bluuebunny/crossref_metadata_2025 huggingface dataset:
Tectonic implications of metamorphism and gravity field in the Penokean Orogen of northern Michigan
Authors: Attoh Kodjopa , Klasner John S.
Published: February 2008

Published geologic data, together with new metamorphic pressure and temperature data and gravity data, provide strong evidence for northward directed thrusting of Lower Proterozoic rocks in northern Michigan and Wisconsin. Metamorphic studies indicate pressures of 7 kbar at Watersmeet node and 4 kbar at the Peavy node. The Republic metamorphic node, located 30 km to the north of Peavy, attained pressures of 2–3 kbar. All three metamorphic highs reached temperatures in the range of 600°–650°C and are correlated with areas of negative gravity anomalies relative to surrounding regions. In the Peavy high the center of the gravity anomaly lies on the sillimanite isograd, and we suggest that the source of this negative anomaly may be remobilized underlying Archean gneiss. The highest grade rocks of the Republic node lie well within a residual gravity anomaly, which is interpreted to have a very shallow source, and the Watersmeet high lies above gneiss domes which show negative gravity anomalies. A north‐south geologic cross section constructed from a two‐dimensional gravity model, which extends northward from the Dunbar dome in the magmatic arc terrane of Wisconsin, across a terrane boundary interpreted as a suture and marked by the Niagara fault, and across the Peavy metamorphic node, suggests that the Dunbar dome was transported northward onto the continental foreland during the Penokean orogenic event. These north verging fold‐thrust sheets or nappes produced prominent tectonic thickening at the Peavy and Watersmeet, as indicated by the relatively high metamorphic pressures there. The thrust sheets evidently thinned to the north, as suggested by the relatively low pressures at Republic. We suggest that the Archean continental edge, defined by the steep gradient in the regional northeast trending gravity high, lies beneath the magmatic rocks of Wisconsin and thus extends south of the Niagara fault suture.
Variation of the regional stress tensor at the western Great Basin Boundary from the inversion of earthquake focal mechanisms
Authors: Vetter Ute R.
Published: February 2008

The orientation of the principal axes of the regional stress tensor in and near the western Great Basin boundary is calculated from the inversion of earthquake focal mechanism data. Data were taken from three regions along the western Great Basin‐Sierra Nevada boundary: Mammoth Lakes, Round Valley, and Chalfant Valley, and at two regions within the Great Basin interior: Mono‐Walker Lake and west central Nevada. The depth range is similar for all data, earthquakes are essentially restricted to the uppermost 16 km of the crust. The stress tensor changes from the Great Basin boundary to the Basin interior, for example, the extension direction changes by about 50° from roughly E‐W at the boundary in the west to roughly NW‐SE inside of the basin. In the boundary region the mean T axis inferred from focal mechanisms rotates clockwise by 27° from N64°E in the Mammoth Lakes area to N91°E in the Chalfant Valley, about 50 km southeast of Mammoth Lakes. However, the components of the best fitting stress tensors in the two regions vary only by 12° so that a common stress tensor with a greatest principal stress azimuth of N10°W and a least principal stress azimuth of N80°E, both components nearly horizontal (favoring strike slip), describes the seismic deformation of the boundary region quite well. The stress tensors for the Mono region and west central Nevada have similar greatest and least principal stress azimuths (northeasterly and northwesterly, respectively), however, the plunges of the greatest principal stress are different: nearly horizontal for the Mono area and about 45° for central Nevada, reflecting the strong contribution of normal faulting in the central Nevada earthquake data. The resulting Φ values, which describe the relative sizes of the three stress components, vary from 0.5 to 0.65, which indicates that the magnitudes of the three principal stresses are of similar size.
Nature of the contact zone between the North Cascades crystalline core and the Methow Sequence In the Ross Lake Area, Washington: Implications for Cordilleran tectonics
Authors: Kriens Bryan , Wernicke Brian
Published: February 2008

Previous analyses of the accretionary history of NW Washington‐SW British Columbia have suggested the possibility of large‐scale, dextral‐slip faulting events to explain the present day regional outcrop pattern. The contact zone between the crystalline Skagit Complex and the volcano‐sedimentary Methow sequence has been considered to be a major fault, named the Ross Lake fault by Misch (1966), and has been considered to be a possible large‐scale strike‐slip fault by later workers. Detailed mapping of this contact zone in the Ross Lake area shows that the brittle faults and mylonites thought by Misch to express dextral shearing along the contact are not continuous, throughgoing structures, and that the contact between Skagit orthogneisses and Methow sequence strata is primarily intrusive. Furthermore, the mylonites show both left‐ and right‐lateral shear. The Skagit‐Methow contact is therefore not a major terrane boundary but rather a tectonized intrusive contact that has not accommodated significant motion between the two regions. Based on these observations and regional synthesis of timing relations, deformation in the contact zone is interpreted to express regional ENE‐WSW shortening, not major dextral slip, in the early Tertiary. Since no terrane‐bounding fault exists, the Cretaceous‐Tertiary history of the Ross Lake area can be interpreted as follows: (1) Jurassic(?)‐Early Cretaceous forearc/rift basin sedimentation (deposition of the lower Methow sequence); (2) 110–95 Ma, imbrication of the lower Methow sequence and its basement of oceanic crustal rocks by east‐vergent thrusting, with concomitant development of a west‐derived foredeep in the upper Methow sequence; (3) 95–85 Ma, arc magmatism, with genesis of the Skagit migmatite from Methow and older basement protoliths; and (4) Paleocene‐Early Eocene folding, faulting, uplift, and exposure of a relatively intact 25+ km crustal section, termed the Skagit‐Methow crustal section by Kriens and Wernicke (1987).
Geoelectrical signature of the Central Mauritanides Deep Structure, Mauritania, West Africa
Authors: Robineau Bernard , Ritz Michel
Published: February 2008

