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THURSDAY, DECEMBER 12, 1889.

THE TEACHING OF FORESTRY. A Manual of Forestry. By William Schlich, Ph.D. Vol. I. (London: Bradbury, Agnew, and Co., 1889.)

PROBABLY it will not for some time be generally re

cognized in England that forestry is a profession in the sense in which we speak of the profession of law or of medicine. And it is a bold step to publish a manual of forestry for English readers in a systematic and strictly technical form. This is the task which Dr. Schlich has undertaken, and the volume before us is the first instalment of a large work, which, when completed, will be the first comprehensive manual of forestry in the English language.

Before going out to India in 1866, Dr. Schlich had passed the examinations for the superior forest service in his own country (Hesse Darmstadt), he had been the pupil of one of the most eminent Professors of Forestry in Germany, the late Gustav Heyer, and he held a distinguished place among his fellow students. At the commencement of his career, the changes which had taken place in Hesse Darmstadt in consequence of the Austrian war were believed to affect injuriously the chances of promation for the younger members of the forest service. This induced him to accept the offer of an appointment in India. Here he was designated at an early date for important positions, and thus, after he had served several years in Burmah, he was sent to Sind, where, under completely different conditions of climate and forest, he did excellent work. He served successively as Conservator of Forests in Lower Bengal and in the Funjab, until he rose to the post of Inspector-General of Forests. In 1985 he consented to relinquish his important position in India, in order to become Professor of Forestry at the Forest School which it had been decided to form in connection with the Royal Indian Engineering College at Coopers Hill.

The volume before us contains the general and introductory part; in a second volume the author proposes to set forth in detail the different sylvicultural operations; while the protection of forests, the utilization of timber and other forest produce, the systematic arrangement of the plans for working, and the financial aspect of forest management, will complete the work. Not the least of the advantages which will be gained by the publication of this manual will be to settle the English forest terminology. The technical terms which had been tentatively used since methodical forest management was begun in India may now be expected to receive general currency, and will be more correctly understood than before.

The primary object of the Coopers Hill Forest School is the training of officers for the Indian Forest Service, but others also may attend the forestry classes in order to qualify for the management of forests and woodlands in! Great Britain and in the colonies. It may therefore be hoped that Dr. Schlich's manual will eventually promote the good management of forests in many parts of the world. In Great Britain and Ireland the author states the area of woods and forests at 2,790,000 acres, and in VOL. XLI.-NO. 1050.

British India the area of Government forests at 70,000,000. No data are available for estimating the forest area in the British colonies. But the area stated is sufficient to demand the systematic teaching of forestry in England.

In the German Empire the total forest area only measures 34,346,000 acres, of which 11,243,000 acres belong to the State. Yet there are no less than nine forest schools in the different States for educating the superior officers in the State and other public forests and the principal wood managers in private estates. The books published on the subject of forestry in all its branches during the three years 1886-88 amounted to 177, or fifty-nine a year on an average. Besides these, there are ten periodicals on forestry, some quarterly, most monthly. One general association of German foresters meets annually, and ten local societies hold their meetings either annually or once in two years. And all these associations publish their transactions. Perhaps it will be urged that this large and daily-growing forest literature is not necessarily an advantage; that German foresters had better attend to the management of their forests instead of writing books. As a matter of fact, however, the management of the German forests, public as well as private, is excellent, and is improving steadily. The best proof of this is the large and steadily growing income derived from these estates by the Government, by towns and villages, and by private proprietors, and, more than that, the improved condition and the increased capital value of these properties.

A commencement, however, of forest literature has been made in the English language. The Transactions of the Royal Scottish Arboricultural Society have attained their twelfth volume, and they frequently contain papers of considerable importance. The Indian Forester, commenced as a quarterly by Dr. Schlich in 1875, is now a monthly magazine, of which fifteen volumes have appeared. In addition to these a number of valuable publications on different branches of forestry might be named that have been published within the last twentyfive years.

