bluuebunny/crossref_metadata_2025 huggingface dataset:
The Ordovician evolution of the South Mayo Trough, western Ireland
Authors: Dewey John F. , Ryan Paul D.
Published: February 2008

The South Mayo Trough, a broad synclinorium containing a 10‐km sequence of Early Ordovician turbidites passing up into shallow water sandstones, is interpreted as a forearc basin with an ophiolitic basement that formed a backstop to an accretionary prism on the northern edge of a north‐facing arc. The arc collided with the Laurentian margin in Early Llanvirn times to deform the Dalradian Supergroup rifted margin clastic sequence. Prior to the late Llandovery, sinistral transcurrent faulting transposed the Connemara Dalradian terrane to its present position on the “outboard” ocean ward side of the South Mayo Trough. The South Mayo Trough was fed principally by arc and ophiolite‐derived elastics during the Arenig with an increasing metamorphic component during the Llanvirn. The Late Ordovician transpressional “docking” of Connemara provided the southerly source for high‐grade metamorphic clasts in the Deny veeny Formation.
A Caledonian age for reflectors within the mantle lithosphere north and west of Scotland
Authors: Snyder David B. , Flack Catherine A.
Published: February 2008

This paper synthesizes geophysical data from two areas north and west of the Scottish mainland, the sites of grids composed of over 1600 and 650 line km, respectively, of deep (≥15 s two‐way travel time) seismic reflection profiles. These grids make possible migration of generally eastward‐dipping reflections in order to locate correctly in three dimensions three reflector surfaces within the uppermost mantle lithosphere. North of Scotland part of the reflector surface strikes to the northwest and forms a plunging fold structure that arches several kilometers into the lower crust near its hingeline. At depths around 50 km the reflector splits into two surfaces, one subhorizontal and one dipping to the east. Gravity modeling suggests that this latter surface may be a normal fault or shear zone and therefore Permo‐Triassic extensional features may be superposed on older, subhorizontal mantle reflectors. Similarities in reflection patterns observed both north and west of Scotland lead us to suggest that these reflections come from three parts of a once continuous structure over 700 km long. Late Caledonian age left‐lateral offsets of over 200 km are inferred to have disrupted this structure. Restoration of this offset plus tens of kilometers of subsequent extension recreates an uppermost mantle feature parallel to the Caledonian erogenic front and dipping toward the Caledonian suture along the Laurentian plate margin. If our restoration is correct in assuming regional‐scale coupling between crustal faulting and uppermost mantle deformation, some mantle structures have persisted for over 400 Ma. Eclogite or metasomatized mantle rock within zones several hundred meters thick appear likely sources of impedance contrast producing the mantle reflections.
Numerical simulation of metamorphic pressure‐temperature‐time paths and fluid production in subducting slabs
Authors: Peacock Simon M.
Published: February 2008

In order to investigate metamorphic reactions and fluid production in subduction zones, a 2‐dimensional finite difference model has been constructed. The model simulates heat transfer in a subduction zone with a 27° dip. A spatial resolution of 1 km is used in the region of the subduction thrust in order to carefully monitor metamorphic reactions; elsewhere the spatial resolution is 5 km. In these calculations, the oceanic crust is assumed to contain 2 wt % bound volatiles, distributed homogeneously within the 7.5‐km‐thick crust. Fluids are released by continuous and discontinuous end‐members of three different dehydration models: pressure‐sensitive, temperature‐sensitive, and amphibole (negative dP/dT) dehydration. Subduction zone pressure‐temperature‐time (P‐T‐t) paths predicted by the model intersect the wet basaltic solidus only at the initiation of subduction. In mature subduction zones, and in the absence of significant frictional heating and induced mantle convection, P‐T‐t paths encounter subsolidus conditions at depths of 100–150 km beneath magmatic arcs, suggesting that slab dehydration reactions play an important role in arc magma genesis. Metamorphic dehydration reactions that consume 50 kJ/kg result in P‐T‐t paths that are only 5 K cooler than models that neglect such reactions. In both the temperature and amphibole dehydration models, the fluid production region moves to greater depths over time as the subduction zone cools. Within the oceanic crust, fluid production starts at the top of the crust and migrates downward in the temperature and amphibole dehydration models. This phenomenon, coupled with the weakening effect of devolatilization reactions, may result in the accretion of oceanic crust to the hanging wall of the subduction zone. For a convergence rate of 3 cm/yr, average fluid fluxes out of the subducting slab range from ∼0.1 kg fluid/(m² yr) for the continuous reaction models to >1 kg fluid/(m² yr) for the discontinuous pressure and amphibole dehydration models. Vertical fluid fluxes on the order of 1 kg fluid/(m² yr) can substantially perturb the thermal structure of overlying rocks and can cause large‐scale hydration and metasomatism of the overlying mantle wedge. In contrast, the thermal effect of fluid flow parallel to the subduction thrust zone is insignificant compared to the thermal effect of subducting oceanic lithosphere.
Evidence for Archean ocean opening and closing in the Southern Slave Province
Authors: Kusky Timothy M.
Published: February 2008