Magnetotelluric soundings have been carried out in southern Mauritania along a 225‐km long profile, extending from the Senegal‐Mauritania coastal basin through the Mauritanide orogenic belt to the West African craton. Results across the belt show a good correlation between upper electrical layers and the main lithostructural units, whose lateral and deep extensions are now better estimated. Soundings reveal a highly anomalous lower crustal unit involving two well defined conductors, one at 35 km in the eastern part of the belt and its foreland, and the second, more conductive and thicker, at a depth of 22 km in its western part. The latter has a resistivity of less than 15 ohm m and a thickness of the order of 14 km, and is probably associated with the thrust zone of mylonites and crush rocks with trapped pore water, representing the deep roots of the Mauritanide nappes. This zone is overlain by a westward‐dipping resistor, separating two tectonic blocks differing in their electrical characteristic. This resistor is inferred to be basic or ultrabasic rocks and may reflect the vestigal trace of a suture between two collided continental blocks. The geoelectrical model derived from magnetotelluric data alone is not unique, but the Mauritanide belt has a characteristic gravimetric signature which is compatible with a gravity model based upon the magnetotelluric model geometry. From the available geological and geophysical data, a schematic cross section for the Central Mauritanide crustal structure is presented.
The physical decomposition of the Earth's permanent magnetic field—No. I. the assumed normal magnetization and the characteristics of the resulting residual field
Authors: Bauer L. A.
Published: February 2008

The object of this paper is to resolve the earth's so‐called permanent field into component ones physically interpretable. It is an elaboration of a preliminary communication read in 1896 before the American Association for the Advancement of Science and the British Association, and entitled “On the Component Fields of the Earth's Permanent Magnetism”2 In this first paper the deductions were based on the measured magnetic components at 84 symmetrically distributed points; namely, at the intersections of meridians 30° apart, with the parallels of latitude ±60°, ±40°, ±20°, and the equator. The present investigation, on the other hand, depends upon the measured magnetic components at 1800 points, situated at the intersections of meridians, 5° apart, with the 5° parallels between 60°N. and 60°S.

If we take a cursory glance at a series of magnetic charts of the Earth, we are at once impressed with the complexity of the distribution of its magnetism. Turn to an isogonic chart, for instance, and behold the peculiar condition of things existing at the present time in Eastern China and Japan. You will note that here we have a closed curve along which the needle is “true to the pole.” Within the oval the needle everywhere points W. of N., while outside, the compass everywhere bears East. What is the cause of the peculiar distribution in this region? Is it due, for example, to peculiarities in the geological structure of this part of the earth? We find, moreover, that this oval is not a permanent feature of that region. It has formed only within the present century, and is now enlarging. In the sixteenth century we had a somewhat similar state of affairs in the Atlantic Ocean, only that in this case the oval inclosed places where the needle stood East, instead of West as in the Asiatic oval.
Erdmagnetische Beobachtungen im Umanaks‐Fjord (Nordwest‐Grönland), 1892–93
Authors: Stade Von Dr. H.
Published: February 2008

Während meines einjährigen Aufenthaltes im dänischen Nordgrönland gelegentlich der von der Gesellschaft für Erdkunde zu Berlin im Frühjahr 1892 dorthin entsandten Forschungs‐Kxpedition, an welcher ich mich als Meteorologe beteiligte, habe ich im Umaiiaks‐Fjord zwölfmal, und zwar elfmal an der von uns gegründeten Station Karajak und einmal bei der dänischen Kolonie Umanak, die absoluten Werte der erdmagnetischen Elemente (Declination, Inclination, Total‐Intensität) bestimmt.

Die Beobachtungen zu Karajak wurden sämtlich streng an demselben Punkte und zwar 40 Meter nördlich vom Stationshaus angestellt; derselbe lag in 23 Meter Meereshöhe und wurde im N, E und S bis 300 Meter Entfernung von niedrigen Felsen nur wenig überragt, während 20 Meter weit im W ein schroffer Abfall zum Fjord stattfand. Zu Umanak wurden die Beobachtungen in etwa 30 Meter Höhe etwas westlich von der Kolonie auf einem' die nördliche und östliche Umgebung ein wenig überragenden, nach Wund S steil zum Meere abfallenden Felsen ausgeführt. Der Boden, auf dem beide Beobachtungspunkte lagen, bestand aus Gneiss, ebenso wie die nähere und weitere Umgebung derselben. Neben demselben finden sich andere Gebirgsglieder im Umanaks‐Fjord nur in ganz untergeordneter Ausdehnung und fern von den beiden genannten Punkten.
The influence of the Earth upon the field of a bar‐magnet
Authors: Griffith W. W.
Published: February 2008

Where the lines of force about a bar‐magnet are determined experimentally under the influence of the earth's field, either by filings or by a short tracing needle, all the curves about the ends of the magnet will be seen to be concave toward the extended axis, when the N seeking pole of the magnet points north. Also, the end curves will all be seen to be open curves for all horizontal positions of the magnet except when the N seeking pole points south. For all positions of the magnet the curves as shown by the filings will be seen to be very different from those shown by the tracing needle. The azimuth of the magnet very materially affects the curvature of the lines, and particularly so when the lines are traced by a short needle.
Dr. Lüdeling's researches on the diurnal variation and on magnetic disturbances in polar regions
Authors: Bauer L. A.
Published: February 2008

By request of the Editor, Dr. Lüdeling has contributed the foregoing summary of the results of his recent investigations. It had been the intention to have the article translated into English, as the author had already published his paper in German. This could not, however, be done in time for the present issue, and accordingly the following brief abstract is given for the benefit of those who have difficulty in reading German.