German forest literature, though it has attained such large dimensions, is of comparatively recent origin. During the eighteenth century sylviculture and the management of forestry had made great progress in many parts of the country, but the methodical and scientific treatment of the subject dates from the labours, during the first thirty years of the present century, of Hartig in Prussia, Cotta in Saxony, and Hundeshagen at Giessen. Scientific forestry in England must necessarily be built upon what has been accomplished in this respect in Germany, and with becoming modesty Dr. Schlich acknowledges that the principal German works have been his guide in the preparation of the present book. Great Britain does not stand alone in this respect. In France also the development of scientific forestry has to a great extent been based upon the progress previously made in Germany. The same may be said of forestry in Italy, Russia, Scandinavia, and other European countries.

Part I. of the manual treats of the utility of forests, directly in producing wood and other forest produce, and indirectly in influencing the climate, in the distribution of rain-water, in the preservation of the soil on sloping ground, in the binding of moving sands, and in affording shelter against winds. All these matters are clearly and ex

G

haustively treated, and in regard to the climatic influence of forests the author gives a most useful summary of the researches which have been made to determine the effect | of forest growth upon the temperature of air and soil, rainfall, humidity, and evaporation, in Germany, Switzerland, and France, mainly by the establishment of parallel stations, one being situated inside a fully stocked forest and the other at some distance in the adjoining open country.

Part II. sets forth the fundamental principles of sylviculture. The author maintains, with justice, that the principles of sylviculture hold good all over the world, but adds that the illustration of these principles must be taken from a limited area. For this purpose he has chosen the timber trees of Western Europe on the 50th degree of north latitude, and the countries immediately to the north and south of it-in other words, the forest trees of England, Northern France, and the greater part of Germany. These species the author does not attempt to describe; he assumes that his readers are familiar with them. The first chapter dwells upon the external conditions which influence the development of forests. He says:

"Soil, including subsoil, and atmosphere are the media which act upon forest vegetation, and they together are in sylviculture called the 'locality.' The active agencies, or factors, of the locality depend on the nature of the soil and the climate, the latter being governed by the situation. The sum total of these factors represents the quality or yield-capacity of the locality. The forester requires to be well acquainted with the manner in which soil and climate act on forest vegetation, in order to decide in each case which species and method of treatment are best adapted, under a given set of conditions, to yield the most favourable results."

Every forester knows that on good soil, and under conditions otherwise favourable, a timber crop is heavier than one of equal age grown under less favourable conditions. In the concluding section of this chapter the author shows how one may use this fact in order to assess the quality of a locality. Numerous measurements of woods of different species and ages, grown under different conditions, have been made in Germany on a systematic plan, and from the data thus obtained yield tables have been calculated, showing the volume of timber produced at different ages on a given area by the principal species on localities of different quality classes. Using the yield tables published for the Scotch pine by Wilhelm Weise, now Professor at the Forest School of Karlsruhe, the author shows that at the ages of 50 and 120 years the volume per acre of timber only, not including faggots, in localities, which according to their yield-capacity are classed as first, second, and third class, is as follows:II. III.

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Cubic feet at the age of 50 years 5060 3940 2700 9060 6950 5340 The figures of these yield tables Dr. Schlich has found to a certain extent to be applicable to Scotch pine forests in England. They can therefore be used in order to assess the yield-capacity of any locality stocked with Scotch pine. Eventually, similar yield tables will doubtless be prepared for the Scotch pine and other forest trees in Great Britain, and it will then be possible with

certainty to say what yield of timber may be expected from plantations made in a certain locality.

The second chapter deals with the shape and development of forest trees, but we can refer only to what the author says regarding height-growth. Building again chiefly upon researches made in Germany, Dr. Schlich explains how the different species have a different mode of height-growth. On p. 163 an instructive diagram will be found exhibiting the relative height-growth of spruce. silver fir, beech, and Scotch pine, in a locality of the first quality. At the age of 50 years the mean height attained by each species is as follows:

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Scotch pine and beech therefore make the principa height-growth during the first period of their life, whereas spruce and silver fir continue to grow vigorously in heigh: to a much greater age, spruce more so than silver fir. The progress of height-growth of the different species is much affected by the character of the soil, by elevation, the more or less crowded state of the wood, and other circumstances, but under otherwise similar conditions ! will always be found that deep, fresh fertile soil produces much taller trees than shallow, dry, or rocky soil.

