bluuebunny/crossref_metadata_2025 huggingface dataset:
Watheroo Magnetic Observatory, April to June 1938
Authors: Green J. W.
Published: February 2008

(Latitude 30° 19′.1 S., longitude 115° 52′.6 or 7h 43m.5 E. of Gr.)

April 13–14—Following a sudden commencement at 11h 43m GMT, April 13, D moved westerly 0′.5 suddenly, then 1′.5 in forty seconds and 5′ during the next three minutes. H increased 27 gammas in three minutes followed by an abrupt decrease of 10 gammas and a further increase of 15 gammas. The numerical value of Z after an initial increase of 2 gammas decreased 8 gammas abruptly followed by an increase of 20 gammas in three minutes. Disturbed conditions prevailed for 24 hours.
International Union of Geodesy and Geophysics, Meeting in Washington, September 4–15, 1939 International Association of Terrestrial Magnetism and Electricity
Authors: Goldie A. H. R.
Published: February 2008

Provisional outline of the discussions

I—Address of President: Trends of Research in Terrestrial Magnetism and Electricity (Friday, September 8, at 14.30)

II—Report of Secretary and Director of Central Bureau

III—Report of Dr. van Dijk on the publication of numerical magnetic character of days

IV—Finances

V—Election of officers of the Association

VI—National reports

VII—Reports of Committees and Reporters appointed at the Edinburgh Assembly

VIII—Polar Year 1932–33—(1) Report on the activity of the Polar Year Commission of the International Meteorological Organization; (2) Discussion of International Polar Year results

IX—Communications on miscellaneous subjects

X—Subjects for discussion during the Assembly

XI—Subjects for joint discussion with the Association of Meteorology

XII—Subjects for deliberation by Committees (subjects requiring world‐wide cooperation in work being done or planned)

XIII—Appointment of Committees and Reporters

XIV—Resolutions
The magnetic character of the year 1937 and the numerical magnetic character of the 1937
Authors: van Dijk G.
Published: February 2008

The annual review of the “Caractère magnétique de chaque jour” for 1937 has been drawn up in the same manner as for the preceding years.1 Sixty‐two observatories contributed to the quarterly tables; fifty‐six of them sent complete data.

Table 1 (reproduced from Table II of the annual review) contains the mean character of each day for each month. The lists of calm days and disturbed days, and the days recommended for reproduction are also reprinted here as Table 2.
The northern light of September 27, 1938
Authors: Landsberg H. , Neuberger H. H.
Published: February 2008

On September 27, 1938, a very brilliant display of northern lights was observed at State College, Pennsylvania (latitude 40° 47′.8 north, longitude 77° 51′.8 west). The phenomenon was first observed as a faint gleam at 19h 30m 75° west meridian time and increased in brightness so that at 20h 10m there could no longer be any doubt that it was actually an aurora. It developed several arcs and streamers and became so pronounced that it was decided to take some measurements of its extent. These measurements started at 21h 30m and were continued until 23h 15m.
The Lorentz “polarization”‐correction in the ionosphere
Authors: Martyn D. F. , Munro G. H.
Published: February 2008

The authors discuss criticisms by Appleton, Farmer, and Ratcliffe, and by Booker and Berkner of their former conclusion that the Lorentz polarization‐term is zero in the ionosphere. They advance further experimental facts in support of their viewpoint, and criticize the views of AFR in detail. The views of BB are also criticized, and it is shown that their experimental results receive a simple explanation in terms of the theory of MM.
The ionosphere at Huancayo, Peru, July, August, and September, 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 submitting results of continuous multifrequency ionospheric recordings at the Huancayo Magnetic Observatory. The current data for the quarter July to September, 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. Figure 1 presents the data of Table 1 in graphical form. The following general discussion of characteristics is pertinent:
Tucson Magnetic Observatory October to December, 1938
Authors: Hershberger John
Published: February 2008

October 7–8—Magnetic conditions during the period covered by this report were relatively calm. The most important storm began October 7, about 6h 14m GMT, with a sharp but moderate rise in H, and lasted until 24h, October 8. The storm was typical for this station, building up gradually to its maximum intensity about 5h, October 8. As usual here, H was the most disturbed, and its average value was considerably reduced during the period of the storm.
Magnetic Declination in the Pacific from observations by the Galilee and Carnegie
Authors: Duvall C. R.
Published: February 2008

With sufficient knowledge of the Earth's magnetism, the magnetic vector at a given time and place on the Earth's surface may be expressed in terms of the given time and of the latitude and longitude of the given place. In particular, for a limited time and area, and to a certain degree of approximation, we may assume that the declination—one coordinate of the magnetic vector—may be expressed as a rational, integral algebraic function of the second degree of the latitude, longitude, and time.
The Swedish magnetic‐survey boat Kompass
Authors: Ljungdahl Gustaf S.
Published: February 2008

During the spring of 1938, the Hydrographic Survey of Sweden (Kungl. Sjökarteverket) launched a small vessel, named Kompass, mainly intended for magnetic measurements in the waters surrounding Sweden. She was built at a shipyard, generally engaged in building wooden motor‐boats for use of fishermen at sea. Her construction and dimensions differ but slightly from the common type of such boats.

