bluuebunny/crossref_metadata_2025 huggingface dataset:
An ionospheric investigation concerning the Lorentz polarization‐correction
Authors: Booker H. G. , Berkner L. V.
Published: February 2008

Some years ago considerable discussion took place concerning the relation between the constitution of the ionosphere and its refractive index for radio waves. The question at issue was whether the force per unit‐charge exerted by the electric field of a radio wave upon an elementary charged particle In the ionosphere should be taken simply as the Maxwellian electric intensity E (the Sellmeyer theory), or whether there should be added a contribution (4π/3)P (the Lorentz theory). The discussion culminated in a theoretical treatment of the subject by Darwin which seemed to point to the conclusion that the Sellmeyer theory should hold good in the ionosphere at radio frequencies.

For reflection from the ionosphere of radio waves of frequency less than the gyromagnetic frequency there is in middle latitudes a clear‐cut distinction in the behavior of the extraordinary wave according to the two theories. Over the past year a large number of records showing magneto‐ionic splitting of ionospheric echoes at these wave‐frequencies have been obtained. We are led to believe that it is impossible to interpret these observations in terms of the Sellmeyer theory but that no objection exists to their interpretation in terms of the Lorentz theory.

On the basis of the Lorentz theory the observations indicate that there is in the E‐region of the ionosphere a level of maximum atomic and molecular ion‐density somewhat below the level of maximum electron‐density.
Radio fade‐outs at Huancayo and Watheroo Magnetic Observatories, Febraury 1937 through June 1938
Authors: Seaton S. L.
Published: February 2008

Automatic vertical‐incidence recording of ionospheric heights has been continued at the Watheroo Magnetic Observatory, Western Australia, and at the Huancayo Magnetic Observatory, Peru, of the Department of Terrestrial Magnetism, Carnegie Institution of Washington, from the date of the last report [see 1 of “References” at end of paper] through October 1937 for Huancayo and through April 1938 for Watheroo using a fixed frequency of 4.8 mc/sec. These records have been examined and all radio fade‐outs are listed in Tables 1 and 2.

From November 1937 and from May 1938 at Huancayo and Watheroo, respectively, fade‐outs were recorded by means of automatic multifrequency equipments recently installed [2] which replace the 4.8 mc/sec fixed‐frequency recording. Records are incomplete during November and December 1937 from Huancayo and during April and May 1938 from Watheroo because of installation and adjustment of the new equipments.
The construction of an azimuthal equidistant map centered about the geomagnetic North Pole
Authors: Pollak M. J.
Published: February 2008

Before describing the construction of the accompanying map it would be appropriate to make some explanatory remarks regarding its purpose, and the particular advantages of the azimuthal equidistant projection.

The map was constructed as an aid to the study of certain magnetic phenomena which take on additional significance when plotted on geomagnetic coordinates. A clear definition of this coordinate system is given by A. G. McNish:1 “Many magnetic phenomena are frequently found to have a relatively simple distribution when consideration is given to the location of the observing stations relative to the pole of the first‐degree harmonics of the Earth's general magnetic field. A coordinate system having this pole as its origin is called a system of geomagnetic coordinates.” The northern geomagnetic pole, the one used as the center of projection of the map, is in latitude 78°.5 north and longitude 69°.0 west.
Provisional sunspot‐numbers for August to October, 1938
Authors: Brunner W.
Published: February 2008

(Dependent alone on observation at Zürich Observatory and its station at Arosa)
Cheltenham Magnetic Observatory July to September, 1938
Authors: Ludy Albert K.
Published: February 2008

(Latitude 38° 44′.0 N., longitude 76° 50′.5 or 5h 07m.4 W. of Gr.)

July 4–5—A storm began abruptly July 4 at 12h 04m GMT, with an increase of 9 gammas in H and small changes in D and Z. The perturbations were irregular and ended at 07h, July 5. Between 20h and 24h, July 4, was the time of greatest activity. Ranges: D, 26′; H, 232 gammas; Z, 122 gammas.
Magnetic Observatory, Capetown April to June, 1938
Authors: Ogg A.
Published: February 2008

(Latitude 33° 57′ S., longitude 18° 28′ or 1h 13m.9 E. of Gr.)

Note: D and Z are negative; changes are in the algebraic sense.
Pulsations in an ionized region at height of 650–800 KM during the appearance of giant pulsations in the geomagnetic records
Authors: Harang Leiv
Published: February 2008

During recent years the occurrence of some very regular pulsations in magnetograms, usually called “giant micropulsations,” has aroused considerable interest. During the International Polar Year 1932–33 and the succeeding years they were frequently recorded on the magnetograms at the Tromsö Observatory, but in the past two years an astonishingly low number of pulsations were recorded in the northern part of Scandinavia and in Iceland. For the first time since March 1938, giant pulsations of the normal character but with somewhat small amplitudes, were recorded on December 28, 1938 between 2h 40m and 4h 10m MET. The waves were clearly developed in D and V, but were not perceptible in the H‐curve, with maximum double amplitudes in D and V of 3.3 and 2.5 gammas, respectively.
The reliability of dust‐counters
Authors: Běhounek F.
Published: February 2008

There are three types of dust‐counters commonly used: The automatic dust‐recorder and the jet dust‐counter, both devised by Dr. J.S. Owens, and the Zeiss Konimeter, based upon the same principle as the jet dust‐counter of Owens, but differing in construction. Recently an automatic device, using a photronic cell for the records, has been described by Russell A. Nielsen. Unfortunately, however, no quantitative results obtained with this apparatus are available at present.

