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of abuse is meant to euphemistically imply all these things. If so, it is a foolish euphemism.

There are certain notable theorists who are so eminent that no one is willing to stultify himself by abusing them ; and inasmuch as the superabundant energy of some of these men often leads them occasionally out of their main pursuits into alien fields of activity, wherein nevertheless they frequently shine as the equals or superiors of smaller men whose life-work lies in the same fields, it is becoming customary to ingeniously attempt to exclude them from the class it is wished to denounce, and to include them in the circle wherein they are comparatively amateurs or dabblers.

At the recent meeting of the British Association the old joke was repeated about claiming Sir William Thomson as an electrical engineer instead of a physicist and mathematician. This is all very well as a joke, but the British public is too apt to take these things in sober earnest. The range of activity of a pre-eminently great man is frequently not a narrow one, and he is extremely likely to shine in whatever he takes up, even if it be only as a pastime, or as relief from more serious work. Sir Isaac Newton made an excellent Master of the Mint. Perhaps therefore, in his day, City men claimed him as essentially one of themselves. Sir William Thomson has amused himself with navigation, as well as with electrical engineering. This outcry against theory is becoming absurd. It used to be confined to the conclusions of mathematics. It is indeed still rampant there, but it is being extended also to conclusions deduced in the laboratory. Everything done in the laboratory or the study is looked at with suspicion. The right place to study the laws of steam-engines is on a locomotive. The right place to study marine engineering is in the hold of a steamship. The only place to study lightning is in at thunderstorm.

Give out these plausible fallacies with a certain unction to a British audience, and you will evoke "loud ap. plause." It is so easy to evoke loud applause by talking pernicious but plausible nonsense. Your British audience hates to think, and likes to have its stupidity tickled by some after-dinner sentiment, which makes it feel that, after all, no one really knows anything about anything; that whoever professes to understand a subject theoretically is ipso facto a quack; and that the only difference between itself and everybody else is that some people cloak their ignorance under a show of learning and mathematical formulæ. These humbugging theorists may therefore be cheaply derided. "There is a lot of arrant humbug stowed away now and then under a mathematical cloak," said a technical paper the other day.

And what of the practical" man? Any man who talks sense and goes to the bottom of things, so as to really understand and to be able to explain what he means and how things are, is essentially a practical man. One class has no right to monopolize this adjective. A mathematician may make statements according completely with facts and phenomena, and leading to the most complete understanding of every-day truths. An empiric may utter the most glaring absurdities, utterly out of harmony with anything in heaven or earth, or under the earth. Is Prof. Stokes therefore to be styled unpractical, and Prof. (shall we say) Pepper practical?

Push the matter to an extreme, and you can enunciate sentences like these. If you want to know about steamengines and compound locomotives, you must go, not to theorists like Rankine, or Unwin, or Cotterill, or even to Mr. Webb. The driver of the Scotch express is the man really able to give you trustworthy and practical information.

If you want to know the principles underlying the construction of ships, and why some ships go quicker than others, do not think of applying to the writings of the late William Froude with his nonsensical paraffin toys, but consult the captain of the Umbria or the City of Rome.

We have set down these sentences as a reductio ad absurdum of some of the claims set forth in favour of empiricism as against science, under the specious and plausible heading of practice against theory: but really they are not a whit more absurd than much that is seriously argued; and were they propounded under favourable auspices to an average British audience, they would very likely be swallowed without nausea. The experiment is almost worth trying, only it would be difficult for anyone himself faithless to avoid some suspicion of irony, which would be fatal to success.

Space may be afforded for a few more very brief extracts from some of the engineering and technical journals during the past month. The first is so choice as to need no comment :-"The world owes next to nothing to the man of pure science. . . . . The engineer, and the engineer alone, is the great civilizer. The man of science follows in his train.” This doctrine is explained and illustrated by insistence on the futility of Faraday's work in connection with magneto-electricity, until taken up and realized by the practical man.

In the same paper, a week later, occurs the following:"No one knows anything with certainty about lightning outside of the common knowledge possessed by most fairly educated people." And again, "We fail to see that what is true in the laboratory must be true out of doors." This is interesting as an almost exact reproduction of one of the historic objections made to Galileo's unwelcome discovery of Jupiter's satellites. It was then similarly maintained that, though the telescope was all very well for terrestrial objects, it was quite misleading when applied to the heavens.