Archean mafic volcanic and plutonic rocks of the Cameron and Beaulieu River greenstone belts outcrop in the southern Slave Structural Province of the Canadian Shield. Lower portions of the greenstone belts have ophiolitic characteristics, but young felsic units may represent superimposed arc magmatism. The greenstone belts are separated from older (circa 2.7–3.2 Ga) quartzo‐feldspathic gneisses of the Sleepy Dragon Complex by a regional décollement zone (Patterson Lake Structural Complex) consisting of deformed mafic volcanic rocks, thin slivers of gneiss, ultramafic rocks, and banded iron formation mixed in a highly‐deformed phyllonitic and phacoidally‐cleaved metapelitic matrix. High synmetamorphic strains are indicated by abundant intrafolial folds, transposed layering, rare sheath folds and by the parallelism of elongated primary features and metamorphic mineral lineations. The Patterson Lake Structural Complex is similar to mélanges of Phanerozoic mountain belts. Adjacent quartzo‐feldspathic gneisses are strongly mylonitized. The mélange and deeper mylonites formed when the greenstone belts were emplaced as thrust sheets. Wildflysch shed from tips of emergent thrusts was in part incorporated into the basal mélange as the allochthon overrode its own detritus. Continued compression involved the basement in the deformation, uplifting the Sleepy Dragon Complex in a structural culmination mantled by the imbricated greenstone stack. Late granodioritic to granitic intrusions formed regional thermal aureoles which overprint earlier metamorphic fabrics.
The secondary magnetic field of the Earth
Authors: Rücker A. W.
Published: February 2008

The magnetic field of the earth may be regarded as that primarily due to a uniformly magnetized globe disturbed by some secondary causes. The probability that the primary field is produced by a deep‐seated system of electrical currents (whose genesis we can not explain), is increased by the fact that iron, magnetite, and basalt all become non‐magnetic if the temperature be raised to the neighborhood of a red heat. The same magnetic effects could be produced on the surface either by magnetized matter or by electrical currents properly distributed within the globe. But if the enormous pressures to which the internal portions of the globe are subjected do not affect the properties with which we are dealing, magnetizable matter can only exist very near to the surface. As we penetrate from the surface downwards, the temperature rises by about I°C. for every 90 feet, or (say) 37° per kilometer, and if this rate of increase is maintained, the temperature at which iron becomes non‐magnetic (which is different for different specimens) would be reached at a depth of about 20 kilometers. Some experiments made in my laboratory by Messrs. Barton and Williams indicate that for magnetite the limiting temperature is less (about 557°), and would be reached at a depth of about 15 kilometers. It is convenient to call that stratum in the earth at which all matter ceases to be magnetic, the magnetic floor.
Report on the magnetic observations made at the magnetic observatory at Val‐Joyeux, France, during the total solar eclipse of May 17, 18, 1901
Authors: Moureaux M. Th.
Published: February 2008

J'ai l'honneur de vous adresser, le relevé, de 3 minutes en 3 minutes, des valeurs de la déclinaison et des deux composantes H et Z, obtenue le 18 Mai dernier, de 2h à 9h du matin, temps moyen de Greenwich.

Vous remarquerez que ces observations ne proviennent pas du Parc Saint‐Maur. Le développement des lignes de tramways électriques à trolley autour de l'observatoire a fait de grand progrès dans le deuxième‐semestre de 1900, et le dépouillement des courbes de variations n'y pré sente plus la garantie nécessaire.
Report on the magnetic observations made at the De Bilt meteorological and magnetic observatory near Utrecht, Holland, during the total solar eclipse of May 17, 1901
Authors: Snellen Maurits
Published: February 2008

I am glad to be able to submit herewith the results of magnetic observations made in de Bilt Observatory during the total solar eclipse of May 17, 1901. I have but to add the following remarks :

A. EYE‐OBSERVATIONS.

Declination. A variometer was made use of, consisting of a telescope with scale and a freely movable magnetic needle, one side of which was polished as a mirror. The distance from mirror to scale was such that one division represented 0.502 of a minute.
Report on the magnetic observations made at Vlissingen (Flushing), Holland, during the total solar eclipse of May 17, 18, 1901
Authors: van Rijckevorsel
Published: February 2008

These observations were taken on a plot of grass land just inside the sea dyke, a little to the southwest of the house of the observer, for the Royal Meteorological Institute. The spot, being too near to the passage of the steamers between the river and the sea, was not to be considered as a perfectly safe one for absolute measurements. However, as it was in every other respect exceptionally convenient, and as it was thought that, if good note were taken of every suspicious circumstance, disturbances due to this cause could be readily separated from those of a cosmic origin, the locality was retained.

A temporary shed was erected for me by the kindness of Mr. P. Hoogenbooin, engineer of the “waterstaat.” I avail myself of this opportunity to express my gratitude to him, as also to the gentlemen who volunteered to assist me, Mr. Engelenberg, C. E., my former very much valued assistant in Brazil; Mr. C. Schoute, the able assistant in the physical laboratory of Groningen University, who assisted me, with the kind permission of Professor Haga, and Messrs. H. I. I. Kress and H. Az. de Ruyter, the former a computer of the Meteorological Institute at de Bilt, and the latter, the observer at Vlissingen.
Die construction des geometrischen bildes des gauss'schen potentials, als methode zur erforschung der Gesetze des Erdmagnetismus
Authors: Umow N.
Published: February 2008

Der Verfasser glaubt zu leicht fasslichen und scharf formulierten Gesetzen des Erdmagnetismus zu gelangen, indem er statt der Beschreibung einer Menge von magnetischen Curven, nur wenige geometrische Gebilde einführt, deren gegenseitige Lage und zeitliche Veränderungen zu erforschen sind. Die Gauss'sche Entwickelung des erdmagnetischen Potentials nach Kugelfunctionen giebt eine Reihe von magnetischen Potentialen 1., 2., 3., 4. Ordnung, welche respective 1, 2, 3, 4 Axen besitzen und ebenso jede ein magnetisches Moment derselben Ordnung (s. Maxwell, “Electricity and Magnetism” Part I, Art. 129 c).