In the automatic dust‐recorder a known volume of air is filtered through white paper producing a dark spot. The degree of impurity suspended in the atmosphere is estimated by comparing the density of the dark spot with a calibrated scale of shades expressed in milligrams of suspended matter per cubic meter of air.
Apia Observatory July to December, 1938
Authors: Sapsford H. Bruce
Published: February 2008

July 30—A short disturbance occurred on July 30. After a sudden increase of 14 gammas at 04h 35m GMT, the horizontal intensity decreased to a minimum at 08h 05m. The range of the disturbance was 157 gammas and the trace had returned to normal by the end of the day.

August 3–6—Shortly after 16h GMT, August 3, the H‐trace became slightly disturbed and a sharp increase of 37 gammas occurred at 21h 35m. A period of rapid fluctuation followed. From the maximum at 21h 39m, H decreased slowly at first and then more rapidly through a range of 195 gammas to a minimum on the 4th at 09h 40m. Conditions remained slightly disturbed until the 6th. Z showed corresponding fluctuations.
Watheroo Magnetic Observatory October to December, 1938
Authors: Green J. W.
Published: February 2008

December 9–1l—This moderate disturbance began gradually at about 12h GMT, December 9, with moderate fluctuations from 12h to 24h, December 10, and slight disturbance on December 11. Ranges, December 10: D, 17′.2; H, 54 gammas; Z, 88 gammas. Ranges, December 11: D, 18′.9; H, 60 gammas; Z, 80 gammas. Storm‐ranges: D, 19′.2; H, 100 gammas; Z, 117 gammas.

December 16–23—This very moderate disturbance began at 07h 40m GMT, December 16. Its most disturbed period was from 12h to 20h, December 18, slightly disturbed conditions followed returning to normal by the close of December 23. The daily range in D was quite normal throughout the entire period, the maximum range being 19′.2, the minimum falling on December 17 and the maximum on December 18. H‐values remained low through December 22, with ranges of 82 gammas on December 17, 101 gammas on December 18, and 112 gammas on December 17–18. The ranges in Z for December 16, 17, 18, 19, 20, and 21 were 111 gammas, 103 gammas, 109 gammas, 87 gammas, 112 gammas, and 96 gammas, respectively. The range in Z for the period of the storm was 142 gammas, the maximum falling on December 18 and the minimum on December 20.
A representation of the sunspot‐cycle
Authors: Anderson C. N.
Published: February 2008

Although sunspots had been observed occasionally back to ancient times, their study may be said to date from their rediscovery by Galileo in the spring of 1610 with the then newly invented telescope. Since then much has been written about their nature, their periodicities and possible influence on human affairs.

The purpose of the study reported on in this paper was to analyze the components of the sunspot‐data and thereby to reconstruct a curve which would not only represent the variation in sunspot‐numbers from 1749 to date but would also be consistent with times of maxima and minima from 1610 to 1749. A number of attempts along this line have been made in the past [see references 3, 4, 5, 6, 7, 9, 11 at end of paper], all of which have neglected the data previous to 1749 and all have used a slightly different method of analysis. It is believed that the agreement in the present study is somewhat better than in those of the past, but nevertheless, no claim is made for any great accuracy in predicting future sunspot‐activity. Harmonic analysis based on a fraction of a period is always a source of danger and furthermore, we have no assurance that all the components of the sunspot‐curve are periodic functions [8]. In fact, some papers have appeared in which each cycle was treated as a more or less independent outburst [2, 10, 12, 13]. Nevertheless, because of the long base‐line over which agreement is obtained in this present study, it is hoped that the results may not be too much in error for at least a few cycles.
The association of radio fade‐outs with solar eruptions
Authors: Giovanelli R. G. , Higgs A. J.
Published: February 2008

Since the announcement in 1936 that radio fade‐outs were coincident in time with solar eruptions, a large number of observations have confirmed this beyond all doubt, but whether a particular eruption will be accompanied by a fade‐out has not, hitherto, received much consideration. This question is examined in detail in the following discussion.

Observations of fade‐outs at the Commonwealth Solar Observatory, Canberra, Australia, have been made since June 1937 with automatic P′ ‐ f (multifrequency) equipment. Briefly, this consists of a pulse‐transmitter, the frequency of which is automatically varied over a range from 2.3 to 12 mc/sec, and a special receiver, automatically tuned to the frequency of the transmitter. The complete cycle of operations is repeated, in the present instrument, every six minutes, while in the first instrument, which was in use until April 1938, the period was made five or fifteen minutes according to the solar activity. The signals picked up by the receiver are delineated, finally, on the screen of a cathode‐ray oscillograph where the “ground‐wave” and reflections, or “echoes,” from the E‐ and F‐regions of the ionosphere are separated. The resulting quasi‐stationary picture is photographed on a moving film. For the purposes of this paper a fade‐out is defined as a period during which no reflections from the E‐region can be seen; a “severe” fade‐out is one in which, in addition, no echoes from the F‐region are visible, while a “minor” fade‐out is one in which some F‐region echoes, though weakened, are present. It should be emphasized that this criterion for a fade‐out is not absolute and refers particularly to the special transmitter and receiver used in the investigation, though it is worth pointing out that such fade‐outs observed here invariably coincide with periods of severe disturbance to commercial radio services.
Alibag Magnetic Observatory July to December, 1938
Authors: Chaudhuri D. L. , Rangaswami M. R.
Published: February 2008