The author investigates graphically the phenomena of the diurnal variation of the earth's magnetism for the eleven stations enumerated on page 246, with the aid of von Bezold's vector‐diagrams. A vector‐diagram is the curve which the north end of a horizontally suspended needle, freed from the mean action of the earth, would describe in the course of a day in consequence of the diurnal variation, if at every instant the half length of the needle represented the magnitude of the horizontal deflecting force. Such diagrams were employed originally by Airy and Lloyd. They, however, took as components of change those along the magnetic meridian and perpendicular thereto, while von Bezold takes his components along the astronomical directions. Von Bezold first showed the full significance of such diagrams. Thus, for example, if the diurnal variation could be referred to an invariable system of magnetic forces revolving around the earth once in twenty‐four hours, then the vector‐diagram for all places along a parallel of latitude would be the same for the same local mean time at each1
The great magnetite deposits of swedish lapland
Authors: Fleming J. A.
Published: February 2008

In this article, which is of particular interest as the result of a personal investigation, the author has introduced his subject by a description of the present laborious route, and of the proposed government railroad to the region of these deposits at a latitude of 67° 57′, and in a range of heights known by the names of Kürunavaara and Luossavaara. The summits of these heights, and the intervening ridges, consist of an almost unbroken outcrop of magnetic iron ore, a fact which, although known some two hundred years ago, has not been put to practical use because of the unfavorable climatic and natural conditions of the country. The region has, however, been the scene of many investigations. The author presents a section showing both the outcrop and non‐exposed extensions of the ore‐mass, which is of peculiar interest as the result of a system of magnetic surveying described by Prof. G. Nordenström, the value of which has been further enhanced by a system of exploration by boreholes under the direction of Mr. Hjalmar Lundbohm.
Magnetic intensity variometers
Authors: Eschenhagen M.
Published: February 2008

For the measurement of the variations of the Earth's magnetic force, advantage is taken of a comparison with a compensating force; e.g., the magnetism of a bar and the directive force of the bifilar suspension. Both forces mentioned are not free from changes in the course of time, and are greatly affected by temperature.

The force of torsion of a unifilar suspension has only been applied with advantage since the invention of quartz fibers. The systems of magnets and suspensions, which weigh at least 20–30 grams usually employed with magnetometers are not suited for quartz fiber suspensions, as too strong fibers must be used. Magnetometers have, therefore, been built at my request by the firm of O. Toepfer, of Potsdam, which are provided with a light system of magnets (weighing about 1.5 g.), and possess several advantages over the instruments used hitherto. Among these are to be mentioned : easy accessibility to the system of magnets, clamping of the lower suspension, so that slight displacements of the mirrors can be made; moreover, a damping adjustable at pleasure; finally, a fixed mirror for photographic registration, which can be displaced with ease and certainty. The system of magnets carries two mirrors, inclined at a certain angle to each other, so that the range of registration is increased twofold. The magnet consists of a well‐hardened laminar piece of watch‐spring steel, 25 mm. long, which can be turned at pleasure about the axis of the system. The frame, supporting mirrors and magnet, is made of aluminum, and is hung, by means of a double hook, on a small cross piece attached to the bottom of the fiber suspension.
Summary of the results of recent investigations in atmospheric electricity
Authors: Exner Franz
Published: February 2008

IV. VARIATION WITH ALTITUDE OF FALL OF POTENTIAL.

That the Earth possesses a negative charge is shown by the generally positive fall of potential. Whether there exist also in the air electric charges, and, if so, whether they be positive or negative, can not be decided by observations made at the surface of the Earth; for this purpose observations in the upper regions alone suffice. If we premise a uniform distribution in the air of the charges in question along horizontal layers, then, in the absence of a charge of the air of its own, the fall of potential should remain constant for the same altitude; in the case of a positive charging of the air the fall of potential must decrease, and for a negative charge, the same should increase. I, therefore, some time ago pointed out the importance of such measurements, and have shown how it would be possible to carry them out in a balloon without conduction with the Earth. Parenthetically it may be remarked, that similar observations on high mountains, on account of the disturbances in the equipotential planes, can not replace, for this purpose, the balloon observations.
The hysical decomposition of the earth's permanent magnetic field: No. II. The composition and characteristics of the uniform magnetic field
Authors: Bauer L. A.
Published: February 2008

In my previous paper, I separated from the Earth's total magnetic field that portion which could be referred to a uniform or homogeneous magnetization about a single diameter inclined 11° 25′.7 to the axis of rotation and intersecting the Northern Hemisphere in longitude 68° 30′.6 west of Greenwich. This diameter is the same as that termed by Gauss, in his celebrated memoir on the theory of the Earth's magnetism, the “magnetic axis” of the Earth, and its position is determined by the coefficients of the spherical harmonic of the first order entering in Gauss's mathematical analysis of the distribution of the so‐called permanent magnetism of the Earth.

