bluuebunny/crossref_metadata_2025 huggingface dataset:
The National Geographic Society—Cornell University Study of Aurora, 1938–1941
Authors: Gartlein C. W.
Published: February 2008

The National Geographic Society and Cornell University are sponsoring a program of research on the aurora borealis. This study will include height‐measurements from Cornell University, Colgate University, and Hobart College and spectroscopic, intensity, and descriptive studies from Cornell. The cooperation of many observers from the ranks of the American Association of Variable Star Observers, the American Meteor Society, and professional astronomers has been enlisted to make visual measurements of the form, intensity, and colors of auroras and of the times of changes in form. This part of the study should lead to further information on the geographical distribution and enable better correlation between auroras and other phenomena (changes in radio transmission, solar disturbances, and magnetic variations).
Variations in the disturbance‐field of magnetic storms
Authors: Cynk B.
Published: February 2008

In his paper on the average characteristics of magnetic storms [see 1 under “References” at the end of this paper] S. Chapman has shown that these characteristics do not differ much in general form while the intensity of disturbance varies over a wide range. This was accomplished by subtracting the daily mean values of horizontal intensity for quiet days from those for all days, and by comparing the resulting differences with those for the daily means of the storm‐time disturbance‐field (designated by Dm) obtained by subtracting the daily mean values on quiet days from those on disturbed days. Results were given for five stations in various magnetic latitudes, namely: Sitka (61°), Pavlovsk (58°); Greenwich (55°); Cheltenham (55°); and Honolulu (21°).
Note on the design of efficient magnets
Authors: Johnson E. A.
Published: February 2008

The purpose of this note is to collect in a convenient form the design‐data for cylindrical magnets. Since the design which leads to maximum stability is not known, except that it appears that stability is greater when the coercive force is great and the energy product BH is great, the data presented here are for the purpose of determining the moment of a cylindrical magnet given the dimensions.

In Figure 1 are given the demagnetization‐curves of Alnico, cobalt steel, and tungsten steel (left‐hand side) and the energy‐density (right‐hand side). In a cylindrical magnet, as in any magnet, the residual flux depends not only upon the externally applied demagnetizing force but also upon the demagnetizing force due to the interaction of the elementary magnets upon each other. This depends upon the magnetic circuit and in the case of a cylinder is composed of the cylinder and the surrounding medium, usually air. This self‐demagnetizing force is very small for an infinitely long cylinder, the case for which the curves are taken. The self‐demagnetizing force is proportional to the remanence in the specimen and the proportionality‐coefficient has been calculated for various ratios of length to diameter. The straight lines in Figure 1 passing through the origin represent these coefficients for the ratio of length to diameter given with each line. The intersection of these lines with the demagnetization‐curve of the selected material then gives the actual residual flux in a cylinder with the length‐to‐diameter ratio represented by the line.
American URSI Broadcasts of cosmic data, October to December, 1938, with American magnetic character‐figure CA, November, 1938 to January, 1939, and summary of CA for year 1938
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 first three columns of Table 1 give (1) the magnetic character according to the scale 0‐2 of the International Commission of Terrestrial Magnetism and Atmospheric Electricity, (2) the type featuring the day other than normal by the letters b, p, o, and i for days marked by day, rapid pulsations, long‐period oscillations, and irregular oscillations, respectively, and (3) the hour and minute of Greenwich mean time marking the beginning of a storm, the end of the storm being indicated in the foot‐note to the Table. The next two columns give the data relating to sunspots: (1) the number of groups of spots and (2) the total number of spots. It is to be noted that sunspot‐numbers such as those from Zürich can be obtained from the number of groups and spots given in the Table by the formula N=k (l0g+s), where the mean value of k for Mount Wilson was 0.53 during 1936; during 1937 this value varied from 0.47 to 0.66 with an average value of 0.53.
Sitka Magnetic Observatory October to December, 1938
Authors: Gebhardt Robert E.
Published: February 2008

October 6–8—A sudden commencement at 18h 43 m GMT, October 6, marked the beginning of a severe magnetic storm. The three components remained very quiet until 07h, October 7, when the activity began to increase. With a sudden decrease of 520 gammas in H the principal part of the storm began. Until 18h, October 7, the three components moved with such rapid motion that the exact changes could not be determined.
Watheroo Magnetic Observatory, June to September 1939
Authors: Parkinson W. C.
Published: February 2008