July 4–5—A moderate disturbance began with a sudden commencement at 12h 02m GMT, July 4, in which the initial movement in H was +10 gammas. H reached a minimum value at 13h 58m, July 4. Two conspicuous bays were noticeable during the periods 20h 56m to 21h 55m on July 4 and from 04h 19m to 05h 34m on July 5. The disturbance ended at 08h, July 5.
Apia Observatory January to March, 1939
Authors: Sapsford H. Bruce
Published: February 2008

February 24–25—A magnetic storm commenced at 17h 07m GMT, February 24, with a sudden increase of 10 gammas in horizontal intensity. The maximum value of H was reached at 17h 17m, and it then decreased by a series of waves to a minimum value at 01h 53m, February 25. During February 25 there were oscillations in H with corresponding but smaller variations in D and Z. Normal conditions were restored by 24h, February 25.
Huancayo Magnetic Observatory January to March, 1939
Authors: Davies Frank T.
Published: February 2008

January 5—A sudden commencement occurred at 04h 09m GMT, January 5. During a period of seven minutes D moved westerly 0′.6, H decreased 50 gammas, and Z decreased 7 gammas. Moderate disturbance continued until 21h.

January 21—From 13h to 21h GMT, January 21, several fluctuations of large amplitude occurred in horizontal intensity. There was an unusually low value of 29491 gammas in horizontal intensity at 18h 36m.
On prediction and mutual correlations of the maps of distribution of magnetic elements and their annual changes
Authors: Weinberg B. P.
Published: February 2008

For theoretical investigations, as well as for practical purposes, it is important to find a possible way to predict the distribution of the isolines of the magnetic elements and of their isopors and also of controlling one such distribution by means of another one.

These two possibilities are given by equations (1), (2), and (3).
Auroral display of July 3, 1939
Authors: Knapp Joseph
Published: February 2008

On July 3, 1939, at 21h 30m (75° west meridian time), a splendid display of Northern Lights was visible at Bridgeport, Connecticut. Long streamers of light stretched from the eastern to the western horizon almost 180° in length, from 40° above the northern horizon to 30° beyond the zenith into the south. The ten bands of light were unusually straight through their entire length, quite regular in width, and nearly uniformly spaced. There was a bright Moon and the sky was cloudless. The stars shining through the uniform bands of light gave the aurora the appearance of the American flag.
Sitka Magnetic Observatory April to June, 1939
Authors: Gebhardt Robert E.
Published: February 2008

April 16–17—A severe magnetic storm began with abrupt movements of all elements at 21h 28m GMT, April 16, and at 0lh 57m, April 17. Thereafter the storm increased rapidly with large bays and short‐period vibrations. The storm ended about 23h GMT, April 17; but the trace remained moderately disturbed for several days. Ranges: D, 238″; H, 1569 gammas; Z, 910 gammas.

April 23—A moderate disturbance of large bays, began gradually and was followed by an abrupt motion of the elements at 05h 52m GMT, April 23. After the 15th hour the disturbance gradually subsided and ended about 02h, April 24. The H‐maximum was too great to be recorded. Ranges: D, 158″; H, 1304 gammas (estimated); Z, 590 gammas.
TUCSON MAGNETIC OBSERVATORY APRIL TO JUNE, 1939
Authors: Hershberger John
Published: February 2008

April 16–17—After an unimportant‐looking beginning at 21h 28m GMT, April 16, a real storm began sharply at Olh 56m, April 17, with a sudden increase in H of 71 gammas, followed within a few hours by an irregular drop of 250 gammas, which was 10 gammas less than the range in H for the storm. The fluctuations continued large but diminishing until 24h, April 17, when the storm appeared to be over except for a low H, However, the traces remained moderately disturbed for a number of days, and had not completely quieted down when the next storm struck.

April 23—This storm began very sharply at 05h 44m GMT, April 23, with an upward jump of 110 gammas in H and smaller changes in the other elements. In a little more than an hour afterward, H had dropped 180 gammas, the range for the storm. At 16h the perturbations became less violent, and within a few hours the storm had gradually ended.
Alibag Magnetic Observatory January to June, 1939
Authors: Chaudhuri D. L. , Rangaswami M. R.
Published: February 2008

February 1–2—;A moderate disturbance began at about 07h GMT, February 1. H reached a minimum value at 20h 08m, February 1, and the storm ended at 10, February 2. Ranges: D, 5″.3; H, 114 gammas; Z, 29 gammas.

February 6–7—A storm of great intensity began at about 04h 43m GMT, February 6. H began to fall rapidly from 08h 54m, February 6, and reached a minimum value at 13h 20m, February 6. Two prominent humps were recorded between 13h.5 and 15h and between 16h and 17h. The storm practically ended at 01h.5, February 7. Ranges: D, 7″.1; H, 196 gammas; Z, 53 gammas.
Huancayo Magnetic Observatory April to June, 1939
Authors: Davies Frank T.
Published: February 2008

April 4—The period from 20h to 22h GMT, April 4, was moderately disturbed. H had a low value.