An instance of a converse proposition is told in a recent popular work on astronomy (is it Sir R. Ball's ?), about a farmer and amateur astronomer, who came to the writer with a revolutionary system of astronomy, based upon a number of observations which he had taken with a sextant of the altitude of the heavenly bodies. The gentleman had thus found that the generally received opinion about the distances of the fixed stars was extremely erroneous. But on inquiry it turned out that his altitudes were all calculated on the common-sense and well-known fact that sixty-nine miles make a degree. Finding it impossible to get the gentleman to put his mind into an attitude for receiving any instruction on the theoretical subject of the measurement of angles, the representative of the orthodox clique who impose their statements on the world as something more trustworthy than common information prevailed on the gentleman to apply his sextant to determine the altitude of his own barn. This reductio ad absurdum was avoided, however, and the overthrow of orthodox

astronomy successfully maintained, by the hoped-for convert "failing to see that an astronomical instrument had any application whatever to terrestrial objects."

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A paragraph recently inserted in an electro-technical journal, with editorial sanction, styles mathematicians "the accountants of science," and goes on in a tone less comic than bitter :-"When some young shaver shoots off his school learning' (i.e. uses some mathematical operation or notation), "I feel inclined to reply to him in Italian, as both are as generally and completely understood in the Society of -"Now if the subject under discussion were, say, passages in Tasso or Dante, an Italian quotation would be very natural, and persons ignorant of the language would hardly be invited, or indeed anxious, to express an opinion. Is it not equally clear that when the subject-matter is numerical magnitude and quantity, the appropriate language may sometimes have to be used?

It has always been customary, as we have before remarked, for the empiric to feel some hostility to the mathematician, especially to the mathematician who endeavours to apply his powerful and beautiful machinery to the elucidation of the facts of Nature. But only recently has it become the fashion to extend the same attitude of mistrust and dislike to the experimental worker in a laboratory. Both these hostilities probably have their root in an instinct of self-protection. Without them the empiric would be constantly suffering wounds in his self-esteem, and might lose confidence in his faith as to the universal prevalence of ignorance and the advantages of rule-of-thumb. For a man of the world professing a certain science to have to recognize a certain number of minds as immeasurably superior to his own, and their conclusions in that very science as being almost certainly correct, although flatly opposed to his own instinct and traditions: this is in many cases intolerable. He cannot away with these great theorists, neither can he in his heart contemn them; but he can do his best to deceive himself and others by extending to them euphemistic terms of abuse, and by pretending that he could do all that they do if only he thought it worth while. He may even go further, and flinging abroad a universal accusation of ignorance will easily deiude a gullible public into the belief that knowledge is after all only a matter of opinion, and that what one man says is quite as good as what is said by another.

And in this procedure he is fairly secure against any retaliation from the great men. They are deeply and painfully conscious of ignorance in one sense their knowledge sits lightly upon them; and when broadside and grotesque accusations of ignorance are hurled at them with the intention of putting them on a level with the uninstructed and, in quite another sense, "ignorant populace, they resent it not; scarcely recognizing, indeed, the absurdity of the position.

The hostility of the "practical man" for the systematic and recondite methods of science was at one time mainly borne by mathematicians, because they it was mainly who spoke a language and thought thoughts too high for common apprehension. Since then experiment has become more exact, more illuminated by theory, more scientific and less empirical; hence it is that the hostility is now being extended to the experimentalist in his laboratory as well.

But really, it may be rather offensively suggested, what other attitude can be taken up? If a man is to be capable of getting schemes through Parliament, of impressing a jury, and generally of playing to the gallery and becoming a power in the State, he cannot, unless very exceptionally endowed, have the aptitudes and powers proper to a man of high science. And yet it will never do to allow even to himself that the scientific man is in his own line immeasurably above him. Such a reverent and submissive attitude would ruin his chance with the gallery at once. Swagger and a confident front are more than the tricks of the trade, they are the essentials to success.