Wollen wir mit V das erdmagnetische Potential auf der Erdoberfläche, mit R den Radius der Erde bezeichnen, so haben wir die Reihe
eine Kugelflächenfunction nter Ordnung ist, mit 2nj+1 Constanten, von denen 2n die Lage ihrer n Axen bestimmen und eine das Moment nter Ordnung bezeichnet. Es seien μj der Cosinus des Winkels einer Axe mit dem Radius eines Punctes P der Erdoberfläche, λij der Cosinus des Winkels zwischen den Axen i, j, und δn das Moment der Function. So haben die Kugelflächenfunctionen folgende Ausdrücke:
Alle Axen gehen durch das Centrum der Erde. Wenn einige Axen in eine und dieselbe Richtung fallen, erhalten wir eine multiple Axe, deren Ordnung der Zahl der zusammenfallenden Axen gleich ist.
On the cause of the earth's magnetism and gravitation
Authors: Sutherland William
Published: February 2008

In this Journal for June, 1900, and June, 1903, the origin of the Earth's magnetism was traced to the rotation of electricity with the Earth round its axis. In the second of these papers, it was shown that a suitable disposition of electricity within the Earth to account for its magnetism could be found in the valency charges of electricity, which hold the atoms of molecules together, if only the negative electrons were on the whole farther from the center of the Earth than the positive by a distance of the order 10−8 cm. But recent investigations, associated with such names as J. J. Thompson, FitzGerald, Lorentz, Larmor, and others, have familiarized physicists with larger supplies of electricity connected with matter even than the valency charges, for the converging conception of investigators has been brought to a focus in the principle that in Nature there is but one inertia, and that therefore matter is made of electricity, its atoms being formed of pairs of opposite electrons, or in other words of electric doublets, the inertia of the atom being the sum of the inertia of its component doublets. Thus, it becomes necessary to inquire under what conditions the rotation of the electric doublets forming the atoms of the Earth can produce its primary magnetic field.
Specific electrical conductivity of the air at sea
Authors: Burbank J. E.
Published: February 2008

Although many observations of potential and dispersion have been made along the sea shores very little has been done at a distance from land. A. Boltzmann,1 in the summer of 1904, obtained some observations on a voyage from Germany to New York and return. He obtained a high ratio of positive to negative ions in the atmosphere, especially at great distances from land.

During a recent voyage of the Leyland Line Steamship “Cestrian” from Liverpool to Boston, the writer was able to obtain, under the auspices of the Department Terrestrial Magnetism of the Carnegie Institution of Washington, some observations of the specific electrical conductivity of the air by means of a new form of instrument recently devised by Dr. H. Gerdien, of Göttingen, Germany.2
The physical theory of the Earth's magnetic and electric phenomena: 2.
Authors: Bauer L. A.
Published: February 2008

a. Introductory Note.

b. On the Non‐Simultaneity of Magnetic Disturbances.
Atmospheric electricity observations on the second cruise of the “Carnegie,” from New York to Colombo
Authors: Kidson Edward
Published: February 2008

The observations were taken with a Gerdien conductivity apparatus, using the same methods as those employed on the first cruise of the Carnegie, as previously described in this Journal.1 The observations were also taken in the same position as on the first cruise. The aluminum leaf electroscope of the Gerdien apparatus was replaced by a string electrometer of the form described by Lutz.2 This instrument proved very satisfactory, as the reading was not seriously interfered with by the rolling of the ship.
Ueber die gegenseitige Einwirkung zweier Magnete in beliebiger Lage
Authors: Schmidt Ad.
Published: February 2008

Die Berechnung der yon zwei Magneten. auf einander ausgeübten mechanischen Wirkungen bildet eine grundlegende Aufgabe der erdmagnetischen Beobachtungsmethoden und ist daher seit jeher eingehend behandelt worden. Die grosse Ausdehnung der dabei auftretenden Formeln und die Weitläufigkeit der zu ihrer Ableitung dienenden Rechnungen hat indessen dazu geführt, dass man sich vorwiegend auf die einfachsten Fäille, die praktisch allerdings auch die wichtigsten sind, beschränkt hat. In Bezug auf die gegenseitige Lage hat man fast stets angenommen, dass sich beide Magnete in ein und derselben Ebene befinden, die zugleich zur Drehungsachse des einen (der Nadel, wie man zu sagen pflegt) senkrecht ist. Nur Börgen1 ist darüber hinausgegangen, indem er den Fall einer beliebigen räumlichen Lage (allerdings unter Beschränkung auf die Berechnung des Drehungsmoments, das der eine Magnet in Bezug auf eine bestimmte Achse erfährt) untersucht hat.
Biographical sketch of William Sutherland, M. A., B. Sc.
Authors: Love E. F. J.
Published: February 2008

The late Mr. William Sutherland, an exceptionally brilliant speculative physicist, was born at Glasgow, on August 4th, 1859; brought by his parents to Australia in 1864, he was educated at Wesley College, Melbourne, then at the Melbourne University, and subsequently at University College, London.

