bluuebunny/crossref_metadata_2025 huggingface dataset:
Note on auroras seen on July 22, August 3 and 4, 1937, in southwestern New Hampshire
Authors: McNish A. G.
Published: February 2008

A report of auroras seen from a place about eight miles south‐southwest of Keene, New Hampshire, has been received from E. M. Brooks. The report is briefly summarized as follows:

July 22—A few isolated beams were seen running upwards from a faint band extending from the north to the northwest at 3h 45m GMT. No indication of the aurora remained after 4h 15m.
Tucson Magnetic Observatory July to September, 1937
Authors: Hershberger John
Published: February 2008

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

July 19–26—A sudden increase of 42 gammas in H occurred at 12h 53m GMT, July 19, and was followed by a prolonged period of disturbance. For two days the disturbance consisted chiefly of short‐period oscillations of H and Z), the latter being of small amplitude. By 13h, July 21, the disturbance appeared to have ended. But about 18h the fluctuations began again very gradually, accompanied this time by a slowly decreasing value of H. At 07h, July 22, there began a series of irregular large movements, which continued with varying intensity for a little more than three days. The minimum of H for the storm occurred at 1h 51m, July 24. By 03h 28m H had increased 122 gammas, this being the largest change in an equivalent interval during the entire period. The disturbance died out very gradually, ending about the middle of July 26.
Relations between terrestrial magnetism and cosmic‐ray intensity
Authors: Hess Victor F. , Demmelmair A. , Steinmaurer R.
Published: February 2008

Certain relations between the variations of the Earth's horizontal magnetic force H and of the observed cosmic‐ray ionization J have been found in the continuous registrations of the cosmic‐ray ionization on the Hafelekar, 2300 meters above sea‐level (near Innsbruck, Austria) during the year 1936–37 as follows:

(1) A positive magnetic effect, ME1 is indicated during magnetic storms with increase of J associated with increase of H and vice versa. A similar effect has been noticed rather often also in the daily mean values of J and H during magnetically undisturbed days. ME1 amounts to +0.57 per mille of the cosmic‐ray ionization for an increase of the horizontal force by one γ (0.00001 gauss).

(2) The analysis of the daily mean values for one year discloses a second effect, ME2, of opposite sign (increase of H accompanied by decrease of J) and smaller than ME1. ME2, for the average of the year 1936–37, is about −0.20 per mille per γ.

(3) A similar negative magnetic effect, ME3, is found from the strong correlation between the diurnal variation of H and J; ME3= −0.2 per mille per γ.

(4) Another negative effect, ME4, can be derived from the anti‐parallel variations of the monthly means of H and J (seasonal curves); ME4 = −1 per mille per γ.

The three first‐mentioned effects can be explained qualitatively by adopting the hypothesis of the electronic ring‐currents in the outer space around the globe. The seasonal effect is not yet explained and it seems possible that its connection with terrestrial magnetism is accidental, in spite of the strong correlation.
The American magnetic character‐figure CA for 1937
Authors: McNish A. G. , Johnston H. F.
Published: February 2008

A new measure of magnetic activity—the American magnetic character‐figure CA—was inaugurated on March 13, 1937. As discussed in a previous paper1 the purpose of this new measure is to supply a timely and adequate index of the Earth's magnetic condition for comparison with related phenomena, particularly radio‐transmission conditions. Since its inception the American magnetic character‐figure seems to have fulfilled this need. Weekly bulletins on the Earth's magnetic activity have been issued to interested persons and organizations by the Department of Terrestrial Magnetism of the Carnegie Institution of Washington on Wednesdays, covering the seven‐day interval ending at 24h GMT the preceding Friday.
Heights of electric currents near the auroral zone
Authors: McNish A. G.
Published: February 2008

Intense magnetic disturbances lasting for an hour or more are frequently observed in the vicinity of the auroral zone. Birkeland1 has named these disturbances “polar elmentary stormsrd” and ascribed them to electric currents produced by the streaming of electrified solar corpuscles through the Eartha's magnetic field. The writer2 has suggested that they are due to electric currents resulting from dynamo‐action in the auroral zone, the atmosphere being heated there by impact of solar corpuscles. This was an extension of the theory proposed by Chapman3 to account for the world‐wide characteristics of magnetic storms.
Provisional sunspot‐numbers for November and December 1937 and January 1938
Authors: Brunner W.
Published: February 2008

(Dependent alone on observation at Zürich Observatory and its station at Arosa)
Tucson Magnetic Observatory, October to December 1937
Authors: Hershberger John
Published: February 2008

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

October 3–4—At 11h 18m GMT, October 3, H increased 25 gammas in three minutes. At the same time east declination decreased 2′. The elements continued moderately disturbed until 24h, when H began to decrease rapidly. This was soon followed by large oscillations in H and D, lasting until 08h, October 4. The larger oscillations also affected Z moderately. Except for minor disturbances of the saw‐tooth variety and a low value of H, the storm ended at 08h, but the elements were not entirely normal for about 19 hours later. The range of H for the storm was 233 gammas. The ranges of D and Z were scarcely larger than the normal diurnal ranges.
Discussion of S. Chapman's note on radio fade‐outs and the associated magnetic variations
Authors: Dellinger J. H.
Published: February 2008

In response to Dr. Fleming's suggestion I am glad to comment on Dr. Chapman's Note above mentioned. Dr. Chapman showed that Dr. Birkeland had listed as a separate type of magnetic perturbation an occurrence in 1902 which is now seen to be one of the type associated with sudden disturbances of the ionosphere caused by solar eruptions. Dr. Birkeland's discernment is an interesting instance of partial recognition of this cosmic phenomenon as revealed by various early records and publications. Other instances, to which I have previously called attention, are the observation by T. L. Eckersley of a separate type of radio transmission interruption in 1928, and the simultaneous occurrences of magnetic perturbations and solar eruptions in 1859, 1872, etc.