We are glad to recognize, however, that the recent outburst against the methods and conclusions of pure science is the work of the camp-followers rather than of the leaders on the commercial side. There have been and are several conspicuous examples not only of the scientific man taking a high position on the commercial side, but also of the commercial man taking a high position in the ranks of pure science. This interchange of individuals, and the further rapprochement which the great extension of science into industrial life of various kinds has caused, and must in the future still further cause, are making it now clearly recognized how intimately pure science and the commercial applications of science are connected together, how great is their mutual dependence on each other, and how essential to the well-being of each is a close and friendly co-operation with the other.

These facts, and the friendly attitude of the leaders on both sides, render the attempt made in the rank and file to sow discord between the two great classes the more absurd, and must make it in the long run entirely futile.

THE MESOZOIC MAMMALIA.

The Structure and Classification of the Mesozoic Mammalia. By H. F. Osborn. Journ. Ac. Nat. Sci. Philadelphia, Vol. IX. No. 2. (Philadelphia: Published by the Academy, 1888.)

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the elaborate memoir before us, comprising eighty quarto pages of text, illustrated by thirty woodcuts and two plates, Prof. Osborn, of Princeton College, New Jersey, gives us the result of his researches into the structure of the Mesozoic and allied Tertiary Mammals, based upon observations carried on both in America and Europe. As a rule, these Mammals are of small size, and are mainly known to us by more or less imperfect jaws and teeth; by far the greater number of specimens consisting of the lower jaw or mandible. Now, it is well known that even in groups of the smaller Mammals which are well represented at the present day, such as the Shrews among the Insectivora, or the Bats, it is almost, if not quite, impossible to recognize many of the genera, to say nothing of the species, when we have to deal only with a series of fossil or sub-fossil lower jaws from the cavern or later Tertiary deposits. And if this be so in groups with which we are well acquainted, the difficulty is of course increased many times over when we have to deal with forms having no close analogues among the existing fauna. The puzzle is further increased by the difficulty of referring such portions of upper jaws as are more rarely found to the species indicated by mandibles;

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and this induces a great danger of founding species or higher groups upon the evidence of upper jaws, which cannot be decisively shown to be distinct from those founded upon the evidence of the mandibles. Osborn, as will be noticed below, has not altogether steered clear of this danger; and we consider it would be advisable in delicate researches of this nature to lay down a rule that family or higher groups should only be formed upon the evidence of homologous parts, even if genera and species have been named upon the evidence of dissimilar parts of the skeleton.

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Before, however, proceeding to any detailed criticism, it will be advisable to take a brief survey of the memoir before us, and to note the scheme of classification which is proposed. The memoir begins with a survey of previous work on the subject, especial attention being directed to the labours of Sir Richard Owen in Europe, and to those of Profs. Cope and Marsh in America. the second page (187) a table is given of all the described genera of Mesozoic Mammals, which include forms from Europe, America, and South Africa; together with certain allied Tertiary genera from North America and France, and Thylacoleo of the Pleistocene of Australia. We may add that since this memoir was sent to press, forms allied to those of the North American Eocene have been described by Señor Ameghino in the Tertiaries of the Argentine Republic. The next section is devoted to a detailed description of the British forms, in which certain generic terms, proposed by the author in a preliminary communication, are fully described and illustrated. We may here mention that the author tells us that the process of passing his memoir through the press occupied an unusually long period, during which certain other memoirs appeared on the subject; and that he thus saw occasion to modify in some respects several statements made in the earlier part of the work, footnotes being usually appended to this effect.

After the descriptive portion we come to what is really the most important section of the whole memoir-namely, that headed the classification and zoological relationships of the Mesozoic Mammalia. It is here observed that these forms may be divided into two large groups. "In the first group, A, one of the incisors is greatly developed at the expense of the others, and of the canine, which usually disappears; behind these teeth is a diastema of varying width, followed by premolars which are subject to great variation in form and number, while the molars bear tubercles. In the second group, B, the incisors are small and numerous, the canine is always present and well developed; the teeth usually form a continuous series, and the molars bear cusps instead of tubercles." These two groups are compared to the Diprotodontia and Polyprotodontia, among existing Marsupials, and the following scheme of classification is proposed :A. First Group.