June 14—This very moderate disturbance, of short duration, began with a small sudden commencement in all three elements at 00h 07m GMT, June 14, when westerly declination increased 1′.7, horizontal intensity decreased 11 gammas, and the numerical value of vertical intensity increased 9 gammas. During the following seven hours the elements were only slightly disturbed, but at 07h 15m there was a second sudden commencement of greater amplitude, when westerly declination increased by 2′.2, horizontal intensity decreased 36 gammas, and the numerical value of vertical intensity increased 20 gammas. For four hours there‐after the movements were moderately large, the maximum activity occurring between 09h and 12h. After this time conditions became more quiet and the elements had regained their normal values by 16h.
American URSI broadcasts of cosmic data, with American magnetic character‐figure CA, January to March, 1940
Authors: Johnston H. F.
Published: February 2008

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

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

In accordance with Resolution 8, passed by the Association of Terrestrial Magnetism and Electricity at the Washington Assembly of the International Union of Geodesy and Geophysics, I have pleasure in sending you herewith the magnetic data obtained by this office in 1938 and 1939. It is expected that our publication containing the magnetic results for the years 1927 to 1937 will be ready for distribution this summer.
The magnetic character of the year 1939 and the numerical magnetic character of days, 1939
Authors: van Dijk G.
Published: February 2008

The annual review of the “Caractère magnétique de chaque jour” for 1939 has been drawn up in the same manner as for the preceding years. Sixty‐two observatories contributed to the quarterly tables; fifty‐three of them sent complete data.

In the introduction a note has been inserted concerning the publication “Caractère magnétique numérique des jours” for 1939, volumes XXX–XXXIII have been published along with the tables of “Caractère magnétique de chaque jour.”
Multifrequency recordings of radio‐wave polarization near the geomagnetic equator
Authors: Wells H. W.
Published: February 2008

Theory of radio‐wave propagation predicts that in the special case of propagation of a wave in the ionosphere with its wave‐normal perpendicular to the Earth's magnetic field at all points along the wave‐path, the two wave‐components returned should be plane‐polarized in mutually perpendicular planes. The Huancayo Magnetic Observatory (Peru) of the Department of Terrestrial Magnetism of the Carnegie Institution of Washington, is suitably located for special polarization‐tests under the conditions above outlined since the inclination of the Earth's magnetic field is only some 2° 14′ from the horizontal. Earlier tests at this location in 1935 confirmed the general theory for propagation in the F‐, F1‐, or F2‐regions. It was shown that a simple doublet antenna oriented in magnetic north‐south plane would record only the ordinary wave‐component; while an antenna in the magnetic east‐west plane would record only the extraordinary wave‐component. Recent tests made with automatic multifrequency apparatus are found to be in complete agreement with earlier results, and evidence is presented which warrants extension of earlier conclusions to include E‐region propagation under certain conditions.
Final relative sunspot‐numbers for 1939 and monthly means of prominence‐areas for 1931–1939
Authors: Brunner W.
Published: February 2008

Table 1 contains the final sunspot‐numbers for 1939, for the whole disk 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.
Cheltenham Magnetic Observatory April to June, 1940
Authors: Ludy Albert K.
Published: February 2008

April 2–4—A mild storm began at 16h 12m GMT, April 2. Its greatest activity took place between 02h and 08h, April 3. It ended at 04h, April 4. Ranges: D, 64′; H, 270 gammas; Z, 315 gammas.
Tucson Magnetic Observatory April to June, 1940
Authors: White Roland F.
Published: February 2008

April 2–4—At 16h GMT, April 2, minor activity started, with some increase in disturbance until 01h 30m, April 3, at which time there was a considerable increase, H having a range of 120 gammas and D a range of 15′ within one hour. This long‐period activity continued for seven hours and was followed by short‐period activity of small amplitudes to 23h, April 3. A slightly disturbed condition prevailed for about one day longer with no definite ending.