The outlines of the entire phenomenon emerged in 1935 and early 1936, when it was discovered that radio, magnetic, earth‐current, and solar effects occur simultaneously, that the three terrestrial effects have characteristics differentiating them from other vagaries (for example, magnetic storms), that are manifestations of a disturbance in the ionosphere, that this disturbance is a sudden increase in ionization below the E‐layer caused by ultra‐violet radiation from a solar eruption, and that the effects vary from a maximum in those latitudes and longitudes where the Sun's rays are vertical to zero in the night hemisphere.
Sitka Magnetic Observatory, January to March 1938
Authors: Gebhardt Robert E.
Published: February 2008

(Latitude 57° 03′.0 N., longitude 135° 20′.1 or 9h 01m.3 W. of Gr.)

January 4—A small disturbance began gradually at about 10h GMT and gradually increased in intensity to a maximum at 13h 30m. Thereafter the disturbance subsided; the trace had gradually returned to about normal values at 24h January 24. Ranges: D, 74′; H, 799 gammas; Z, 608 gammas.
Bursts in cosmic radiation in the equatorial zone
Authors: Korff S. A.
Published: February 2008

Bursts in cosmic radiation observed in Peru and in northern latitudes are compared. It is found that the bursts have the same distribution in energy both at high altitudes in the equatorial zone and at sea‐level in northern latitudes. The number of bursts is found to vary approximately as the third power of the number of ions in the burst. The number of bursts increases with altitude approximately as the square of the total ionization measured in the same instrument. Bursts are found to produce about one part in 1000 of the ionization observed in the instrument.
The ionosphere at Huancayo, Peru, January, February, and March 1938
Authors: Wells H. W. , Stanton H. E.
Published: February 2008

This report is in continuation of that published in this JOURNAL (43, 169–171, 1938) on ionospheric data from continuous multifrequency ionospheric recordings at the Huancayo Magnetic Observatory for January, February, and March, 1938.

Table 1 contains mean hourly values of virtual height and critical frequency for the ionospheric regions for each hour during the first quarter of 1938. Also included are mean hourly values of the lowest frequency recorded (designated ƒmin) during the frequency‐sweep from 16.0 to 0.516 mc/second, which give a relative measure of absorption of radio signals in the lower ionosphere during the day. The data of Table 1 comprise recordings for each hour of the day and for every day of the month except for short intervals necessary for maintenance to the equipment.
Provisional sunspot‐numbers for May to July 1938
Authors: Brunner W.
Published: February 2008

(Dependent alone on observation at Zürich Observatory and its station at Arosa)
The non‐magnetic R.R.S. Research
Authors: Edgell J. A.
Published: February 2008

Readers of this JOURNAL have learned from brief notes published from time to time, that a non‐magnetic vessel, the Research, is being built by the British Admiralty to continue the magnetic survey of the oceans inaugurated by the Carnegie Institution of Washington through its Department of Terrestrial Magnetism and carried on by the non‐magnetic vessel, Carnegie, from 1909 until her destruction by explosion and fire in November 1929. It is especially fitting that Great Britain should assume the responsibility of continuing this important work in view of her great maritime interests. For many years the magnetic charts issued by the hydrographic services of the various countries have been based in increasing degree on data obtained by the Carnegie, but serious gaps in available data which would have been filled had she completed her last cruise, and the absence of information regarding the secular change in certain regions render imperative the resumption of the interrupted oceanic survey both from theoretical and practical considerations.

To remedy this condition, the construction of the Research was authorized over three years ago but the keel was not laid until September 9, 1937. Since that time good progress has been made. In order to assist in designing the vessel and her instrumental equipment, the Carnegie Institution of Washington, upon invitation of the Admiralty, made arrangements that William J. Peters, first commander of the Carnegie and designer of many of the special and improved types of magnetic instruments used at sea, spend a year in London as consultant on the design of the new vessel and of her special instruments. In addition all information regarding the Carnegie was placed at the disposal of the British Admiralty, thus facilitating greatly the design of the new vessel.
Ionospheric Measurements at Central China College, Wuchang, China, October 1937 to June 1938
Authors: Sung P. L. , Kwei C. T.
Published: February 2008