He commenced his career as an investigator in 1885, and during the succeeding twenty‐six years published no less than sixty‐four papers. As illustrating the versatility of his genius, the following may be quoted from the list: the Mechanical Integration of the Product of Two Functions, the Laws of Molecular Force, the Electric Origin of Rigidity, Gravitation and Terrestrial Magnetism, the Chemistry of Globulin, and Bode's Law. But there is not the slightest doubt that it is on his long series of memoirs, mostly theoretical, dealing with the Molecular Theory of Matter, that his fame will ultimately rest. That all his hypotheses will be .accepted, even in their final forms, is unlikely, but his discussions of them are of permanent value.
Terrestrial isomagnetic lines for South Africa for the epoch July 1, 1903
Authors: Fisk H. W.
Published: February 2008

This paper is an amplification of the discussion by the same author of his observations in South Africa in 1900–1906, published in his Report of a Magnetic Survey of South Africa (1909). The latter work treats the results at about 400 stations lying between the southeast coast and a northeast‐southwest line passing through latitude 26 degrees South and longitude 24 degrees East. These data were combined in fifteen groups or districts, the mean value being given for the mean position in each case. After resolving the resulting mean :values into components along the three rectangular axes (north, west, vertical), the true isomagnetic lines were charted.
On certain matters relating to the theory of atmospheric‐electric measurements
Authors: Swann W. F. G.
Published: February 2008

If a conducting body is placed above the surface of the Earth, and connected to Earth by a conductor, it is necessary for the body to take a charge in order to maintain itself at the potential of the Earth in opposition to the influence of the field at the point where it is situated. The greater the height of the body the greater the charge which it must take. One of the objects of the present paper is to consider the theoretical effect of this phenomenon in certain cases.

CASE OF THE EBERT ION COUNTER.
Preliminary report on the results of the aurora‐polaris expedition to Bossekop in the spring of 1913
Authors: Störmer Carl
Published: February 2008

1. In this Journal for September 1913, I gave a short account of an aurora‐polaris expedition which I made to Bossekop in the spring of 1913, for the purpose of completing the results of my expedition to the same place in 1910.

The working up of the very extensive material from this expedition has since been continued, but only one sixth of the whole has been finished. This nevertheless gives about 600 very exact measurements of the altitude of the aurora and of its position in space. The material considered is from the nights of March 3–4, 4–5, and 11–12, 1913. From the last of these nights, especially, we have a large number of very interesting observations.
Progress of the magnetic survey of the Russian Empire
Authors: Rykatchew M.
Published: February 2008

The project of the magnetic survey of the Russian Empire laid before the government by the Academy in 1914, not yet having been approved by it, the activities of the Commission have necessarily been limited to the means appropriated by the Academy and by the provinces.

The survey has been continued during 1914 in two regions; in the southwest, in Bessarabia, adjacent to the Government of Podolia, the survey of which was completed the preceding year, and in the northeast, in the District of Velsk.
General results of the magnetic survey of the Pacific Ocean
Authors: Bauer L. A. , Peters W. J.
Published: February 2008

A systematic survey of the ocean areas, which include nearly three‐fourths of the Earth's surface, was begun at San Francisco just ten years ago. At that time little was known of the magnitude of the errors that were supposed to exist in the magnetic charts covering the high seas; and the Pacific Ocean especially was, with the exception of the voyage of the Challenger, nearly a blank as regards magnetic observations. As is well known, the Carnegie Institution of Washington authorized its Department of Terrestrial Magnetism to undertake the magnetic survey of the Pacific Ocean, which has since been extended to include all the oceans.

The first vessel selected for the purpose was the wooden brigantine Galilee, which was chartered from Matthew Turner, of San Francisco, in July 1905. A non‐magnetic flying bridge for the installation of the magnetic instruments was built between the fore and main masts. The steel rigging was replaced by hemp, and all iron, as far as was practicable, was removed from the vicinity of the instruments. The deviations were thus reduced to a minimum and, indeed, were smaller than those of any other vessel previously engaged in magnetic observations at sea. But small deviations, though vastly preferable to large ones, since the error in their control is also smaller, require practically the same laborious computations and the same wait for completion of all the swings of a cruise, before final results can be obtained, as are required for large deviations.
Biographical sketch of Friedrich Bidlingmaier
Authors: Bauer L. A.
Published: February 2008

Among the early victims of the present unfortunate European war was our lamented colleague, Professor Dr. Friedrich Bidlingmaier, who lost his life on September 23, 1914, in the battle of Verdun, at the age of 39 years.

Born at Lauffen, on the Neckar, on October 5, 1875, he obtained his early education at Maulbronn and Blaubeuren, and from 1894–1898 pursued studies in mathematics and physics at the universities of Tübingen and Göttingen. During the period 1898–1900 he was assistant in the Physical Institute of the “Technische Hochschule” in Dresden.
Pulsations magnétiques à Zi‐ka‐wei et à Lu‐kia‐pang
Authors: de Moidrey Par J.
Published: February 2008

Nous relevons les pulsations depuis 1896. Il peut paraître temps de faire un court résumé de ces mesures. Il aidera au moins à compléter les travaux du Dr. W. van Bemmelen sur ce sujet.