April 25–26—A moderate storm began at 02h 05m GMT, April 25, with an increase in H of 45 gammas in two minutes, followed by a decrease of 190 gammas to a minimum at 05h 00m and then a return to normal. During the same period D increased 25′ and returned to normal at about the time of the minimum in H. The storm continued with moderate long‐period changes and a lowered H to an indefinite ending at about 12h, April 26.
Watheroo Magnetic Observatory March to June, 1940
Authors: Parkinson W. C.
Published: February 2008

March 23–28—This disturbance, of major importance, began at 06h 16m GMT, March 23, with rather sudden movements in all three elements; H increased by 27 gammas, the corresponding movements in Z and D were quite small. Apart from a brief period of activity between 09h 10m and 09h 20m on the same day, the traces were only moderately disturbed during the ensuing 30 hours; an interesting feature, however, was the increasing rapidity of the fluctuations, though of small amplitude, after 00h, March 24. At 13h 49m, March 24, the main activity of the storm was heralded by a sudden commencement, where the H increased by 55 gammas, the Z decreased by about 7 gammas and the westerly declination decreased by about 2′. Thereafter the fluctuations became so violent that some of the movements were too rapid to record; it is probable, however, that the maximum intensity of the disturbance was at about 01h, March 25, when the horizontal intensity reached a value about 500 gammas lower than the normal, this representing a decrease of over two per cent in the force.
Apia Observatory July to September, 1940
Authors: Sapsford H. Bruce
Published: February 2008

September 26–27—A sudden commencement occurred at 17h 03m GMT, September 26, with an increase of 29 gammas in H and 11 gammas in the numerical value of Z. The three elements were moderately disturbed until 07h, September 27. The range in H was 82 gammas.
Cosmic Radiation and Magnetic Storms [Reply to “Comments on A. R. Hogg's Paper ‘Cosmic Radiation and Magnetic Storms’”]
Authors: Hogg A. R.
Published: February 2008

The comments by Mr. Forbush1 raise an interesting point in relation to the storm commencing at 3h.1, August 22, 1937.

The world‐wide effect relative to Huancayo, has been shown by Mr. Forbush “reference 2 of comments” to be 1.11 for Cheltenham, 1.58 for Teoloyucan, and in the comments, 2.0 for Canberra. These figures have been used to effect a comparison between the Teoloyucan (1) and Canberra results (Fig. 1). There is quite a resemblance between these two curves, both showing a depression during the storm‐period. The depression for Teoloyucan, however, is not well marked, and in the average mentioned by Mr. Forbush is obliterated by the results from the other two stations (Huancayo and Cheltenham) combined with it.
Geomagnetic Three‐Hour‐Range Indices for the Years 1937 and 1940
Authors: Johnston H. F. , Heck N. H.
Published: February 2008

Tabulations are given of three‐hour‐range indices for five magnetic observatories for 1937 and for seven observatories for 1940 (Table 1), of weighted average of reduced three‐hour‐indices (Table 2), and of daily indices derived from the weighted reduced‐indices (Table 3). Graphs are given showing the relationship of the sums of weighted, reduced indices with the American magnetic character‐figure CA and with the International magnetic character‐figure C.
Watheroo Magnetic Observatory, January to March,, 1941
Authors: Parkinson W. C.
Published: February 2008

January 3–4—A small magnetic disturbance began with a sudden commencement at 15h 43m GMT, January 3. A quiet period of eleven hours ensued, after which the traces were mildly disturbed until normal conditions resumed at 12h, January 4. Ranges : D, 14′.1; H, 85 gammas; Z, 59 gammas.

January 24—During somewhat disturbed conditions which prevailed on January 24, there was one noteworthy feature. Between 12h and 14h there was a wave of large amplitude in all three elements. In H the movement began at 12h 20m with a bay which reached its minimum at 12h 42m and then rose sharply to a peak at 12h 59m, then gradually falling to approximately normal value by 13h 50m. Ranges: D, 23prime;.9; H, 107 gammas; Z, 135 gammas.
Tucson Magnetic Observatory, July to September, 1941
Authors: Nelson J. H.
Published: February 2008

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

July 4–8—The storm began with a sudden increase in H of 41 gammas at 03h 42m GMT, July 4, with evidence of mild activity until 00h, July 5. During the following five hours there was a gradual increase of activity. At 05h 00m, July 5, another sudden increase in H marked the beginning of a severe magnetic storm. The extreme activity of the storm ended at 15h, July 5. Moderate disturbance with considerable short‐period and some long‐period variations continued until about 09h July 8. Approximate ranges: H, 393 gammas; Z, 156 gammas; D, 36′.
Some Early Contributions to the History of Geomagnetism—II AND III
Authors: Harradon H. D.
Published: February 2008