The position as above given was based upon the latest and most complete analysis made thus far; viz., that of Dr. Adolf Schmidt, of Gotha. The magnetic moment of this uniform or “normal field,” as I called it in my previous paper, was 0.32298 R8, c. g. s. units, R being the Earth's mean radius.
Ueber eine neue form der lloyd'schen wage
Authors: Eschenhagen Von M.
Published: February 2008

Die sichere Ermittelung der Variationen der Verticalintensität bietet zur Zeit noch mancherlei Schwierigkeiten, die wesentlich auf instrumentellem Gebiete liegen. Die Lloyd'sche Wage, zur Zeit das zuverlässigste Instrument für derartige Beobachtungen, besitzt mancherlei Mängel, von denen die Reibung auf der Schneide, und die Veränderlichkeit des Nullpunctes wie des Scalenwertes die wesentlichsten sind, während andererseits durch geeignete Aufstellung die Empfindlichkeit des Instrumentes beliebig gesteigert werden kann. Bezeichnen wir mit γ den Winkel, welchen die Verbindungslinie vom Schwerpunct und Unterstützungspunct mit der magnetischen Axe bildet, und nennen wir a das Azimut, in welchem dieselbe sich zum Meridian befindet, und ι die Inclination, so ist bekanntlich der Ausdruck für das Maass der Empfindlichkeit der folgende Scalenwert:1 worin l den Scalenabstand bedeutet. Es ist aus demselben ersichtlich, dass im Fall die Wage mit der magnetischen Axe im Meridian steht, d. h. a = o ist, die Empfindlichkeit nicht beliebig gesteigert werden kann, auch wenn der Winkel γ ein sehr kleiner wird.
Wild's new method for determining the variations of magnetic inclination
Authors: Cady W. G.
Published: February 2008

This is one of the the most important contributions to the study of the Earth's magnetism since the invention of the Weber earth‐inductor, of which it is a modification. The fact that the Weber inductor is always used with the zero‐method, makes it unfit for use as a variation instrument. This defect has been entirely removed in the Wild inductor; a needle hung from a vertical suspension not only shows the same variations in a horizontal plane that a frictionless dipping‐needle would experience in a vertical plane, but the absolute value of the total deflection is the same in each case.

If we have two equal coils of wire, the one turned about a horizontal, the other on a vertical axis with equal velocities, the two induced currents are:Iz = Z. C and Ih = H. C′respectively, H and Z being the horizontal and vertical components of the Earth's field, C and C′ constants involving character of the coils, velocity, etc. If the two coils are exactly alike, C = C′ and we have for the inclination,

urn:x-wiley:00968013:media:tma3107:tma3107-math-0001
The unifilar magnetometer of the magnetic survey of India
Authors: Fraser H. A. Denholm
Published: February 2008

The illustration gives a general view of the instrument, and shows the form of the magnets and of the stirrup.

The long or vibration magnet is a true hollow cylinder, .4 inch external diameter, .3 inch internal diameter, and 3.65 inches long.
Report on the magnetic observations made at the magnetic observatory at Zi‐Ka‐Wei, China, during the total solar eclipse of May 17–18, 1901
Authors: de Moidrey J.
Published: February 2008

The Observatory at Zi‐ka‐wei has been desirous of co‐operating in the simultaneous observations suggested in the December, 1900, number of “Terrestrial Magnetism.” Our station (8h 5m 44s east of Greenwich, 31° 11′ 33″ north) is situated outside the zone of visibility of the eclipse, but very near the line of single contact.

An unforeseen accident prevented our beginning the observations, as we wished, one hour before the eclipse. The registration could not be set going until 11h 20m (15h 14m Gr. m. t.). I send, nevertheless, what we have obtained. On the 17th a scale determination, made with care and at two distances, showed that the self‐registering instruments, and in particular the Lloyd balance, were in perfect condition. On the 18th the sensitiveness of the bifilar was doubled, and a new scale determination was made at two distances.
The central physical observatory of Russia
Authors: Hazard D. L.
Published: February 2008

The completion of fifty years of activity and usefulness by the Central Physical Observatory of Russia has been deemed by its director, General Rykatchew, a fitting occasion to give a general history of its work during that period.

The Part I before us begins with an account of what had been accomplished in the fields of meteorology and terrestrial magnetism prior to the establishment of the Central Physical Observatory, shows the gradual development of that institution from the small beginnings of Kupffer at the University of Kazan, and details its work under the direction of Kupffer from 1849 to 1865, and of Kämtz for the next three years.
Forthcoming advances in the terrestrial magnetism of Antarctica
Authors: Littlehales G. W.
Published: February 2008

Under the imperial flags of Great Britain and Germany, two cooperating expeditions equipped with exceptional completeness, are penetrating into the high southern latitudes for the advance of knowledge concerning the south polar regions.

