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which discharged icebergs at the mouths of of forest growth. It is uncertain whether fiords in western Norway. Finland was Britain was connected with the continent. overwhelmed, and the Baltic basin was 12. Sixth Glacial Epoch.—This is indicated occupied by a great ice stream, which in- by the latest raised beaches of Scotland, vaded north Germany and Denmark. As indicating twenty or thirty feet of depresthe ice melted, a wide area in Scandinavia sion. The snow line stood at an elevation was submerged in a cold sea communica- of 3,500 feet, and thus a few small glaciers ting with the Baltic. In the Alps the snow could exist in the loftiest highlands. In the line was 300 feet lower than now.

western Alps there were some high level 9. Fourth Interglacial Epoch.The British moraines. Islands were connected with the continent. 13. The Present.—The sea has retreated Deciduous trees spread far north into re- to its present level, drier conditions prevail gions now bereft of them. The Baltic sea and permanent snow fields have disappeared became converted into a great lake ; Den- from most of the regions in northern Europe mark and Sweden were united; the Rhine once so completely submerged by glacial flowed quite near England and Scotland, ice. The term post-glacial properly deover the upraised bed of the North Sea, scribes only the present epoch. meeting the main ocean above Bergen; the Professor Geikie devotes three chapters Seine flowed through the English channel to a discussion of the presence of man in the beyond Brest, and there was a large river Pleistocene. His bones and implements flowing over the bed of the Irish Sea, hav- are found chiefly in the extra-glacial regions, ing the Severn for a tributary, and meeting associated with the remains of both extinct the ocean quite near the mouth of the and living mammalia, such as have been Seine, and there was a land connection be- mentioned as occurring in several of the tween the continent, Great Britain, Iceland interglacial epochs. Man would naturally and Greenland. When the salt water fin- migrate towards the glaciers as they receded, ally returned, the fauna was more temper- and retreat southerly as they advanced. ate than it is at present. This epoch is not The large animals would have done the yet recognized in the Alps.

same; hence a perfectly satisfactory corre10. Fifth Glacial Epoch.—In Scotland the lation of the several terranes in the glaciatsnow line reached an average height of ed and extra-glacial regions is of difficult 2,500 feet, the shore line being fifty feet attainment. Our author concludes that lower than it is now. Occasionally glaciers Paleolithic man existed abundantly in the discharged bergs into the sea on the north- second interglacial epoch in company with west coast of Scotland. Most of the corrie the elephas antiquus and hippopotamus. rock-basins of the British Islands were ex- Some of the caves occupied by him appear cavated in this epoch, each one marking the to have been abandoned before the third presence of a distinct glacier. In the Alps glacial epoch reached its climax, because there were advances of the glaciers giving they are sealed up by the moraines of that rise to terminal moraines, the snow line stage. During this epoch Paleolithic man reaching a depression of 1,600 feet below the seems to have retired to southern France,

and, if negative evidence is of value, he 11. Fifth Interglacial Epoch.The upper never revisited northwestern Europe. buried forests of northwest Europe show American geologists will be more than that this epoch was characterized by drier pleased with the sketch of the glacial pheconditions and a remarkable recrudescence nomena of North America by Prof. Cham

present limit.

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berlin. The facts correspond in a general fundamentally glacial for the countries
way with those described by Professor Gei- above forty degrees of latitude on both
kie in Europe. The attempt is made to sides of the equator; ice-action character-
group the stages of glaciation and deglacia- izes the time. The writer has hitherto
tion both on a two-fold and a three-fold ba- been esteemed an advocate of unity; but
sis, without deciding which is the more ac- he has repeatedly insisted that the several
ceptable. The foundation of the grouping margins of glacial accumulation indicate
is what is called ' imbrication of the till, just so many phases of more intense glacia-
or the superposition of the later or more tion, and that they are to be our criteria
northern sheets upon the earlier or more of classification. He is satisfied that they
southern ones. The oldest is the Kansan, can be interpreted to correspond with the
next the East Iowan,and thirdly the East Wis- several glacial and interglacial epochs es-
consin stage of glaciation, followed by six, tablished by Professor Geikie.
seven or more terminal moraines. Professor It remains only to notice the chapter upon
Geikie says that these general conclusions the cause of the climatic and geographical
harmonize with the results obtained in Eu- changes of the glacial period. The ratio of
rope, and without hesitation he correlates precipitation was the same as now prevails.
the Kansan stage with his second glacial Snow fields gathered most abundantly in
epoch, the time of maximum glaciation, those regions which in our day enjoy the
after which the ice sheets declined in im- largest rainfall. What are now dry regions
portance.