(II) Francisco Falero—During the great age of discovery which followed the voyages of Columbus, Spain and Portugal took an important part in maritime enterprises and the exploration of lands beyond the sea. These ventures were responsible for the improvement of instruments and methods of navigation and the production of charts and maps. At that time it was widely believed that the determination of longitude at sea could be obtained from magnetic data, particularly from those of the declination, a belief which persisted throughout the seventeenth century and encouraged the making of many magnetic observations which, although useless as far as longitude‐determinations were concerned, at least furnished data of great value in advancing knowledge of geomagnetism.

The first person who announced practical methods of determining the magnetic declination in printed form was Francisco Falero or Faleiro, a Portuguese in the service of the Spanish Navy, to whom we are indebted for the first real manual of navigation. This work entitled “Tratado del esphera y del arte del marear; con el regimie˜to de la altura; cõ algũas reglas nueuame˜te escritas muy necessarias,” is extremely rare—so rare in fact that its existence has sometimes been doubted. The National Library in Madrid, however, possessed a copy and Hellmann was enabled to reproduce its title‐page which we in turn present herewith in Plate 2. (A free translation of the title is as follows: 'Treatise on the sphere and the art of navigation with manual of altitudes with some very necessary written rules. With imperial privilege. A. D. 1535.”) The work was printed in gothic type and consists of 52 unnumbered folio pages. In the eighth chapter of the second part under the title "Del nordestear de las agujas,” a translation of which we present (page 80), magnetic declination is discussed in detail for the first time in print and three methods are given for its determination, namely (1) by the azimuth‐determination of the magnetic needle at true noon when the shadow of the pin falls to the north, (2) by observation of the shadow‐azimuths at corresponding altitudes of the Sun before and after noon, (3) by observation of the azimuth at sunrise and sunset.1 These methods are perhaps intended for an instrument (brújula de variación) devised by Filipe Guillen although no mention is made of it.
On the Observational Evidence for Changes in Ionization of the Upper Atmosphere Attributable to the Moon
Authors: Stetson Harlan T.
Published: February 2008

Evidence for the effect of the Moon upon radio‐wave propagation has been previously presented by the author on several occasions [see 1, 2 of “References” at end of paper]. The evidence presented was based upon studies of field‐strength measurements showing variations in field‐intensities at broadcast‐frequencies over fixed paths with the hour‐angle of the Moon. The variations noted indicated a single rather than a double maximum for the lunar day. It was suggested that the considerable variations observed were greater than would be easily satisfied by an explanation based on the lunar gravitational tide in the Earth's atmosphere alone. Analyses of long years of magnetic observations have clearly shown a lunar component in changes in declination and intensity of the Earth's magnetic field, the major part of which may be ascribed to changes in ionic distribution in the upper atmosphere.

It is interesting to note that at the Rome meeting of the International Scientific Radio Union, Appleton [4] reported a lunar semi‐diurnal variation of the level of the E‐layer of approximately one km, the maximum occurring about three‐quarters of an hour before the lunar transit. The results were based upon a single year's investigation in the determination of equivalent heights by reflection from the E‐region of the ionosphere. Appleton regards the results as showing a pressure oscillation of a relative amplitude of 0.068 at a level of 100 km and calls attention to the fact that the measurement of the lunar barometric oscillations at ground‐level show a corresponding relative amplitude of only 0.0000115. If this interpretation is correct, the tide at 110 km, he points out, is 5900 times that of ground‐level. The phase of the upper atmospheric tide was found by Appleton to be the same as that at ground‐level at Greenwich, a result not consistent with deductions made from lunar magnetic variations, assuming such variations to arise from currents flowing in the E‐region.
Discussion of “Atmospheric‐Electric Observatories at Huancayo, Peru, during the Solar Eclipse, January 25, 1944”
Authors: Gish O. H.
Published: February 2008