Nous entendons par pulsations des oscillations très petites et de période, comme d'amplitude, sensiblement constante. Pour une étude statistique il est nécessaire que la vitesse de l'enregistrement soit constante, et c'est notre cas, que les photographies soient également nettes, ce que malheureusement nous ne pouvons prétendre avoir bien réalisé, et enfin que la sensibilité soit aussi constante. Ge dernier point nous force à diviser notre série en trois périodes, celle de Zi‐ka‐wei, de 1896 à 1908, où la sensibilité était environ 0,000170; la première de Lu‐kia‐pang, de 1908 à 1912, avec sensibilité 0,000145; et la période actuelle, de 1913 à 1916, avec sensibilité 0,000060. A Zi‐ka‐wei, nous ne notions pas la rapidité des pulsations. Actuellement nous mesurons la durée de chaque série de pulsations, et le nombre d'oscillations durant ce temps est compté. La vitesse étant sensiblement constante, nous en déduisons la période et c'est le meilleur moyen comme le plus rapide.
The magnetic storm of May 13–17, 1921, at Alibag Observatory, India
Authors: Chinmayanandam T. K.
Published: February 2008

A violent magnetic storm began on May 13, 1921, and lasted for about 90 hours. Magnetic disturbances are classified at the Bombay (Alibag) Observatory into four groups: Small, Moderate, Great, and Very Great. The present disturbance is one of the greatest that have been recorded during the past 50 years. In point of duration there were only two disturbances, in July, 1883, and May, 1891, respectively, which lasted for a longer time than the present one; but they were not so violent in character.
Terrestrial magnetism and electricity at the Rome meeting, May, 1922
Authors: Bauer Louis A.
Published: February 2008

The second triennial meetings of the International Astronomical Union and of the International Geodetic and Geophysical Union, established at Brussels in 1919 under the auspices of the International Research Council, were held at Rome, May 2 to 10, 1922, in the quarters of the Accademia de Lyncei, at the Palazzo Corsini. Some three hundred delegates and guests attended these highly successful gatherings. After preliminary general sessions of the Unions, the various sections and committees had separate meetings, and at the conclusion general sessions again were held on May 10 for the transaction of matters pertaining to the entire unions.

While there were some decided advantages of having the two unions meet at the same time and in the same place, many of the representatives, because of the necessary overlapping of sessions, could generally attend only the section or committee in which they were specifically interested. The only time when general intercourse became usually possible was at the social events, provision for which had been abundantly made by the National Committee of Italy. It was considered, however, that the experiment might be tried of having in future separate meetings of the two unions. Accordingly, the next meeting of the International Astronomical Union will be held at Cambridge, England, in 1925, and that of the International Geodetic and Geophysical Union at Madrid, Spain, in 1924—probably during September.
Chief results of a preliminary analysis of the Earth's magnetic field for 1922—No. 1.
Authors: Bauer Louis A.
Published: February 2008

From a new analysis of the Earth's magnetic field for 1922, made as free as possible without assumptions as to the composing systems and restricted to the region of the Earth (86 per cent), from 60°N to 60°S, the author concludes that for a satisfactory representation of the observed data it is necessary to recognize the existence of an internal magnetic system, I, an external system, E, and a non‐potential system, N, or of three equivalent systems, X, Y, Z. The system I constitutes about 94 per cent of the total field, and E and N each about half of the balance of 6 per cent.

He shows that the magnetic secular variation system is as complex as the Earth's total magnetic field existing at any one time, and that in addition to changes in the direction of magnetization with the lapse of time there is also a change in the average equivalent intensity of magnetization. The latter quantity has been steadily diminishing during the past 80 years at the average annual rate of about 1/1,500 part.

For further statement of results, reference may be made to the “Summary of Chief Conclusions” at the close of the paper.
Lerwick Observatory, Shetland Islands
Authors: Mitchell A. Crichton
Published: February 2008

Position: Latitude, 60°8′45′′N; Longitude, 1°10′50′′W; Height above M. S. L., 79.3 metres.

The object of the Observatory is the study of terrestrial magnetism and auroral phenomena. The magnetic elements (declination, horizontal force, vertical force) are recorded photographically in a brick‐walled concrete building. Absolute observations are made twice weekly.
Note on a preliminary discussion of the magnetic observations made by the National Observatory of Mexico during the total solar eclipse of September 10, 1923
Authors: Ault J. P.
Published: February 2008

The declination results at Yerbanis showed rather large variations during the period of observation, but there was the same sharp increase in easterly declination, beginning about one hour before totality and reaching a maximum shortly after totality which was observed at Point Loma, California, by the Department of Terrestrial Magnetism.1 The apparent divergence from normal amounted to nearly five minutes of declination. This is an estimation based upon a comparison with the results at the Teoloyucan Observatory, since no comparison observations were taken at Yerbanis. Some of this large divergence may be due to the variation in temperature, which amounted to a decrease, followed by an increase, of nine degrees during the two hours of the eclipse period, due to the fact that the observations were made in the open air.
Bemerkung zu der Abhandlung der Herren Watanabe und Kawamura “The measurement of the horizontal intensity of the Earth magnetic field with portable electric magnetometers”
Authors: Uljanin Von W.
Published: February 2008

Im Jahre 1915 gab ich die Beschreibung eines transportablen Sinusgalvanometers zur Bestimmung der Horizontalintensität des erdmagnetischen Feldes. Dabei wies ich ausdrücklich auf den grossen Vorteil, ohne besonderes Galvanometer zur Abgleichung der richtigen Stromstärke nach der Kompensationsmethode auskommen zu können. Der durch den Strom in den Ablenkungsspulen (Helmholtz‐Spulen) abgelenkte Magnet, empfindlicher als im unabgelenkten Zustand in der Meridiansebene, dient zugleich als Nullinstrument mittels eines zweiten Paares möglichst naher Galvanometerspulen, welche im Normalelementenzweig eingeschaltet sind.

