tra of the solar corona and of the gaseous nebulae can be accounted for theoretically by the electrical vibrations of very simply constituted atoms, and Bohr, employing the new theories of radiation, shows that the hydrogen series may be similarly explained. The cause of these singular phenomena is not yet understood. Photometry. Parkhurst, in his Yerkes Actinometry, gives measurements of the brightness of some 600 stars within 17 deg. of the North Pole, made photographically, both on ordinary plates (that is, with violet light) and on isochromatic plates, using a color screen transmitting yellow and green light. The difference in the brightness of a star measured in these two ways gives an accurate measure of its color. The spectra of the stars were also photographed, and the relation between the "color index" just described and the The system of classifying stellar spectra which has been developed at the Harvard Observatory was adopted by the International Union for Solar Research for general use, pending the adoption of a definitive classification. According to this system, the six principal types of stellar spectra are denoted by the letters B, A, F, G, K and M, and interme- class of spectrum determined, with diate classes by the "decimal notation;" for example, a spectrum half way between the B and A types is called B5A, or simply B5. Eberhard and Schwarzschild find that the H and K lines of calcium are reversed, (bright), in the spectra of Arcturus and some other stars of class K, which in this respect, as in some others, resemble the spectra of sun spots. Stellar Temperatures.-Rosenberg, from the distribution of energy among the different wave lengths in the spectra of some 60 stars, deduces the effective temperatures of their surfaces, finding, like previous observers, a steady decrease in temperature from class B to class M. The range of his computed values, from 40,000 deg. for class B to 2,300 deg. for class M, is, however, much greater than that found by some earlier observers (A. N., 4621). Spectroscopic Binaries.-The rate of discovery of these interesting systems still far exceeds that at which the necessary observations for the computation of their orbits can be secured. Among those whose orbits have been computed may be noticed Ursae Majoris, with the unusually long period of 4.15 years, and RR Lyrae, with the very short period of 13 hours (see infra). Belopolsky finds that in the spectrum of a Canum Venaticorum certain lines vary greatly in intensity, with a period of 5.5 days, while the rest are unaltered. The variable lines show periodic changes in radial velocity, while the others do not. results agreeing well with those of other observers. If two stars of spectra A and M appear equally bright to the eye, or on the isochromatic plates, the former will appear four times as bright as the other on the ordinary plates. (Ap. J., XXXVI, 169). Variable Stars.-One hundred and thirteen new variable stars whose changes in brightness have been confirmed by independent observations have received definitive names between June, 1912, and June, 1913. Much attention is being paid to the theory of stellar variation. In the case of the eclipsing variables, which are usually of constant brightness but lose light at regular intervals owing to the interposition of a fainter companion, the theory is in a very satisfactory state. Shapley, using the methods devised by Russell, has worked out the orbits of 87 such systems. His principal conclusions are: It is usually certain, and always probable, that the eclipsing companion has some light of its own. For the most accurately observed systems, there is definite evidence that the stars appear brighter at the centers of their disks than at the edges, as is the case with the sun. In many cases the two stars of a pair keep always the same faces toward one another, and are elongated into ellipsoids by their mutual attraction, the effect being greater the nearer they are together. The faint companion is often larger than its brighter primary, and, when its color is known, is also redder and presum. ably colder, but nevertheless it is al- Præsepe cluster in Cancer, which are most certainly much less dense. All receding from us at the rate of 36 but one of the 87 stars are less dense km. per second. These stars have than the sun, the white stars, of small but equal proper motions, and spectra B and A, having usually den- appear to be travelling in space in sities from one-fifth to one-fiftieth almost the same direction and at althat of the sun, while the yellow most the same rate as the Hyades stars, of spectra F, G and K, fall into cluster, in which case their distance two groups, one about half as dense from us must be about 500 lightas the sun, and the other of ex-years. tremely low density. The Cepheid variables, which change regularly and continuously in brightness in a manner not explicable by eclipses, are still a