I. Sub-order Multituberculata.

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The Multituberculata, excluding Thylacoleo, extend in time in Europe and North America from the Uppe Trias to the Lower Eocene, but the recently discovered South American forms may be of later age. In dis cussing the relationship of this group of families of p. 212, the author states that, admitting their Mar supial relationship, it is clear that the genera "are close' related to each other, and widely separated from the Diprotodontia by their dental structure, which is very dissimilar, and indicates that they probably branched of from the stem of the recent Marsupials at a remote period. probably the Triassic." They are accordingly regarde on the following page as a sub-order of Marsupials, characterized by the tuberculated characters of the molars. If, however, as suggested on p. 214, Thylacole which is evidently only an aberrant and specialize. Phalanger, has any sort of relationship to the Plag aulacida, then it will be evident that this group cannot be even subordinately separated from the Diprotodon's Further observations upon the relationships of this group, are given upon pp. 251 and 254, the latter section having evidently been written subsequently to the earlier sections. On the former page evidence is adduced to show that in some of these forms the first upper incisor has been lost, and the second becomes hypertrophied, whereas in existing Marsupials it is the first which always persists an becomes enlarged. There is no evidence as to the serial homology of the lower incisor. On p. 254 and the following pages, the suggestion of Prof. Cope, based or

the resemblance of the molars of the Multituberculata to the aborted teeth of Ornithorhynchus, that these forms may be Monotremes, is discussed at some length, but without any definite conclusion being reached. We presume, however, that in writing this part of the memoir the author had come to the conclusion that the relationship of these forms to Thylacoleo is altogether a myth. It is. however, at first sight not very easy to believe that the general similarity in the structure of the cutting fourth premolar in the Multituberculata and the modern Diprotodontia is not indicative of a real affinity between the two: and as to the argument that the peculiar structure of the two molars is of itself sufficient to indicate the subordinal distinction of the Multituberculata, we think that a sub-order which contains such different types of molar dentition as are shown by Macropus, Pseudochirus, Phar

colarctus, and Phascolomys, could surely also find room for the Multituberculate type. The evidence of the homology of the incisors is, however, a weighty one in the author's favour.

Prof. Osborn places the Triassic Microlestes with the Plagiaulacida rather than the Bolodontidæ, but we think the existence of a cutting fourth lower premolar ought to be proved before this view can be definitely admitted. There may also be considerable hesitation in accepting the view expressed on p. 217, that there are five premolars in the upper jaw assigned by Prof. Marsh to Ctenacodon; but beyond these and other small points the author's classification of this group appears to commend itself. We cannot say the same in regard to the classification of the second group, which, as we have seen, it is proposed to split up into one distinct order, into one sub-order provisionally referred to the Marsupialia, and a second assigned with more hesitation to the Insectivora. In this group the author has, we venture to think, found differences which, if they exist at all, are by no means of the importance he attributes to them; while at least one case occurs to us, where, to say the least, there is a considerable presumption that specimens assigned to the two sub-orders may really be referable to a single genus.

Sufficient account does not, indeed, appear to have been taken of the variation in the dentition of different recent genera of Marsupials which are usually included in a single family; as, for example, Thylacinus, Dasyurus, and Myrmecobius among the Polyprotodonts, and Phalanger, Pseudochirus, and Phascolarctus in the Diprotodonts. In the case of obscure fossil forms like the present, it appears to us that there ought to be the greatest hesitation in making groups of higher value than family rank; and that even in the case of families their limits ought to be much more loosely drawn than among existing forms, where we have full evidence before us. It is, indeed, far more advantageous to keep all such obscure forms more or less closely associated until absolutely decisive evidence is forthcoming as to their right to wide separation. In the present instance, however, the author has, to put it in the mildest form, by no means adduced any such decisive evidence; while, as already mentioned, there is a strong presumption that in certain particular cases he has widely separated closely allied, if not absolutely identical, forms.

The first so-called order-the Protodonta-is formed for the reception of the American Triassic Dromatherium1 and Microconodon; if, indeed, the latter be really entitled to generic distinction. The grounds for the ordinal distinction of these forms are that the roots of the cheekteeth are not fully divided; but stronger evidence than this is required before these obscure forms can be definitely regarded as entitled to constitute more than a family. And even if they belong to an order distinct from the Marsupials, there is no evidence to show that they are not Monotremes, or perhaps rather Prototheria.

