that of the small star. The radius of the latter is twice that of the sun while its mass is over five times as great. The densities are 0.7 for the brighter and 0.0017 for the fainter, in terms of the density of the sun. tude five, but after that did not the mass of the big star is but a third brighten much. It passed perihelion in the middle of October. Comet 1919c was discovered by Metcalf on Aug. 22 and independently by Borelly on Aug. 23. It was of the tenth magnitude when discovered, and, although later brightening considerably, did not become visible to the naked eye. It passed perihelion outside the earth's orbit in December. Comet 1919d, discovered by Sasaki on Oct. 25 at the Kyoto Observatory, turns out to be identical with Findlay's Comet, which was expected to return in 1919. Schaumasse's periodic comet 1911: VII has apparently returned as 1919e, discovered by Fayet on Oct. 29. The Orion Nebulosities.-Slipher has secured spectra of several of the nebulosities lying within the great encircling cloud of nebulosity in Orion. The spectra are found to vary with distance from the Great Nebula. "If these nebulosities are to be regarded as parts of one great nebulous formation centering about the Trapezium, and it seems that they are really such, then the variation in spectrum may be said to begin in the center with the usual emission type which loses strength (different substances differently) with distance outward and ends finally, in the most distant masses, with a continuous spectrum of the normal stellar absorption type." These most distant nebulosities are apparently illuminated by reflected star light, and as these nebulosities are in regions strikingly deficient in stars, they probably extend beyond the limits of their luminous portion and absorb the light of the more distant stars. (Publ. Astron. Soc. Pacific, xxxi, 212.) A study of the Orion Nebula has also been made by Reynolds, who by the use of screens has secured photographs showing the distribution of nebulium and hydrogen in this region. Hydrogen extends out much farther than nebulium. (Monthly Notices Roy. Astron. Soc., lxxix, 561.) Absolute Dimensions of Eclipsing Binaries. Very few of the known eclipsing variables are bright enough in both components to permit a spectrographic determination of their orbits. When such is the case, however, such data can be combined with that secured from the interpretation of a good photometric light curve and the absolute dimensions of the system determined. Four such cases have been completely solved during the year, W Ursa Majoris and Z Herculis by Adams and Joy, and U Ophiuehi and R S Vulpeculae by Plaskett. The first and last are of especial interest. The orbital revolution of the components of W Ursa Majoris is completed in the exceptionally short time of eight hours. The stars are so big compared with the orbit that the distance between them is very small, and they are very much elongated in the line connecting their centers. The difference in velocity in the line of Bright-Line Nebulae. The prosight, due to the rotation of each star, gramme of measuring the radial vemay be as great as 240 km. for the locities of all known objects of the two limbs. This difference obliterates bright-line nebulae bright enough to the faint lines entirely and so widens be observed with exposure times of and weakens the stronger lines as to practicable length having been commake them difficult of measurement. pleted by the Lick Observatory staff, The densities of the components are some of the statistical results have exceptionally high, being 2.8 and 1.9 been published. In addition to the times that of the sun. The compo- 18 nebulae in the Magellanic clouds nents of R S Vulneculae are remark- there are six planetary nebulae, loably unlike. The total light of the cated in a very small area of the sky, fainter is nine-tenths that of the the observed radial velocities of which brighter, but the diameter of the for- exceed 115 km. per second. The mer is five times that of the latter. system of the remaining 101 nebulae The surface brightness of the fainter as a whole is substantially at rest is therefore only about one-twenty- with reference to our stellar system. eighth that of the brighter. Further, Planetary nebulae the diameters of which are less than five seconds have ages. It must be assumed, therefore, been called "stellar" nebulae. Exclud- that there exists within the stars ing the six planetaries of high veloci- some unknown store of energy of ties, the 31 stellar nebulae show an enormous magnitude. Russell