A brief description is given of a manually operated ionospheric equipment with which a single operator can take necessary readings of virtual heights and critical frequencies. Data for noon‐hour runs from October 1937 to January 1938 and from April to June 1938, and half‐hour evening‐runs in March and April, 1938, are arranged in two tables. Sample and average diurnal‐variation curves for virtual heights and critical frequencies are plotted. It is found that the critical frequencies at Wuchang are higher than those at Washington for both the E‐ and F2‐layers during the same months. The E‐layer critical frequency, as is the case elsewhere, reaches a maximum near the local noon, whereas for the F2‐layer the critical frequency reaches a high value about 14h and maintains nearly the same value till about 17h, 120° east meridian time. When plotted month by month, the E‐layer critical frequency increases with the approach of summer, while the F2‐layer critical frequency tends toward a minimum in July with two probable maxima in October and April. This would make the Wuchang seasonal characteristics approximate those of Watheroo rather than of Washington, but it must be emphasized that data are insufficient to make this point definite. Very often the E‐layer virtual height undergoes a dip when a higher layer begins to appear and continues to keep its normal height long after the upper layer has appeared. In a few cases, the E‐layer echoes persist even after the F‐ or F2‐layer has been penetrated. Magnetic splitting is quite evident, especially for the readings during daylight. The observed mean value of 620 kc, as the difference between the ‐component and the x‐component of the F2‐layer penetrating frequency, checks very well with the theoretical value of 614 kc. A case is reported of a chain of closely packed echoes (scattered reflections) following the first echo from the F‐layer on April 2 between 22h 30m and midnight, 120° east meridian time (or 14h 30m to 16h GMT). It is interpreted to be a multiple‐reflection phenomenon, when the two F‐layers are approaching each other to form one layer in an unsteady fashion.
The ionosphere at Huancayo, Peru, April, May, and June, 1938
Authors: Wells H. W. , Stanton H. E.
Published: February 2008

This report on ionospheric conditions is in continuation of those published in preceding issues of this Journal (43, 169–171, 257–260, 1938) submitting results of continuous multifrequency ionospheric recordings at the Huancayo Magnetic Observatory. The current data for the months, April, May, and June, 1938, are obtained from recordings for each hour of the day and for every day of the month except for short intervals necessary for maintenance to the equipment.

Table 1 contains mean hourly values of virtual height, critical frequency, and lowest frequency received for the second quarter of 1938. Figure 1 presents the data of Table 1 in graphical form. The following general discussion of characteristics seems pertinent:
The Bernard Price Institute of Geophysical Research
Authors: Schonland B. F. J.
Published: February 2008

The University of the Witwatersrand, Johannesburg, provides higher education for the largest City in the Union of South Africa and, as a result of the considerable mining and industrial activities of the City, is well staffed and equipped on the scientific and engineering sides. The University has recently been able to establish a geophysical research laboratory through the generosity of the Carnegie Corporation of New York and of Dr. Bernard Price, a Director of the Victoria Falls and Transvaal Power Company. The Bernard Price Institute of Geophysical Research, as it is called, will be opened officially in October of this year.
A 27.3‐day period in the aurora borealis
Authors: Dixon F. E.
Published: February 2008

In the course of a general study of the frequency of occurrences of aurora in Scotland during the years 1858–1938 a well‐marked period of length about 27.3 days was found to exist. Commander W.R. Priston has found a similar period in other meteorological elements, and it was his work (not yet published) which prompted the present investigation. The period is more than the well known 27‐day recurrence observed in many magnetic and associated phenomena, since that usually continues for only a few solar rotations, whereas this period has persisted for 80 years.

The data used in this investigation were simply the dates on which aurora was seen from one or more of the meteorological stations in Scotland, including Orkney and Shetland. From 1858 to 1919 these are available in the Journal of the Scottish Meteorological Society and since 1924 they have been included in the Lerwick section of the Observatories' Year Book. For the intervening years the Reports of the Registrar General for Scotland were consulted, the required information being included in the meteorological notes appended thereto. In a few cases, chiefly in the earlier years, the original climatological returns have been referred to. This was necessary when the published information was indefinite, for example “Aurora was seen on nearly every night in October.” There were 5224 nights on which aurora was seen, an average of 66 nights per year and 5.1 per 27.3‐day period. The number of nights varied from 161 in the year July 1869 to June 1870 to five in 1912–1913.
The ionosphere at Watheroo, Western Australia, January, February, and March, 1939
Authors: Parkinson W. C. , Prior L. S.
Published: February 2008

This report continues from those previously submitted in this Journal (44, 199–204, 1939) 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, January, February, and March, 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 me/sec. Figure 1 gives the data of Table 1 in graphical form. The 120° east meridian standard times of sunrise and sunset were 5h 28m and 19h 20m, 5h 54m and 19h 04m, 6h 15m and 18h 34m for January 15, February 15, and March 15, 1939, respectively.
Note on early fade‐out investigations
Authors: Braaten Arthur M.
Published: February 2008

In communications by Chapman [see 1 of “References” at end of paper], Kirby [2], Dellinger [3], and Appleton [4] there have been pointed out several interesting instances of early observations of the various effects associated with visible eruptions in the Sun's chromosphere. I should like to add to the store of information on the subject by presenting some material which I believe has not been generally available heretofore. As a matter of historical interest, it may be noted that as early as 1928 there had been advanced an explanation relating the Sun, the ionosphere, and radio fade‐outs.

