers have decreased 

 notably in volume, since the clearing of the districts 

 about their sources. We have seen a small stream, a 

 tributary of the Oder, which, within the memory of living 

 persons, turned in its short course two or three corn 

 mills. At the time of our visit it was dry all the summer 

 months, save immediately after a thunderstorm. 



In many districts of Southern France the destruction 

 of the forests has caused much more striking mischief. 

 The rain, instead of falling as heretofore in moderate 

 showers, now comes in violent gushes, with long periods 

 of drought between. As the natural consequence the 

 grasses and other low-growing plants perish, their roots 

 wither away, and the soil, no longer held together by 

 their fibres, is washed away by the occasional violent 

 rains and carried down into the taeds of the rivers. The 

 hill-sides and the higher plains remain as barren wastes 

 of sand, gravel, and shingle. 



A similar process has been going on in Spain, Italy, 

 Greece, in Algeria, Morocco, and, in short, all around the 

 Mediterranean. Countries which were once the grana- 

 ries of the world, and which supported a numerous and 

 thriving population, are now little better than deserts. 

 Nor has this mischief been confined to Europe. The 

 vegetable wealth of South Africa, when it first became 

 known to Europeans, |,was remarkable. The " Cape " 

 was the source of numbers of our finest greenhouse 

 plants. But now vast tracts have been rendered so 

 desolate that a troop of the Colonial cavalry on the 

 march actually gave three cheers at the sight of a tree. 

 Even in the United States, once regarded as eminently 

 the land of forests, many regions have lost, first their 

 vegetation, and then their soil, in consequence of tree- 

 felling. 



It may, perhaps, here be objected that, fully admitting 

 all these unfavourable changes, they may possibly have 

 been produced by unknown causes, and would have 

 occurred all the same if the woodlands had not been in- 

 terfered with. This plea can easily be refuted. In 

 many of the countries above mentioned replanting has 

 been undertaken on the large scale by individuals, by 

 communities, and by Governments, and with the most 



decisive results. Wherever such attempts have been 

 made the climate becomes less extreme, the rainfall more 

 uniformly distributed, and public health is improved. 

 Such beneficial changes have been distinctly recognised 

 in North-Western India, where fertility is gradually re- 

 turning to the deserts. In France, within about twenty 

 years, 250,000 acres of mountain lands, and nearly the 

 same extent of sandy coast lands, have been replanted — of 

 course at great expense, but with the most satisfactory 

 results. 



In America, also, replanting is being vigorously carried 

 on. An eminent agricultural authority in the United 

 States has given it as his opinion that, if one-fourth of a 

 country is left covered with trees, the remaining three- 

 fourths will yield a better return in the shape of crops 

 than would the whole if stripped bare. 



It may, perhaps, here be urged that in England we 

 have in most seasons decidedly more rain than our 

 farmers and gardeners relish, or, at any rate, if not a 

 greater annual depth of rain, yet a greater number of 

 rainy days. But at the same time Britain and Ireland 

 have been stripped of their forests to an extent scarcely 

 equalled in any other part of the globe. 



It must be remembered, however, that our geogra- 

 phical position is decidedly exceptional. Our western 

 shores are washed by the Gulf Stream, and we thus have 

 an atmosphere overladen with vapour. This moisture, 

 on coming in contact with colder air-currents, is con- 

 densed and precipitated in the form of rain. Thus our 

 experience forms no exception to the general truth, that 

 in the absence of forests the rainfall becomes, if not 

 scantier, at least more irregular and capricious. 



But if deforestation has not rendered these islands 

 subject to drought, it has done great injury to agriculture 

 and horticulture by promoting the play of the winds. 

 High and strong winds during the spring, summer, and 

 autumn certainly rank among the chief enemies which 

 the farmer and the gardener have to encounter. In 

 early spring the blossoms and the " setting " fruits are 

 dashed off the trees ; a little later the fructification of 

 corn is interfered with ; in the summer the mowing-grass 

 or the ripening grain are beaten down ; and in Sep- 

 tember and October apples, pears, etc., are prematurely 

 shaken from the branches. How well the nurseryman 

 and market gardener are aware of the injurious effects 

 of wind may be seen from the hedges with which they 

 intersect their grounds at short intervals, not as fences, 

 but simply as screens. It would have been well for this 

 country if our moorlands had remained covered with 

 trees, and if the cultivated parts of the country had been 

 left intersected with belts of timber. 



It must be remembered that, contrary to vulgar pre- 

 judice, the " clearing " of a country is apt to render it, 

 not more, but less, salubrious. In epidemics — e.g., in 

 the cholera epidemic in Trinidad — it was found that, 

 whilst the population in open plains was decimated, the 

 inhabitants of houses well screened by trees almost in- 

 variably escaped. Man, in fact, is, by his origin, a wood- 

 land animal — a truth which, though couched in different 

 language, is taught alike by Moses and by Darwin. 



■>-^»»^i'^5<f-i- 



Petroleum Oil. — The Droojba Fountain at Baku sends 

 up a column of oil 200 to 300 feet high iSin. in diameter, 

 and forces the oil out of the earth at the rate of 2,400,000 

 gallons every twenty-four hours. This is nearly equal to the 

 output of all the 20,000 wells in the oil fields of the United 

 States. 