In the third chapter, which deals with the character and composition of woods, the author points out that the object of sylviculture is not to rear isolated trees, but considerable masses of trees, forming more or less crowded woods. Pure woods consist of one species only, or of one species with a slight admixture of others, whereas mixed woods contain a mixture of two or more species. advantages of mixed woods are clearly set forth, and the author's remarks on this subject may be specially recom. mended to the attention of proprietors and managers of woodlands in Great Britain.

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The last and most important chapter deals with the sylvicultural systems-that is, the different methods under which the creation, regeneration, tending, and utilization The three well-known classes of woods are effected. are: first, high forest, originating in seedlings, either self-sown or artificially raised; second, coppice, which regenerates itself from coppice shoots; and third, coppice with standards, a combination of seedling and coppice forest. The modifications of these three main systems are numerous, and particularly the treatment of high forest has developed in a great variety of ways. On this subject we must refer the reader to the manual. These are matters which can hardly be fully understood without opportunities for obtaining practical experience of forests treated under the various systems described. Such opportunities may, to some extent, be found in Great Britain. The high forests of larch and Scotch pine m Scotland, raised by planting, are excellent, and in some

districts Scotch pine woods are regenerated by self-sown seedlings. The oak woods of the Forest of Dean, and the beech woods on the chalk downs of Buckinghamshire, are instances of high forests with different character and different method of treatment. Most instructive, again, are the natural oak forests in Sussex-coppice, with a large proportion of standards. So are the coppice woods of ash and sweet chestnut for the production of hop-poles 1 Kent, and the osier beds on the banks of the Thames. The dificulty is, that the treatment of these woods is entirely empirical, and that, without authentic statistical data regarding yield in timber, regarding income and tlay, no forest can properly be used for purposes of instruction. If the student wishes fully to understand this and other portions of the excellent manual before us, he must study the forests of Germany, public and private. This may be a disadvantage, but under the circumstances of the case it cannot be helped.

Appended to the first part of the book are two treatises which will be read with interest by those who may not care to study the more technical portion of the manual. They deal with forestry in Great Britain and Ireland and in British East India. The physical configuration of India, its climate and rainfall, the distribution of the forests, and the forest policy pursued by the Government of India during the last thirty years, are clearly set forth. The protection and systematic management of its forests are matters of the utmost importance for the welfare of the millions inhabiting the British Indian Empire, of infinitely greater importance than good forest management is for Germany or other countries of Europe. Enthusiastic foresters in India have long maintained that, by improving the condition of existing forests, so as to make them more dense and compact, by extending their area, and by creating forests where none exist at present, the rainfall in seasons of drought might be increased, and famines raight thus be averted. Dr. Schlich fully discusses this subject, and states several cases in which the presence of dense forest growth seems to accom pany an increased amfall; but at the same time he fully explains the reasons why a final conclusion does not seem justified. The result is that, though the local influence of forests in lowering the temperature and preserving moisture is undeniable, we are not justified in hoping for an improve"Dent of the Indian climate. The favourable influence of forests in India upon the irrigation from wells and tanks is, however, beyond doubt, and this is a vital question. To illustrate the effect of forest growth in protecting loose soil on hill-sides, the author mentions the Siwalik bills at the foot of the North-West Himalaya. We quote his words:

"Anyone who has ever stood on the hills behind Hushiarpur in the Punjab, and looked down upon the plain stretched out towards the south-west, has carried away an impression which he is not likely to forget. In that part the Siwalik range consists of an exceedingly fnable rock, looking almost like sand baked together. Formerly, the range was covered with a growth of forest vegetation, but a number of years ago cattle owners settled in it, and under the combined attacks of man, cows, sheep, and goats, the natural growth disappeared, while the tread of the beasts tended to loosen the soil. The annual monsoon rains, though not heavy, soon commenced a process of erosion and of carrying away the

surface soil. Gradually, small and then large ravines and torrents were formed, which have torn the hill range into carried into the plains, forming, commencing at the places the most fantastic shapes, while the débris has been where the torrents emerge into the plain, fan-shaped accumulations of sand which reach for miles into the plain, and which have already covered and rendered sterile extensive areas of formerly fertile fields. Indeed, one of these currents or drifts of sand has actually carried by no means reached its maximum extent, and if curative away a portion of the town of Hushiarpur. The evil has measures are not adopted at an early date, the progress of transporting the hill range into the plain will go on, until the greater part of the fertile plain stretching away from its foot has been rendered sterile."

The author might have added the denuded hills, and the rivers, formerly navigable, but now silted up, in the Ratnagiri district of Western India, and other similar instances.

That a country so populous as India requires immense quantities of timber, bamboos, and firewood, goes without saying. Among other articles of forest produce, cattle fodder is an important item. In the drier portions of the country the supply of grass, particularly during seasons of drought, is more plentiful under the shelter of trees than out in the open. In times of scarcity, grain can easily be carried long distances to provide food for the people, while cattle fodder cannot be so easily carried. As a matter of fact, where forests have been formed and protected in the drier parts of India, they have proved a great help in enabling the people to maintain their cattle in times of drought and scarcity.

In India the duty of taking action necessarily devolved upon the State. The result has been the formation of extensive forest estates, called reserved forests, which at present, the author states, aggregate 33,000,000 acres, or three times the area of State forests in the German Empire. If forest matters in India continue to be properly managed, these estates will not only secure the well-being of the people, but will be an important source of strength to the Government, financially and otherwise. As yet, the revenue which they yield is insignificant in relation to their extent. But it is growing steadily. Dr. Schlich shows that during the three years 1864-67 the average annual net revenue from the Government forests amounted to £106,615, and during the five years 1882-87 to £384,752; and he states it as his opinion that, twenty-five years hence, the net surplus will be four times the present amount. More important, however, than the annual revenue is the steadily increasing capital value of these Government forest estates.

In Great Britain the aspect of affairs is different. The small area of the Crown forests, burdened as they are with prescriptive rights, cannot reasonably be expected materially to help the development of systematic forest management. But there are over 2,500,000 acres of woods and forests in the hands of private proprietors, and there are 26,000,000 acres of barren mountain land and waste, a portion of which might be planted up. Proprietors, as a rule, desire to augment their income and to increase the capital value of their estates. In many cases this might be effected by a more systematic management of their woodlands, and by the planting up of waste lands. The chief obstacle to progress in this direction is the low

price of timber and the high rent at present obtained by all they require in such modern works as Sprung's the letting of grouse moors and deer forests.

Upon data which cannot be gainsaid, Dr. Schlich has based important calculations, which will be found on pp. 17-19. Space forbids the discussion of details, but the result is that Scotch pine forests cannot be expected to yield more than 2 per cent. on the capital invested (the value of the land and of the growing crop).

"All land, therefore, which can be let for the raising of field crops, for shooting, or other purposes, at a rental equal to, or upwards of, 2 per cent. of the capital value of the land, had better be so let. On the other hand, land which would realize a rental of less than 25 per cent. of its value, may with advantage be planted with Scotch pine or other similarly remunerative trees."

These conclusions are based upon circumstances as they exist at the present time. But a change of circumstances is not impossible. The author points out that 6,000,000 loads of timber are imported annually into the United Kingdom from Europe and North America, and that only a small portion of the forests which furnish this large supply are under systematic management and control. It may be regarded as certain that the supply from Sweden and Norway and from North America, amounting at present to nearly 4,000,000 loads a year, will continue to diminish, and, under the circumstances of the case, the necessary result of such diminution will eventually be a rise in the price of timber. Again, if proprietors of woodlands in England and Scotland were in a position to offer large quantities of home-grown timber of good quality for sale, regularly at stated seasons, timber traders would make their arrangements accordingly, and in many cases better prices would be obtained. Firewood is at present almost unsaleable in the United Kingdom, but if—and this may happen the price of coal should rise considerably, firewood would in some districts become an article of general consumption, as it was 150 years ago, and to some extent this would improve the money yield of

woodlands.