On October 10, 1928, a catastrophic disturbance affecting short‐wave radio transmission occurred. The phenomenon, manifested by a sudden cessation of reception, was of such a nature as to immediately attract considerable interest. The salient features of the disturbance were: Suddenness and simultaneity of onset; completeness of effect; relative rapidity of recovery, absence of any associated magnetic perturbation. It may be stated here that a few fades of similar character had been observed previously, both in this country, by the Radio Corporation of America [5], and in England, by the Marconi Company [6]. These were presumably not as devastating or far‐reaching in effect as the later fade; at least they had apparently occasioned no more than ordinary interest.
Edward Kidson (1882–1939)
Authors: Barnett M. A. F.
Published: February 2008

Edward Kidson was born at Bilston, Staffordshire, England, on March 12, 1882. The son of Mr. and Mrs. Charles Kidson, he belonged to a family well known in Nelson and Christchurch. He was educated at Nelson College obtaining an Entrance Scholarship and taking his university course at Canterbury College. In 1906, he won a Senior Scholarship and was awarded the degree of M.Sc. with first‐class honors in physics.
Night‐sky light and nocturnal E‐layer ionization
Authors: Bradbury N. E. , Sumerlin W. T.
Published: February 2008

In accordance with the suggestion that the sporadic nocturnal E‐layer ionization may be associated with variations in the luminosity of the night‐sky, a simultaneous investigation of both these phenomena has been carried out. The intensity of night‐sky light was determined by means of a recording electrometer and photoelectric cell, measurements being made only after twilight and during such times as the Moon was below the horizon. At different times both a Kunz KH‐cell and a CeO‐cell were employed. The ionosphere was investigated simultaneously using a pulse‐transmitter and photographically recording receiver operating at a frequency of 2.1 megacycles. The blue portion of the night‐sky luminosity appears to increase after sunset to a maximum shortly after midnight with a subsequent slow fading. The light in the red region of the spectrum shows much greater fluctuations in intensity and is brightest after sunset and decreases continuously thereafter. Practically no correlation has been found between the intensity of the night‐sky light and the character of the ionospheric reflection. Various possibilities may be suggested to explain this result.
The fourth centenary of William Gilbert of Colchester
Authors: Harradon H. D.
Published: February 2008

In view of the important contribution to the science of terrestrial magnetism made by William Gilbert, it seems fitting to recall that 1940 marks the fourth centenary of his birth. We are indebted to the article by E. C. Smith, Nature of January 6, 1940, for some of the facts given below.

He was born at Colchester, County Essex, England, in 1540. Little is known with certainty of his early days but at the age of twenty he graduated from St. John's College, Cambridge. He later spent several years in travel and study on the Continent and in 1569 obtained the degree of M.D. Four years later he settled in London to practice medicine, becoming ultimately physician to Queen Elizabeth. In due time he rose to be President of the Royal College of Physicians and to it he bequeathed his books, globes, and apparatus, which unfortunately were all destroyed in the great fire of London in 1666. Although he was thus a physician of no mean standing, the work which won him immortality had little to do with medicine, in which field, moreover, no important discovery is attributed to him. He died at Colchester, November 30, 1603, and was buried in Holy Trinity Church where a monument was erected by his brothers.
Note regarding resolution No. 4, Washington Assembly, International Association of Terrestrial Magnetism and Electricity
Authors: Fleming J. A.
Published: February 2008

Resolution No. 4 adopted in September 1939 at the Washington Assembly of the International Union of Geodesy and Geophysics as published in the December 1939 number of the Journal (p. 478) is not complete. In its final form it is as follows:

(4) Control of variometers and absolute instruments—(a) The Association reaffirms its Resolution 3 adopted at the Edinburgh Assembly of the great need of examination at regular intervals, at least every two years, of magnetic instruments, including the control of the direction of the magnetic axes of the magnets in variometers.
The atmospheric potential‐gradient at Poona, India
Authors: Sil J. M. , Agarwala K. S.
Published: February 2008

In this paper the data for the potential‐gradient at Poona collected on undisturbed days during September 1930 to December 1938 have been considered. The basis of these data is the continuous record of the Earth's electric field which was obtained here photographically. The undisturbed days at Poona are few and far between. A brief note on topography of the place and the general atmospheric conditions prevailing here is given below:
Annual variations of the critical frequencies of the ionized layers at Tromsö during 1939
Authors: Harang Leiv
Published: February 2008

Regular determinations of the critical frequencies of the ionized layers, which were begun at the Auroral Observatory in April 1935,

were continued during 1939. Regular observations were usually taken on six days during the week at 10h, 12h, and 14h, local time. At Tromsö, situated near the auroral zone, the conditions of the ionosphere are strongly influenced by magnetic storms and the echoes are often lacking during disturbed periods, or more‐or‐less irregular and scattered echoes appear which sometimes make a precise critical‐frequency determination difficult.
Note on scale‐value equation of the CIW induction‐variometer
Authors: McNish A. G.
Published: February 2008

H. H. Howe of the United States Coast and Geodetic Survey has recently called attention to the fact that the equation of equilibrium for the CIW induction‐variometer [Terr. Mag., 41, 161–172 (1936)] should contain the term Z2 instead of Z. Including this modification in the equation introduces a factor of 1/2 in the theoretical scale‐value equation of the instrument, higher order terms being neglected. Fortunately this blunder occasioned no error in practice since the scale‐value has been determined empirically thus far.

