the present attainment in various branches of science. It contains a general account of the composition of the atmosphere; a study of its various properties and phenomena and an explanation of the principles of weather prediction. It is obviously a book of information for the interested reader rather than a treatise for the more serious student.

F. E. B.

8. Etude sur Le Système Solaire; by P. REYNAUD. Pp. xiv, 82. Paris, 1919 (Gauthier-Villars et Cie).-Volumes of obsertions upon physical and astronomical phenomena are added to our collections each year, but in spite of all the material little progress is being made in coordinating it and deducing the laws which govern the phenomena. The first statement of a law will usually appear in some empirical relation. There was a time when Kepler's Laws and Mendeleeff's Periodic Law were simply empirical. The former have now a sound dynamical basis, and the latter is fast developing from the theory of atomic structure. The study of Dr. Reynaud is a commendable attempt to discover whether any relation can be found to describe the location of the planets in the solar system and the disposition of the satellites about a planet. Bode's law, despite its successful prediction of the orbits of the asteroids and Uranus, could not survive its failure in the case of Neptune, and has been relegated to the mathematical curiosities. Reynaud considers that since the evolution of any planet and its satellites has followed the same laws as the evolution of the solar system there must be some analogy in the spacing of the members of the system, and he works out some rather striking relations or at least coincidences. By arranging the planets in two groups, between which the asteroids form the dividing line, it may be seen that the distances from the sun in the first group fall approximately into the suite 1, 2, 4, 6, 8 while those of the second have 30 times the same numbers except that the place 1 is vacant in the first series and the place 30 X 8 in the second, or we may assign to these places the hypothetical planets Vulcan and Pluto. Now by introducing L 26.25 million kilometers, the lower limit for any possible planet, and D = 1.41 the specific gravity of the sun, our author finds that the distance of any planet may be expressed by a formula of the form L Dm where m takes on integral values. The success of such a formulation may best be judged by the following table in which the distances are in million kilometers:

The perihelion distances have been quoted for the inferior planets and the aphelion distances for the superior, on the assumption that since the mass of Jupiter so far exceeds that of any other planet it would influence the distances in these directions.

If it is surprising that this relation fits the planetary distances so well, it is not less so that the author is able to apply a similar formula to the satellites of Jupiter, Saturn, and Uranus with nearly the same success. As he remarks, "if this law had been established in 1891 it would have been possible to have predicted with a high degree of precision the position of the 5th, 7th, 8th, and 9th Satellites of Jupiter." Fulfillment of prediction would have given great weight to a hypothetical law, and it is a field that is still open for there are several vacant places in Reynaud's tables. He has also developed curious relations between the densities, the rotations and the inferior limit of satellites but whether his formula is an approximate representation of the progressive condensation of the solar nebula or not, can hardly be answered until we have a better dynamical theory of the evolution of a planetary system.

F. E. B.

9. The National Physical Laboratory; Report for the Year 1919. Pp. 151 with 37 figures. London 1920 (His Majesty's Stationery Office).-A perusal of this report will leave the impression that not all the consequences of the war are malign. That critical period set on foot a great train of investigations in the domain of physics, many of which promise a fruitful harvest for the arts of peace. It is not possible to present any resumé of such a report, but opening it casually one may find illustrations of the kind of thing just mentioned.

P. 35. A catalytic lamp in which the combustion of gasoline proceeds without the production of flame. The products of combustion and the hot air may be utilized on aeromotor- or other engines as such lamps may be inserted under the hood without danger of fire.

P. 60. The invention of a soft valve containing a silver anode amalgamated with mercury. When used as a receiver for loud wireless signals the illumination of the vapor due to collisions makes it possible to read signals by visual observation of the tube.

P. 126. A successful study has been made of the alloys of aluminum with copper and zine, with iron and silicon, and with magnesium and silicon. Tests have been made of their fitness for general castings; for working parts at high temperatures, e. g. pistons of aero-engines; for wrought material for

the structural parts of aeroplanes; for very thin sheets to serve as a strong and non-inflammable covering for aeroplane wings. A considerable section of the report is devoted to gauge testing by means of optical projectors.

II. GEOLOGY AND MINERALOGY.

F. E. B.

1. The Geology of Anglesey; by EDWARD GREENLY. Vols. I and II, pp. 980, with 60 plates in the text, 17 folding plates, and 346 text figures. Memoir of the Geological Survey of Great Britain, 1919. These two handsome volumes, excellently illustrated and well bound, embody the results of the author's work on the geology of Anglesey during a period of twenty-four years. Greenly resigned from the Geological Survey in 1895, but, within a few weeks after his resignation, he began a detailed study of Anglesey, being irresistibly drawn to this task by the fascination of the crystalline schists. In appreciative recognition of his work the Geological Society of London has lately awarded him the Lyell medal.

Volume I deals with the Mona Complex, as the metamorphic rocks of Anglesey are termed. They have long been of chief interest in the geology of the island. They embrace an area of 200 square miles and are by far the largest area of metamorphic rocks in southern Britain. They are of Pre-Cambrian age and are 20,000 feet thick, exclusive of the gneisses upon which the other members of the Complex are supposed to lie unconformably. The Mona Complex lends itself particularly well to a study of the relation of the degree of metamorphism to the tectonics. The author has been able to recognize three different successions in the Complex: a stratigraphic, a tectonic, and a metamorphic. The rocks have been folded into three master primary recumbent folds, the horizontal amplitude of which is as much as 60 miles. Superimposed on the primary folds are secondary and subordinate folds, probably due to the same dynamic impulse that produced the major folding. The regional metamorphism of the Mona Complex is of dynamic origin, and is ascribed to the superimposed foldings. The three primary recumbent folds, piled one on the other, constitute three tectonic horizons, within each of which the intensity of metamorphism progressively decreases upward. Thus, a waxing and waning of metamorphism is repeated thrice hypsometrically. The author explains this remarkable sequence by the fact that although metamorphism is a function of depth, it is a function of the thickness of the cover that was present at the time it was developing, not of the cover that may have been imposed after it had developed. Metamorphism may develop in a higher fold without appreciably intensifying the crystalline condition of a subjacent fold. For the conversion of the energy of folding into the molecular energy necessary to effect metamorphism can take place only at the actual locus of folding, and the underlying fold was therefore metamorphically inert, dead, when the next recumbent fold was rolled rit.