Her length is 17.0 meters, beam 5.4 meters, and displacement 50 tons. She makes 7.5 knots driven by a twin‐cylinder crude‐oil engine of 60 horse‐power. The small sails are intended mainly for emergency and to reduce movements when in heavy seas.
The ionosphere at Huancayo, Peru, October, November, and December, 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 submitting results of continuous multifrequency ionospheric recordings at the Huancayo Magnetic Observatory, Department of Terrestrial Magnetism, Carnegie Institution of Washington. The current data for the quarter October to December, 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 of the equipment.

Table 1 contains mean hourly values of virtual height, critical frequency, and lowest frequency received, for the last quarter of 1938. Figure 1 presents the data of Table 1 in graphical form. The following general discussion of characteristics is pertinent: (1) F‐region—Virtual heights during the daylight hours show little difference for October and November. Daytime heights for December were generally greater than for the preceding two months. The maximum heights for each month were recorded during the post‐sunset “hump.” The average maximum amplitudes for October and November are about the same but the amplitude of the December peak is somewhat less than the others. Also notable is the fact that the crests occurred at 19h, 20h, and 21h for October, November, and December, respectively.
Provisional solar and magnetic character‐figures, Mount Wilson Observatory January, February, and March, 1939
Authors: Mulders Elizabeth Sternberg , Nicholson Seth B.
Published: February 2008

Twelve sunspot‐groups were observed on February 24, none very large or active. One of these was within 3° of the center of the solar disk when the storm of February 24 began.

The storm of March 21–23 was probably due to the active group 57° west, 15° south. Several other groups were present on the Sun. The largest was at 25° east, 15° north. Two very small groups were directly in the center of the disk during the storm, one on March 22.4, and the other on March 23.4.
On magnetic anomaly in Latvia
Authors: Slaucitajs L.
Published: February 2008

In the southeast part of Latvia (mean geographical coordinates, 56° north and 25°.8 east) a large gradient in magnetic declination has been found. Along one line, nine km in length, the magnetic declination, for epoch 1937.5, varies from 18° east to 19° west. The “normal” isogonic for this region is 3° east for the same epoch. Horizontal intensity for 1937.5 varied from 0.1250 to 0.1800 CGS, and vertical intensity from 0.458 to 0.578 CGS. The “normal” values are 0.1665 and 0.463 CGS, respectively.
Cheltenham Magnetic Observatory January to March, 1939
Authors: Ludy Albert K.
Published: February 2008

February 5–7—A sudden commencement occurred at 19h 51m GMT, February 5. H decreased 17 gammas and immediately increased 38 gammas. The abrupt changes in D and Z were small. The pulsations following were irregular and not of great amplitude.
Provisional sunspot‐numbers for May and June, 1939
Authors: Brunner W.
Published: February 2008

(Dependent alone on observation at Zürich Observatory)
The influence of the surrounding air upon the time of vibration of a magnet
Authors: Veldkamp J.
Published: February 2008

In 1935 a dissertation was published by A. Burger about the error in the time of vibration of a magnet, caused by air‐masses moving with it. A summary of the measurements was given by G. Fanselau in Zeitschrift für Geophysik (12, 58, 1936).

As Lamont had already found, a vibrating magnet sets the surrounding air in motion. In order to determine the moment of inertia, the magnet is loaded with a bar of known inertia. From the times of vibration with and without the bar the moment of inertia of the magnet is calculated; the enveloping air‐masses moving with it, however, may cause an important error.
The ionosphere at Huancayo, Peru, January, February, and March, 1939
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 submitting results of continuous multifrequency ionospheric recordings at the Huancayo Magnetic Observatory, Department of Terrestrial Magnetism, Carnegie Institution of Washington. The current data for the months January, February, and March, 1939, are obtained from recordings for each hour of the day and for every day of the month except for short intervals necessary for maintenance of the equipment.

Table 1 contains mean hourly values of virtual height, critical frequency, and lowest frequency received, for the first quarter of 1939. Figure 1 presents the data of Table 1 in graphical form. The following general discussion of characteristics is pertinent:
American URSI broadcasts of cosmic data, April to June, 1939, with American magnetic character‐figure CA, May to June, 1939
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 antractic zone of maximum auroral frequency
Authors: White F. W. G. , Geddes M.
Published: February 2008

Summary—The auroral data collected by expeditions to the Antarctic Continent are examined in order to determine the position of the Zone of Maximum Auroral Frequency. It is found that these data are not of a form permitting accurate estimation of the position of this Zone but the approximate position has been determined from a general discussion of the data. It is found that the Zone is probably circular with center at 75° south and 129° east, a point near the magnetic axis‐pole. The radius of the zone is about 18°.
The ionosphere Huancayo, Peru, April, May, and June, 1939
Authors: Wells H. W.
Published: February 2008

This report on ionospheric conditions is in continuation of those published in preceding issues of this Journal1 submitting results of continuous multifrequency ionospheric recordings at the Huancayo Magnetic Observatory, Department of Terrestrial Magnetism, Carnegie Institution of Washington. The current data for the months April, May, and June, 1939, are obtained from recordings for each hour of the day and for every day of the month except for short intervals necessary for maintenance of the equipment.