great puzzle. It is known that they are very remote, are really of great brightness (several hundred times that of the sun), resemble the sun in spectrum, and are all spectroscopic binaries, the time of maximum brightness being always the same as that when the star is approaching us most rapidly, and the minimum coinciding with the most rapid recession. Kiess, studying the star RR Lyrae, which in its very short period of 13h. 37m., and other characteristics of its variation resembles the variable stars which occur in certain star clusters, finds it to be a spectroscopic binary with the typical Cepheid characteristics. Ludendorff has shown that the observed ranges in radial velocity and in light variation among these stars are very nearly proportional to one another. Luizet develops a theory of their variation, assuming that the principal star of each system is brighter on one side than on the other, and rotates, not uniformly, but so that the bright side always faces in the direction of the orbital motion. There remain, however, many unexplained difficulties. Star Clusters and Nebulae.-Adams and Van Maanen find that nine of the brighter stars in the great cluster in Perseus are all approaching us at the unusually rapid rate of 43 km. per second. The proper motions of these stars are very small, and the distance of the cluster probably very great. Schwarzschild finds a similar community of radial velocity among the brighter stars of the Fath finds that the spectra of a number of globular star clusters are intermediate between those of Procyon and the sun; and that those of the Andromeda nebula and of some this, finding also bright lines in the solar type, which indicates that they are really vast clusters of stars resembling the sun. Wolf confirms this, finding also bright lines in the spectrum of the Andrómeda nebula, and a faint line in the spectrum of the great nebula in Orion whose existence has been predicted theoretically by Nicholson. Slipher finds that the spectrum of the faint streaky nebulosity in the Pleiades is an exact copy of that of the brighter stars of the cluster, which seems to prove that this nebula consists of some sort of dust or fog, and shines by reflected light. Hertzsprung strongly confirms this theory by measuring the brightness of this nebula at several points and finding that it is only from four to one per cent. as bright as a white screen illuminated by the light of the stars would be. He estimates the distance of the Pleiades as 300 light-years and shows that the total mass of the dust clouds need not exceed that of the sun. (A. N., 4679.) Fath finds that the spectrum of the light of several regions of the Milky Way is of the solar type, indicating that the multitude of very faint stars, from which most of the light comes, are yellow, though the brighter ones are well known to be white (Ap. J., XXXVI, 362). Slipher, from four plates of the spectrum of the Andromeda nebula, finds that it is approaching us with the enormous radial velocity of 300 kilometres per second. XXV. GEOLOGY, METEOROLOGY, AND GEOGRAPHY GEOLOGY DYNAMIC AND STRUCTURAL J. W. Spencer (Amer. Jour. Sci., GEOLOGY SIDNEY POWERS 1 International Geological Congress.The most important geological event of the year was the twelfth session of the International Geological Congress, which convened at Toronto, Aug. 7 to 14. The meeting was preceded and followed by excursions throughout Canada which are described on a sub sequent page (see International Geological Congress, infra). XXXV, 561-73). The agreement between physiographic researches and Hayford and Bowie's geophysical determinations is such as to show the fallacy of the theory that postglacial deformation was due to the melting of ice caps. Spencer further shows that the recent changes of level of the land and sea at the continental shelves ocRecent deformation in the Great Lakes curred in areas deficient in gravity. region is due to unequal sinking of zones resting on foundations of unequal rigidity. Dynamic Geology: Isostasy. The Coal Formation.-The formation of physics of the earth's interior with rethe coal-beds in the Northern Appagard to isostasy is being investigated lachian basin and the nature of the in this country and in India, with re- rocks associated with these coal meassults which confirm the views of Hay-ures are discussed by J. J. Stevenson, ford and Bowie (A. Y. B., 1911, P. (Stechert & Co., 1913). The author 581; 1912, p. 605). Hayford (Jour. concludes that the conditions of depoof Geol., XX, 562-78) replies to a sition recall those now observed on criticism by H. Lewis that there was the Siberian Steppe and other river an error in the computations of the depth and completeness of the isostatic regions. There was an eastern and a western valley, in each of which compensation. Hayford shows that was a longitudinal river. The main the observed deflection from the vertical at any station can be