April 16—A sudden commencement occurred at 21h 29m GMT, April 16, in H and Z. During a period of five minutes H increased 40 gammas and Z increased 7 gammas. The trace was quiet afterwards.
The E‐region of the ionosphere during the annular solar eclipse of April 7, 1940
Authors: Hulburt E. O.
Published: February 2008

It is noted that ionospheric observations during the annular solar eclipse of April 7, 1940, visible in Mexico, may provide data for testing various assumptions underlying the theory of solar‐radiation origin of the E‐region and may yield a fairly accurate value of the ionic recombination‐coefficient α that occurs in the theory. E‐region ionization‐curves during the eclipse are worked out for a number of assumed values of α. Observations of solar flocculi during the eclipse may yield information concerning F. L. Mohler's suggestion of ionizing radiations from the flocculi [Science, 90, 137–138, 1939].
The ionosphere at Watheroo, Western Australia, April, May, and June, 1939
Authors: Parkinson W. C. , Prior L. S.
Published: February 2008

This report continues from those previously submitted1 and, as before, Table 1 gives the mean hourly values of minimum virtual heights and critical frequencies for the ionospheric regions for each hour of the three months, April, May, and June, 1939, and also includes mean hourly values of the lowest frequencies recorded, fmin, when this frequency exceeded the lower limit of the frequency‐sweep, 16.0 to 0.516 megacycles per second. Figure 1 gives the data of Table 1 in graphical form. The 120° east meridian standard times of sunrise and sunset are shown on the graphs by broken vertical lines, these times being for the middle day of the month involved.
On the variation of magnetic character‐numbers at Dombås Observatory
Authors: Wasserfall K. F.
Published: February 2008

The international character‐number, C, was introduced in 1906. The meeting of the Magnetic Commission in September 1905 agreed on the following scale of classification, proposed by Ad. Schmidt: “0” =quiet days; “1”=disturbed days; “2”=very disturbed days. It was left to the discretion of individual directors to fix limits for defining these divisions [see 1 of “References” at end of paper]. The data for the individual observatories are tabulated at De Bilt, the daily mean values being expressed in tenths of the unit used by the observatories.
On some recently detected important variations within the auroral spectrum
Authors: Vegard L.
Published: February 2008

§1. Indications of hydrogen‐showers in the auroral region—As pointed out in previous papers [see 1, 2, 3 of “References” at end of paper] lines from hydrogen do not ordinarily appear in the auroral spectrum. Even spectra which in the regions, where the Balmer lines appear, give very weak auroral lines or bands do not show any trace of the hydrogen‐series. Spectrograms obtained with large dispersion giving with great density the red bands of the first positive group near the red Balmer line do not show any trace of Ha [4].
The ionosphere at Watheroo, Western Australia, July to September, 1939
Authors: Parkinson W. C. , Prior L. S.
Published: February 2008

This report continues from those previously submitted. Table 1 gives the mean hourly values of minimum virtual height and critical frequency for the ionospheric regions for each hour of the three months July, August, and September, 1939 and also includes mean hourly values of the lowest frequency recorded, fmin, when this frequency was higher than the lower limit of the frequency‐sweep, 16.0 to 0.516 megacycles per second. It should be noted that after July 1939, the scaling of the E virtual height was discontinued. Figure 1 gives the data of Table 1 in graphical form.
Padre Luis Rodés, S.J., 1881–1939
Authors: Macelwane J. B.
Published: February 2008

In the death of Father Louis Rodés, June 7, 1939, at Biniaraix on the Island of Majorca, the Observatory of the Ebro lost its capable director and geophysicists throughout the world an esteemed colleague and friend.

Louis Rodés was born at Santa Coloma de Farnés, Spain, December 31, 1881. At the age of sixteen he entered the Society of Jesus. After two years of novitiate at Gandia and seven years of brilliantly successful classical, scientific, and philosophical studies at Saragossa and Tortosa he matriculated in the Faculty of Science of the University of Barcelona. While at the University during the years 1906–1910 he filled with distinction the post of Professor of Physics in the Jesuit College of Sarriá.
Alibag Magnetic Observatory July to September, 1939
Authors: Chaudhuri D. L. , Rangaswami M. R.
Published: February 2008

July 3–4—A moderate storm began at 00h 40m GMT, July 3, with a sudden increase of 0′.4 in westerly D and 14 gammas in H, and a decrease of 3 gammas in Z. H began to rise slowly till 03h 36m, July 3, when there was a steep rise of 26 gammas. Thereafter it began to decrease slowly till 07h 16m, July 3, when there was a second sharp increase of 26 gammas. At 07h 30m, July 3, there was a further sudden rise of 27 gammas in H, to reach its maximum at 07h 32m, July 3.
Total and uncharged nuclei at Washington, D.C.
Authors: Sherman K. L.
Published: February 2008

Observations of the concentration of both uncharged and total condensation‐nuclei were made at different times and places near Washington, using an Aitken nuclei‐counter in conjunction with a cylindrical, electrical condenser through which air was drawn at a desired rate by a spring‐driven turbine. The ratio (S) of the concentration of uncharged to that of all nuclei, serves as a measure of the relative magnitude of the coefficients of combination and those of attachment between small ions and charged and uncharged nuclei, respectively, provided the assumptions usually made in this connection are valid. Diverse values of S have been found heretofore when these were determined from the same data but by different methods. It is shown in the theory of least squares that the method of determining the best estimate of a quantity of this character depends upon the manner in which weights should be assigned to the data. It is shown here that the weight assigned to the observed number of particles falling on a square of the counter, should vary inversely as that number. The proper method of determining the best estimate of S, when weights are assigned in this manner, and also two other simpler methods were applied to these data. The surprisingly small differences in the three results, indicates these data are homogeneous.