Table 1 contains mean hourly values of virtual height, critical frequency, and lowest frequency received, for the second quarter of 1939. Figure 1 presents the data of Table 1 in graphical form. The following general discussion of characteristics is pertinent:

(1) F‐region—The downward trend of virtual heights during daylight hours which was remarked for February and March, 1939, in the preceding issue of this Journal was followed by an upward trend during this entire quarter. Maximum heights for each month were recorded during the characteristic post‐sunset hump which was most pronounced at 19 h, although for June the peak of evening heights exceeds the maximum daytime heights by only a few kilometers. The general trend of the evening peak‐values during this period is downward with a sharp drop during June. In general, these characteristics conform to the characteristic trends outlined for the year, 1938, in a summary of ionospheric data from Huancayo2 in which attention was called to the apparently anomalous conditions which show that maximum daytime heights at Huancayo are recorded around June and December, while maximum evening heights are recorded around March and September.
Sitka Magnetic Observatory July to September, 1939
Authors: Gebhardt Robert E.
Published: February 2008

July 3—A moderate disturbance began abruptly at 00 h 38 m GMT, July 3, with a sudden movement of all components. The storminess of the trace increased gradually with a very stormy period beginning at 11 h. After 14 h the elements began to return to normal values. Ranges: D, 97′ H, 961 gammas; Z, 517 gammas.
Magnetic character for the year 1938
Authors: van Dijk G.
Published: February 2008

In the “Caractère magnétique de l'année 1938” issued by the Royal Meteorological Institute of the Netherlands, the following corrections should be made. In Tableau I, the figures for June 11 should read “7, 34, 5, 44” instead of “7, 5, 34, 73”; in Tableau II, the character‐figure for June 11 should read “1.0” instead of “1.6”; the mean for the month of June should read “0.57” instead of “0.59”; and the mean for the year should read “0.758” instead of “0.760.” Under “Jours troublés” June “11 (1.6)” should read “11 (1.0).”
Sitka Magnetic Observatory October to December, 1939
Authors: Gebhardt Robert E.
Published: February 2008

October 3–4—A small disturbance began gradually at about 08h 30m GMT, October 3, and increased slowly during the first five hours. The conditions continued mildly disturbed until 15 h, October 4. Ranges: D, 126′; H, 1053 gammas; Z, 760 gammas.

October 6—A short period of disturbance occurred between 04h and 11h GMT, October 6. H increased steadily during the first period until 05h 30m, then suddenly decreased 450 gammas during the next ten minutes. Thereafter the traces gradually returned to normal. Ranges: D, 102′; H, 585 gammas; Z, 500 gammas.
Magnetic Observatory, Capetown July to September 1939
Authors: Ogg A.
Published: February 2008

Note: D and Z are negative; changes are in the algebraic sense.

July 3—A small storm began with a sudden commencement at 00h 40m GMT, July 3. At about 03h 55m bays developed in the three traces and also at about 18h 30m larger bays with peaks occurred. The ranges of the larger bays were ± 10′ in D, +42 gammas and −26 gammas in H, and the numerical value of Z decreased 56 gammas and increased 24 gammas. The storm ended at 24h.
The mobility‐spectrum of atmospheric ions
Authors: Yunker E. A.
Published: February 2008

The mobility‐spectrum of atmospheric ions has been measured in the range of mobilities between 2.0 cm/sec/volt/cm and 10−3 cm/sec/volt/cm using a divided‐electrode air‐blast method. A continuous recording method was employed and the entire spectrum covered in about one hour. The spectrum shows the ordinary small ions, a group of ions at a mobility of about 0.5, and then a practically continuous distribution out to the lowest mobilities measured. The group having a mobility of 0.5 may be correlated with laboratory experiments of Chapman in which ions of this character were formed in the spray of dilute salt solutions. Simultaneous continuous measurements of the variation of density of condensation‐nuclei lead to a lower limit for the size of the nuclei measured in the cloud‐chamber of diameter 3.3 × 10−6 cm.
The Eighth American Scientific Congress
Authors: Harradon H. D.
Published: February 2008

