SCIENTIFIC BOOKS The Origin of Continents and Oceans. By ALFRED WEGENER, 1922. (Translated from the Third German Edition by J. G. A. Skerl, New York, 1924, E. P. Dutton and Co.) THIS book is a translation of the well-known publication by Professor Alfred Wegener, of the University of Graz, Austria, "Die Entstehung der Kontinente und Ozeane." (Vieweg, 1922.) Since the first presentation of Professor Wegener's theory of continental sliding, in 1912, European geologists have given it considerable attention. In North America, however, it has remained essentially unknown, and the publication of this translation is to be welcomed for the opportunity it will give American geologists to study the theory for themselves. In short, the theory postulates the existence of only one continent on the earth up to Permo-Carboniferous time, when it began to break up into the present continents, North and South America sliding westward from Europe and Africa, and Antarctica and Australia sliding southward and southeastward-leaving the Indian Ocean in their wake. The movement has been more or less continuous up to the present and has progressed, of course, at a very slow rate. Labrador and Greenland have, according to the theory, been separated from northern Europe since the maximum extension of the Pleistocene ice cap. It is even held that longitude observations reveal a present westward drift of Greenland, and this point, together with similar data for other places, constitute part of the more important evidence. An important feature of the theory is the wandering of the earth's axis of rotation with respect to the continents. ( (Whether there has been a change of the axis within the body of the earth is left an open question.) In Permo-Carboniferous time the south pole was situated at the southeastern extremity of Africa. Thus, with one orientation, the author accounts for the Permo-Carboniferous glaciation of South America, Africa, India and Australia (which were clustered about South Africa at that time), also for the tropical coal basins arranged along the PermoCarboniferous equator, and likewise, for the desert regions, as shown by the "red beds" which were formed 20 to 40 degrees north of this equator. The positions of the poles are also established from Silurian time to the present, though the evidence, for other geologic periods than the Carboniferous, is not so definite and hence the determinations are more tentative. The theory is a natural outgrowth of unreserved acceptance of a condition of perfect isostatic balance 1 A contributory volume has lately been published by W. Köppen and the author ("Die Klimate der geologischen Vorzeit," Berlin, Borntraeger). for the earth's crust. Without the isostatic foundation the "displacement" theory, as it stands, could by no means have been developed. It is postulated that somewhat "rigid" continental sheets (sial), which are about 100 kilometers thick, float in a more viscous, basaltic stratum (sima), which is exposed on the ocean bottoms, and which is thought to extend to a depth of about 1,500 kilometers. Gravitational and tidal forces are supposed to set up differential stresses sufficient to cause movement of the continental blocks through the less rigid "sima." Evidence for the former union of continents consists of material taken from various fields, such as the matching of geological formations and intrusive bodies on opposite sides of the continental rifts, comparison of living faunas and floras, assembling and correlating the facts of paleoclimatology, together with facts drawn from the fields of geophysics and geodetics. The displacement theory seems to be especially weak in its excessive demands on the very small forces available to produce sliding of continental masses. It is likewise apparently on very insecure ground when it attempts to draw, from the facts of Pleistocene glaciation, evidence for the very recent separation of North America, Greenland and Europe. Most American geologists will also believe that Professor Wegener is without sufficient foundation in his extreme acceptance of a fluid and viscous earth. Moreover, a careful review of the evidence for a westward drifting of Greenland by Sir Charles Close (Geographic Journal, Vol. 63, p. 147, 1924), has resulted in his finding that the evidence available at present is inconclusive, and that another exact determination of longitude at one of the Greenland stations, in about ten years, by means of wireless signals, should settle the question. Even though the theory is highly heterodox in the eyes of many American geologists, the book is, nevertheless, an able presentation of the subject. A great number of very suggestive facts have been marshalled in support of this interesting doctrine. Considerable leeway is, in all fairness, to be allowed the author in the presentation of such a revolutionary conception. A large European literature has already grown up around this hypothesis and, in America, Coleman, Daly and Washington2 have recently contributed to the discussion. 