The sub-order Prodidelphia is defined as including primitive Marsupials, generally characterized by the presence of four premolars and numerous molars, the latter having distinctly divided roots. It is, however, added (on p. 259) that "no definite sub-ordinal character can be

1 Prof. Osborn proposes to alter the spelling of this name to Dromotherium.

assigned; but in view of the retention of several features, and of their ancestral position, these Mammals may be distinguished from the recent Marsupials as the sub-order Prodidelphia." In our own judgment, the formation of a large group which confessedly cannot be distinguished from one already established is unjustifiable, and not conducive to any advantage. The first family of this group is the Triconodontidæ, in which, as shown above, our author includes a large number of genera. The genus Triconodon, together with the allied or identical American Priacodon, has, however, such a totally different facies from all the other forms, that we are inclined to follow Prof. Marsh in regarding it as alone constituting the family. We are, morever, rather at a loss to find the value of the characters which Prof. Osborn regards as distinctive of the enlarged family; for, whereas he states in the definition of the family (on p. 227) that the" condyle is low," on the opposite page the genus Amphitylus is described as having the " condyle lofty." Some very interesting observations are recorded (p. 198) as to the changing and development of the teeth in Triconodon, in which it is concluded, as had been previously indicated by Mr. O. Thomas, that the replacement was limited, as in modern Marsupials, to a single premolar; while it is further shown that in many instances it appears probable that the last true molar was never developed. In classing Phascolotherium, of the Stonesfield Slate, in the Triconodontidæ, the author appears to have been greatly influenced by regarding Triconodon as having the condyle placed low down on the mandible. We have, however, considerable doubts whether this is a character of much importance, as it varies so much in the allied Phascolotherium and Amphitylus. In considering that the whole of the seven cheek-teeth of Phascolotherium are true molars, the author departs very widely from the view taken by Sir R. Owen, and a great deal more evidence is required before it can be considered proved that at least the first two of these teeth are not premolars.

In making such mention as space permits of some of the other genera, we must take those included under the Prodidelphia and the so-called Insectivora Primitiva together. In this connection it appears that a great deal depends on the interpretation of the dental characters of the original genus Amphitherium, to which Prof. Osborn refers the fragment of a mandible figured on p. 192. It is stated, with great fairness, that when the author examined this specimen he regarded it as totally distinct from Amphitherium, but that comparisons of his drawings with figures led him to change his opinion. On p. 192 it is observed that "when these mutilated crowns [of the type] are compared with the perfect crowns of the newlyacquired jaw, there can be no doubt that they belong to the same pattern. If this be the case, the latter specimen is of great interest, as it enables us for the first time to fully characterize the molar dentition of Amphitherium.” We have purposely italicized portions of the above sentences, since they show a somewhat curious instance of the author's method. Thus, in the first sentence the teeth of the new jaw are definitely stated to be of the type of those of Amphitherium, while in the second a provisional element is introduced; and yet subsequently this jaw is again definitely taken as affording the true structure of the Amphitherium molar. Far be it from us

was the very one which had a claim to such a position In regard to the new genus Kurtodon—the type of the Kurtodontida-we can only say that there appears to us to be no evidence that the upper jaws on which it is founded may not belong to one of the genera named on the evidence of the mandible.

Other points might be noticed if space permitted ; but we have indicated enough to show that a great deal more must be absolutely proved before many of the genera admitted by Prof. Osborn can be even allowed to stand as definitely distinct; while, as to the proposed division of the Polyprotodont forms into Insectivora and Marsupialia, we have shown that in its present form it breaks down hopelessly at every point, although we are far from saying that all the known forms are certainly Marsupial. It appears, however, desirable. till we attain much fuller knowledge of their organization, to leave a large proportion of them in a single ill-defined family.