The Eighth American Scientific Congress was held in Washington, D.C., May 10–18, 1940, under the auspices of the Government of the United States of America. Congresses previously held with their places of meeting are as follows: Buenos Aires, 1898 (on the occasion of the celebration of the Silver Jubilee of the Argentine Scientific Society); Montevideo, 1901 ; Rio de Janeiro, 1905; Santiago de Chile, 1908; Washington, D.C, 1915–16; Lima, 1924–25; Mexico City, 1935. At the Lima Congress a decision was reached that the next meeting of the series should take cognizance of the fact that it would be the seventh of the international assemblies inaugurated at Buenos Aires in 1898, three of which had been termed “Latin‐American” and three “Tan‐American” Scientific Congresses. This Seventh Congress was to have taken place at San José, Costa Rica, in 1929, but because of the crisis which paralyzed the economic world in that year, the convening of the Seventh Congress was twice postponed, it finally being held in Mexico City in 1935.
Midday F2‐region critical frequencies for Deal, New Jersey
Authors: Goodall W. M.
Published: February 2008

Midday F2‐region critical frequencies as obtained at Deal, New Jersey, are given in Table 1. The values given are in mc/sec and are for the o‐component. The period covered by these readings is from May 1939 to April 1940. Nearly ail of the readings were obtained near noon.
Huancayo Magnetic Observatory January to March, 1940
Authors: Wells H. W.
Published: February 2008

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

January 3—There was a sudden commencement at 14h 41m GMT, January 3, which was followed by generally disturbed conditions through 24h, January 3. Range: H, 625 gammas.
Watheroo Magnetic Observatory January to March, 1940
Authors: Parkinson W. C.
Published: February 2008

(Latitude 30° 19′.1 S., longitude 115° 52′.6 or 7h 43m.5 E. of Gr.)

January 3—A short disturbance of moderate intensity began at 06h 39m GMT, January 3, with sharp movements in all three elements. Horizontal intensity increased by 15 gammas, declination moved easterly by rather less than 1′, and the numerical value of vertical intensity decreased by 3 gammas. Following the sudden commencement there was a comparatively quiet period lasting almost exactly eight hours. At 14h 40m the horizontal intensity increased suddenly by 42 gammas while the other two elements barely showed a change. Wide fluctuations ensued shortly afterwards in all the elements, and lasted for about three hours, after which time the traces were only slightly disturbed until 24h. Ranges: D, 14′; H, 185 gammas; Z, 94 gammas.
Wide‐range magnetograph at Abinger Observatory
Authors: Jones H. Spencer
Published: February 2008

A wide‐range magnetograph has recently been set up at Abinger to record variations of declination and horizontal intensity on a scale corresponding to 20 gammas per millimeter in each element. The magnetograph has been in regular operation since the beginning of June 1940, and has already proved its worth by showing plainly, on June 25, a large and extremely rapid movement of the H‐trace which possibly would have escaped notice on the trace of the ordinary la Cour magnetograph.
Solar and magnetic data, April to June, 1940, Mount Wilson Observatory
Authors: Nicholson Seth B. , Mulders Elizabeth Sternberg
Published: February 2008

The magnetic storm of April 2–3 probably belonged to the series of disturbances which began with the great magnetic storm of March 23–28 and which was obviously associated with the active sunspot‐group, Mount Wilson No. 6783. When the storm of April 2–3 began, however, Group 6783 was 98° west of the central meridian and therefore was not visible. At the beginning of the storm of April 25–26 this same group was at 40° west longitude, having crossed the central meridian for the second time. In May the group returned again and was 22° east of the central meridian at the beginning of the storm of May 18, and 54° west at the beginning of the storm of May 23–25.
Apia Observatory April to June, 1940
Authors: Tremewan C. W.
Published: February 2008

April 2–3—Disturbance began gradually from 16h GMT, April 2. After 01h, April 3, a rapid decrease of 179 gammas occurred in H, a minimum being recorded at 06h 00m. The elements remained disturbed during April 3. Sharp oscillations in H and Z with a period of ten minutes occurred at times between 11h and 22h.
The ionosphere at Huancayo, Peru, January to June, 1940
Authors: Wells H. W. , Coile R. 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 ionospheric regions as obtained from the automatic multifrequency ionospheric recording apparatus. A complete discussion of these data will be made in an annual summary at the end of 1940.

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.
Sitka Magnetic Observatory July to September, 1940
Authors: Gebhardt Robert E.
Published: February 2008

July 13–14—A small disturbance began gradually at 09h.5 GMT, July 13, with decreasing values of horizontal and vertical intensities. At 11h 40 m the activity increased sharply and remained disturbed until about 14h 30m. Thereafter the values returned gradually to normal. The trace remained moderately disturbed until the close of July 14.
Summary of the Year's Work, Department of Terrestrial Magnetism, Carnegie Institution of Washington
Authors: Fleming J. A.
Published: February 2008