From 620 individual samples of both uncharged and total nuclei, S was found to be 0.75 with a standard error of 0.02. This value of S is distinctly greater than that reported for other places but it is in close agreement with values previously determined at Washington with other equipment. No significant evidence of a dependence of S, upon time, upon place, or upon concentration of nuclei, such as some observers report, is provided by these data. An examination of the standard deviation of S for a single sample indicates that the variations which do appear are no greater than those which are to be expected from random errors. Systematic errors in all measurements of this sort may arise from the adsorption of nuclei on the walls of the apparatus. The differences in the values of S found at the different places may in part be attributed to this source. Four hundred individual samples taken, both before and after the air passed through the condenser with no field applied, indicate that 0.85 of the nuclei which enter this condenser get through. The procedure followed here was such that errors in the calculated value of S from this source are eliminated provided charged and uncharged nuclei are adsorbed with equal facility.
Tucson Magnetic Observatory January to March, 1940
Authors: Hershberger John
Published: February 2008

(Latitude 32° 14′.8 N., longitude 110° 50′.1 or 7h 23m.3 W. of Gr.)

January 3—A moderately severe but short‐lived storm began at 14h 40m GMT, January 3, and ended about three hours later. The principal feature was a drop in H of 198 gammas, followed by a return to its normal value in an hour and a half. D fluctuated through a range of 12′ and Z was slightly disturbed.
General meteorological aspects of thunderstorm electricity
Authors: Byers Horace R.
Published: February 2008

Physicists studying the details of lightning‐discharges have in recent years progressed quite satisfactorily in analyzing the observed electrical phenomena. On the meteorological side, where the mechanism of the thunderstorm as a cloud in relation to the development of the strong potential‐gradients which have been observed is to be investigated, the progress is, by comparison, relatively slight. It is the purpose of this paper to discuss some of these meteorological factors, particularly to bring them to the attention of the physicists as well as of the meteorologists who must work side by side in this field.

Measurements have shown that the potential‐gradient, at least near the ground, is usually positive in fine weather or in the absence of thunderstorms and that this gradient is generally greatest at those times when the air is thermodynamically in a stable state of equilibrium and therefore not subject to the formation of thunder‐showers. In the relatively weak gradients of convection‐weather, however, as soon as a convection‐cloud develops, the electrical field suddenly becomes very intense until, as the convection‐cloud forms into a mature cumulo‐nimbus,the phenomenal thunder‐storm potentials appear.
American URSI broadcasts of cosmic data with American magnetic character‐figure CA, April to June, 1940
Authors: Johnston H. F.
Published: February 2008

The data for terrestrial magnetism, sunspots, and solar constant are the same as given in previous tables.

The three columns for each month in Table 1 give (1) the magnetic character according to the scale 0–2 of the International Commission of Terrestrial Magnetism and Atmospheric Electricity, (2) the type featuring the day other than normal by the letters b, p, o, and i for days marked by bay, rapid pulsations, long‐period oscillations, and irregular oscillations, respectively, and (3) the hour and minute of Greenwich mean time marking the beginning of a storm, the end of the storm being indicated in the foot‐note to the Table.
F‐region critical frequencies at Deal, New Jersey, during partial solar eclipse of April 7, 1940
Authors: Schafer J. P.
Published: February 2008

F‐region critical frequencies were obtained at Deal, New Jersey (latitude .30° 01′ north, longitude 75° 15′ west), on the day of the solar eclipse of April 7, 1940. The eclipse was partial in the vicinity of Deal with a magnitude of approximately 0.70 (60 per cent area).

The results obtained are given in Figure 1 which shows the variation in F‐region critical frequency throughout the day of the eclipse as well as similar curves for the two days preceding and one day following. The solid‐line curve for the day of the eclipse shows the actual variations measured, while the dashed line for the same day indicates the possible trend in the absence of eclipse.
Notes on Isomagnetic Charts: IV—Geomagnetic Dip‐Poles, their Nature and that of the Isomagnetic Lines in their Neighborhood
Authors: Chapman S.
Published: February 2008

Summary—Geomagnetic dip‐poles are singular points (on the terrestrial surface) of the magnetic equipotential lines, and vice versa. The dip‐poles of a uniformly magnetized sphere have many special properties not in general characteristic of dip‐poles. The principal geomagnetic dip‐poles are defined as the principal maximum and minimum of the surface magnetic potential; the equipotential lines surrounding them are elliptic, not circular. The nature of the magnetic meridians and the iso‐magnetic lines for V, I, H, F, and Z near a dip‐pole is examined; dip‐poles are in general ordinary points as regards F and Z; for H they are principal minimum foci of a special conical type, and for I they are principal maxima of conical type. Dip‐poles are in general not isogonic ray‐poles. The isomagnetic lines near special types of dip‐pole are considered.
Magnetic Disturbances and Region F2 of the Ionosphere
Authors: Bannon J. , Higgs A. J. , Munro G. H.
Published: February 2008

§ 1. Introduction—In a recent publication by Bannon, Higgs, Martyn and Munro [see 1 of “References” at end of paper] it was shown, by statistical methods, that there is a connection between electron‐density in region F2 of the ionosphere, and meteorological conditions at the ground. The maximum density at noon is, on the average, greater on a non‐frontal than on a frontal day. From March 1937 to October 1938, inclusive, for the Commonwealth Solar Observatory, Mount Stromlo, Canberra (latitude 35° 20′ south, longitude 149° 10′ east) this average noon density for the non‐frontal day exceeded that for the frontal day by 11 per cent. The excess at the Liverpool, New South Wales, field‐station (latitude 33° 55′ south, longitude 150° 59′ east) for the same period was six per cent.
Huancayo Magnetic Observatory, October to December, 1940
Authors: Ledig Paul G.
Published: February 2008

October 7–8—A mild disturbance in H accompanied by subnormal values occurred on October 7, beginning rather gradually at 00 h GMT, and lasting until about 21 h on the same day. Other low values in H were observed on the following day.