No important modifications of the theoretical operating‐characteristics of the instrument result from the inclusion of this correction provided the field‐changes are small as compared with the total value of vertical intensity. However, as Mr. Howe points out, serious effects may be encountered in regions where vertical intensity is extremely small, namely, close to the magnetic equator. In particular, the variometer would be unable to discriminate between positive and negative values of vertical intensity if the variations in that element pass through zero. This condition can be remedied by using an auxiliary magnet and thus increasing the value of vertical intensity so that at no time will the modified field reverse sign. If an auxiliary magnet is used no restrictions are imposed on the utility of the variometer by recognition of the correction in the equation of equilibrium.
Capetown Magnetic Observatory October to December, 1939
Authors: Ogg A.
Published: February 2008

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

October 3–4—A storm began gradually at about 08h 55m GMT, October 3, and ended at 08h, October 4. Conditions, however, remained somewhat disturbed until October 8. Ranges: D, 28′.2; H, 159 gammas; Z, 133 gammas.
A valuable new book on geophysics
Authors: Vestine E. H.
Published: February 2008

In any science the virtue of a great work is best perceived after it has aged under the purifying influence of time. When a useful collective volume appears in a science laboring without the help of a systematic treatise, its most certain immediate virtue is its organization of scattered material. The work that achieves much more is rare. Its value is then notably enhanced and we may sense a latent promise of many future benefits and expect it to mean fresh inspiration and impetus in the science.
The ionosphere at Watheroo, Western Australia, January to June, 1940
Authors: Parkinson W. C. , Prior L. S.
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 ionospheric regions as obtained from the automatic multifrequency ionospheric recording apparatus.

Commencing with January, 1940, some desirable changes were made in the scaling of the heights of the layers. Besides the minimum virtual height, the actual heights of maximum electron‐density, uncorrected for presence of lower layers, are now scaled, using the method described by Booker and Seaton.
Solar and magnetic data, July to September, 1940, Mount Wilson Observatory
Authors: Nicholson Seth B. , Mulders Elizabeth Sternberg
Published: February 2008

Many sunspots were observed in July, August, and September, nine of them large enough to be visible without a telescope. Nevertheless, the Earth's magnetic field showed little disturbance.

When the magnetic storm of July 13 began, two large groups, Mount Wilson Nos. 6902 and 6905, were in longitude 78° west and 39° east, respectively.
Alibag Magnetic Observatory April to June, 1940
Authors: Rangaswami M. R.
Published: February 2008

April 25–26—A moderate disturbance began at 02h 04m GMT, April 25, with a sudden rise of 31 gammas in H. At 02h 45m, April 25, H reached its maximum and then began to fall. The vibrations became larger after 17h, April 25. The minimum in H was attained at 21h 32m, April 26.
Huancayo Magnetic Observatory July to September, 1940
Authors: Wells H. W.
Published: February 2008

July 13—There was a sudden commencement at 08h 00m GMT, July 13, which was followed by a moderate disturbance lasting until 19h.
K‐Index According to the U.S.S.R. Observatories
Authors: Benkova N. P. , Kosuhina O. Y.
Published: February 2008

In accordance with the resolution of the Washington Assembly of the International Association of Terrestrial Magnetism and Electricity in September, 1939, the Sloutzk Magnetic Observatory began to tabulate magnetic disturbances by means of the index K. Following the suggestion of the Association a K‐scale was adopted according to which the intervals with an amplitude greater than 600 gammas were gaged by the index K = 9. Comparison of the Sloutzk and Niemegk frequency‐occurrences of K‐indices shows that the choice of such a scale was quite favorable. Table 1 gives the frequency‐distribution of K for these two observatories during January and February, 1938.
Greenwich Frequency‐Statistics of Geomagnetic Disturbance
Authors: Chapman S.
Published: February 2008

Summary—The sum of the hour‐to‐hour changes (regardless of sign) of the horizontal magnetic intensity, H, at Greenwich, from one Greenwich noon to the next, is denoted by νH; it has been determined for 21,323 days, covering a period of 62 years (1848–1913, less 1864–67). On quiet days νH is governed by the quiet‐day solar daily variation, Sq; on disturbed days the disturbance‐field D makes the main contribution to νH. Frequency‐tables are given, showing the proportion of days on which νH lies within assigned ranges, (i) for the mean of the year, (ii) for the mean of each calendar month, and (iii)—for each of three seasons—for five groups of years of different mean sunspot‐number, and (iv) for two groups of years of similar mean sunspot‐number, but taken from the ascending and descending parts of the sunspot‐cycle.