has average radial velocity with refer- suggested some of the probable genence to the stellar system of 28 eral characteristics of this unknown km. per second. That of the other store. The process comes into operaplanetaries (having diameters greater tion only under extreme conditions of than five seconds) is slightly greater. temperature or pressure; the energy Stellar nebulae are found exclusively is derived from a finite store which is in one quadrant of the Milky Way. gradually exhausted, more slowly as Structure of the Sidereal Universe. the remaining supply decreases; the -In his later studies Shapley has rate of transformation of energy does completed the determination of the not accelerate to the point of explodistances of all known globular clus- sive catastrophe; and heat is supplied ters, 86 in number; has collected fur- to the star at almost exactly the rate ther data regarding their ellipsoidal at which the star radiates heat to form; and has drawn some conclu- space. Without entering into any sions as to the arrangement of the sidereal universe. Of 41 clusters studied, 30 show an appreciable elongation, analogous to that of the spiral nebulae and the galactic system but of a very much lower order. Globular clusters are small compared with the galactic system. There is a striking similarity in dimension and content. Open clusters appear to occur in the dense stellar regions of the galactic plane where globular clusters are not found. The globular clusters are apparently as a class approaching the sun, and are, as Shapley infers, approaching and falling into the dense stellar strata of the general galactic system. On the other hand, the brighter spiral nebulae as a class are receding from the sun and from the galactic plane. Their distribution is also in sharp contrast to that of the globular clusters. The heterogeneous makeup of the galactic system indicates that this system may be largely composed of disintegrating clusters. As a preliminary hypothesis it is suggested that "the discoidal galactic system originated from the combination of spheroidal star clusters and has long been growing into its present enormous size at their expense that the galactic system now moves as a whole through space, driving the spiral nebulae before it and absorbing and disintegrating isolated stellar groups." discussion as to the nature of the AITKEN, Robert Grant.-The Binary BELOT, Emile.-L'Origine des Formes de JEANS, J. H.-Problems of Cosmogony and Stellar Dynamics. (Cambridge Univ. Press, 1919.) KAYE, G. R.-The Astronomical Observ atories of Jai Singh. (Calcutta, Supt. of Govt. Printing, 1918.) ichte und Literatur der veranderlichen Sterne. Band I. (Leipzig, Poeschel & Trepte. 1918.) Sources of Stellar Energy.-It has MULLER, G., and HARTWIG, E.-Geschbecome increasingly evident that gravitational contraction must be but a small source of the energy which the sun and stars have radiated in past PLUMMER, H. C.-An Introductory Treatise on Dynamical Astronomy. (Cambridge Univ. Press, 1918.) GEOLOGY DYNAMICAL AND STRUC- J. B. WOODWORTH heretofore known as "contorted beds" in the chert formation of the Upper Huronian (Animikie) of the Mesabi range in Minnesota to algal growths. on Coral Reefs.-T. Wayland Vaughan ("Fossil Corals from Central America," etc., U. S. Nat. Museum, Bull. 103, 1919) discusses the bearing of the conditions under which the West Indian, Central American, and Floridian coral reefs have formed theories of coral-reef formation. He points out that the elevated Pleistocene fringing reefs of the West Indies are separated by erosion unconformiTemperature of the Earth.-C. E. ties at their bases from the geological Van Ostrand (Jour. Wash. Acad. formations they overlie, but that they Science, ix, July, 1919) calls atten- were usually formed during intermittion to the observations concerning tent uplift following considerable detemperature in deep wells in Texas pression. The offshore reefs were and Oklahoma. The curves of tem- formed during or after depression and perature increasing with depth are grew upon, or are growing upon, generally marked by a convexity antecedent flats, only a small part of towards the axis of depth. In the the surface of which was or is covered Goff well the rate varies continuously by reefs. Such flats occur outside of from 1° F. in 97.5 ft. at the surface to 1° F. in 46.5 ft. over the interval 6,000 to 7,000 ft. Temperatures obtained at similar depths in the oil fields of Texas and Oklahoma differ widely from those obtained in the Appalachian field. the coral seas. The submergence of the basements of fossil reefs seems to the author reasonably explained by differential crustal movement. But the development of living reefs seems to him in large part a result of a geologically recent rise in the ocean level, seemingly as much as 20 fathoms, and in places facts indicate a maximum between 30 and 40 fathoms. The available evidence is held to accord with the hypothesis that glacial control is one of the important factors in bringing about the formation of living coral reefs. Glacial Deposits.