The main purposes are to determine, as far as possible, the extent and nature of the south polar land, to ascertain the nature of its glaciation and the condition of the ice‐cap, to observe the condition of the underlying rocks, and to make a magnetic survey south of 40° of south latitude. Much importance is also attached to the meteorological observations, and especially in the regions south of 74° of south latitude. Deep‐sea soundings with temperatures are to be taken, and biological observations are likewise to be made. Observations of atmospheric electricity and of polar lights are also provided for in the program.
A theorem on Fourier series, and its application in geophysics
Authors: Nippoldt A.
Published: February 2008

If we put the interval 2 π, in which a Fourier series assumes every possible value, equal to the natural period2 of a geophysical element, we obtain the most natural and appropriate of all the common representations of the periodic process, since in this case the representing function and the function represented have the same periodicity. In addition to this, the individual waves attain a real significance in certain circumstances; for example, when the periodic process is to be attributed to stationary vibrations, as in the case of the diurnal variation of the atmospheric pressure. But even in the case in which the waves of higher order are to all appearances merely computation quantities, the physical analysis of the process represented, according to its causes, can still be effected by the series, though of course only with the assistance of modes of procedure lying quite outside the method (of Fourier); namely, by the comparison of the coefficients for different times and places in which the different causes act in opposite senses.

It was with such aid that the author succeeded in showing that that field to which, according to Schuster‐Bezold,3 the diurnal variations of the Earth's magnetism are to be attributed, is composed of two parts, one corresponding to the “solar” part of the weather, the other to the “terrestrial” part. Both parts have the period 24 hours, so that in the Fourier representation the solar part is given by the first term, and the terrestrial part by the sum of all the rest. The solar part is thus represented by a stationary vibration, and the terrestrial part, in a purely mathematical way, by the terms of the second order; while the individual waves have, beyond this, no independent existence.
Professor Max Eschenhagen: His life and work
Authors: Cady W. G.
Published: February 2008

In the life of Max Eschenhagen the world has a notable example of sterling ability winning its way through successive stages to a position of eminence and responsibility. He was born October 22, 1858, in Eisleben, and at the age of twenty‐two took the doctor's degree at Halle, working chiefly in mathematics and physics. For the next two years he was employed in teaching. In 1883 he was appointed to a position on the German Polar Commission, and began what proved to be his life‐work—the study of terrestrial magnetism.
Note sur l'amplitude de l'oscillation diurne de la déclinaison magnétique et son inégalité mensuelle
Authors: de Moidrey J.
Published: February 2008

L'amplitude de l'oscillation diurne de la déclinaison présente une variation annuelle bien connue: on peut se demander s'il n'y a pas aussi une inégalité mensuelle.

A Zi‐ka‐wei, l'amplitude est mesurée pour chaque jour sur la courbe photographique elle‐même. Comme 1mm=0′.605, si on admet qu'un calculateur exercé et soigneux ne se trompe pas de plus de 0mm 2, on pourra estimer que l'amplitude est connue pour chaque jour à 0′.1 près, et indépendamment des erreurs des mesures absolues, du déplacement lent de la base, etc. L'oscillation considérés est toujours celle du milieu du jour, dont l'elongation orientale ou minimum a lieu environ 2 heures après le lever du soleil et la digression occidentale, maximum, vers 13h . De fait, même en hiver, cette ondulation est, à peu près sans exception, la principale.
Divergence of long plumb‐lines at the Tamarack mine
Authors: McNair F. W.
Published: February 2008

In September last two very long plumb‐lines were hung in No. 5 shaft of the Tamarack Mine at Calumet, Michigan. They were 4,250 ft. in length, being longer than in any previously recorded instance. They were of No. 24 piano wire and the bobs were of cast iron, weighing fifty pounds each. Great care was taken that there should be no interference from projecting objects nor from dropping water, of which, indeed, there is not a great deal in the shaft.
Records of earthquakes on quickly‐driven magnetographs
Authors: Farr C. Coleridge
Published: February 2008

On the morning of Saturday, November 16, 1901, Christchurch, New Zealand, was visited by a severe shock of earthquake. The earthquake did much damage in the Cheviot District about sixty miles to the northeast from here, wrecking chimneys, etc., over a considerable area. In this city the chief and almost only damage done was to the spire of the cathedral which was cracked in two places, and the portion of the lower crack has since had to be removed. The earthquake was among the more severe of New Zealand shocks.
Tromholt's catalogue of Norwegian auroras
Authors: Abbe Cleveland
Published: February 2008

No one has labored more faithfully to elucidate the problems of the aurora than Dr. Sophus Tromholt, of Rostock, Norway, who died April 17, 1896.

Among his most important works was that done when he, in 1882‐3, personally occupied a station at Koutokeino in Finmark, Norway, in order to study the auroras observed by the Norwegian party at Bossekop, Norway, and the Finnish party at Sodan‐Kyla. Tromholt was about sixty‐six miles south of Bossekop and two hundred miles northeast ot Sodan‐Kyla, and observations of the auroras were made at all three stations at prearranged moments of time, for the express purpose of determining their altitudes. The results of these special observations have as yet been only partially published.
The lunar diurnal variation as obtained at the Cheltenham Magnetic Observatory from a single complete lunation during February, 1903
Authors: Bauer L. A. , Nyswander R. E.
Published: February 2008

The attempt, was made to determine how well the lunar diurnal variation of the magnetic elements,could be determined from simply one complete lunation, instead of using records extending over a period of a year or more.