In einer neulich erschienenen Arbeit, welche denselben Gegenstand behandelt, beschreiben die Herren Watanabe und Kawamura ein ähnliches Instrument aber mit besonderem Galvanometer, und benützen meine Methode dadurch, dass sie die Galvanometerspulen an ihren Apparat befestigen, nur dann, wenn ein zweiter Beobachter nicht vorhanden ist. Dadurch erscheint bei ihnen diese Anordnung nur als Notbehelf und zwar als minderwertiger. Denn sie behaupten, sie könne unter Umständen zu falscher Stromabgleichung führen. Bei unrichtigem Hauptstrom in den Helmholtz‐Spulen werde, beim Schliessen des Normalelementenzweiges, der Magnet aus zwei Gründen abgelenkt: (1) durch den durch die Galvanometerspulen fliessenden Normalelementenstrom, (2) durch die dadurch hervorgerufene Aenderung des Hauptstromes. Wenn nun diese beiden Wirkungen entgegengesetzt sind, sollen sie sich aufheben können, und desshalb soll ein Nullausschlag nicht notwendig Nullstrom im N‐E Zweig bedeuten. Nur gleichgerichtete Wirkung beider Spulenpaare garantiren eine richtige Stromabgleichung. Die Verfasser setzen vor die Galvanometerspulen einen Kommutator, um jedesmal die richtige Stromrichtung herstellen zu können.
Latest data concerning magnetic observatories, 1924
Authors: Fleming J. A.
Published: February 2008

DISTRIBUTION OF MAGNETIC OBSERVATORIES, 1924.

It will be seen that the geographic distribution of magnetic observatories is still far from satisfactory; about 40 per cent of the observatories are in Europe and only about 9 per cent in the Southern Hemisphere.
Results of magnetic observations at Kazan, Russia
Authors: Uljanin W.
Published: February 2008

(Latitude 55° 50′N.; Longitude 48° 51′E.)
Reading board for magnetographs
Authors: Baldwin J. M. , Holmes W. M.
Published: February 2008

This recording board was designed and constructed for use with the magnetograms obtained from the Eschenhagen variometer at the Toolangi Magnetic Observatory. The board is 30′′×12½×1′′ and carries a straight edge S which can move laterally through a distance of 1 inch. When the clamping nut C is released S can be traversed by hand, the rod R sliding freely in a hole bored in the end of S. When C is clamped to R, S is traversed by means of the nut N.
Note on a device to facilitate compilation of data in investigational work
Authors: Ennis C. C.
Published: February 2008

In connection with the investigation1 of a 27‐day period in earth‐currents, computers of the Department of Terrestrial Magnetism of the Carnegie Institution of Washington have been using to great advantage a simple and easily constructed device for selecting from a list of consecutive values any values occurring at specified intervals before or after a selected date.

The method used in the treatment of this 27‐day periodicity involves the selection of a number of maximum, and an equal number of minimum values of the daily ranges in the earth‐current values for each month during the year. These selections having been appropriately designated, it is then necessary to select and record the values occurring on an arbitrarily chosen number of days contiguous to and centering about a period 27 days prior or subsequent to each one of the previously selected maximum and minimum values. Where there is a large mass of data to be treated in this manner, the ordinary processes of reckoning the times of these periodic recurrences are somewhat slow and laborious, and it was to facilitate and expedite this work that the device herein described was planned.
Principal magnetic storms recorded at the Cheltenham Magnetic Observatory, January to March, 1926
Authors: Hartnell Geo.
Published: February 2008

(Latitude, 38° 44′.0 N.; longitude, 76° 50′.5, or 5h 07m.4 W. of Greenwich.)
Studies concerning the relation between the activity of the Sun and of the Earth's magnetism: No. II
Authors: Bauer Louis A. , Duvall C. R.
Published: February 2008

This article is a continuation of the previous one by the authors on the same subject. With the aid of additional data, it is once more found that the quantities a and b in the formula Q = a + b S vary with sunspot activity, and apparently also with time; Q is the measure of magnetic activity, and S that of solar activity.

The parameter a varies directly, and b inversely with sunspot activity. The measure of magnetic activity, Q, is evidently subject to the same periodicities as found by various authors from analyses of the sunspot numbers. Thus an analysis of concomitant magnetic and sunspot data for the period 1841 to 1910 made by G. N. Armstrong and C. R. Duvall at the Department of Terrestrial Magnetism, in the summer of 1914, indicated the existence of periods of about 11.4 years, 22 years, and a third in the neighborhood of 70 years.
Die elektrische Leitfaehigkeit der Atmosphaere und ihre Ursachen
Authors: Hess Victor F.
Published: February 2008

Seit dem letzten Erscheinen von grösseren zusammenfassenden Darstellungen der atmosphärischen Elektrizität in deutscher Sprache, nämlich der Monographien von A. Gockel (1908) und von H. Mache und E. v. Schweidler (1909) sind fast zwei Jahrzehnte verflossen. Der Fortschritt, der in dieser Zeit erzielt worden ist, ist durchaus vergleichbar mit jenem in der Zeit von 1899 bis 1909, in der die Anwendung der Lehre von den Gasionen und der Nachweis der radioaktiven Substanzen im Erdboden, in den Gewässern und in der Atmosphäre der luftelektrischen Forschung neue Wege wies.