October 26—There was a mild disturbance in H which began with a sharp rise and fall at 13 h 22 m GMT, October 26, and was followed by a single “bay” between 14 h 40 m and 15 h 00 m. The disturbance was followed by several hours of subnormal H‐values.
New Magnetic Observatory at Sitka, Alaska
Authors: Patterson Wm. D.
Published: February 2008

The Sitka Magnetic Observatory was established by the United States Coast and Geodetic Survey in the year 1901, and was placed in operation on January 1, 1902. A seismological observatory was added in 1902. The buildings of the Observatory were constructed on a small plot of ground, reserved by the Government for this purpose, located about 150 yards outside the residential section of the town, which was then a small fishing village. Since the beginning of work on the Naval Air Base near Sitka in 1937, the town has rapidly increased in size to a present (1940) population of nearly 2,000. Early in 1938 it was recognized that the extension of private building construction, containing large amounts of magnetic materials, toward the Magnetic Observatory would soon render the observations worthless, and steps were initiated to move the Observatory to a more suitable location.
Watheroo Magnetic Observatory, October to December, 1940
Authors: Parkinson W. C.
Published: February 2008

November 12–13—This small disturbance began at 07 h 06 m GMT, November 12, with a small sudden commencement. The traces until 17 h November 13 were disturbed but at no time were the movements of any great amplitude. The most active period of this storm was between 16 h, November 12, and 07 h, November 13. Ranges: D, 15′.2: H, 141 gammas; Z, 76 gammas.
AmericanURSI Broadcasts of Cosmic Data, with American Magnetic Character‐Figure CA, October to December, 1940, and Summary of CA for Year 1940
Authors: Johnston H. F.
Published: February 2008

The data for terrestrial magnetism, sunspots, and solar constant are the same as given in previous tables.

The three columns for each month in Table 1 give (1) the magnetic character according to the scale 0–2 of the International Commission of Terrestrial Magnetism and Atmospheric Electricity, (2) the type featuring the day other than normal by the letters b, p, o, and i for days marked by bay, rapid pulsations, long‐period oscillations, and irregular oscillations, respectively, and (3) the hour and minute of Greenwich mean time marking the beginning of a storm, the end of the storm being indicated in the foot‐note to the Table.
The Daily Variation of Irregular Disturbances of the Earths's Magnetic Field at Bombay
Authors: Narayanaswami R.
Published: February 2008

Besides the quiet‐day solar diurnal variation and the variations associated with magnetic storms, the intensity of the Earth's magnetic field at any place is subject to many irregular, short‐period fluctuations. The paper contains an analysis of the diurnal variation of these irregular disturbances during the eleven‐year period 1923–33. As a measure of the disturbance, the departures of the hourly ranges of the horizontal forces from the mean hourly range on the five international quiet days in that particular month were used. In calculating the disturbance, due regard was paid to the sign of the change of the element during the hour. The diurnal variations of the irregular disturbances depend on the season of the year and on the sunspot‐activity. These variations are analyzed and compared with the results of disturbance diurnal variation in higher latitudes. The main conclusions that emerge from the analysis are:

(i) The hour of minimum disturbance occurs early in the morning usually between 04h to 05h or 05h to 06h local time and that of the maximum near about noon.

(ii) There are two secondary maxima, one at 16h to 18h and another at about 22h to 23h local time.

(iii) Analyzing the results according to month, the day maximum is most pronounced in the months April to August. In the winter months, there is a tendency for the variation to approach the European type (as shown by the analysis of the data of Eskdalemuir (magnetic latitude Φ=59°.5) and of Wilhelmshaven (Φ = 54°.5) in which there is one minimum in the morning at about 09h local time and a maximum in the evening at about 22 h.

(iv) If days of magnetic character 2 are excluded, the diurnal variations are similar, but the late evening maximum is suppressed, leaving the noon maximum more pronounced.

It is generally believed that “in the latitudes between the two auroral zones, that is, up to at least 65° magnetic latitude, Di has a simple diurnal variation with its maximum in the evening; as the auroral zone is approached the hour of maximum gets later, from about 21h at 55° to midnight at 70°. Up to this latitude the form of the daily variation of Di does not vary much either with season or with the general intensity of magnetic disturbance” [Chapman]. The present analysis of the Bombay data shows that in low magnetic latitudes, the main variation is a maximum near noon with a minimum a little before sunrise. The evening maximum of temperate latitudes is superposed on this simple variation.

It is suggested that the maxima of disturbance‐variation at Bombay at about noon and in the afternoon are associated with the maxima of ion‐density in the E‐ and F1‐layers and in the F2‐layer, respectively. The late evening maximum is presumably due to fluctuations in F2‐layer caused by electrified particles from the Sun concentrating on the night side of the Earth on account of the deflecting action of its magnetic field.
Magnetic Horizontal Intensity at Oslo, 1843–1930
Authors: Wasserfall K. F.
Published: February 2008

The Oslo Magnetic Observatory was founded by Professor Christopher Hansteen. The geographical coordinates of the station are ϕ = 59° 54′.7 north, λ = 10° 43′.4 east.