The correlation, reported by Jones and Giesecke, between certain variations in atmospheric‐electric elements, and the progress of the solar eclipse, appears to be more significant than any seen by the writer, in similar observations made elsewhere during solar eclipses [see 1, 2, 3, 4 of “References” at end of paper] except the observations [1] made at Lakin, Kansas, during the eclipse of June 8, 1918, which show effects that appear to have about the same significance. A comparison of the eclipse‐effects indicated at these two places derives some of its interest from the fact that the “normal” diurnal variation of potential‐gradient and that of air‐conductivity at Lakin seems to be of about the same character as that found for the respective elements at Huancayo on most fair‐weather days, namely, values of air‐conductivity are conspicuously larger at night than in daylight, while the values of potential gradient are larger in daylight and small at night and at both places the diurnal variation of air‐earth current is apparently free from this local time‐component. Although the data bearing on diurnal variation, obtained at Lakin, Kansas, consist of manual observations for one 24‐hour period only, confidence in the indicated character of diurnal variation is strengthened by the fact that the four independently measured elements, namely, potential‐gradient, positive conductivity, negative conductivity, and positive ion‐concentration, all show the pronounced and consistent difference between daylight and night.

Meteorological conditions reported for the period of observations at Lakin are favorable for the development there of a stable stratum of air adjacent to the Earth at night. The latter is an important feature in the mechanism proposed by the writer [5] to explain the remarkable local aspect of diurnal variation in the several elements at Huancayo and it accordingly seems likely that the diurnal variation observed at Lakin is also attributable to such a mechanism. One may therefore expect an eclipse of the Sun to affect the atmospheric‐electric elements in a similar manner at the two places, namely, tend to establish, during the eclipse, values which are characteristic of night.
Summary of Earth‐Current Records from Tucson, Arizona, for a complete Sunspot‐Cycle
Authors: Rooney W. J.
Published: February 2008

The final results of the cooperative project of the Department of Terrestrial Magnetism of the Carnegie Institution of Washington, the United States Coast and Geodetic Survey, and the Bell Telephone Company, for the measurement of earth‐currents at Tucson, Arizona, are summarized in eight tables. These tables give for each component yearly and monthly values of the mean diurnal variation as recorded on all days and on the ten calmest days of each month. From the yearly values the general correlation between earth‐current activity and solar activity, as indicated by sunspot‐numbers is apparent. The monthly values confirm in detail a number of interesting and unusual features previously reported in connection with the seasonal variation in earth‐current flow at Tucson. Since the records cover a full sunspot‐cycle and are quite complete and homogeneous it is believed that they afford exceptionally useful material for further study of the relationship between magnetic variations, earth‐currents, and the conditions existing in the ionized layers of the upper atmosphere.
Five International Quiet and Disturbed Days for January to March, 1944
Authors: Johnston H. F.
Published: February 2008

Reports of geomagnetic activity for the first quarter of 1944 have been received from a sufficient number of magnetic observatories so that the international quiet and disturbed days may be selected in accordance with the method outlined on pages 219–227 in the December 1943 issue of this JOURNAL. The selection is based on the reports of magnetic character on a scale of 0, 1, and 2 from 35 observatories and of K‐indices from 23 observatories.
On the Determination of Magnetic Vertical Intensity, Z, by Means of Surface Integrals
Authors: Taylor James H.
Published: February 2008

Introduction— The. main result of the present paper is a separation of Z, the normal component of a magnetic field, into parts Ze and Zi due to external and internal sources, respectively. The resolution is given in terms of surface integrals whose integrands involve the observed surface values X and Z of the field. The paper may well be regarded as a sequel to an article by Vestine [1 of “References” at end of paper].

The author is greatly indebted to Dr. Vestine, who proposed the investigation and gave invaluable suggestions regarding it. The author is also grateful to Dr. Davids, who provided certain computational details relating to the eccentric dipole field, and who made available results that he had obtained which seemed to have a bearing on the problems under consideration.
Analysis and Interpretation of Geomagnetic Anomalies
Authors: Vestine E. H. , Davids N.
Published: February 2008

The analysis and interpretation of geomagnetic anomalies is discussed. Techniques are described for estimating depth and strength of magnetized ore‐bodies, using tables and graphs of the fields of simple models. Relations among surface‐components of field of anomalies are derived, using fitting or representation of anomalies by Fourier series, Fourier‐Bessel series, and power series. A method based on the analysis of surface magnetic fields by integrals is also described.