were formerly regions of limited snowfall. Granting the correctness of the corre- But the amount of precipitation was greater, spondence of the Kansan stage to the sec- snow in the north and rain in the south. ond or maximum glacial epoch of Geikie, Arctic currents prevailed near the equaAmerican geologists can easily complete the torial in the cold epochs, but the reverse correlation. The Lafayette or Orange sand was true in the interglacial phases. The deposit will correspond to the first or Plio- land seems to have been elevated at the cene phase of the glacial epoch. This refer- commencement of every cold epoch and ence will be satisfactory to those who be- depressed at its close, submergence having lieve in elevation as a prime cause of re- been more characteristic of the glacial than frigeration, as it is generally conceded that of the interglacial phase. The fiord valthe late Pliocene was a time of continental leys were mostly excavated before glacial uplift. It should be satisfactory to the ad- times. The Scandinavian flora migrated to vocates of the unity or continuity of the Greenland after the close of the fourth ice-age, because there was just one pe- glacial epoch, when the land was continuous riod of maximum intensity or culmination between the continents. There are conof refrigeration—the Kansan phase. It siderations favorable to the view that the was preceded by the Pliocene-Lafayette accumulations of ice in the several glacial flood, and followed by the gradually less epochs produced depressions, not excluding intense Iowan, Wisconsin and later phases. epeirogenic warpings of the crust. The It will, however, enlarge our conceptions cause of the remarkable connection between of the magnitude of the ice age in geo- glaciation and depression is still an unlogical history; for we cannot deny that solved problem. All the proposed astrothe remotest centers of dispersion have nomical causes of refrigeration are rejected been active from the beginning of refrigera- as untenable, except that of Dr Croll, tion. The latest geological epochs are supplemented by Ball, who believed the

Summers

climatic changes of the glacial period chair of Zoölogy in Owens College, and conresulted from the combined influence of tinued to occupy the chair until his death. precession of the equinoxes and sec- His additions to the literature of science ular changes in the eccentricity of the have been of two general types. There are earth's orbit. In favor of this view, the first a series of papers embodying the results mean temperature of the globe was lowered, of original research. These, because of his and the ratio of the precipitation increased; intimate association with Balfour, were at the dominant set of the currents in the At- first of an embryological nature, while some lantic was from north to south in the colder of the later ones were more distinctly anaterms. In the interglacial climates the tomical. His chief contributions to science

were cooler and the winters of this sort were upon the Segmental value of warmer, while the Atlantic currents flowed Cranial Nerves, the Pennatulida of the Pornortherly. The maximum glaciation came cupine and Triton Expeditions, and upon The early, succeeded by cold epochs of diminish- Nervous System of the Crinoids. The second ing severity. Glacial epochs in the north- class of his papers were more distinctly ern hemisphere were necessarily contempo- characteristic of his special powers. They raneous with interglacial conditions in the were of a more general character and insouthern hemisphere. Hence the astronom- cluded a text-book on The Frog, on Practical ical theory would appear to offer the best Zoology, and a more recent work upon Versolution of the glacial puzzle; while it is tebrate Embryology. In addition, we have conceded that this answer is not completely in the recent posthumous volumes a large satisfactory. C. H. HITCHCOCK. number of lectures and addresses given in

various places before various societies. Biological Lectures and Addresses, by AR- Above all things, Professor Marshall was

THUR MILNES MARSHALL. Macmillan & a teacher. It was in this direction that his Co., New York. Price $2.25.

powers showed at their best. He had the Lectures on the Darwinian Theory, by ARTHUR happy way of putting subjects so that they

MILNES MARSHALL. Macmillan & Co., New were intelligible to his audiences, and had the York. Price $2.25.

somewhat unusual power of putting himself It was a curious coincidence by which ac- in the position of his audiences, in such a cidents in mountain climbing deprived Eng- way that he could understand how and lish science of two of its prominent biolo- what was needed in his teaching to render gists, and two who were at the same time his subjects clear. His lectures were always personal friends. Prof. F. M. Balfour, as abundantly illustrated both by drawings, every one remembers, lost his life in a and especially by homely though terse illusjourney in the Alps, and Prof. Arthur Milnes trations. His illustrations for rendering Marshall, upon the last day of 1893, in a scientific facts intelligible were drawn somesomewhat similar manner, met his death in times from the most surprising sources, and · mountain climbing. Prof. Balfour and altogether rendered his addresses and his Prof. Marshall were personal friends and class lectures of the very highest character naturally worked upon kindred subjects, al- in the way of scientific teaching. Since his though their work was very unlike. Prof. death Macmillan & Co. have published his Marshall was still a young man, only about collected lectures and addresses in the two forty years of age. Early in life he entered volumes which are the subject of this notice. upon studies looking toward the profession The first series consists of miscellaneous of medicine, but in 1879 gladly accepted the addresses given by him at various intervals between 1879 and the time of his death, are so handicapped by the abundance of and before a number of debating societies material in that Darwinian classic that the and scientific organizations, ending with thread of the argument is lost, and they are his presidential address before the British just as likely to confuse Darwin's views Association in 1890. These addresses are with those of Lamarck as they are to underall designed for a somewhat popular audi- stand Darwinism. Few students who are ence, and treat of different scientific subjects beginning the study of modern biology will in a clear, entertaining manner. Among the have any proper appreciation of Darwinism most interesting of them the lectures that from the study of the Origin of Species, or, will, perhaps, first commend themselves to indeed, from the study of most of the scienthe reader are those on Fresh Water Ani- tific writings on evolution, unless the esmals, on Inheritance, on Shapes and Sizes sential facts are presented to them in some of Animals, and the one upon the Recapitu- form of introduction. For this reason the late Theory. Professor Marshall possessed series of lectures on the Darwinian theory in a wonderful degree the power of seizing by Professor Marshall are especially valhold of the salient points of abstract scien- uable. These lectures are not encumbered tific subjects and isolating them from the

