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The thermal motions of ions in an inhomogeneous magnetic field give rise to a systematic ion drift. A study of the motion of ions executing long free paths and spiralling about an inhomogeneous impressed magnetic field has shown that a systematic drift is imposed which is oppositely directed for the positive and negative ions. The resulting drift velocity is proportional to the component of the magnetic gradient that is perpendicular to the magnetic field itself. Under the conditions of radial symmetry and a closed circuit a current flows which is in such a direction as to reduce the inhomogeneity of the impressed field and increase the total flux enclosed by the current circuit. This increase in the flux enclosed by the circuit shows that the phenomena may be regenerative. Certain applications to the sun's atmosphere, sun-spots and the permanent magnetic field of the sun and earth are suggested.
Measurements were made with a quartz mercury lamp, a quartz spectrograph and a recording densitometer of the attenuation of ultra-violet light from 3000 to 2050A by the atmosphere at sea level. For wave-lengths from 5000 to 3000A the absorption was too slight to be observed at distances up to 400 meters; for wave-lengths below 2800A there was pronounced absorption above that attributable to molecular scattering. The absorption was the same day and night, was unaffected by changes in the humidity, but increased with haze. The thicknesses of clear air necessary to reduce the light to 10-2 were about 22, 5, 0.57 and 0.20 km for 2800, 2500, 2200 and 2050A, respectively. The absorption in the lower atmosphere around 2800 to 2900A was not sufficient to account for the sharp cessation of the solar spectrum in this region. This result is in keeping with the fact that the ultra-violet limit of the solar spectrum is due to ozone in the high atmosphere. The absorption in the lower atmosphere at 2200 to 2050A, a spectrum region where ozone is relatively transparent, is great enough to prevent sunlight of these wave-lengths from penetrating to sea level.
ON Feb. 27-28 occurred one of the greatest magnetic storms recorded at this Observatory in the present solar cycle. The range in declination (100') has been exceeded once only, on Oct. 15, 1926 (>164'), in the cycle, and that in horizontal force (530gamma) has been exceeded on three occasions only, namely, on July 8, 1928 (>600gamma), Oct. 15, 1926 (>717gamma), and April 14-15, 1926 (586gamma). In both the recent storm and that of last July the minimum of H.F. was beyond the limits of registration, so that it is not possible to give the exact value of the range.
Measurements between two stations 0.4 km apart with a thermocouple and galvanometer and with spectrograms, properly calibrated, of the absorption of light by fog for wave-lengths from 0.4 to 3mu showed that the absorption increased slightly with decrease in wave-length, but hardly enough to indicate that red light is appreciably better than blue light for the purpose of penetrating fog. For a fairly dense fog, such that in daylight dark colored objects at about 0.6 km could barely be be seen, the distances necessary to reduce the light to 10-2 of its original value were about 710, 843, 910, 970, 980 and 980 meters for wave-lengths 0.4, 0.5, 0.6, 1.0, 2.0 and 3.0mu, respectively.
The ultra-violet light theory of aurorae and magnetic storms suggests (1) that because of winds and unusual production of ions the ionized region of the high atmosphere may be in violent agitation during the day of a magnetic storm, that it grows calmer at night and becomes agitated the next day if the storm continues, (2) that there may be auroral displays in polar regions with no magnetic storms in temperate latitudes, (3) that auroral displays in temperate latitudes should as a rule be accompanied by magnetic storms, and (4) that polar aurorae should follow several hours or a day after strong magnetic disturbances observed in temperate latitudes. These inferences are shown to be in agreement with the data from magnetic observatories and observations of aurorae in temperate and polar latitudes.