Volume II deals mainly with the rocks younger than the Mona Complex. The Ordovician rocks are the next most important after those of the Complex. They are described in detail, as are also the later Paleozoic rocks, the Pleistocene glaciation, the origin of the land forms, and the economic resources. Under the latter is described, so far as present conditions allow, the old copper mine of Parys Mountain, once the most productive copper mine of Europe, which still yields annually a modest amount of copper, obtained, however, from the cupriferous waters that flow from the old, caved-in workings.

ADOLPH KNOPF.

2. Abriss der Allgemeinen und Stratigraphischen Geologie; by EMANUEL KAYSER. 2d revised edition. Pp. viii, 460, 212 text figs., 54 plates of fossils, 1 large geologic map, Stuttgart (Ferdinand Enke), 1920.--Professor Kayser, formerly of the University of Marburg, and now at Munich, is the author of the widely used "Allgemeine Geologie," and "Geologische Formationskunde." These books have become too detailed for undergraduates, and in the present "Abriss, now in its second edition, he has presented the earth sciences for this class of students. Less than one-half of the text (195 pages) is devoted to physical geology, while the greater part (224 pages) deals with historical geology. We see therefore that in Germany historical geology is held to be equally as important as dynamic and structural geology, a viewpoint far less popular in this country. The book has an excellent geologic map of central Europe, and is a good volume for American teachers to have on their shelves.

C. S.

3. The Geology and Mineral Resources of Bexar County; by E. H. SELLARDS. Univ. of Texas Bull., No. 1932, pp. 169, 1 pl., 1 map, 6 text figs., 1919 (1920).-This report treats at length of the geologic and economic resources of the Lower and Upper Cretaceous and Cenozoic formations, having together a thickness. of over 4,800 feet. They rest upon ancient schists. The outcrops of the formations are mapped.

C. S.

4. The Geology of Tarrant County; by W. M. WINTON and W. S. ADKINS. Univ. of Texas Bull., No. 1931, pp. 122, 6 pls., 2 maps, 6 text figs., 1919 (1920).-Here is described and mapped the geology of the Fort Worth area, the surface strata being in the main of the Lower Cretaceous. The various formations are discussed in considerable detail, with lists of their characteristic fossils.

C. S.

5. Mineralogy: an Introduction to the Study of Minerals and Crystals; by E. H. KRAUS and W. F. HUNT. Pp. 561, 696 figs. in the text. McGraw-Hill Book Co., 1920.-This latest addition to the list of elementary mineralogies has many features that will commend it to the instructor of mineralogy. It covers all the different branches of the field, is concise and well written, and on the whole is unusually well illustrated. A novel and attractive feature is the inclusion of a number of photographs of eminent mineralogists with added brief biographical statements. These serve to give an historical perspective to the subject that is as pleasing as it is unusual.

It is to be questioned if it is worth while to include in an elementary book a brief and therefore necessarily unsatisfactory treatment of the difficult subject of the optical properties of crystals. The determinative tables which are based upon the physical properties of minerals seem to be unnecessarily bulky and consequently difficult to use.

W. E. F.

6. The Ore Deposits of Utah; by B. S. BUTLER, G. F. LOUGHLIN, V. C. HEIKES and Others. U. S. Geol. Surv., Prof. Paper 111, 1920. Pp. 672, 74 figs., 57 pls.-This is the second professional paper to appear detailing the geology and ore deposits of a single state. In 1910 a similar report on New Mexico was published and reports dealing with other states are in preparation. While a large part of the material in the present volume has been previously published in other reports, the gathering of it together in a condensed form into a single volume and including with it a general study of the ore deposits of the state makes it a most valuable addition to the literature of economic geology. From this study of the state as a whole has come the following important generalization.

The value of an ore deposit found in connection with an igneous stock will be largely determined by the amount of erosion the stock has undergone. Deposits around the apex of stocks are larger and more valuable than those located at greater depths in and around the stock. Consequently stocks that have been least eroded will be more favorable as locations of ore deposits. The amount of erosion of a given stock can be estimated from the chemical character of the igneous rocks exposed. The lower portion of the stock is uniformly more siliceous, the character of the rock changing from monzonite and diorite at the apex to granodiorite and granite at greater depths.

OBITUARY.

W. E. F.

Dr. HENRY A. BUMSTEAD, professor of physics and director of the Sloane Physical Laboratory at Yale University, and for the past half-year on leave from the University as Chairman of the National Research Council of Washington, D. C., died suddenly on the train on the night of December 31 while returning to Washington from Chicago. A notice is deferred until a later number.

SIR WILLIAM DE WIVELESLIE ABNEY, the gifted English astronomer, died on December 2 at the age of seventy-seven years.

PERCIVAL SPENCER UMFREVILLE died at Harpenden, England, at the age of sixty-two years. His chief work was in physical chemistry, dealing with the phenomena concerned in the formation and solution of salts.

WILLIAM ARTHUR HOWARD, research fellow in the Imperial College of Science and Technology, died suddenly as the result of a laboratory accident on December 6 at the age of twenty-six

years.

Dr. YVES DELAGE, professor of zoology in the University of Paris, died recently at the age of sixty-six years.