The activities of the Department in previous years have had to be directed chiefly toward obtaining field‐ and observatory‐data, but during the year ended June 30, 1940, continued reduction and intensive study of results previously obtained and development of attack by experiments in the laboratory have constituted the major portion of the Department's work. Improved delineation of fact and extension of theory have emerged from these investigations. An important factor in such delineation and extension, particularly in terrestrial magnetism and electricity, is the interchange of ideas and the coordination of effort facilitated by international scientific gatherings. Three such congresses were held in the United States during the year. These were the Sixth Pacific Science Congress, in Berkeley, Stanford University, and San Francisco; the Seventh (triennial) Assembly of the International Union of Geodesy and Geophysics and its seven Associations, and the Eighth American Scientific Congress, in Washington. In all these, papers, discussions, and resolutions pertaining to geomagnetism and its associated fields were out‐ standing features. The staff of the Department participated actively in the first and last, and took a leading part in preparing and conducting the second.
Cosmic Radiation and Magnetic Storms
Authors: Hogg A. R.
Published: February 2008

Summary—This paper deals with the results of cosmic‐radiation measurements in relation to magnetic storms during 1936–39. The results show that over this period of four years:

(a) Major deviations of the cosmic‐radiation intensity were always negative in sign.

(b) Such major deviations were, in the great majority, if not in all cases, associated with disturbances in the Earth's magnetic field.

(c) The cosmic‐radiation disturbance usually became apparent a few hours after the onset of the magnetic storm.

(d) Magnetic storms were in all cases accompanied by a decrease in cosmic‐radiation intensity, ranging from one‐half per cent to five per cent.

(e) The greater the range of H during the storm, the greater, on the average, was the cosmic‐ray disturbance.

(f) The average course of a cosmic‐ray disturbance bears some broad resemblance to the course of a magnetic storm.
Capetown Magnetic Observatory, January to September, 1940
Authors: Ogg A.
Published: February 2008

January 3—There was a sudden‐commencement storm at 14 h 41 m GMT, January 3, with a sudden increase of 25 gammas in H. Ranges: D, 15′; H, 194 gammas; Z, 153 gammas.

January 10—The interval from 13 h to 21 h GMT, was disturbed. Ranges: H, 118 gammas; Z, 149 gammas.
Gustaf S. Ljungdahl (1882–1940)
Authors: Åslund Sven
Published: February 2008

By the sudden death of Dr. Gustaf S. Ljungdahl on November 2, 1940, at his home in Lidingö (near Stockholm), the Magnetic Section of the Hydrographic Service (Kungl. Sjökarteverket), and the Observatory at Lovö lost their capable chief, and magneticians in many parts of the world an esteemed colleague and friend.

Gustaf S. Ljungdahl was born at Helsingborg on November 2, 1882. He attended the University of Upsala, where he received the degree of Bachelor of Arts in 1904. During 1910 to 1,912 he served as a geodesist in the General Land Survey of Sweden receiving valuable training in field survey‐work. In 1913 he continued his studies under the eminent professor of physics, Knut Ångström obtaining an M.A. degree. He was later an assistant at the Royal Nautical Meteorological Bureau (Kungl. Nautisk‐Meteorologiska Byrån) until 1921; here he had the opportunity of acquiring a thorough experience with liquid compasses. During this period he began magnetic survey‐work both on land and sea. Several of the areas of greatest local magnetic disturbance known at present in Swedish waters were surveyed and charted. In 1921 he obtained his doctorate, his dissertation being entitled “The storm‐flood in Skagerrak‐Kattegatt on December 4, 1914, and connected fluctuations of water‐level.”
The Ionosphere at Huancayo, Peru, October, 1940, to March, 1941
Authors: Wells H. W. , 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 that 0.516 Mc/sec.
Sitka Magnetic Observatory, January to March, 1941
Authors: Gebhardt Robert E.
Published: February 2008

January 17–19—A sudden commencement was recorded at 00h 10m GMT, January 17; the disturbance gradually increased but was not very great at any time. By the close of January 19 the conditions were normal. Ranges: D, 40′; H, 552 gammas; Z, 405 gammas.

January 23–25—A moderately disturbed period began gradually at about 08h GMT, January 23, with the disturbance increasing gradually in intensity until about 13h, January 24. It then began to subside. The magnetic elements were normal at the close of January 25.
The Ionosphere at Watheroo, Western Australia, April to June, 1941
Authors: Parkinson W. C.
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 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 0.516 Mc/sec.
Solar Phenomena Preceding the Ionospheric Storm of March 1, 1941
Authors: Dodson Helen W. , van Dijke Suzanne E. A.
Published: February 2008

At the Whitin Observatory at Wellesley College a 60‐mm Zeiss refractor has been used in conjunction with the Hale spectrohelioscope to study the visual spectra (λ4800–λ7000) of bright chromospheric eruptions. The spectra of 20 eruptions were examined between November, 1940, and June, 1941. In general, they showed the hydrogen lines in bright emission, the helium line, λ5876, in absorption, and no change in the intensity of the continuous background of the spectrum. There were two conspicuous exceptions to this pattern.
Solar and Magnetic Data, April to June, 1941, Mount Wilson Observatory
Authors: Nicholson Seth B. , Mulders Elizabeth Sternberg
Published: February 2008

The magnetic storm of May 21, 1941, ended a sequence of four which began with the great storm of March 1. Each storm of this sequence was apparently associated with a different sunspot group: That of March 1 with Mount Wilson No. 7132, 24° west, 16° north at the beginning of the storm; March 28 with No. 7156, 13° east, 8° north; April 24 with No. 7172, 7° east, 6° south; May 21 with No. 7192, 0°, 16° south. These storms, however, may have been associated with other less active groups or with hypothetical activity in the region of No. 7132, although no spot or other activity was seen in that region after it passed from view at the west limb on March 4.