In criticizing this memoir we have not hesitated, in what appear to us to be the true interests of science, to speak freely. We should, however, be unjust if we failed to recognize the amount of labour of a very try ing kind which the author has bestowed on the subject: and we especially commend the value of his observations on the Multituberculata. It is also a decided advantage to have all the American and European forms compared together by one who has had the good fortune to study so many of the types from both areas. Finally, no one can fail to be struck with the excellent illustrations with which the monograph is adorned, a large number of which, we believe, are from the author's own drawings.

to say that this jaw does not belong to Amphitherium-the reduction of its lower incisors to the Eutherian three, it very probably does; but it certainly does not afford decisive evidence on which to base an extensive superstructure, and to make Amphytherium the type of one family, while Amphitylus and Amphilestes (regarded by Owen as closely related to the former) are referred to the Triconodontide. Then, again, exception may be taken to the interpretation of the molar structure in the jaw in question. Prof. Osborn regards the teeth as consisting of two cusps and a talon in line, approximating to the fashion of Amphilestes; but to us they appear to resemble those of the Upper Jurassic genus Amblotherium, in which the molars consist of a trilobed blade and a posterior talon. Now, Amblotherium is made the representative of a family which is taken as the type of the Insectivora Primitiva. Apart from the question of what Amphitherium really is, the molar teeth of Amblotherium, as already said, differ considerably from those of Amphilestes (Prodidelphia); but, since precisely analogous differences occur in a single family of existing Marsupials, these differences do not appear to afford grounds for even family, let alone ordinal, distinction. No definite characters are, indeed, given by which the Insectivora Primitiva (p. 235) are to be distinguished from the Prodidelphia; and if we compare the figure of the mandible of Amphilestes, given on p. 228, with that of Amblotherium, represented in Plate ix., Fig. 11, the resemblance in the contour of the posterior portion of the jaw is so close that scarcely even generic distinction could be drawn from this part. The conclusions drawn from this portion of the jaw in the different forms are indeed very remarkable. Thus we have already noticed how the low condyle is given as a character of the Tritylodontida, and yet the feature is totally wanting in the first genus, Amphilestes, which agrees exactly with Amblotherium in its lofty condyle. The alleged broad and narrow coronoids of the two forms may be in great part due to the effects of pressure. The absence of inflection in the angle of Amblotherium is shared by some of the forms included in the Triconodontidae. Then, again, we are totally unable (after repeated examinations of the types) to see how the lower jaw, on which Peraspalax was founded, can be even generically distinguished from Amblotherium, the dental formula being, with the exception of an additional lower molar, identical; and yet the one genus is referred to the Prodidelphia, and the other to the Insectivora Primitiva. As another instance, the general similarity in the structure of the lower molars of Spalacotherium to those of Chrysochloris coupled with an analogous similarity existing between the upper ones of Peralestes and those of the same existing genus, suggests at all events a very considerable presump tion that the two fossil genera may be identical. We find, however, Spalacotherium placed in the Triconodontide, while Peralestes is made the type of another family of the Prodidelphia, which includes the above-mentioned Peraspalax. Now, even if the above obvious resemblance is ignored, we totally fail to see any reason for including Spalacotherium in the Triconodontidæ, and agree with Prof. Marsh in regarding it as the type of a distinct family. If, moreover, any of these forms are to be referred to the Insectivora, we should have thought that Spalacotherium, with its Chrysochloris-like molars, and

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EARTH SCULPTURE.

Les Formes du Terrain. Par Lieut.-Colonel G. De la
Noë, avec la collaboration de Emm. de Margerie.
2 Vols. (Text, pp. 205; Plates xlix.). (Paris, 1888.)
THE
'HE origin of the features of the earth's surface must
always prove an attractive subject no less to the
geographer than to the geologist. The one describes and
the other expounds; and the work before us is an admir-
able example of what may be done by the joint labours of
geologist and geographer in illustrating and explaining
the form of the ground.

In turning over the pages of the work, and in contem plating the many instructive diagrams and pictorial illustrations, one is prepared for a more exhaustive treatment of the origin of scenery than is really to be found in these volumes. So far as the geologist is concerned, the work is mainly a treatise on sub-aërial denudation, and with special reference to France. It is almost entirely occupied with the method of denudation by rain and rivers, and with an account of the features which they originate. We are told how different rocks are disintegrated by surface agencies, and how the broken material is afterwards transported by streams. Attention is especially called to the action of running water on rocks of varying character and inclination, to the influence of vegetation in preserving slopes at certain inclinations, and to the effect of rain in diminishing the angle of slopes. The influence of climate is dwelt upon, and it is shown how the perme

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