For this purpose the comparatively “magnetically calm” month of February, 1903, was selected and the photographic records obtained at the Cheltenham Magnetic Observatory of the Coast and Geodetic Survey with an Eschenhagen Magnetograph were utilized. The scale values used were: 1 mm. ordinate, declination = 1.014 minute, 1 mm. ” horizontal intensity = 0.00002 C. G. S. unit.
The magnetic elements of forty‐four stations in Madagascar, determined by Prof. P. Colin, director of the Tananarive Observatory
Authors: Froley J. W.
Published: February 2008

The magnetic elements of the first thirty‐six stations given in the table were communicated by Prof. Colin to the Comptes Rendus for June, 1902. On application to him for information as to the positions of the stations, he sent me a French Army chart with these thirty‐six stations and eight additional ones plotted thereon. The co‐ordinates of the positions were expressed in grades which have been reduced to degrees and the origin of longitudes has been transferred from Paris to Greenwich. The longitudes of all the stations are made to depend on that of Tananarive Observatory as given by French Hydrographic charts.
Department of International Research in Terrestrial Magnetism of the Carnegie Institution
Authors: Bauer L. A.
Published: February 2008

The Trustees of the Carnegie Institution, founded at the City of Washington by the munificence of the well‐known philanthropist, Andrew Carnegie, at their annual meeting in December, 1903, took the necessary steps to establish what is now to be known as the ”Department of International Research in Terrestrial Magnetism.“ An allotment of twenty thousand dollars ($20,000) was made, with the expectation that, if the proposed work should be successfully organized, a similar sum would be granted annually for the period requisite to carry out successfully the plan submitted by the writer and published in Year Book No. 2 of the Carnegie Institution.

The Executive Committee at its meeting in February, 1904, considered the organization of this Department, and it was decided to ask the writer to be the Director of the Department, his function to be the planning and directing of the proposed work. This trust he has accepted. Arrangements have been made so that the direction of the magnetic survey and the magnetic observatories of the United States, under the Coast and Geodetic Survey, remains likewise in his charge.
Earthquake records from Agana, Island of Guam, 1892–1903
Authors: Abbe Cleveland
Published: February 2008

The observations on earthquakes here presented were made by the officers and enlisted men detailed for the Metereological Station at the U.S. Naval Station of Agana, the chief settlement on the island of Guam which is the largest of the islands forming the Marianas Archipelago, and is located in latitude 13° North, longitude 145° East.1

The time used in making all these observations is local mean time from which 9 hours and 39 minutes must be subtracted to give Greenwich mean civil time.
Mesures magnétiques en Chine
Authors: de Moidrey J.
Published: February 2008

Le R. P. Froc, directeur de l'observatoire de Zi‐ka‐wei, a profité d'un rapide séjour à Hong‐kong, le mois dernier, pour y faire quelques observations magnétiques. Il s'est servi de nos petites boussoles de voyage, par Chasselon, identiques à celles qui sont décrites dans les Annales du Bureau Météorologique de France (1898 B. 59. 60). Les constantes ont été déterminées par des comparaisons répétées avec les instruments fixes de Zi‐ka‐wei, immédiatement avant et après le voyage.

Les observations ont été faites, le 20, le 23, le 24, et le 27 décembre, 1904, à Bowen Road, à l'est de Victoria, un peu au S.W. de l'hôpital de la marine; le 22 à Pokfulum, au sud du Pic, sur un petit plateau à 800m environ au S.S.E. des réservoirs; le 26, à Macao, près de la chapelle de Penha, presque au lieu où le R. P. Saderra Mata avait observé en 1892 avec des instruments identiques de Brünner.
Principal magnetic disturbances recorded at Cheltenham Magnetic Observatory, March 1, to May 31, 1905
Authors: Wallis W. F.
Published: February 2008

7. Began at 20h on March 31st, and ended at about 8h on April 2d, but continued as a moderate disturbance till about midnight of April 5th. The maximum and minimum ordinates are as follows:
Magnetic survey of the Dutch East‐Indies
Authors: van Bemmelen W.
Published: February 2008

In 1905, circumstances did not permit occupying more than seventeen stations, of which four had been previously visited in 1903 and 1904.

Though the maintenance of a group of repeat‐stations, regularly distributed over the whole area, is prohibited by the enormous extension of the region involved, because of “ the availability of but one observer, there has been found opportunity,” nevertheless, to revisit some of the stations.
Magnetic elements determined at Tripoli, Barbary
Authors: Palazzo L.
Published: February 2008

The Department Terrestrial Magnetism of the Carnegie Institution of Washington intrusted me with the task of making magnetic and electric observations at Tripoli in Barbary on the occasion of the total solar eclipse of last August 30, 1905, and provided the necessary funds for the accomplishing of the same.

During my brief sojourn at Tripoli it was very natural I should devote my time also to the taking of absolute magnetic measurements, partly because I considered it interesting to know the magnetic elements of Tripoli, and partly in order to get the base‐line values for the registrations obtained with the magnetograph, which I had set up in the Royal Italian Technical‐Commercial School in Tripoli for the purpose of ascertaining the eventual magnetic variations connected with the eclipse.
Some results for magnetic declination and inclination
Authors: Klotz O. J.
Published: February 2008

The geographic positions given, refer to my astronomical stations at the cable stations, the above results having been obtained in connection with my telegraphic longitude work for the Canadian Government. The instrument was a Tesdorpf Field Magnetometer with dip circle similar to those made for the German Antarctic Expedition.

Descriptions of Stations.