Unsere Kenntnisse von der Elektrizitätsleitung der Atmosphäre sind wesentlich erweitert und vertieft worden. Die luftelektrischen Verhältnisse über dem Ozean haben durch die ausgedehnten Forschungsfahrten der Carnegie‐Institution von Washington in allen Meeren volle Klärung gefunden. Auf Ballonfahrten in Europa hat man eine neue Quelle der Ionisation gefunden, eine von oben her die Erdatmosphäre durchsetzende Strahlung hoher Penetrationskraft, die sogenannte Höhenstrahlung. Die Wirkung dieser und der übrigen ionenbildenden Faktoren an der Erdoberfläche und innerhalb der ersten zehn Höhenkilometer der Luft (Troposphäre) sind nun auch quantitativ ziemlich gut bekannt.
Preliminary note on the effect of dust, smoke, and relative humidity upon the potential gradient and the positive and negative conductivities of the atmosphere
Authors: Wait G. R.
Published: February 2008

It is known that the conductivities and the potential gradient of the atmosphere are affected by the presence of dust, smoke, and water vapor in the atmosphere. Very few published data exist showing the effect of dust particles upon the conductivity. The data for the effects of atmospheric pollution on the potential gradient, although more numerous, have not always been consistent, possibly because of the varying conditions under which they were collected. If, for instance, the dust is charged with about the same amounts of positive and negative electricity, then in general one should expect an increase of potential gradient with increasing amount of dust due to a decreasing conductivity.
Some observations upon telluric currents and their application to electrical prospecting
Authors: Leonardon E. G.
Published: February 2008

The application of the potentiometric methods of electrical prospecting to the search for ore‐bodies or to the study of structural and stratigraphical problems requires the measurement of very minute differences of potential.

The firm with which the writer is connected has thus explored in the course of its consulting practice hundreds of square miles; the magnitude of the individual electrical measurements obtained amounted ordinarily to only a few millivolts. This kind of research, aside from its precise commercial purpose, involves necessarily the possibility of making a series of investigations upon the electrical phenomena occurring in the Earth's crust, namely, the earth‐currents and the electro‐capillarity of the soil.
Final relative sunspot‐numbers for 1927
Authors: Brunner W.
Published: February 2008

The numbers in the table are based on observations made at the Zürich Observatory, supplemented by series furnished by 40 other observatories for the 68 days (indicated by asterisks) on which no observations were made at Zürich. The small increase of only 5.1 over the mean for 1926 (63.9) shows that we are nearing a sunspot maximum and, indeed, a rather low one.

Figure 1 is a detailed graphical representation of the daily relative sunspot‐numbers for 1927 in which the times are plotted as abscissas, and the relative numbers, taken from the table, as ordinates. The limits of the successive solar rotations are indicated by vertical arrows in the upper edge of the figure. The secondary maxima and minima succeeding the rotation periods do not represent real fluctuations in sunspot‐activity but are rather to be attributed to the influence of solar rotation, and moreover, to a certain stability of centers of activity for spots and the special distribution of these centers in the direction of rotation.
Principal magnetic storms recorded at the Sitka Magnetic Observatory, January to March, 1928
Authors: Ulrich F. P.
Published: February 2008

January 27, 1928—This is a small storm with abrupt beginnings recorded on all three of the components. Beginning at 10h 30m H and Z drop considerably and come back to normal about an hour later, making the curves appear like a sharp wedge at this time. The active part begins at 9h and lasts about four hours.

March 11, 1928—The beginning of this storm is gradual, the Z seeming to just wander up and off the paper till the storm is over. The D and H are moderately active until the thirteenth hour, D increasing and H decreasing to that time. From 13h to 16h these elements are very active, the spots being faint lines only because of the rapidity of the motion, and both record very low values. At 16h the storm begins to decrease with fluctuations and is soon back to normal.
Principal magnetic storms and earthquakes recorded at the Watheroo Magnetic Observatory, January to March 1928
Authors: Johnston H. F.
Published: February 2008

(Latitude 30° 19′.1 S.; longitude 115° 52′.6 or 7h 44m E. of Gr.)

There were no marked magnetic disturbances during the first quarter of 1928.
The diurnal variation of the normal earth‐current in northern Sweden
Authors: Stenquist David
Published: February 2008

During August, 1924, to July, 1927, measurements of earth‐currents were made in southern Sweden at the telegraph‐office of Lund (latitude 55° 42′ north, longitude 13° 11′ east). During 1924 to 1928 similar measurements were made also in northern Sweden at the telegraph‐offices of Luleå and Haparanda and at the telephone‐offices of Matarengi (Övertorneå) and Jokkmokk. The north latitudes and east longitudes of these four places are: Jokkmokk, 66° 35′ and 19° 5l′; Matarengi, 66° 21′ and 23° 37′; Haparanda, 65° 50′ and 24° 08′; Luleå, 65° 35′ and 22° 10′.