Methods are given for estimating probable minimum and maximum depths to magnetic sources beneath the Earth's surface, using measurements of field at the surface. The locations of sources cannot be uniquely inferred from magnetic data alone. The use of gradients of field in locating sources of anomaly is indicated.
On the mutual consistency of magnetic charts
Authors: Davids Norman , Bernstein Arthur
Published: February 2008

Introduction— This paper is the result of a study to find and apply a method of improving the accuracy of world isomagnetic and isoporic charts using only the data provided in the original construction, the final results to be in accord with the requirements of electromagnetic theory. It contains, mainly, an appraisal of the curl‐test for mutual consistency of magnetic charts which was proposed and used by Chapman [see 1 of “References” at end of paper].

This statement of the problem does not presume that the cartographer did not make the best use (by reference to the criteria he actually employed) of the data at his disposal, but rather that certain conditions provided by theory were ignored. Consider, for example, the world‐charts for horizontal intensity (H) and declination (D) [or north intensity (X) and east intensity (Y)]. Each is drawn separately, the contours of the one being sketched without reference to the other, and the curves then are smoothed visually. The observations upon which the charts are based are poorly distributed, of varying reliability, and no trustworthy observations at all obtain for some significantly large areas. The main function of the test for consistency and scheme of adjustment is to assist in improving chart‐values in the poorly surveyed regions.
A model of the ionosphere
Authors: Woodward R. H.
Published: February 2008

Observations and theories of a number of geophysical phenomena associated with the ionosphere are summarized. A proposed model of the ionosphere seems to provide qualitative interpretations of most of these phenomena. In low and intermediate latitudes electrons are assumed to rise; they migrate through the upper ionosphere to the polar region, where they fall and complete the circuit through the ground. Under the action of an electric field, positive ions, which are formed at great heights by ultraviolet light, tend to rise, whereas negative ions descend. Since the ions are constrained to helical paths along the sloping magnetic lines of force, positive ions tend to collect in a ring near the plane of the geomagnetic equator; negative ions accumulate in the polar regions. Solar radiation‐pressure distorts the ion‐ring and blows the tail to a height of several Earth‐radii. Electric discharges between the positive ion‐ring and the negative polar caps produce magnetic disturbances and the associated auroral displays.
On a new method for exploring the upper ionosphere
Authors: Bailey D. K.
Published: February 2008

The extensiveness and intensity of the ionization in the region above the height of maximum ionization of the F2‐layer of the ionosphere is not known. It is shown that measurements of the refraction experienced by radio waves arriving at the Earth after passage through the entire ionosphere can yield information about the uppermost regions of the ionosphere. An expression for the refraction of radio waves which pass through a parabolic‐layer model is derived. This permits a range of frequencies to be specified within which profitable refraction‐measurements can be made. Either the Sun, which emits radio waves in the form of noise, or the Moon, which can be used to return radio waves originating on the Earth, is a suitable extraterrestrial source of radio waves. An experimental technique for measuring refraction is described and discussed.
Tucson Magnetic Observatory October to December, 1947
Authors: Nelson J. H.
Published: February 2008

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

September 30‐October 3—A magnetic storm of moderate intensity began suddenly at 18h 08m GMT, September 30. Activity for the first nine hours was very light. Between 03h, October 1, and 03h, October 2, the traces were moderately rough, but without special characteristics. Large, irregular changes in D and H, with a markedly depressed H, began early on October 2 and continued until the end of the storm about 14h, October 2, Ranges: D, 25′; H, 194 γ; Z, 62 γ.
Geophysical Institute of Huancayo October to December, 1947
Authors: Giesecke Albert A.
Published: February 2008

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

Note: Except for a sudden‐commencement type of storm on November 24, there were no disturbances throughout this period that reached worth‐while proportions; however, those periods of abnormal activity, as indicated by H, are described below.
Studien über das atmosphärische Potentialgefälle: 1—Das Auswahlprinzip der luftelektrisch “ungestörten Tage”
Authors: Israël H. , Lahmeyer G.
Published: February 2008