2 Coleman, A. P., "Ice ages and the drift of continents," Amer. Jour. Sci., Vol. 7, 1924, pp. 398–404. Daly, R. A., "The earth's crust and its stability," Amer. Jour. Sci., Vol. 5, 1923, pp. 349-371. Daly, R. A., "Decrease of the earth's rotational velocity and its geological effects," Amer. Jour. Sci., Vol. 5, 1923, pp. 372-377. The translation has been very carefully made. In fact, the degree of literality is, in many places, so great that good English usage is not found. This is, however, probably to some extent intentional on the part of the translator, for the sake of exactness in presenting the author's views. Mr. Skerl has done a valuable piece of work in presenting this translation to English-speaking investigators. COLUMBIA UNIVERSITY FRANK A. MELTON SCIENTIFIC APPARATUS AND LABORATORY METHODS REGELATION AND LOW TEMPERATURES EVERY year we show the freshman class in physics, that a loaded wire will cut through a block of ice leaving the block intact. Every year the students read the insufficient discussions in their text-books (there is one recent text that does explain fully), most of them not getting beyond "The pressure melts the ice." If pushed for a further analysis, they say that the energy to melt the ice comes from the descending weight, and they accordingly conclude that the cutting of the block would go on at any temperature. After several years of arguing, finding the students uniformly unconvinced and even the instructors often doubtful, and never in the whole time having met an inquirer who had seen the experiment tried at low temperatures, I decided to bolster up "I can see, with my mind's eye" with "I have seen with my own eyes." A rectangular block of ice, taken from the refrigerator and treated in the usual manner, was cut through by the loaded wire in forty minutes. The whole apparatus was then put out of doors for several hours and then the wire loaded as before. During the eighteen hours that the experiment was continued the temperature of the surrounding atmosphere varied from 0° Fahr. to -20° Fahr. In that time the only effect of the wire on the ice was a mechanical chipping out of a bit at each of the sharp upper corners of the block. Across the top of the block the wire touched only the highest points and even there produced no observable effect. This experiment is reported as just one more instance where the time and energy required to make the convincing test is but a small fraction of the time and energy spent in fruitless office-chair debate about how nature ought to operate. CORNELL UNIVERSITY HARLEY E. HOWE SPECIAL ARTICLES THE S-CHROMOSOMES IN ORNITHOGALUM L. As my paper on the chromosomes of the Ornithogalum, which I wrote in 1923, is not yet printed, I should like to publish a preliminary note concerning the chromosomes possessing satellites, which I call chromosomes S. In 1915 D. J. Persidsky found in O. umbellatum L. satellites of a length hitherto unknown. This discovery was made in the laboratory of Professor S. G. Nawaschin and remains unpublished. When, in 1921, I began the investigation of other species of Ornithogalum, I found that in them there are also chromosomes with satellites-one pair of such chromosomes in each diploid nuclear plate of each species. The length of the satellites was, however, found to be very unequal in different species. The same can be stated also about the length of the "body" itself of the chromosomes S. Nevertheless, I take it for certain that the S-chromosomes of one species are homologous with the S-chromosomes of the others. The S-chromosomes are easily distinguishable and therefore very convenient for comparative studies. In Fig. 1 are represented the S-chromosomes of three species: 0. Narbonense L. (N), O. tempskyanum Fr. et Sint. (tp) and O. oligophyllum Clarke (0). the sum of the lengths of all the chromosomes of the set is smaller in the species with reduced inflorescences. In my first paper2 I formulated the proposition that the historical process of changes in chromosomelength is of common occurrence. Since that time I have been able to prove the existence of this process for the Muscari3 and to establish it for the Bellevalia3 and Ornithogalum. However, I admit at present that the scheme of degradation of the chromosomes that I gave in my first paper is not universal: we are obliged to acknowledge that the length of those chromosomes, which have no satellites, and never had them, has also changed. All the data I have in my possession point out clearly that the chromosome-length changes as the species diverge, within very wide limits: the satellites in O. Narbonense are nine times longer (and three times broader) than in O. oligophyllum! The bodies of the S-chromosomes are in the first species twice as long as in the second. The historical process of the change of the chromosome-length is one of those phylogenetic processes which must be established by the comparative study of chromosomes in different systematic groups. L. DELAUNAY Chemistry in old Georgia: C. J. BROCKMAN. There was no Colonial chemistry in Georgia. From the time of its foundation as a colony in 1732 until the expulsion of the British in 1782 Georgia, as a colony, was dependent upon its sister colonies for its explosives and even its rum. The University of Georgia was founded in 1785, but was not active until about 1807 under the presidency of Josiah Meigs, a Yale graduate who introduced the study of "Chemistry, with actual experimental demonstration of its principles." Apparatus for the course in "Philosophical Investigations" to the extent of 205 pounds sterling was imported. Natural philosophy was divided 2 Delaunay, L., 1915. Étude comparée caryologiques de quelques espèces du genre Muscari. Comm. prélim. Mém. Soc. Natur. Kiew, vol. 25, pp. 33-64, pl. 1, fig. 1–2. (Russian with French résumé.) 