The results published in this paper are based on magnetic data left by Hansteen and on the work done by his successors. The large bifilar magnet was mounted in May, 1841. This magnet is 1.2 meters long and weighs 13 kg. The suspension, which is nine meters long with 35 mm between the two threads, is solidly fixed to the vault of the central hall of the building. The two‐story hall has a gallery on the second floor—the vault carrying the astronomical equatorial tower of the building.
American URSI Broadcasts of Cosmic Data, Giving American Magnetic Character‐Figure, CA Three‐Hour‐Range Indices, K and Mean K‐Indices, KA, for January to March, 1941
Authors: Johnston H. F.
Published: February 2008

Summaries of American URSI broadcasts have appeared regularly in this Journal since the issue for December 1930.

As set forth in this Journal for June, 1937, “The Department of Terrestrial Magnetism and the United States Coast and Geodetic Survey with the cooperation of the United States Army and the United States Navy communication‐services and several amateur radio stations have undertaken to supply the American character‐figure based upon the reports of the seven American‐operated observatories—those of the Department of Terrestrial Magnetism at Huancayo in Peru and at Watheroo in Western Australia, and those of the United States Coast and Geodetic Survey at Cheltenham (Maryland), Honolulu (Hawaii), San Juan (Puerto Rico), Sitka (Alaska), and Tucson (Arizona).” This character‐figure is being designated CA, and its values for the first twelve, the second twelve, and all twenty‐four hours of each Greenwich day for January to March, 1941, are given in Table 1.
The Variability of Lunar Magnetic Variation
Authors: Schneider O.
Published: February 2008

A possible way of localizing the lunar diurnal variation L in the ionosphere is by studying its variability and its relations to the solar variation S. This problem is complicated by the impossibility of separating two oscillations of so nearly equal wave‐length. It is suggested to investigate, instead of deviations on individual days, rather the mean variability of L by trying to deduce from frequency‐distributions for (S+L) those for L alone. The question is analyzed in harmonic dials which contain Fourier coefficients grouped into elliptical point‐clouds. The ellipses representing such frequency‐distributions would follow a periodicity with a wave‐length of about a week if the statistical fluctuations of S and of L were completely independent of one another; if there existed on the other hand a strict correlation by which phase‐shifts and relative‐amplitude deviations of the solar and lunar waves were connected, the period of that oscillation in the parameters of the elliptical distributions should be semimonthly. A mathematical model is suggested for an intermediate stage which allows for any proportion between two such parts of the L‐variability, one correlated and the other independent. This permits us to define some kind of correlation‐index between L and S. Examples are given illustrating the behavior of such a model‐distribution for different degrees of correlation. By means of empirical data from Batavia it is shown that very large series of observations would be necessary for proving the validity of the model; the present preliminary results seem to confirm, however, former presumptions of the author that the variability of L contains a considerable independent part, not correlated with S.
Atmospheric‐Electric Results from Watheroo, Western Australia, for the Period 1924–1934
Authors: Wait G. R. , Torreson O. W.
Published: February 2008

Measurements with continuously recording instruments of the potential‐gradient and positive and negative conductivities of the air, have been made since 1924 at the Watheroo Magnetic Observatory, Western Australia. Atmospheric‐electric data for the 11‐year period, 1924–34, have been summarized and curves drawn snowing the behavior of the recorded elements and the calculated air‐earth current through the day and year. The pronounced effect of smoke on the various elements from burning bush is illustrated and discussed. The calculated ratio of the columnar resistance of the air over Watheroo to that over the ocean shows a diurnal variation which has essentially the same character for all seasons of the year and also appears to be similar in character to that for Huancayo, Peru, and for Tucson, Arizona, when each is plotted on its own local time. The summer, but not the winter potential‐gradient diurnal variation, is in good accord with that found over the ocean. Examination of the factors controlling this element has led to an understanding of the cause for the lack of agreement in the case of the winter curves.
American URSI Broadcasts of Cosmic Data, Giving American Magnetic Character‐Figure, CA, Three‐Hour‐Range Indices, K, and Mean K‐Indices, KA, for April to June, 1941
Authors: Johnston H. F.
Published: February 2008

Summaries of American URSI broadcasts have appeared regularly in this Journal since the issue for December, 1930.

As set forth in this Journal for June, 1937, “The Department of Terrestrial Magnetism and the United States Coast and Geodetic Survey with the cooperation of the United States Army and the United States Navy communication‐services and several amateur radio stations have undertaken to supply the American character‐figure based upon the reports of the seven American‐operated observatories—those of the Department of Terrestrial Magnetism at Huancayo in Peru and at Watheroo in Western Australia, and those of the United States Coast and Geodetic Survey at Cheltenham (Maryland), Honolulu (Hawaii), San Juan (Puerto Rico), Sitka (Alaska), and Tucson (Arizona).” This character‐figure is being designated CA, and its values for the first twelve, the second twelve, and all twenty‐four hours of each Greenwich day for April to June, 1941, are given in Table 1.
Alibag Magnetic Observatory, January to March, 1941
Authors: Rangaswami M. R.
Published: February 2008

January 16–17—A moderate disturbance began at about 16h GMT, January 16, with a gradua commencement. H began to rise very gradually till 22h, January 16, when the oscillations became more pronounced. The disturbance practically ended at 20h, January 17, though minor movements continued for some hours. Ranges: D, 7′.1; H, 130 gammas; Z, 41 gammas.
Huancayo Magnetic Observatory, April to June, 1941
Authors: Ledig Paul G.
Published: February 2008

April 7—Small disturbances began at about 09h GMT, April 7. Large bays developed on all traces from 23h to 24h. Ranges: D, 14′; H, 60 gammas; Z, 62 gammas.