calculated streams were sluggish and often infrom a degree of compensation for surface was covered broadly by a sheet terrupted. During high water the any assumed depth, the degree of com- of water, and the débris from differpensation differing greatly for different streams was mingled. Subsidence ent stations at a certain depth. He also shows that his gravitative deter- prevailed in the basin until the later minations agree with those of Lewis, stages. During the whole of the Pennsylvanian a great part of the basin although calculated by a different was near sea level and apparently no method. Hayford's method has been applied in India (Geol. Surv. India, than 100 ft. below tide. portion of it was at any time more Prof. Papers No. 12 and 13), where the depth of compensation is found to be greater than in the United States. The relationship between terrestrial gravity and observed earth movements of eastern America is discussed by 1 The acknowledgments of the author are due to Prof. J. B. Woodworth for suggestions and criticism. Faults.-The committee on the nomenclature of faults, appointed by the Geological Society of America, has issued a lengthy and comprehensive of the Society (XXIV, 163-86). W. M. report, published in the Proceedings Davis has treated the physiography of faults in a separate paper (Bull. Geol. Soc. of Amer., XXIV, 187-216). R. W. Richards and G. R. Mansfield describe (Jour. of Geol., XX, 681-707) the Bannock overthrust in southeastern Idaho and northeastern Utah. The trace of this fault extends for about 270 miles in a direction a few degrees to the west of north, and the direction of thrust is a little to the north of east. The fault surface is deformed and erosion has cut deeply through the overthrust strata into the underlying rocks, making it difficult to trace the original horizontal displacement. The displacement has been estimated at over 35 miles. The youngest rocks involved in the faulting are early Cretaceous sandstones, and the trace of the fault is concealed by basal Eocene conglomerates. Hence, it is probable that the faulting occurred at the close of the Cretaceous. There are a number of thrust faults in the region north of the Bannock thrust, apparently in the same zone of crustal readjustment. Diastrophism. - T. C. Chamberlin writes on "Diastrophism and the Formative Processes" (ibid., XXI, 517, 577), discussing the elastico-rigid earth under the planetesimal hypothesis of its origin. Then he applies the principle to the diastrophic origin of the shelf-seas, discussing the characteristics of these seas and their relation to submarine life. He concludes that the traditional view "that the systematic sedimentations and the systematic evolutions of faunas of the higher order are to be assigned directly to vertical or epeirogenic movements of the earth's crust" should be abandoned. Structural Geology.-The Report of the State Geologist of Vermont (1912) contains, among other contributions to the geology of the state, a general account of the geology of the Green Mountains by G. H. Perkins, the Director of the Survey. The Virginia Survey has issued a bulletin (No. 4) on the physiography and geology of the coastal plain province of the state, by W. B. Clark and B. L. Miller. Similarly, the Georgia State Survey has issued a report on the coastal plain of Georgia (Bull. 26) by O. Veatch and L. W. Stephenson, describing a series of sedimentaries aggregating over 4.500 ft. in thickness. The Wisconsin Survey has issued a bulletin (No. 25, 1912) on the sandstones of the Wisconsin coast of Lake Superior, by F. T. Thwaites, who describes two conformable groups of Upper Keweenawan sediments believed to have been deposited subaërially in a basin formed by the folding of earlier Keweenawan strata. The geology of south-central South Dakota is described by E. C. Perisho and S. S. Visher in a bulletin (No. 5, 1912) of the state Geological Survey. The United States Geological Survey has issued the following folios of the geologic atlas of the country since the last issue of the YEAR BOOK: 183, Llano-Burnet, Texas; 184, Kenova, Kentucky West Virginia - Ohio; 185, Murphysboro-Herrin, Illinois; 186, Asiphaha, Colorado; 187, Ellijay, Georgia - North Carolina - Tennessee; 188, Tallula-Springfield, Illinois; 189, Barnesboro-Patton, Pennsylvania; 190, Niagara, New York. In the educational field, Structural Geology, by C. K. Leith (Holt, 1913), is a welcome contribution in a line which receives insufficient treatment in many American textbooks. C. H. Clapp presents the results of several years of field work in a memoir on the geology of southern Vancouver Island (Can. Geol. Surv., Mem. 13, 1912). Recently new index fossils have been found on the island (Int. Geol. Cong. Guide Book No. 8, 280341). A marked unconformity between the Carboniferous and Devonian strata in the Upper Mississippi Valley is described by C. R. Keyes (Amer. Jour. Sci., XXV, 160-64). The