8 Delaunay, L., 1922. Vergleichende karyologische Untersuchungen einiger Muscari- und Bellevalią- Arten. Moniteur du Jardin Botan. de Tiflis, série 2, livr. 1, pp. 1-32, fig. 1-11. (Russian with very short German résumé.) 4 The unpublished article. 5 L.c., p. 51, fig. 2. See also Tischler, G., 1922. Allg. Pflanzenkar., p. 632, fig. 375. in 1822 into separate parts, i.e., physics and chemistry. Dr. Henry Jackson became professor of natural philosophy in 1811 and was given leave of absence to serve as secretary of the legation at Paris a few years later. A scientific library valued at several thousands of dollars was maintained. In 1854 a gift of $20,000.00 was made by Terrell to advance the knowledge of agriculture. This gift is unique in the history of the science. The course of lectures to be given was to include: (1) Agriculture as a science; (2) practice and improvements of different people; (3) chemistry and geology so far as they may be useful in agriculture; (4) manures; (5) analysis of soils; (6) domestic economy, particularly referring to the southern states. The aid of Dr. White, of the chemical department, in tracing some of this information is appreciated. Chemistry and alchemistry in the Arabian nights: C. J. BROCKMAN. The Arabs were the people who preserved the Greek culture during the Dark Ages and then brought it into western Europe. From the advent of Mahomet to the Renaissance, Arabian culture was spread into Egypt, Morocco and Spain by the fanaticism which was peculiar to Islam. Most of this culture has been lost through religious and racial prejudices. Very slowly the records are being searched for information that will reveal the glories of the Arabic influence when at the height of the tide. The "Arabian Nights Entertainments' are probably the only extant authority on the Arabic "folk-lore" from Mahomet to the disintegration of his empire. These tales contain much that is fantastic and supernatural, but in the background there must be something of real historical value. The "Nights" contain many references and inferences concerning the use of chemical substances as cosmetics, drugs, foods, etc., and for the transmutation of metals. The Houris and the dancing girls colored their finger and toe nails with henna and blackened their eyelashes and eyelids with "kohl," from which word is derived our present term alcohol. The Bedouin understood the uses and applications of aphrodisiacals as a cure for impotence, one of the horrors of old age. The hypnotics, sedatives and narcotics as bhang, hashish, henbane and hemp found extensive use. Gum benzoin measured by volume was a criterion of female physical beauty. Leather, metals, synthetic drinks and foods, earthenware and glass vessels were manufactured in quantity. Beer and wines were used for the purpose of producing intoxication, not for social courtesy. An anti-intoxicant was found in myrtle which also served the dual purpose of a flavor for new brandy. Extensive directions are often given for the transmutation of lead and mercury into gold and silver. Extraordinary combinations of foods and drugs were prescribed as cures for leprosy and other dread diseases. The Arabian Nights in places could easily be called the popular chemistry of the Arabs. Though very voluminous and not by any means a treatise on the chemistry of the age, the Nights possess a fascination which makes them what is now called "interesting reading." LYMAN C. NEWELL, Secretary SCIENCE VOL. LXII JULY 10, 1925 CONTENTS No. 1593 LAW, DESCRIPTION AND HYPOTHESIS The "Undertow": DR. WALLACE CRAIG, I. BRANT, Retardation of the Action of Oxidases by Bacteria: 34 36 YOUR invitation to deliver the first Steinmetz lec- This lecture is an attempt to describe briefly how In its mathematical form Coulomb's law is identical Newton's great essay, "Principia Philosophiae Nat- 1 The first Steinmetz lecture delivered on May 8, 1925, Leyden jar discharges, had no obvious connection with the Newtonian school of natural philosophy of the eighteenth century and, therefore, the Royal Society failed to recognize their full significance. One may imagine how welcome Coulomb's law was to some natural philosophers of the eighteenth century, to whom Newton's Principia was as final as the book of Genesis is to some people of our own generation. Faraday was the first to point out a fundamental difference between Newton's law of gravitational