Small magnetic disturbances beginning on June 9 and 13, were probably associated with group No. 7201, which crossed the central meridian on June 9.3, 12° north of the center of the disk.
Comparison of Long Periodic Variations in Magnetic Elements and Air‐Temperature
Authors: Wasserfall K. F.
Published: February 2008

Introduction—In 1938 I published a paper [see of “References” at end of paper[ on the results of the long periodic variation in the diurnal range of the horizontal intensity, reduced from observations left by Hansteen, This series gives an unbroken record for 88 years from 1843 to 1930. Hansteen made two observations daily, each of ten single elongation‐readings, with the large horizontal variation‐magnet, which is suspended from the dome of the central hall of the Magnetic Observatory at Oslo. The readings were taken at 09h and 14h local mean time and their difference was tabulated for every day. The resulting mean annual values of the diurnal range are used for the investigation made in this paper.
The Aurora and Geomagnetic Storm of September 18–19, 1941
Authors: McNish A. G.
Published: February 2008

The greatest auroral display observed in the eastern United States during recent times accompanied the geomagnetic storm of September 18–19, 1941. Favored by a clear sky and a moonless night the phenomenon is one which will be remembered for many years by millions of people who have never before had the opportunity of witnessing a great display.

Reports of the aurora have been received from many parts of this country. The most intense effects were observed in the east where they extended as far south as Florida, although accounts of the display have been received from Pasadena, California. At Washington, D.C., the auroral activity was so intense and prolonged that an auroral log was maintained throughout the night by the writer upon which the following account is based.
Summary of the Year's Work, to June 30, 1941, Department of Terrestrial Magnestism, Carnegie Institution of Washington
Authors: Fleming J. A.
Published: February 2008

The effective investigation of the Earth's magnetism and electricity requires international collaboration since many fundamental researches depend on observations of geomagnetic and geoelectric phenomena from all parts of the world. During the year ended June 30, 1941, many of the countries from which, in the past, needed data were obtained have been enmeshed in war and thus have had little opportunity for geophysical research or collaboration. Necessarily, therefore, the activities of the Department have been directed to further detailed study of the accumulated material at hand.

In the United States also many specialists were called to develop the scientific aspects of projects concerned with national defense. In conformity with the action of the Trustees, the services of the regular scientific and administrative personnel and use of equipment, site, and buildings have been contributed without cost to the Government. Thus for the year ending June 30, 1941, nearly 20,000 hours and over 5000 hours of the budgeted scientific and administrative personnel, respectively, were diverted from the Department's program of geomagnetic, geoelectric, and nuclear‐physics investigations. Five men of the regular staff are also on leave of absence at the Naval Ordnance Laboratory and the Naval Research Laboratory. Seventy‐five additional investigators, including physicists, engineers, assistants, and technicians—many through the generous granting of leave from universities and commercial organizations—had been engaged prior to June 30, 1941, to assist in development of urgent projects submitted by the Navy and Army through contracts with governmental agencies.
Apia Magnetic Observatory, July to December, 1941
Authors: Sapsford H. Bruce
Published: February 2008

(Latitude 13° 48′.4 S., longitude 171° 46′5 or 11h 27m.4 W. of Gr.)

July 4–5—A sudden commencement occurred at 03h 43m GMT, July 4, when H increased 20 gammas. The curves were slightly disturbed until 19h when the record failed. Records were not obtained again until 19h, July 5, at which time the traces were highly disturbed, H being about 200 gammas below normal. Recovery was rapid.
Main Features of the Daily Magnetic Variations at Cape Town
Authors: Gotsman B.
Published: February 2008

§ 1. Purpose—It was found desirable to provide for observatories collaborating in providing three‐hour‐range indices (K) a set of graphs expressing, in condensed form, the main features of the solar daily variations in the magnetic elements H, D, Z, or in the force‐components X, Y, Z. Graphical tables have been published for Potsdam1, and for Sitka, Cheltenham, Tucson, San Juan, Honolulu, Huancayo, and Watheroo2. Of these observatories only two are in the Southern Hemisphere, namely, Huancayo, near the equator, and Watheroo, in Western Australia. It is therefore desirable to have a set of similar graphs for Cape Town, which is also providing three‐hour‐range indices and is at the southern end of the African Continent far removed from the other observatories.
Chalmers Ionospheric Observatory, Göteborg, Sweden
Authors: Rydbeck Olof E. H.
Published: February 2008