Suva, Fiji. Magnetic station was on vacant land 158 ft. southwesterly from the pier of the astronomical station and 10 ft. from the low bank bordering the sea beach. The solar observations for azimuth of the reference object were made by G. Heimbrod, and the adopted reduction by O. Klotz.
The diurnal variation of the amount of radioactive emanation in the atmosphere
Authors: Dike P. H.
Published: February 2008

It is a well‐known fact that the atmosphere contains a radioactive emanation capable of making a negatively charged wire exposed to it temporarily active. It has also been observed that the amount of the emanation present, as measured by the intensity of the excited activity of the wire, exposed for a given time, varies widely and seems to be dependent on a variety of conditions,—the direction and velocity of the wind, the height of the barometer, etc.

In view of the fact that experiments at present being carried on at the Cavendish Laboratory show a more or less regular diurnal variation in the spontaneous ionization of the air inside a closed vessel, it was thought to be of interest to determine if the amount of radioactive emanation present in the atmosphere shows a similar variation, as this might be of aid in explaining the former fact.
Records of seismographs in North America and the Hawaiian Islands: no. III
Authors: Reid Harry Fielding
Published: February 2008

The following contains the records of seismographs in North America and the Hawaiian Islands for the first half of 1905. The times are Greenwich mean civil times beginning at midnight, counting the hours from 0 to 24. The following abbreviations are used:

P. T.‐preliminary tremors; P. P.‐principal part, sometimes called long waves.
Das magnetische filial Observatorium bei Seddin
Authors: Schmidt Ad.
Published: February 2008

In aller Kürze teile ich Ihnen mit, dass unser neues Observatorium bei Seddin (Breite = 52° 16.′7, Länge = 13° 0.′6 E. v. Gr. = 52m 2.S4; h = 45m) am Beginn dieses Jahres seine Tätigkeit aufgenommen hat. Es werden die drei Komponenten X, Y, Z, daneben gelegentlich auch die Deklination, sämtlich mit ungefähr 2 γ Empfindlichkeit (was bei D äquivalent mit 0.′36 ist) registriert.

Absolute Beobachtungen werden zunächst nicht gemacht; die Basiswerte der Kurven werden durch Vergleich mit denjenigen des nur 13 km. entfernten Potsdamer Observatoriums unter der im Mittel mehrerer Stunden an ruhigen Tagen berechtigten Annahme einer konstanten Differenz gewonnen. (Der Fehler dieser Annahme liegt weit unterhalb der Fehlergrenze der absoluten Messungen.) Bei passenden Gelegenheiten sollen mit einem zwreiten Satze von Magnetometern Feinregistrierungen vorgenommen werden. Sobald die Störungen durch den elektrischen Bahnverkehr von Berlin (dessen Centrum 40 km. von der Station entfernt ist) die empfindlichen Registrierungen zu beeinträchtigen beginnen sollten, würde für diese eine Aufstellung in einer transportablen Hütte gewählt werden, die nach Bedarf bald hier, bald dort aufgestellt werden kann.
Helwan Magnetic Observatory, Egypt
Authors: Keeling B. F. E.
Published: February 2008

Since 1898 regular absolute observations have been made at Helwan. In 1904 the meteorological observatory was moved from Abbassia, (a suburb to the N. E. of Cairo) to Helwan, and a special building for terrestrial magnetic work was provided. The recording instruments arrived in the autumn of 1906. The installation and determination of the temperature co‐efficients occupied some months, and on April 1, 1907, the regular records commenced.
Magnetic survey of the Dutch East Indies
Authors: van Bemmelen W.
Published: February 2008

In 1907 Mr. F. H. Staverman, retired Lieutenant in the Dutch Navy, acting subdirector of the Batavia Observatory, on two trips completed the magnetic survey of the Dutch East Indies. The first trip undertaken in April and May extended from Bandjermasin along the eastern and southern coast of Borneo and up the river Barito to Central Borneo. The second trip during October and November extended from Makasser to the southern and eastern coast of Celebes and the neighboring islands, and back from Makasser to Java along Kalu Kalukuang in Strait Makasser, Great Solombo, and Bawean in the Java Sea. The instruments and methods of observation were the same as used by me in previous years.
The Earth's residual magnetic field
Authors: Tanakadate A. , Bauer L. A.
Published: February 2008

“Dr. L. A. Bauer has constructed the map of residual magnetic field after deducing the first harmonics in Gaussian expansion from the observed values of each component, and has shown in a marked way several centers of attractions and repulsions on the Earth's surface. The question naturally arises, What will be the residual field after deducing all the harmonics from the observed values? The following table and map [reproduced on reduced scale], constructed from the differences in Tables III and VIII in Prof. Ad. Schmidt's Paper in the XXI Jahrgang of Aus dem Archiv der Deutschen Seewarte, furnishes the answer. The map was originally constructed on a globe of 30 inches diameter by two of my assistants, Messrs. T. Kato and T. Yasuda.”

“Those residuals, though still presenting certain aspect of continuity, the relation between the horizontal and vertical components does not in general show centers of attractions or repulsions, except in few cases which may be real or accidental. Considering the way in which the data (the Beobachtete Werthe at regular intervals of longitude and latitude), these residuals would seem to have but little physical sense, as is duly remarked by Prof. Schmidt himself.”
The solar eclipse of August 30, 1905, and magnetic phenomena
Authors: Chree C.
Published: February 2008

I have read with interest Mr. Charles Nordmann's contribution1 to the study of the effects produced on the magnetic declination by the total solar eclipse of August 30, 1905. Whilst appreciating, as it deserves, Mr. Nordmann's ingenuity, I must confess that the facts which he advances, p. 23, seem to me to be inconclusive, and to bear most probably a different interpretation from that which he supposes. Before explaining my reasons for this view, I should like to make some preliminary remarks.