In arranging the lines and in making the measurements I have had the great help of C. G. Wahlberg, Chief Engineer; H. Reine, Telegraph‐commissary; and G. Lidén, Telegraph‐commissary. My wife has assisted me in the time‐consuming calculations. The measurements at Haparanda, here published, were made during July 1927 to June 1928. Because this series of observations is longer than those of Jokkmokk, Matarengi, and Luleå, it is described first. At the telegraph‐office of Haparanda there was a recording instrument for each of the two lines. One line is in a northerly direction from Haparanda to Tanos, the other line is in a westerly direction from Haparanda to Palovaara, The length of the Tanos‐line was 3.1 kilometers and of the Palovaara‐line, 3.3 kilometers. Haparanda is 90 kilometers from electric tram and it is believed that no disturbing effect from industrial currents existed during the observations.
Huancayo Magnetic Observatory August to September, 1928
Authors: Ledig Paul G.
Published: February 2008

(Latitude 12° 02′.7 S.; longitude 75° 20′.4 or 5h 01m W. of Gr.)

August 4, 1928—At approximately 12h on August 4, a mild magnetic storm began with a moderate disturbance in the horizontal intensity and the declination, and at 17h 07m there was a sharp increase in horizontal intensity of 79 gammas in 5.5 minutes. The vertical intensity and the declination also showed a slight change at this time, but were only very slightly disturbed during the period of the storm. On August 4, the horizontal intensity was only moderately disturbed, but on August 5, beginning at 0h the intensity was low and during the daily maximum the trace showed a marked saw‐tooth appearance. The disturbance ended rather abruptly at 22h 06m on August 5.
Distribution‐coefficients for vertical‐intensity magnetic variometers
Authors: McComb H. E.
Published: February 2008

Scale‐values were determined in the usual manner by means of a small deflector at short distances and with the deflection‐bar set for various azimuths. These were referred to the values obtained with a large deflector at a great distance as standard, and from the resulting differences the distribution‐factors were computed.
Note on Earth‐current storm, July 31–August 1, 1929
Authors: Gish O. H.
Published: February 2008

A record of fluctuating currents in an oil‐pipe line in Southern California was obtained by Logan, Rogers, and Putnam on the above date while investigating pipe‐corrosion.1 Examination of the earth‐current records of the Watheroo Observatory showed that an earth‐current storm was in progress when the pipe‐line record was being obtained. The attached curves show the variation with time of the westward and southward components of earth‐current potentials as recorded at Watheroo (Western Australia) and Huancayo (Peru) in comparison with the curves of potential drop in the pipe‐line obtained by Logan et ah Since the four lines at the observatories are of different lengths and since the soil‐resistivity at, Huancayo differs considerably from that at Watheroo, the amplitudes of the curves are not directly comparable either on the basis of potential gradient or current‐density. The timescale for the observatory curves is accurate to 0.01 hour.
Les éléments du magnétisme terrestre à Jassy en 1931
Authors: Procopiu Par St.
Published: February 2008

Déterminations magnétiques en Roumanie—Les éléments du magnétisme terrestre, déclinaison, inclinaison et composante horizontale, n'ont été que très rarement déterminés en Roumanie. Ainsi, on connaît une détermination de déclinaision à Bucarest, faite en 1772, qui a donné la valeur 11° 36′ W, et une série de déterminations, toujours de la déclinaison, pour 28 localités des pays roumains, effectuées entre 1828 et 1832 par les officiers de l'état majeur russe, à l'occasion de la guerre russo‐turque, en vue d'un levé de carte des pays roumains. On a trouvé à cette date (1828) pour Bucarest,D= 11° 14′ W, et pour Jassy,D= 11° 52′ W. Des calculs, postérieurs à cette date, faits par Hepites, ont indiqué que la déclinaison à Bucarest a passé aux environs de l'an 1798 par un maximum (D= 13° 50′ W) et que, depuis lors, la déclinaison diminue continuellement.
Observations of micropulsations in the magnetic records at Tromsø
Authors: Harang Leiv
Published: February 2008

In an interesting paper Dr. Bruno Rolf has drawn attention to a number of giant micropulsations registered at Abisko in the period 1921–30. In one case (that of the micropulsations which occurred September 12, 1930( the curves from the Observatory of Aurora Borealis at Tromsø (latitude 69° 39′.8 north, longitude 18° 56′.88 east) are reproduced. During the pulsations of September 12, 1930, an absolute determination of the magnetic elements was taken at Tromsø. As the times of the readings on the theodolite are marked on the curves (the same system of time‐marking is used as at the observatories at Godhavn and Lovo), we were able to show that the micropulsations in declination (D), horizontal intensity (H) and vertical intensity (V) had a noticeable phase‐difference relative to each other.
Statistical methods for research on diurnal variations
Authors: Bartels J.
Published: February 2008

It is explained that research on the variability of the diurnal variations is necessary, because the usual method of discussing the average variations alone leads one to overlook characteristic features of the phenomenon. The use of harmonic dials for this purpose is described, and the formulae for numerical and graphical work are given. The use of the two‐dimensional standard deviation and of the probable ellipse for estimating the accuracy of average diurnal variations is explained. The procedure is applied to the diurnal variation of declination on quiet days at Huancayo observatory in southern summer, and the results are discussed. The variability is surprisingly large and affects both amplitudes and phases of the sine‐waves. Some days with particularly large and small amplitudes are picked out. Preliminary results of similar calculations for Watheroo Observatory are summarized, among others the remarkable dial for the 24‐hourly wave in horizontal intensity, which indicates that the focus of the diurnal atmospheric current‐system passes on some days north, on other days south of Watheroo. Some remarks on future work are added.
A new theory of magnetic storms
Authors: Chapman S. , Ferraro V. C. A.
Published: February 2008

PART I—THE INITIAL PHASE (Continued)*

9. The variation of pressure, density, and temperature near the head of the stream