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"Lehrbuch der Meteorologie," and Ferrel's "Recent Advances in Meteorology," the high merit and originality of which last are somewhat veiled under its more obtrusive title "Part 2 of the Report of the Chief Signa! Officer of the [U.S.] Army for 1885." But these works are hardly suited for popular instruction; and for that large class of students whose mathematical acquirements are more limited, but who nevertheless desire to understand the movements and internal changes of the atmosphere, and to interpret them rationally in accordance with mechanical and physical laws, there has hitherto been little guidance, save such as they may obtain from casual references to them in works devoted to the general teaching of these sciences. It is perhaps in consequence of this divorce of the deductive from the inductive treatment of meteorological subjects that the contributions of English observers to the science of meteorology bear but an insignificant proportion to the labour expended on observational work, and that so much of this work is abortive, and practically of little value, owing to the absence of guiding and suggestive theoretical knowledge. It is, then, with no ordinary degree of satisfaction that we hail the publication of Prof. Ferrel's treatise, the title of which heads this notice. As the originator and discoverer of many of the most important problems dealt with in these pages, no one could be better fitted to explain them in terms suited to general comprehension. and this task he has performed with a completeness and lucidity which leave but little to be desired. The work is, as it professes to be, a "popular" treatise, but popular only in the higher sense of the word. A system of movements so complex as those of the earth's atmosphere cannot be made clear to anyone who is not capable of following a chain of close reasoning, or who is not prepared to bring to the study that concentrated attention that is requisite to master any problem in deductive science. But, these being granted, no further demand is made on the student than some familiarity with the elements of algebra, and the simplest conceptions of The action of the plane trigonometry and kinetics. mechanical and physical forces that determine and regulate the wind system of the globe is clearly explained in the first two chapters of the work.

The most important and original portion of the book is that which deals with the general circulation of the atmosphere, in relation to which the cyclones and anticyclones that cause the vicissitudes of local weather are but matters of subordinate detail. The magnitude of the work achieved by Prof. Ferrel in this field has hitherto been recognized only by the few. It is not too much to say that he has done for the theory of atmospheric circulation that which Young and Fresnel did for the theory of light; and that the influence of his work is not more generally reflected in the literature of the day, must be attributed to the want of some popular exposition of the theory.

Starting with the fundamental conditions of a great temperature difference between equatorial and polar regions and a rotating globe, and postulating in the first instance a uniform land or water surface, it is shown how the convective interchange of air set up by the former must result in producing two zones of maximum

pressure in about lat. 30° in both hemispheres, two principal minima at the poles, and a minor depression on the equator, together with strong west winds in middle and high latitudes, and an excess of easterly winds in equatorial regions. The two tropical zones of high pressure determine the polar limits of the trade winds, and the whole system oscillates in latitude with the changing declination of the sun. Further, as a consequence of the fact that the great mass of the land is restricted to the northern hemisphere, whereas the southern hemisphere presents a comparatively uninterrupted sea surface, on which the retarding friction is less than in the northern hemisphere, the west winds of middle and high latitudes are much stronger in the latter than in the former, and by their lateral pressure cause a slight displacement of the tropical zones of high pressure and the equatorial zone of low pressure to the north of their normal positions on a hypothetical uniform terrestrial surface.