-R. W. Sayles ("Seasonal Deposition in AqueoGlacial Sediments," Mem. Mus. Comp. Zool. Harvard Coll., xlvii, Feb., 1919) describes in detail the banding in glacial clays and summarizes in affirmation the thesis that the alternations from light and coarse to dark and fine bands represent, respectively, R. A. Daly (Am. Jour. Science, summer and winter conditions of de- Aug., 1919) amplifies certain probposition, found not only in the clays lems concerning the development of of the last glacial period but in cer- coral reefs during and after the tain lithified clays of the Permo- glacial period with emphasis on the Carboniferous sections, associated effect of successive episodes of glaciawith tillite beds. F. F. Grant and tion and deglaciation with concurrent T. M. Broderick (Am. Jour. Science, rise and fall of sea level. The effect Sept., 1919) refer certain structures of mud and sand stirred up by vacillating sea level in checking coral E. W. Shaw contributes a paper on cludes that the Lafayette formation so-called is a residual mantle of no one epoch but is made up of unrelated cene and Pleistocene time. He finds coasts, materials accumulated during Plioa large amount of deformation of Geology of the United States. took place in Pliocene or early Pleisstrata in Mississippi, which probably Among the larger contributions of tocene time. the U. S. Geological Survey published which A triangular area of since the YEAR BOOK for 1918 (see Natchez form the corners has been elJackson, Vicksburg, and also IX, U. S. Geological Survey) are evated in and perhaps after Pliocene Prof. Paper 110, "A Geologic Recon- time. There appears also to have noissance of the Inyo Range and the been an east-west and a northeastEastern Slope of the Southern Sierra, southwest belt of uplift through JackNevada, California," by Knopf, including a geological map of southeast corner of the state, the Adolph son, and another uplift east of the the Owen's Lake region and Mt. maximum uplift amounting to at Whitney; Prof. Paper 120-B, "Geol- least 200 ft. The investigation of oil ogy of Northeastern Montana," by Ar- and gas fields has resulted in several thur J. Collier; and 120-D, "The reports dealing with structural geolStructure and Stratigraphy of Grav- ogy (anticlines), such as Bull. 686, ina and Revillagigedo Islands, in the on the structure and oil and gas reSouthern Part of the Panhandle of sources of the Osage reservation in Alaska," by Theodore Chapin, de- Oklahoma. scribing a region of strata from probably late Carboniferous to upper Tri- Taconic System Resurrected," Am. Schuchert in a brief note ("The assic age overthrust towards the Jour. Science, Feb., 1919) records his southwest along with the included agreement with Lapworth's proposal upper Jurassic batholithic injections to employ the name Taconic for the of granodiorites and quartz diorites. period or epoch of the world-wide Prof. Paper 108, comprising a group of Olenellus zone of the so-called lower shorter contributions to general geol- Cambrian, repeating ogy made in 1917, has an article by made in 1918 that this resurrected a suggestion G. S. Rogers on baked shale and slag Taconic should be regarded as a peformed by the burning of coal beds in riod ranking between the Cambrian the Northwest. The author is of the above and the pre-Cambrian below. opinion that most of the burning of Bailey Willis (Bull. Geol. Soc. Am., western coal beds has been spontan- xxx, March, 1919) under the term eous under conditions in which the "Pacific ranges" includes the Coast physical factors promoting ignition Range and the Sierra Nevada, the are a finely divided condition of the structure of which is described as an coal or lignite, a slight increment of effect of compressive stress, differing heat from an outside source, and suf- from that of the Appalachians in that ficient volume of coal to retard loss of the folds and low-angle overthrusts heat by radiation. N. H. Darton of the latter region are in the Pacific writes on a comparison of a Palæozoic ranges replaced by a