action and Coulomb's law of electrical action. The action of a gravitational mass upon another gravitational mass is not influenced by the medium separating the two, but the action of an electrical charge upon another electrical charge is influenced very much by the medium separating the two. Coulomb's law, unaided by other considerations, was unable to explain this difference. Additional knowledge was needed which Coulomb did not possess. Faraday was the first to enter into these considerations, and his first guide may be said to have been a hypothesis which maintained that all electrical charges trace their origin to the molecules and atoms of material bodies, which in their normal state contain, according to Franklin, the same amounts of positive and negative charges. This hypothesis of the atomic origin of electrical charges was undoubtedly suggested by Faraday's classical studies of the behavior of electrolytes, which revealed a new truth, namely, that a definite electrical charge is attached to each valency of atoms. The granular structure of ordinary electrical charges and the whole modern electron theory was first foreshadowed in these experiments. But how did this hypothesis affect Coulomb's law of force between Coulomb charges which are surrounded by a material medium? Consider the insulators. The hypothesis suggested that in an insulator each molecule contains a definite quantity of positive and an equal quantity of negative charge which can be separated from each other by the action of an external electrical force impressed upon them, but that the distance of separation can not exceed the dimensions of the molecule. Adopting this picture of the electrical structure and behavior of insulators there was readily deduced a modified form of Coulomb's law of force between charges separated by an insulating medium, and this modified form of Coulomb's law says: The force between two point charges in an iusulating material medium is equal to that in a vacuum divided by a constant, called the specific inductive capacity of the material medium. But experiment told us that the hypothesis mentioned above concerning the process of separating molecular charges and everything inferred from it can be only approximately true, because the specific inductive capacity of material insulators is usually neither constant nor does it always have a definite meaning. This law, therefore, could not be taken as our infallible guide in the study of the electrical fields of force in material insulators. The question arose then: Is there any other law to which we can appeal for guidance? Faraday's study of the electrical action of insulators, a subject to which Benjamin Franklin first drew attention, showed a way leading to the answer of this question. This study suggested one of the two great foundation pillars of the modern electromagnetic theory, which I venture to describe here briefly. Faraday's method of representing graphically the field of force of electrical charges is well known, and it finds its simplest illustration in the well-known conical tubes of force drawn from a point charge as vertex and expanding into all space. We are also familiar with Faraday's tubes2 of force for any distribution of electrical charges. Faraday's pictorial method of describing the field of force leads to the same numerical results as Coulomb's law when the surrounding medium is free space without any material bodies in it. When, however, the surrounding medium contains material insulators then Coulomb's law offers small assistance in our study when these insulators have a variable specific inductive capacity and deviate otherwise from the characteristics of an ideal dielectric. It will be pointed out below that there are electric and magnetic fields which are not due to charges and in which Coulomb's law is altogether inapplicable. Faraday's picture of the field in terms of the tubes of force suggested to Maxwell a new law of force which is broader than Coulomb's law both in its meaning and its applicability. Faraday's ideas concerning the physical character of the tubes of force were a guide to Maxwell, whose earliest studies of electrical phenomena, while still an undergraduate at the University of Cambridge, related to Faraday's "Physical Lines of Force." In these early studies Maxwell made wonderful attempts to show by imaginative description and ingenious mechanical models what he saw in Faraday's tubes. But all these things were only a temporary scaffolding around a new structure which Maxwell was building. When the structure was finished the scaffolding disappeared and what do we see to-day? I shall try to answer this question. In Maxwell's mind, just as in the mind of Faraday, the tubes of force were not mere geometrical pictures but represented physical entities capable of actions and reactions. Each volume element of a tube of electric force is according to Faraday and Maxwell the seat of an electrical re 2 The term "tubes" is preferable here to "lines" because it brings out clearly the three-dimensional character of these structures. |