The great modification and extension of Hadley's theory thus introduced by Prof. Ferrel depends mainly on twy points of the first importance. By all previous writers it was assumed that a mass of air at rest relatively to the earth's surface on the equator, if suddenly transferred to some higher latitude-say, e.g., 60°-would have a relative easterly movement in that latitude equal to the difference of rotary velocities on the equator and on the 60th parallel, or about 500 miles an hour, the difference being proportional to that of the cosines of the latitudes. This, however, would be true only in the case of rectilinear motion. In reality, as Prof. Ferrel was the first to demonstrate, the mass of air would obey the law of the preservation of areas, like all bodies revolving under the influence of a central force, and its relative eastward velocity in latitude 60 would be 1500 miles an hour, being as the difference of the squares of the cosines. If, on the other hand, any mass of air at rest in latitude 60° were suddenly transferred to the equator, it would have a relative westerly movement of 750 miles an hour, and any mass of matter whatever moving along a meridian is either deflected-or if, like a railway train or a river between high banks, it is not free to yield to the deflecting force, presses-to the right of its path in the northern, and to the left in the southern, hemisphere.

The second point first established by Prof. Ferrel is that, in virtue of centrifugal force, this deflection or pressure to the right in the northern, and to the left in the southern, hemisphere is suffered in exactly the same degree by bodies moving due east and due west, or along a parallel of latitude, and therefore also in all intermediate azimuths.

From the first of these principles it will be readily seen why the west winds of middle latitudes are so much stronger than the easterly winds of the equatorial zone; and from the second, how these opposite winds, by their mutual pressure, produce the tropical zones of high barometer and the polar and equatorial regions of low

barometer.

In subsequent chapters are discussed the modes in which the general circulation of the globe affects the climates of different latitudes by determining the distribution of rainfall in wet and dry zones, and inequalities of temperature through the agency of marine currents. Also the causes that modify and disturb the regularity of

the ideal system, the chief of which is the mutual interaction of expanses of land and sea. The general excellence of these demonstrations is indisputable, but we bave marked one or two passages which appear to us to be of doubtful validity, and which we recommend to the reconsideration of the author when the time comes, as we doubt not it will ere long, for the issue of a second edition of his work.

The first point to which we would take exception is what seems to us the too great influence ascribed to mountain-chains in deflecting the great atmospheric currents. That they deflect the surface winds, like other irregularities of the surface, and in proportion to their magnitude, is, of course, a matter of universal experience; but, in the absence of other causes operating to produce a diversion of the greater currents, their action in this respect appears to us to be merely local. As an instance │we will take the case of the Western Ghats of India, an escarpment from 3000 to 7000 feet in height, running athwart the direction of the summer monsoon of the Arabian Sea. The wind charts of the Arabian Sea, issued by the Indian Meteorological Office, show no appreciable deflection of the monsoon wind on the windward face of this range; and if the same cannot be asserted of the corresponding wind in the north of the Bay of Bengal, where it impinges on the coast range of Arakan, it is evident that the deflection of this current to north, and eventually to north-west, is caused by the indraught towards the heated plains of Northern India.

We believe that a similar explanation will be found to hold good in all the more conspicuous cases cited by Prof. Ferrel. Thus, at p. 183 he says:

"The air of the lower strata of the atmosphere in the trade-wind zone of the North Atlantic, having a westerly motion, and impinging against the high table-lands and mountain-ranges of Mexico, is deflected around towards the north over the south-eastern States, and up the Mississippi valley into the higher latitudes, where it combines with the general easterly flow of these latitudes, and adds to its strength. This completely breaks up the continuity of the tropical calm belt and dry zone, so that, instead of a dry region with scanty rainfall, such as is found in North Africa, Arabia, Persia, Beloochistan, and Cabul, we have on the same parallels in the southern and eastern United States a region of abundant rainfall, and all the way up the Mississippi valley and in the interior of the continent there is much more rain than in the interior of Asia."

Taking this passage as it stands, or only together with the immediate context, it might be understood to imply that the author ascribes this great diversion of the winds of the Gulf of Mexico, together with all the rainfall they bring to the southern States of America, solely to the influence of the comparatively low mountain-chain of Central America. That such, however, is not his meaning is evident from his subsequent remarks on p. 215, where, in describing the monsoons of North America, after noticing the high temperature of the land area in summer, he says:

"On the southern and south-eastern coast, in connection with the deflection referred to [in the passage quoted above], it causes the prevailing winds to be southerly and south-easterly, instead of north easterly, as they would otherwise be in these trade-wind latitudes."

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