rotated mounsection in southern New Mexico, rec- tain block guided by a high-angle upognizing a thick development of the thrust forming the eastern face of early Ordovician (El Paso forma- the Sierra, now appearing as a nortion), 150 to 400 ft. of upper Ordo- mal fault plane, but regarded in this vician (Montoya beds), and a varia- hypothesis as a curved thrust surface, ble section of Silurian strata (Fussel- curving back under the block. man beds). The lower formations thin out northwards so that the Pennsylvanian series lies directly on the Pre-Cambrian in central New Mexico. Texas, of the A-shaped and V-shaped fault | Camsell and W. Malcolm (Mem. 108) blocks into which the Austin chalk report on a geological reconnoissance beds are broken. The New York Geological Survey reports (Report of the Director of the State Museum, 1917) that the field work on the Gouverneur, Lake Placid, Schroon Lake, Phelps, and Richfield Springs quadrangles has been completed or revised in some particular. H. P. Cushing found on the Gouverneur quadrangle that the Pre-Cambrian Grenville strata were closely folded in pitching isoclines invaded by granite sills protruded from an underlying body believed to be sy enite. H. L. Alling in the same report has a paper on the geology of the Lake Clear region, and John M. Clarke publishes a map of the peninsula of Percé, P. Q., with explanation. (See also IX, State Geological Surveys.) of the Mackenzie River basin and summarize existing knowledge of the geography and resources of the district about the upper "great lakes" of North America. The report contains a useful bibliography. Geology of South America.-Anselmo Windhausen (Bol. Acad. Nacional de Ciencias de Cordoba, xxiii., 319) describes the geological history of the coastal plain of northern Patagonia, introducing the idea of intersecting northeast- and northwesttrend lines of fracture as controlling the outline of the coast and certain features of the interior. The same author and Roberto Beder (ibid., 255) report the presence of fossiliferous Devonian shales intercalated between sandy beds in the hill Aparipi in central Paraguay. K. Walther (Revista del Instituto Nacional de Agronomia de Montevideo, Dec., 1918) has published an account of the geology of Uruguay accompanied by a geological map showing the distribution of the crystalline rocks of southern Uruguay and the overlying Permian-Triassic beds of central and northern Uruguay. Geology of Alaska.-The Nenana coal field of Alaska has been described by G. C. Martin (U. S. Geol. Survey, Bull. 664, 1919). The beds are Tertiary, from 1,200 to 1,500 ft. thick. The coal areas are in the form of shallow basins in which the beds are locally steeply folded or faulted against masses of crystalline rocks which separate the basins. G. L. Harrington (Bull. 683, 1918) describes the geology of the Anvik-Andreafski region of gold placers in Alaska. Stephen H. Capps (Bull. 687) gives an account of the geology in appearance, is published by the of the Kantishna region, Alaska, illustrated with striking reproductions of photographs of the country north of Mt. McKinley. Bibliography.-The Journal of Geology (Univ. of Chicago Press) contains currently notices and reviews of articles on geological subjects. An annual bibliography, usually late U. S. Geological Survey; the latest issue is John M. Nickles, Bibliography of North American Geology for 1917 (U. S. Geol. Survey Bull. 684, 1918). Emmanuel de Margerie, translator, La Face de la Terre. Tables générales de l'Ouvrage (Paris, Librairie Armand Colin, 1918), forming the last part of Vol. III of Suess' great work in the French translation, is the most complete work extant giving references to the geology of the various countries and continents described in the text. Geology of Canada. The summary report of the directing geologist of the Geological Survey of Canada, William McInnes, for 1917 reports 84 memoirs of the Geological Series published. The geological map of the Duncan quadrangle, Vancouver Island, by Clapp is accompanied by sections showing a mountain-built district of folded and intruded rocks followed by normal faulting and erosion between the Jurassic and the Cretaceous. J. S. Stewart (Mem. 112) has mapped and described the folded and faulted Jurassic, Cretaceous, and Ter- Petroleum Deposits.-In 1919 few tiary strata in the foothills of south- papers of major theoretical interest ern Alberta. The faults are chiefly in economic geology were published, upthrusts from the west. Charles and descriptive articles appeared in ECONOMIC GEOLOGY |