The motion of ions, executing short free paths under the influence of thermal agitation in an inhomogeneous magnetic field, in crossed magnetic and gravitational fields or in crossed magnetic and electric fields are shown to produce drift currents. The ion drifts are found to be opposite in direction to the drifts produced in the analogous cases of long free path. Under the condition of radial symmetry and a closed circuit the magnetic gradient gives rise to circular currents which flow in such a direction that magnetic regeneration takes place. Regeneration is limited by demagnetizing currents arising from the thermal motions of the ions interacting with the resultant magnetic field and an internal electric or gravitational field. The magnetic moments of the sun and earth are calculated from data which are approximately known and the correct magnitudes obtained. The permanent fields arise from the thermal energy of the body and would be maintained if the bodies ceased their rotation. The asymmetry of the earth's magnetic field indicates that the hemisphere embraced by the Pacific Ocean is at a higher mean internal temperature than the rest of the earth.
It is shown that the lines of force of the earth's magnetic field can be treated as if rotating with the earth in so far as the calculation of ion paths are concerned only if there exist positive charges over the poles accompanied by negative charges over the equator. The earth would have a total charge of -72 coulombs although observers on the earth would be aware of no electric field. Assuming that the earth is an uncharged, conducting, uniformly magnetized sphere, rotating about its magnetic axis with angular velocity Omega, it is shown that ion paths progress to the west, the velocity of progression increasing with altitude so as to approach the limiting value -Omega×r which measures the progression that would exist if the earth's field were solely magnetic relative to observers who do not partake of the rotation. The earth would have an apparent charge of +72 coulombs although actually uncharged. It is shown that a uniformly distributed charge q on the earth merely changes the value of the limiting westward velocity found above, increasing the westward progression if q is positive, and decreasing it if q is negative.
IT was recorded in NATURE of Sept. 3, 1927, that, in experiments carried out for the Radio Research Board of the Department of Scientific and Industrial Research, evidence had been obtained of the existence of at least two ionised regions in the upper atmosphere. This evidence was derived, in the first instance, from observations made at night using wireless waves of medium length as the atmospheric exploring agency, but, more recently, the use of short waves has made it possible to carry out similar experiments during the daylight hours. The results of these experiments confirm the earlier conclusion as to the existence of the two ionised regions while the use of short waves, as was anticipated, markedly lengthens the period during the twenty-four hours when the lower region is penetrable and the upper region accessible. Using a wave-length of just under 100 metres, it is found that even about mid-day the lower region is penetrable on some days. On other days it is found that, due to the inhomogeneity of the lower region, waves of this length are `reflected' by it one moment and a short time later get through. This is illustrated by a typical series of observations made at King's College, London, on Jan. 13, 1929, using 99.8 metre waves emitted by the National Physical Laboratory transmitter at Teddingtpn, for which the following equivalent heights (km.) of `reflection' were recorded at 10-minute intervals between 1000 and 1400 G.M.T.: 229, 229, 236, 244, 217, 229, 229, 230, 204, 196, 229, 100, 99, 93, 98, 99, 96, 98, 232, 99 (and 220), 99, 229, 229, 99.
ON Mar. 15 last I received information from the State Telegraphic Department that earth currents were disturbing the telegraphic service. Believing that we should have an aurora in the evening, I warned my four photographic stations, Oslo, Kongsberg, Tömte, and Oscarsborg, to be ready for action immediately after sunset. Using the excellent type of direct vision spectroscope described by Lord Rayleigh,1 I was able to localise an aurora arc in the northern sky during the twilight, long before it was possible to distinguish it visually.
A recent theory of the authors attributed terrestrial magnetic storms and auroral displays to the effect of unusual flares of ultra-violet light from the sun falling upon the terrestrial atmosphere. Such flares would be expected to cause changes in comets, and therefore comet changes should be closely connected with magnetic storms. This connection is supported by the evidence brought out in the present paper in a discussion of the behavior of 31 comets scattered through the years 1848 to 1927. A general statistical result was that in the month preceding each comet's activity there occurred on the average 6, 4, 2.9 and 1.5 times as many magnetic storms of strength 4, 3, 2 and 1, respectively, as there should have occured according to chance. Outstanding comet changes, 28 in number, were observed on the average 5 days after strong magnetic storms. The positions of the comet, sun and earth at the epochs of the comet changes indicated that the solar flare was in a wide angle, contrary to the narrow beam hypothesis of Maunder.