April 9–11—This period was moderately disturbed.
The Ionosphere at Watheroo, Western Australia, July to September, 1941
Authors: Parkinson W. C.
Published: February 2008

This report is a continuation of those already published in this JOURNAL and gives monthly mean hourly values of the heights and penetration‐frequencies of the ionosphere as obtained by means of automatic multifrequency ionospheric recording apparatus located near Watheroo, Western Australia, in latitude 30° 19′.1 south, longitude 115° 52′.6 east of Greenwich, which operates over the frequency‐range 0.516 to 16.0 Mc/sec.

Table 1 gives the monthly mean hourly values of the height of maximum electron‐density (hmax), uncorrected for retardation in lower regions2, and the minimum virtual height (hmin) for both the F1‐ and F2‐regions, the penetration‐frequencies for the E‐, F1‐, and F2‐regions, and the lowest frequency at which echoes were observed when that frequency was higher than 0.5.16 Mc/sec.
Hermanus Magnetic Observatory, July to September, 1941
Authors: Ogg A.
Published: February 2008

(Latitude 33° 57′ S., longitude 18° 28′. or 1h 13m.9 E. of Gr.)

July 3–10—There was a small sudden commencement at 12h 16m GMT, July 3, which was followed by a disturbed period of about three hours. There was a larger disturbance beginning with a sudden commencement at 03h 43m, July 4. The changes were: D moved 3′ easterly in five minutes; H increased 17 gammas in three minutes; Z decreased numerically 19 gammas in five minutes. The disturbances continued for about five hours. At 15h the storm increased, forming considerable bays on all traces until on July 5, from 06h to 07h, there were large changes leading to a large storm. Ranges: D, 57′.9; H, 456 gammas; Z, 293 gammas. The disturbances continued until July 10. The ranges in horizontal intensity were 100 gammas on July 6 and 59 gammas on July 7.
Auroras Observed at the Blue Hill Observatory, 1885–1940
Authors: Stetson H. T. , Brooks C. F.
Published: February 2008

Two recent articles have appeared in this JOURNAL based on studies of a list of auroral occurrences observed at the Blue Hill Observatory since its founding in 1885 [see 1, 2 of “References” at end of paper]. It has been suggested that because of the importance of the relationships existing between solar activity, auroras, and other geophysical phenomena, so comprehensive a list of observations as has accumulated at Blue Hill should be made generally available.

The list accordingly has been prepared to include well‐established auroras seen from Blue Hill or the adjacent territory and found on the records of the Observatory at Milton, Massachusetts. A few doubtful entries of suspected auroras have been deleted. Because of the large number of those who have participated in the meteorological observations since the establishment of the Observatory, it does not appear possible to list all the observers.
The rate of ion‐production at any height in the Earth's atmosphere: I—The spherical harmonic representation of its world‐wide distribution
Authors: Chapman Sydney , Mian A. Majid
Published: February 2008

Summary—Part I: The world‐wide distribution of the rate of ion‐production by monochromatic radiation, at any level in an atmosphere in which the density of the absorbing ionized constituent is an exponential function of the height, is represented by a series of Legendre functions. The coefficients may be calculated approximately and simply by means of expressions which we call index‐sums. Numerical calculations and comparisons are thus made, with results that are shown to be satisfactory, for the case when the curvature of the level layers in the atmosphere is neglected. It is shown also how the curvature may be taken into account.
American URSI Broadcasts of Cosmic Data, Giving American Magnetic Character‐Figure, CA, Three‐Hour‐Range Indices, K, and Mean K‐Indices, KA, for October to December, 1941, and Summary for Year 1941
Authors: Johnston H. F.
Published: February 2008

Summaries of American URSI broadcasts have appeared regularly in this JOURNAL since the issue for December, 1930.

As set forth in this JOURNAL for June, 1937, “The Department of Terrestrial Magnetism and the United States Coast and Geodetic Survey with the cooperation of the United States Army and the United States Navy communication‐services and several amateur radio stations have undertaken to supply the American character‐figure based upon the reports of the seven American‐operated observatories—those of the Department of Terrestrial Magnetism at Huancayo in Peru and at Watheroo in Western Australia, and those of the United States Coast and Geodetic Survey at Cheltenham (Maryland), Honolulu (Hawaii), San Juan (Puerto Rico), Sitka (Alaska), and Tucson (Arizona).” This character‐figure is being designated CA, and its values for the first twelve, the second twelve, and all twenty‐four hours of each Greenwich day for October to December, 1941, are given in Table 1.
Cheltenham Magnetic Observatory, October to December, 1941
Authors: Ludy Albert K.
Published: February 2008

(Latitude 38° 44′.0 N., longitude 76° 50′5 or 5h 07m.4 W. of Gr.)

October 10–13—A disturbance occurred from 14h 48mGMT, October 10, to 01h, October 13. The highest K‐index was 6 which occurred but once. Ranges: D, 41′ H, 156 gammas; Z, 91 gammas.