Mr. Nordmann's curves, p. 22, have no claim to acceptance except as the embodiment of the figures quoted on p. 20. The unit of force employed is said to be only 0.14 γ (γ = 1 × 10‐5 C. G. S.). Of the five stations dealt with, Stonyhurst has the lowest horizontal force, and there I γ answers approximately to 0.′2 of declination. Thus when Mr. Nordmann on p. 20 gives values to 0.1 of his unit, he is practically recording declination changes to 0.′003 or less. It is unusual to measure declination curves to nearer than 0.′1 (answering usually to 0.′1mm approximately), and two observers will often differ by this amount in their estimate. Mr. Nordmann, it is true, has used not his actual curve measurements, but smoothed means of the type (a + 2b + c)/4; but even taking this into account one cannot but regard the figures on pp. 20 and 21 as suggesting an accuracy at least ten times that ordinarily attempted.
Carnegie Institution comparisons of magnetic standards during 1908
Authors: Fleming John A. , Pearson J. C.
Published: February 2008

The proper correlation of the magnetic data obtained by different organizations and institutions within the accuracy attainable in field work, is a matter of importance in the general magnetic survey of the globe undertaken by the Department Terrestrial Magnetism of the Carnegie Institution of Washington. In the course of its work thus far, the Department during the period 1904‐07 has made comparisons between its instruments and those at the following observatories: Apia (Samoan Islands), Baldwin (Kansas), Cheltenham (Maryland), Havana (Cuba), Honkong (China), Honolulu (Hawaiian Islands), Melbourne (Australia), Zi‐ka‐wei (China), Sitka (Alaska), Sydney (Australia), Tokyo (Japan), Toronto‐Agincourt (Canada), Vieques (Puerto Rico), and during 1908 at Christchurch (New Zealand), Kew (England), Helwan (Egypt), and Tiflis (Russia). The 1908 comparisons form the subject matter of the present paper. Those at Kew, Helwan and Tiflis were secured by Magnetic Observer J. C. Pearson en route to the field work assigned him in Asia Minor and Persia, whereas those at Christchurch were obtained during December 31, 1907, to January 6, 1908, by the ocean magnetic party of the Galilee.
The Carnegie Institution marine collimating compass
Authors: Peters W. J.
Published: February 2008

The recent cruises of the Galilee in the Pacific Ocean gave many opportunities for observing magnetic declinations at sea and on land, with the various instruments generally used in ordinary navigation. The observations were made with great care and no effort was spared to eliminate errors due to motion at sea and to obtain good determinations on land of the instrumental corrections.

The results of this large collection of data indicate that the determination of magnetic declination can be made on land with a Ritchie eight‐inch liquid compass using either the cylindrical mirror, or the dark plane mirror, within an accuracy of two‐tenths of a degree and with special care within one‐tenth. These devices, however, do not afford such precision when used at sea, for it has been found that the results from eight different sets of ten pointings each may differ as much as one‐half degree. The Kelvin azimuth attachment on the dry compass frequently gave even more discordant results, which, however, may have been in some measure due to the near synchronism of the card oscillation and the roll of the ship. The Bamberg compass which is used in the German Navy, has an alidade arrangement like a pocket prismatic compass, but officers who have used it say that the observations are difficult and unsatisfactory when there is much rolling.
Peculiar magnetic disturbances in December, 1908
Authors: Hazard D. L.
Published: February 2008

In “Nature” for January 7, 1908, Dr. Chree reports that the Messina earthquake of December 28, 1908, was recorded by the Kew magnetograph in the form of 4 burrs on the trace corresponding in time to four maxima recorded by the seismograph. A similar record was made by the magnetographs at four of the Coast and Geodetic Survey magnetic observatories at the time of the San Francisco earthquake of April, 1906, as well as at the times of other earthquakes. These, in general, were evidently mechanical disturbances of the magnets, the magnetographs acting as seismographs and recording the principal portions of the earthquakes; however, there are sometimes cases in which this conclusion can not be immediately drawn.

On May 8, 1902, there was a magnetic storm of considerable magnitude which began abruptly at the time of the eruption of Mont Pelée, Martinique, as nearly as could be determined. This had the usual characteristics of a magnetic storm and lasted for 40 hours.
United States magnetic tables and magnetic charts for 1905
Authors: Bauer L. A.
Published: February 2008

The present publication is the author's concluding one while in charge of the magnetic work under the United States Coast and Geodetic Survey from 1899‐1906. It portrays the state of the Earth's magnetic forces in the United States for the date January 1, 1905, and accordingly contains tables of the observed magnetic elements as far as available in the regions covered and their values when reduced to the common epoch. There are furthermore given graphical representations (magnetic charts Nos. 1–5) of the actual distribution of the magnetic elements—declination, dip or inclination, horizontal component of the total intensity of the Earth's magnetic force, the vertical component, as also the total intensity. The iso‐magnetic lines are shown in red on a base map of the scale 1/7,000,000, and on the first three are likewise added in blue the lines of equal annual change.