Similar frequency‐tables, for the same years (plus 1914), and for the same sub‐divisions of the material, have previously been given, for 20,762 Greenwich lunar days, for RDD, the daily range of the variation of the Greenwich magnetic declination, D, after the monthly mean solar daily variation S has been removed; RDD thus depends on the D‐field, except that when this field is weak, RDD will partly measure the day‐to‐day variation of the Sq‐field.

The frequency‐distributions for Vh and RDD, especially as regards their dependence on the season and the sunspot‐epoch (divisions ii, iii, and iv of the data) are rather similar. A method of correcting the νH‐statistics for the influence of Sq is devised, and applied to the annual mean frequency‐curve; the RDD‐statistics are more tentatively corrected for the influence of the Sq day‐to‐day variability on quiet days; the corrected frequency‐curves for H and D are in notably good agreement.

The numerical measure νH, which except on quiet days is largely determined by the D‐field, is shown to be rather closely correlated with the international daily magnetic character‐figure C, for nearly all the months of a sample year (1901).
Comparison of Methods for Computing Air‐Earth Current
Authors: Sherman K. L.
Published: February 2008

Average hourly values of air‐earth current determined by the indirect method at College, Alaska, for 11 months in 1932–33 are tabulated. It is shown that because of the usual negative correlation between gradient and conductivity, the values of current derived from these elements if averaged over periods greater than one hour will generally exceed those derived from values averaged over hourly intervals. The magnitude and variation of this excess at College are given in detail for the case where the longer period is an hour from all the days selected in each month. The maximum excess in an hourly mean value is 29 per cent. The effect upon the amplitude of the diurnal variation would be approximately 25 per cent of the true variation in current. The excess computed from values of gradient and conductivity averaged over other periods of time and for some other places is also given and discussed. The maximum excess in the daily mean values at College would be approximately 50 per cent whereas at other stations it may often be greater than this. These considerations suggest that because of the difficulty of computing exact values, the indirect method of measurement may be expected to yield greater values of air‐earth current than the direct method.
Radioactivity of Rocks and Ionization‐Balance of the Atmosphere
Authors: Hess Victor Francis
Published: February 2008

It is shown that if one computes the ionization produced by gamma rays from radioactive substances in rocks and soil from figures given recently as average values for representative classes of rocks by Evans and Goodman the expected ionization turns out considerably smaller than the one actually observed by placing ionization‐vessels over land and over water.

Two methods are developed theoretically which make it possible to determine simultaneously the residual ionization, the effect of cosmic rays and of the gamma rays from radioactive substances in the Earth, and to separate these components of the total ionization. Comparisons of ionizations determined by one of these methods with values computed from given figures of radioactive material in well‐defined rocks are planned.
The Ionosphere at Huancayo, Peru, July to September, 1941
Authors: Ledig P. G. , Coile R. C. , Jones M. W.
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 ionospheric.regions as obtained from the automatic multifrequency ionospheric recording apparatus located near Huancayo, Peru, South America, in latitude 12° 02′.7 south, longitude 75° 20′.4 west of Greenwich, which operates over a frequency‐range 0.516 to 16.0 Mc/sec. A complete discussion of these data will be made in an annual summary.

Table 1 gives the monthly mean hourly values of the actual heights of maximum electron‐density (hmax), uncorrected for retardation in lower regions2, and the minimum virtual height (hmax) for both the F1‐ and F2‐Vregions, the penetration‐frequencies for the E‐, F1‐, and F2‐regions, and the lowest frequency at which echoes were observed when that frequency was greater than 0.516 Mc/sec.
The Distribution of the Ellipticity Statistic Le when the Hypothesis is False
Authors: Girshick M. A.
Published: February 2008

In the June 1940 issue of this JOURNAL, John W. Mauchly has considered a statistic Le as a measure of ellipticity and obtained its distribution for the case of two varites under the assumption that the hypothesis of “sphericity”, is true.

The object of this note is to find the distribution of Le when the hypothesis of sphericity is false. This distribution will be useful in determining the probability of accepting the hypothesis of sphericity when in fact it is false. More specifically, this distribution will permit the calculation of the probability of accepting the hypothesis that the true value λe of Le is unity when in fact it has some other value lying between zero and unity. Moreover, this distribution may be used to evaluate the size of the sample required such that the probability of accepting the hypothesis of sphericity (for any specified value of the population‐index of ellipticity λe) shall be of a given magnitude.
Huancayo Magnetic Observatory, July to September, 1941
Authors: Ledig Paul G.
Published: February 2008

(Latitude 12° 02′.7 S., longitude 76° 20′.4 or 5h 01m.4 W. of Gr.)