The ionospheric observatory of Chalmers Institute of Technology, Göteborg (latitude 57° 41′ north, longitude 11° 59′ east), Sweden, started regular, automatic ionospheric observations in November 1941. Before that time manual observations had been made at irregular intervals, while experiments with various radiating systems and different frequencies were carried out. The present equipment includes two transmitters, one for fixed‐frequency measurements and the other one for sweep‐frequency measurements. The fixed‐frequency outfit has a peak‐pulse output of about 500 watts and operates on a frequency of 2927 Kc/s (at present) by authority of the Royal Administration of Telegraphs and Telephones.
Further notes on the electron‐density distribution of the upper ionosphere
Authors: Rydbeck Olof E. H.
Published: February 2008

The problem of obtaining the true electron‐density distribution from the ionospheric virtual‐height data has been treated by the author in several communications [see 1 of “References” at end of paper]. Since then the true electron‐density distribution has been computed for a number of ionospheric records. The nature of the electron‐density distribution of the F2‐layer has attracted much interest during recent years [2]. A publication of some of our later results, therefore, should complete the earlier communications.
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, 1942
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, 1942, are given in Table 1.
Dan Barfod la Cour, 1876–1942
Authors: Egedal J.
Published: February 2008

Dan Barfod la Cour was born in Copenhagen September 12, 1876, the son of Poul la Cour, Danish physicist, who was then Superintendent at the Danish Meteorological Institute and later became teacher with the title of Professor at the most prominent Danish Folk‐Highschool.

In his earlier years la Cour did not attend school regularly but took private lessons. He then entered the University of Copenhagen, where in 1902 he took the degree of M.A. In 1939 he received the honorary degree of Doctor of Science from the George Washington University of Washington, D.C.
Meteor observed in the Azores
Authors: Agostinho J.
Published: February 2008

A meteor was observed to fall in the vicinity of the Island of Fayal on May 2, 1942. The phenomenon occurred in broad daylight at 14h 40m local time (16h 40m GMT) and was seen throughout the Azores. Fernando Rocha reported from the Island of Corvo at the northwest end of the Azores, that the meteor was observed falling in the southeast, leaving behind a luminous trail and white smoke which remained visible for a long time. Armando Monteiro of Villa do Porto, reported from Santa Maria Island, at the opposite end of the Azores and 370 km from Fayal, that a luminous body was seen to the west‐northwest falling into the sea.
Magnetic survey of Argentina
Authors: Lützow‐Holm O.
Published: February 2008

Reoccupations of old stations and the establishment of new stations in the magnetic survey of Argentina have now been completed at 177 points at the end of June 1942. During January 1941 to June 1942, data were obtained at 87 stations, of which 15 were stations not previously occupied. Intercomparisons between the standard instruments of the Observatory and magnetometer‐inductor 102 of CIW design used in the survey show excellent maintenance of constants, observed corrections being less than 0′.2 in declination and inclination and less than 0.00008 H in horizontal intensity. The mean errors in latitude and longitude are less than 0′.3 and two seconds of time, respectively.
Summary of the year's work, to June 30, 1942, Department of Terrestrial Magnetism, Carnegie Institution of Washington
Authors: Fleming J. A.
Published: February 2008

The progress of geophysical research in which international collaboration plays an important part has been further retarded during the year ended June 30, 1942, by the extension of the War in which all the great powers of the Earth have become involved. Studies of terrestrial magnetism and electricity have not escaped the disastrous effects of this crisis. Those field‐operations of the Department, which have been one of the international aspects of the regular program, have had to be abandoned until the return of normal intercourse among nations. Fortunately, the long‐continued and ever‐increasing programs of the Department for magnetic surveys by organizations and individuals in many countries have offset in some degree the inadequacy of data caused by this curtailment.
Sitka Magnetic Observatory July to September, 1942
Authors: Pinckney Harold W.
Published: February 2008

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

July 8–9—A disturbance beginning gradually at 00h GMT, July 8, continued through 03h, July 9. Except for sharp drops in H and Z from 09h 15m to 12h, during which time a K‐index of 8 was recorded, the variations were moderate and characterized by rapid oscillations.
Apia Observatory April to September, 1942
Authors: Sapsford H. Bruce
Published: February 2008

(Latitude 13° 48′.4 S., longitude 171° 46′5 or 11h 27m.1 W. of Gr.)

There were no noteworthy magnetic disturbances during April to September, 1942.
Vector‐diagrams of annual variation of magnetic activity in declination and horizontal intensity, Oslo, 1843–1886
Authors: Wasserfall K. F.
Published: February 2008

The reduction of horizontal‐intensity determinations made by Christopher Hansteen and his successors at the Oslo Observatory (latitude 59° 54′.77 north, longitude 10° 43′.4 east) during 1840 to 1930 was published in 1941 in two papers [see 1 and 2 of “References” at end of paper]. The first paper [1] contains complete daily data for horizontal intensity, H, at 09h and 14h with a short explanatory text, while the second paper [2] gives detailed data of the complicated reductions of the absolute determinations of declination, D, and includes summarized tabulations, graphs, and discussion.