Zusammenfassung—Die in der luftelektrischen Praxis übliche Methode, statistische Bearbeitungen nur auf die sog. “ungestörten Tage” zu stützen, führt zu einem einseitigen Bild der luftelektrischen Verhältnisse, einer “Schönwetter‐Luftelektrizität”. Es wird gezeigt, dass ein Aussonderungsverfahren nur insofern eine innere Berechtigung hat, als aus einer auf das ganze zielenden Untersuchung solche Werte ausgeschlossen werden dürfen und müssen, die während Störungen des stationären luftelektrischen Gleichgewichtszustandes gemessen werden. Danach werden die bei Gewitter und Niederschlägen aller Art gemessenen Werte bezw. Stundenmittel ausgeschieden. An einigen Beispielen wird gezeigt, dass zwar die Tagesgänge in ihrem Charakter und ihren prozentualen Schwankungsamplituden durch die “Auswahl ungestörter Tage” gegenüber der aus dem Gesamtmaterial folgenden nicht verändert werden, dass aber die mittleren Absolutwerte und die Amplituden der jährlichen Veränderlichkeit durch Beschränkung auf “Normaltage” merklich vergrössert werden. Zur Analyse des luftelektrischen Gesamtgeschehens genügen Gefällemessungen allein nicht, vielmehr ist die gleichzeitige Bestimmung von mindestens einem der beiden anderen Grundelemente Leitfähigkeit oder Vertikalstrom notwendig. Es werden Richtlinien für luftelektrische Bearbeitungen vorgeschlagen, nach denen in Zukunft anstelle irgendeiner Auswahl alle niederschlagsfreien Werte zugrundegelegt werden. Für Stationen die bisher nur die Mittel und Gänge nach “ungestörten Tagen” mitgeteilt haben, sollte die Gesamtbearbeitung noch nachträglich durchgeführt und mitgeteilt werden.
On the distrubution and the secular variation of terrestrial magnetism; No. IV: On the component fields of the Earth's permanent magnetism
Authors: Bauer L. A.
Published: February 2008

This paper is a continuation of the attempt begun in No. II of these researches to localize the centers of disturbance in the Earth's permanent magnetic field. In the previous paper (No. II) the normal distribution of the Earth's magnetism was taken as that resulting from a homogeneous magnetization about the Earth's rotation axis. The residual field, among other things, showed a decided polarization along the equator. The next logical step then in the breaking up of the Earth's complex field into component fields would be to deduct from the residual field this one due to the equatorial polarization.
Effects of water table conditions on water level changes near pumping wells
Authors: Stallman R. W.
Published: February 2008

Unconfined flow of water to wells is related to anisotropy of the aquifer, changes in the coefficient of storage with time, degree of penetration of the pumping well, and position of the water table. Sluggish response of observation wells to changes of head in the aquifer may lead to erroneous analysis of pumping‐test data. The manner and extent to which these factors affect water levels have been studied by field observation, by analytical equations, and by electric analogs. The typical S‐shaped curves of log drawdown versus log time, observed around wells pumping from water table aquifers, can be explained by an infinity of combinations of possible flow patterns and observation conditions. Equations developed for artesian flow cannot be used for analysis of tests made under water table conditions unless steady‐state conditions have been approached or reached. From a practical standpoint the time required to approach steady flow is much greater than the duration of most pumping tests. Thus if pumping tests are to be used for measuring the hydraulic properties of unconfined aquifers, the boundary conditions attending unconfined flow must be recognized in the analysis of test data.
Recreation benefits from water pollution control
Authors: Stevens Joe B.
Published: February 2008

A methodology for estimating direct recreational benefits from water pollution control was developed through a model of biological and behavioral relationships involved in sports angling. A biological production function was envisaged between inputs of angling effort and the output, or yield, of fish taken. The marginal product, angling success per unit of effort, was taken to represent the ‘quality’ of the recreational experience. Water pollution would cause deteriorations in dissolved oxygen, temperature, or toxicity characteristics of the water, thus shifting the production function downward and causing reductions in angling success, angling effort, and recreational value of the fishery. Demand equations and ‘success‐effort’ elasticities were estimated for three estuarial sports fisheries, and the methodology was illustrated by means of an assumed reduction in angling success. The direct recreational benefits were identified as the consumer surplus that would result from the prevention of water pollution. (Key words: Economics; quality of water; recreation.)
The accuracy of the prediction of floods of high return period
Authors: Nash J. E. , Amorocho J.
Published: February 2008

Expressions in terms of sample size and parameters of the probability distribution are obtained for the standard errors of sample estimates of flood magnitudes corresponding to given return periods for normal and double exponential universes. These errors are shown to converge toward fixed proportions of the estimates for very high return periods. (Key words: Floods; frequency analysis; statistics.)
Tracer dilution sampling technique to determine hydraulic conductivity of fractured rock
Authors: Lewis David C. , Kriz George J. , Burgy Robert H.
Published: February 2008