July 4–5—Beginning suddenly at 03h 45m GMT, July 4, with an increase of 45 gammas in H in three minutes and followed by almost twenty‐four hours of only very mild disturbance, a very severe magnetic storm was recorded on July 5. It began approximately at midnight and developed its maximum at about noon and then fell off again by the end of the day. It was marked by several peaks and bays with particularly large ones at about 12h and 13.5h. Both D and Z were also markedly effected.
The New Isogonic Chart of the United States
Authors: Knapp David G.
Published: February 2008

The discussion explains some of the factors affecting the production of isogonic charts, and presents a comprehensive plan which is expected to promote uniform standards of treatment for future work. The scheme used for the chart for 1940 is outlined as a modification of that plan, designed primarily to correlate that chart with the previous (1935) one. The behavior of secular change as reflected in the new chart is discussed» and the use of shading in a way not previously employed in this series of charts is also explained.
The Ionosphere at Huancayo, Peru, October to December, 1941
Authors: Ledig P. G. , Coile R. C. , Jones M. W.
Published: February 2008

This report is a continuation of those already published in this JOURNAL1 and gives monthly mean hourly values of the heights and penetration‐frequencies of the ionospheric regions as obtained from the automatic multifrequency ionospheric recording apparatus located near Huancayo, Peru, South America, in latitude 12° 02′.7 south, longitude 75° 20′.4 west of Greenwich, which operates over a frequency‐range 0.516 to 16.0 Mc/sec. A complete discussion of these data will be made in an annual summary.

Table 1 gives the monthly mean hourly values of the actual heights 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 greater than 0.516 Mc/sec.
Eatrh's Magnetic Field and Actual Heights in Ionosphere
Authors: Wells H. W.
Published: February 2008

One influence of the Earth's magnetic field on the propagation of radio waves is to separate the single incident wave into wave‐components, each having different indices of refraction. Hence they are normally returned from different electron‐densities and from different levels in the ionosphere. Exploration of the ionosphere by the pulse‐and‐echo method of Breit and Tuve records apparent heights of the radio echoes as well as the wave‐frequencies which just penetrate through the several ionospheric regions, as illustrated in Figure 1. These penetration‐frequencies give a measure of maximum electron‐density in each layer. The penetration‐frequencies for the ordinary and for the extraordinary wave‐components independently measure the identical maximum electron‐density of any ionospheric region.
Alibag Magnetic Observatory, July to September, 1941
Authors: Rangasvvami M. R.
Published: February 2008

(Latitude 18° 38′.3 N., longitude 72° 52′.3 or 4h 51m.5 E. of Gr.)

July 5—A severe storm with a sudden commencement in all elements began at 04h 59m GMT, July 5. H attained its maximum at 05h 46m and began to fall rapidly, from 08h 23m onwards, the H magnet became unsteady and the value of horizontal force rose and fell with rapid fluctuations. The minimum in H occurred between 11h 40m and 12h 30m when the trace was beyond the recording limit of the magnetogram. The storm ended at about 23h.5, Ranges: D, 14′.2; H, greater than 726 gammas; Z, 94 gammas.
The Reduction of Magnetic Observations to Epoch, Part I
Authors: Vestine E. H.
Published: February 2008

§ 1—Introduction—A number of writers have frequently mentioned the need for removing the effects of various geomagnetic variations from the field‐measurements of magnetic surveys. These variations introduce the influences of various superposed fields upon measures of the Earth's permanent field. It is the purpose here to consider the removal of these spurious effects, when surveys are undertaken on a world‐wide scale, and when the undesired effects themselves appear fairly simple and widely distributed over the Earth. In Part I the approximate removal of the magnetic post‐perturbation from field‐measurements is considered, or the correction from mean of day to mean of year. In Part II (to appear subsequently) the approximate removal of the contribution of the solar daily variation (Sq) and the disturbance daily variation (SD) is studied, or the reduction from hour of observation in the field to mean of day. The influence of highly localized irregular fluctuations, infrequently large in lower latitudes but important in high latitudes, is considered but tentatively.
The 27‐Day Recurrence‐Tendency of Magnetic Storms
Authors: Benkova N. P.
Published: February 2008

§ 1. The study of the 27‐day recurrence‐tendency of magnetic storms is one of the methods of investigation of the relationship between geomagnetic and heliophysical phenomena and, at the same time, a means of investigating the nature of magnetic storms. During recent years the investigation of this phenomenon has acquired also a practical interest in connection with the attempts to predict magnetic disturbances undertaken by some magnetic observatories of the Soviet Union.

The 27‐day recurrence‐tendency, discovered by Broun [see 1 of “References” at end of paper] as far back as 1858, attracted the attention of a number of investigators. The chief results concerning the dependence of the recurrence upon the intensity of the disturbance, as well as the more precise definition of the length of the recurrence‐interval and its fluctuation during the 11‐year cycle of solar activity, we owe to the works of Maunder, Chree, Stagg, Greaves and Newton, and Archenhold. The aim of the present work is to verify the results of the former investigators on the basis of the recently completed Sloutzk catalogue of magnetic storms [2].
Solar and Magnetic Data, January to March, 1942, Mount Wilson Observatory
Authors: Mulders Elizabeth Sternberg , Nicholson Seth B.
Published: February 2008

All the magnetic storms recorded at Mount Wilson during February and March were probably associated with a large active sunspot‐group, which on its three appearances was numbered 7365, 7378, and 7397, respectively. This group was first seen at Mount Wilson on February 1 as a very small group near the central meridian. It reappeared at the east limb on February 22 and again on March 21. The largest spot in the group had several umbrae, of which the two largest had opposite polarities. These two umbrae, which were darker than normal, had magnetic fields about 25 per cent more intense than those usually found in large spots. The magnetic field of the following umbrae, which had 5‐polarity, was the more intense.
Giant Micropulsations
Authors: Ogg A.
Published: February 2008

A magnetic storm of medium intensity for this Observatory started at about 07h 26m GMT, March 1, 1942. The ranges of the storm were: D, 38′.2; H, 224 gammas; Z, 205 gammas. Giant pulsations appeared on all three traces (D, H, and Z), at about 14h 30m GMT and continued for 3‐1/2 hours. These pulsations are unique in our experience at this Observatory.
Sitka Magnetic Observatory, January to March, 1942
Authors: Gebhardt Robert E.
Published: February 2008

(Latitude 57° 03′.0 N., longitude 135° 20′.1 or 9h 01m.3 W. of Gr.)