geology of the Columbus Quadrangle, Ohio, is described in Bulletin 14 of the State Survey. A geologic map of Canada has been prepared by the Canadian Geological Survey on a scale of 100 miles to one inch (1:6,336,000), giving the geology in greater detail than Willis' map of North America, because of its more limited area. A geologic map of Nova Scotia on a scale of 12 miles to one inch (1:760,320) accompanies Fernow's report on "Forest Conditions in Nova Scotia" (Commission on Conservation, Can., 1912), but this map should be used with the knowledge that practically all of what is mapped as Devonian is really Carboniferous. The geology of Nova Scotia is brought up to date by Guide Book No. 1 of the International Geological Congress, which is the most comprehensive treatment of the subject since Sir J. W. Dawson's Acadian Geology appeared. Fossils have for the first time been found in the Huronian and are described by A. C. Lawson and C. D. Walcott from the Steeprock Lake dis trict, Ontario (Can. Geol. Surv., Mem. 28, 1912). J. B. Woodworth describes a geological expedition to Brazil and Chile, 1908-9, the first of the Shaler memorial series (Bull. Mus. Comp. Zool., Harvard Coll., 1912). The Permean glaciation of southern Brazil is discussed in detail. The geomorphology of south Brazil and the changes of level of the coast of southern Chile are also treated. Alaska.-The Alaskan Division of the U. S. Geological Survey, under the direction of A. H. Brooks, has published a number of papers on geological reconnaissances and mineral resources during the year. The general geology of the Mt. McKinley region is treated by Brooks (U. S. G. S., Prof. Paper 70). Glaciation in northwestern Alaska is discussed by P. S. Smith (Bull. Geol. Soc. Amer., XXIII, 563-70). L. M. Prindle describes the Fairbanks Quadrangle (U. S. G. S., Bull. 525), A. G. Maddren, the Koyukuk-Chandlar region (U. S. G. S., Bull. 532), and F. H. Moffit, the Nome and Grand Central Quadrangles (U. S. G. S., Bull. 533). Glacial deposits of the continental type in Alaska are described by R. S. Tarr and L. Martin (Jour. of Geol., XXI, 289-300). The presence of glaciers is found to be related to topography, and the deposition of loess and eolian silt to glacial outwash and wind work. The coastal glaciers of Prince William Sound and Kenai Peninsula are treated by U. S. Grant and D. F. Higgins (U. S. G. S., Bull. 526). In the Bulletins of the U. S. Geological Survey the following regions are described: the Yentna district by S. R. Capps (No. 534), the Rampart Quadrangle by H. M. Eakin (No. 535), the Circle Quadrangle by L. M. Prindle (No. 538). Philippine Islands.-W. D. Smith, Chief of the Division of Mines of the Science Bureau, writes on the geology of Luzon (Jour. of Geol., XXI, 2961). This forms a valuable contribu tion on Philippine Cordilleran geology. The formations exposed are Tertiary or younger, with the possible exception of some igneous rocks, for the reason that the older formations are deeply buried under the continental shelf. The mineral resources of the islands are treated in a publication of the Science Bureau, Manila. Stratigraphy.-Among the most important works on stratigraphy is C. D. Walcott's monograph on Cambrian Brachiopoda (U. S. G. S., Monogr. 51) in two volumes. The first monograph of the Brazilian Geological Service is devoted to a treatise by J. M. Clarke on the Devonian of southern Brazil and the Falkland Islands. The illustrations from this monograph are reprinted in the Ninth Report of the Director of the Science Division, New York State Museum. In the same report Clarke traces the origin of the Gulf of St. Lawrence (pp. 132-37). Bailey Willis has published an "Index to the Stratigraphy of North America" (U. S. G. S., Prof. Paper 71) in coöperation with the Geological Survey of Canada and the Instituto Geológico de México. This index is accompanied by a geologic map of North America. It comprises discussions on stratigraphy, citations of fossils, and views on correlations. The Lower Silurian shales of the Mohawk Valley are described by R. Rudemann (N. Y. State Mus., Bull. 162). A. W. Grabau contributes a textbook on Principles of Stratigraphy (Seiler & Co., 1913). C. A. Hartnagel has published a classification to the geologic formations of New York State (State Museum Handbook No. 19). The Geological Survey of Maryland has issued a monograph on the Lower Cretaceous of that state (1912). The age of the Judith River formation has been placed by A. C. Peale (Jour. of Geol., XX, pp. 738-58) as equivalent to the Lance formation and above the Fox Hills formation, which is in turn underlain by the Pierre shales and Niobrara formation, themselves the equivalent of the Belly River series. L. G. Westgate and E. B. Branson describe the later Cenozoic history of the Wind River Mountains, Wyoming (ibid., XXI, 142-59). Glacial Geology. - The Pleistocene geology of New York State was the |