The relationship between relative humidity and the mobility of negative ions in air at atmospheric pressure has been examined with a view to possible applications in hygrometric measurements. The method employed was a modification of Zeleny's original method, the end of a wind channel being closed by a disc of gauze fitted with a guard ring through which a steady stream of air of definite humidity was pumped.
The motion of the negative ions due to the action of the air stream was balanced by a counter potential gradient, and the mobility was deduced from the critical potential required to produce a balance. The rate of air flow was measured by means of a Ewing ball and tube flowmeter, a hollow glass sphere being used to make it suitable for low air rates. Efforts were made to construct a direct indicating instrument by amplifying the current sufficiently to obtain deflections on a robust moving-coil indicator, but the variations in the amplification factor were found to be too serious.
In this paper we have sought to offer some further contribution to the Kennelly-Heaviside layer problem; first, in the form of experimental data showing clearly evidence of the diurnal cycle in layer height, and secondly, in the form of a discussion of methods for the interpretation of group time and phase retardation experiments and the problem of determining the relationship between the "virtual" and "true" heights. Methods of successive approximation for arriving at the "true" height, from group time or phase retardation measurements, are also discussed and applied. Close accord is found between the results of these methods and the approximation used by Schelleng in a recent paper. The results shown in Fig. 16 also indicate the necessity for further experiments in the important frequency range from 1 to 4 megacycles where no data are available.
Graphic records of radio signals transmitted from high-frequency aircraft radio transmitters are observed to show periodic variations of fairly constant frequency over considerable time intervals. A theory is evolved connecting this frequency with the transmitting distance, the ground speed of the plane and the effective height of the Kennelly-Heaviside Layer. Records of such periodic fading are reproduced from which, in accordance with this theory, the height of the layer is computed. A short discussion is given of the results obtained.
Die radiale Begrenzung des Magnetfeldes der Sonne
- J Bartels
- Bartels
El Observatorio Magnético de Huancayo
- Forbush S. E.
Second report of the Commission appointed to further the study of solar and terrestrial relationships
- International Research Council
Die Verteilung der regelmässigen täglichen Variationen des Erdmagnetismus in Mitteleuropa
- Nippoldt G.
Sur la stabilité de l'aimantation permanente de certaines roches
- Sramkov E.
Sur la nature des rayons untrapénétrants (rayons cosmiques)
- Auger P.
Contribution à l'étude de la matière fulminante
- Mathias E.
Progress in lightning research
- Peek F. W.
Summary of prominence observations for the first half of the year 1928
- Royds T.
Report on the operations of the Royal Survey Department, Ministry of War, for the year 1926–27
- Bangkok
- Bangkok, Royal Survey Department
Bericht über die Tätigkelt des Preussischen Meteorologischen Instituts im Jahre 1928
- Preussischen Meteorologichen Berlin
- Institut
- Berlin, Preussischen Meteorologichen Institut
Remarks on magnetism and the aurora
- Blanchet G. H.
Cosmical magnetic phenomena
- Chapman S.
87 mit 2 Taf. und 6 Karten). 30 cm. [A detailed account of the magnetic survey of Bavaria carried out during the period 1903-1911 by J. B. Messerschmitt, embracing in all 187 stations
- Fr Burmeister
- Burmeister
Report of the Astronomer Royal to the Board of Visitors of the Royal Observatory, Greenwich
- F W Dyson
- Dyson
Erdmagnetische Messungen in der Lichtenwörther Gegend und am Steinfelde in Niederösterreich
- Hopfner F.
Soixante-dix-neuvième année. 1927. B. Magnétisme terrestre
- De Bilt
- , Observatory
- Annuaire
- De Bilt, Meteorological and Magnetic Observatory
Magnetisk Aarbog, 1ste del: Danmark (undtagen Grönland) — Annuaire magnétique, lère partie: le Danemark (excepté le Groenland). 1927
- Det Danske Meteorologiske Copenhagen
- Institut
- Copenhagen, Det Danske Meteorologiske Institut