February 23‐24—A small magnetic disturbance began gradually at about 13h 30m GMT, February 23, with a gradual decrease in values of the elements. After 18h conditions began to return to normal, the trace remaining moderately disturbed until 12h, February 24. The maximum K‐index during the disturbance was 8.
Huancayo Magnetic Observatory, January to March, 1942
Authors: Ledig Paul G.
Published: February 2008

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

January 2—This short magnetic disturbance began with a sharp rise in H of 63 gammas at 12h 34m GMT, January 2, and was followed by several narrow peaks and bays of comparable amounts during the following six hours, the disturbance ending at about 19h. D and Z showed only slight disturbances.
Sitka Magnetic Observatory of the United States Coast and Geodetic Survey
Authors: Gebhardt R. E.
Published: February 2008

In 1899 a much more liberal appropriation made it possible to begin a systematic magnetic survey of the United States and to establish several magnetic observatories for the control of the field‐data. The original site of the Sitka Observatory was selected by L. A. Bauer and John A. Fleming after a careful magnetic survey of southeastern Alaska to find a region reasonably free from local magnetic disturbance. The site at Sitka was chosen partially because of an old Russian observatory operated on Japonski Island from 1842 to 1867 and also because the region around Sitka is relatively free from local magnetic anomalies. The site of this old Russian observatory was found unsuitable, however, due to other construction work on the island, so that it was necessary to select another site.
Solar and magnetic data, July to September, 1942, Mount Wilson Observatory
Authors: Nicholson Seth B. , Mulders Elizabeth Sternberg
Published: February 2008

A small magnetic storm recorded on July 11–12 began when the bipolar sunspot‐group Mount Wilson No. 7455, which had developed rapidly on July 4, was four days past the central meridian. Another small magnetic storm on August 23–24 began when the active bipolar group No. 7478, which developed on August 22, had just crossed the central meridian. A third small magnetic storm occurred on September 11–12. Only a very small sunspot‐group was present on those dates.
Cheltenham Magnetic Observatory July to September, 1942
Authors: Hershberger John
Published: February 2008

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

July 10–11—A moderate storm began at about 23h 35m GMT, July 10, and lasted about twenty‐four hours, although the elements remained somewhat disturbed for twice that length of time. The principal feature of the storm was a number of large bays, particularly in D and Z, resulting in K‐indices of 5, 5, 6, S, and 5 for the first three‐hour periods of July 11. A sharp rise of about 70 gammas in H occurred at 20h 39m, July 11, but the activity thereafter was unimportant.
The mutual consistency of successive monthly means of declination, Huancayo Magnetic Observatory
Authors: Scott W. E.
Published: February 2008

In reducing the declination‐records for 1942 of the Huancayo Magnetic Observatory of the Department of Terrestrial Magnetism, Carnegie Institution of Washington, the changes in base‐line values appeared to be somewhat larger than usual. Thus the adopted base‐line during January 1 to 10, 1942, was 6° 33′.0 east and the observed values of declination required a regular progression of changes to May 15, when for the next succeeding 20 days the adopted base‐line was 6° 33′.9. Hence the excellence of adopted base‐lines was tested by plotting the monthly means. Vestine, in his article “Reduction of magnetic observations to epoch” [Terr. Mag., 47, 97–113 (1942)], has pointed out that “the geomagnetic east component of the departures is small in all latitudes.”
EDMOND HALLEY AND GEOMAGNETISM
Authors: Chapman Sydney
Published: February 2008

This annual lecture, commemorating Edmond Halley, a great son of Oxford, is devoted to astronomy and terrestrial magnetism. My subject to‐day is Halley's geomagnetic work considered in its historical setting, but I will preface this by a few remarks on Halley as poet—a seldom remembered aspect of his remarkable versatility.

Halley's Latin verses
PERIODIC CHANGES IN ΔD AT OSLO, 1843–1930
Authors: Wasserfall K. F.
Published: February 2008

Introduction—Christopher Hansteen began measurements in 1842 of magnetic variation at the Oslo Observatory (latitude = 59° 54′. 7 north, longitude = 10° 43′.4 east). Daily readings of declination (D), horizontal intensity (H), and inclination (I) were made, almost without interruption during 1842‐1930. Observations were made twice daily—at 09h and 14h local mean time (LMT).

The results for H have been published [see 1 and 2 of “References” at end of paper]—the first gives complete tables of daily values for H at 09h and 14h and for ΔH = (H14−H9), while the second summarizes and discusses the results.