with numerous details, but seize hold of the cumbersome mass of details with which they thread of the Darwinian argument and preare associated in ordinary scientific discus- sent it before the reader in such a way that sions. The result is that in a few pages he cannot fail to understand evolution and the reader obtains a clearer conception of Darwinism after having finished such a the salient points in a subject like embryol- volume. This series of essays will, thereogy by reading the last of the essays in this fore, be perhaps the best literature to which volume than he might obtain from the care- a student can be sent at the present time to ful perusal of many lengthy books upon the enable him to understand what evolution subject. Details, of course, are left out, but was before Darwin, what Darwin added, and the salient and interesting points which em- what have been the subsequent modificabryology teaches and attempts to teach are tions and criticisms of Darwin's theory. presented with wonderful clearness. The Professor Marshall writes as a partisan and addresses are, in short, popular science of thorough believer in Darwin, and presents the highest type, and one does not wonder his facts in such a way that his readers after reading them that Professor Marshall cannot fail to recognize the full force of the was one of the most popular lecturers in Darwinian argument. Indeed, he naturally the University Extension courses.

exaggerates the force of many arguments, Every teacher is aware how difficult it is frequently begs the very question of the to send a young student to literature that issue, and the essays are by no means calcuwill give him a clear, succinct account of lated to be critical discussions. The lectures evolution. Scientific discussions of one and cannot be considered as a fair presentation another phase of the subject are abundant of the Darwinian theory. The innocent but usually they are beyond the compre- reader will conclude that the argument hension of the ordinary reader. Many a upon Darwinism is all on one side, that student having been recommended to read

every essential feature of it is abundantly Darwin's Origin of Species reads the book demonstrated and all criticisms are refuted. with an utter failure to comprehend Dar- But, in spite of this fault, which comes winism. Nor is this the fault of the student. naturally from one who is attempting to Even the better class of thinking students teach a theory in which he so fully believes,

the outline of the Darwinian theory is an it evident, however, that he has had very exceptionally good one. Certain it is that little actual experience in that sort of work. nothing in our literature at the present time It reads rather strangely, for instance, to will give such a terse, clear presentation of be told that the way to find the value of a the Darwinian hypothesis with the argu- micrometer-screw revolution is to 'note ments in its favor, and of the additions how many turns correspond to the sun's which have been made to this hypothesis diameter.' subsequent to the writings of Darwin Regarded as an elementary presentation himself.

of 'Astronomy 'taken as a whole, the book These two books are, then, designed for must be pronounced extremely one-sided popular reading. They are perhaps as good and defective. Astrophysics is most inadean illustration of the especial character of quately dealt with; the whole subject or Prof. Marshall's power in teaching as could spectroscopy is dismissed with six pages be found. They are valuable additions to and a single old diagram of the dispersion that class of books in which the English of light by a prism; and all physical matlanguage is beginning to abound, viz., pop- ters relating to sun, planets, comets, stars ular scientific writings that actually teach and nebulæ are treated on the same general science. H. W. CONN. scale.

C. A. Y. WESLEYAN UNIVERSITY.

Qualitative Chemical Analysis of Inorganic Elements of Astronomy.—By GEORGE W. PAR- Substances-As practiced in Georgetown

KER, of Trinity College, Dublin. Long- College, D. C. American Book Co., New mans, Green & Co., London and New York. 1894. York. 8vo., 236 pages. $1.75.

Rev. H. T. B. Tarr, S. J., formerly proThe book is designed as a connecting link fessor of chemistry in Georgetown College, between the elementary school-astronomies prepared a series of tables for analytical and the higher treatises used as text-books purposes, which have been wholly recast in the universities. It treats the subject and incorporared into the work now before almost exclusively from the geometrical The present editor, Rev. T. W. Fox, point of view, breaking up the matter into S. J., speaks of the book as being useful in propositions, corollaries and problems, ar- a course such as is given at Georgetown ranged in an order which is probably logical and in similar institutions throughout the enough in its mathematical sequence, but country.' strikes one as rather peculiar. The book The grouping of the bases' is that generwill be found useful by teachers who have ally adopted by writers on qualitative anexamination papers' to draw up, since it alysis the world over. We believe, howpresents a large number of them, as well as ever, that it would have been wiser and numerous exercises' and problems well better for the student had the author divided suited to test a student's understanding of his third group, consisting of the metals the subject-matter.

precipitated by ammonium sulphide from What the book professes to do is in the neutral or alkaline solutions, into two main very well done. The statements and groups. But this is merely a matter of definitions are intelligible and correct, and opinion. the reasoning is generally clear and logical. We observe that the properties of the The writer's description of the instruments metals are first studied, after which the and methods of practical astronomy make author draws up a table for the analysis of

us.

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