About two years ago the author began compilations of the daily data for D for the same interval, 1843 to 1930 [3]. These for 09h and 14h during 1843–1886, that is for four of the eight 11‐year epochs, are now completed. It seemed worthwhile to compile vector‐diagrams of the annual variations in D and H and of ΔH = (ΔH14 − ΔH09) and ΔD = (ΔD14 − ΔD09) given in Table 1.
Sitka Magnetic Observatory October to December, 1942
Authors: Pinckney Harold W.
Published: February 2008

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

October 2–5—Beginning gradually just before 09h GMT, October 2, a disturbance of moderate severity continued through the night of October 5. K‐indices of 7 were recorded for the periods 12h–15h on October 2 and 03h–06h on October 3.
Cheltenham Magnetic Observatory October to December, 1942
Authors: Hershberger John
Published: February 2008

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

October 2–5—A moderately severe storm began rather indefinitely at about 10h 50m GMT, October 2, and lasted until about 15h, October 5. The first ten hours of the storm were marked by very short‐period activity, particularly in H, superimposed on slower variations. The severest part of the storm came in the first six hours of October 3, during which two K‐indices of 6 were recorded. Thereafter the activity was not violent.
Huancayo Magnetic Observatory October to December, 1942
Authors: Ledig Paul G.
Published: February 2008

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

October 2—Beginning at 02h 47m GMT, October 2, with a sharp short rise in H, there was a moderate magnetic disturbance which was marked by a number of narrow peaks and bays in the H‐trace with a maximum range of about 200 gammas during the daylight hours of October 2 and followed by subnormal H‐values for several days. D and Z were only mildly affected during the hours of maximum disturbance.
Huancayo Magnetic Observatory, January to March, 1943
Authors: Ledig Paul G.
Published: February 2008

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

January 4—Beginning at about 11h GMT, January 4, there was a short, sharp magnetic disturbance during the daylight hours which was characterized by rapid small changes in H superimposed on several narrow peaks and bays. The range was only 150 gammas during the eight hours of the disturbance and the maximum K‐index was 6. D and Z were also somewhat agitated during the active period of the storm.
FINAL RELATIVE SUNSPOT‐NUMBERS FOR 1942
Authors: Brunner W.
Published: February 2008

Table 1 contains the final sunspot‐numbers for 1942, for the whole disc of the Sun, based on observations made at the Zürich Observatory, supplemented by series furnished by other cooperating observatories for days (indicated by asterisks) on which no observations were possible at Zürich.

Table 2 gives the yearly means of the relative numbers, R, since the last minimum 1933 and the number of days without spots.
GEORGE WASHINGTON LITTLEHALES, 1860–1943
Authors: Harradon H. D.
Published: February 2008

George Washington Littlehales, Hydrographic Engineer at the United States Hydrographic Office from 1900 to 1932, died suddenly at his home in Washington, D.C., August 12, 1943, at the age of 82 years.

Mr. Littlehales was born October 14, 1860, in Schuylkill County, Pennsylvania. He entered the United States Naval Academy as a midshipman in 1879 from which he was graduated in 1883 and after spending two years at sea in the North Atlantic Squadron he received the post‐860‐1943 graduate diploma and returned to civil life. In 1888 the Columbian (now George Washington) University awarded him the degree of Civil Engineering which he had earned in the course of studies there. In the summer of 1885 he joined the staff of the United States Hydrographic Office with which he was continuously associated until his retirement in 1932. He was professor of nautical science in George Washington University during 1913‐1927.
HUANCAYO MAGNETIC OBSERVATORY APRIL TO JUNE, 1943
Authors: Ledig Paul G.
Published: February 2008

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

There were no magnetic disturbances worthy of description during the quarter. PAUL G. LEDIG, Observer‐in‐Charge
SOME EARLY CONTRIBUTIONS TO THE HISTORY OF GEOMAGNETISM—V
Authors: Harradon H. D.
Published: February 2008

As the fifth contribution in our series of early documents pertaining to geomagnetism, we are privileged to publish a translation of “Estromento de Sombras” (1537) by Pedro Nunes as reproduced by Hellmann in this Rara Magnetica. This is a section of the extremely rare book “Tratado da Sphera com a Theorica do Sol e da Lua”1 in which Nunes describes an improvement to Guillen's instrument (brújula de variación) consisting of the addition of a device permitting the observation of the Sun's altitude. He also gives a new method of determining the latitude at any hour of the day.

We are under deep obligation to Dr. J. de Sampaio Ferraz of Rio de Janeiro for the following translation of “Estromento de Sombras.” Dr. Sampaio Ferraz also informs us that there is a copy of the rare “Tratado da Sphera com a Theorica do Sol e da Lua” in the Biblioteca Nacional at Rio de Janeiro. His comparison of the two texts showed that the edition in Rio de Janeiro, published at Lisbon in 1537, differs only in a few minor orthographical details from the text as reproduced by Hellmann.