Groundwater in foothill and mountain watershed areas commonly occurs in fractured rock. The small well diameters and low apparent groundwater velocities in fractured rock require modification of normal techniques for the investigation of unconfined groundwater movement. The determination of hydraulic conductivity by the tracer dilution method normally employs injected radioisotope tracers. The dilution is determined by monitoring the isotope activity in the well with a scintillation probe. A modification of this method, using fluorescent dye tracers and physical sampling and analysis to determine dilution, has been applied in small wells with consistent results. Hydraulic conductivities of 0.02 to 0.5 ft/day have been determined in sixteen wells. Where comparison is possible, the values agree favorably with hydraulic conductivities determined by pumping tests. (Key words: Groundwater; permeability; tracers; wells)
Pontacyl brilliant pink as a tracer dye in the movement of water in phreatophytes
Authors: Robinson T. W. , Donaldson Donald
Published: February 2008

In connection with evapotranspiration studies Pontacyl Brilliant Pink, a fluorescent dye, was used to trace the movement of water in two species of woody phreatophytes, willow and wildrose. The dye was introduced into water surrounding the plant roots on August 4, 1964. Thereafter, leaf samples were collected periodically until the end of the growing season in October. Fluorometric measurements showed the presence of the dye in the leaves. Dye was also found in samples of roots and stems and in transpired water collected in plastic bags. Dye concentration was greatest in the upper part of the stems. As a tracer the dye offers a rapid method for studying the source, movement, and disposal of water used by phreatophytes. The method is rapid and inexpensive, and the laboratory determination is not difficult. The fluorometric determinations were made with a GK Turner Fluorometer Model 111, which has a sensitivity of 1 ppb.
Some comments on the use of factor analyses
Authors: Matalas N. C. , Reiher Barbara J.
Published: February 2008

Factor analysis is a technique that purports to explain observed relations among several variates in terms of ampler relations that provide insight into the underlying structure of the variates. The analysis, however, is technically underdeveloped, and its usefulness for studying interrelated hydrologic variates is questionable because of the inherent indeterminacies in the factor model, the lack of knowledge about the sampling properties of the factor loadings, the fact that the factors are not directly observable, and the inability to use the results of factor analyses in other analytic studies.
Growth and decay of groundwater‐mounds in response to uniform percolation
Authors: Hantush Mahdi S.
Published: February 2008

The rise and decay of the water table in response to deep percolation depends on the shape of the recharging area, among other factors. Solutions describing this phenomenon when the recharging area is rectangular or circular in shape are developed for the case where the underlying aquifer is effectively infinite in areal extent. The solution when the recharging area is circular is given in terms of a function that can be easily tabulated for a practical range of the parameters. Approximate solutions in terms of already tabulated functions are presented also. The solution when the recharging area is rectangular is obtained in terms of a function that depends on two parameters. This function is tabulated for a wide range of the parameters. This tabulation, as well as approximate relations, affords a means for relatively simple calculation. The solutions are applicable if the rise of the water table relative to the initial depth of saturation does not exceed 50%.
A Laplace transform proof of the theorem of moments for the instantaneous unit hydrograph
Authors: Diskin M. H.
Published: February 2008

Use is made of Laplace transforms to derive a general relationship for the moments about the origin of the three functions that appear in the convolution integral. The resulting equation can be used for the successive evaluation of the unknown moments of the instantaneous unit hydrograph from the known moments of the rainfall excess hyetograph and of the direct surface runoff hydrograph. Simplified forms of the moments equations are given for the moments of lowest orders. (Key words: Unit hydrograph; floods; streamflow)
A simple evaporimeter for use in cold areas
Authors: Wilcox J. C.
Published: February 2008

An evaporimeter has been developed that uses a porous carborundum block for an evaporating surface. The evaporating liquid used consists of 22% methanol and 78% distilled water by weight, which does not freeze until about 0° F. The liquid is fed to the evaporimeter by suction. This evaporimeter has proved to be well suited for use during the growing season at locations difficult of access, in northern areas, and at high elevations.
Finite differencing methods
Authors: Brakensiek D. L.
Published: February 2008

Today analytical techniques, numerical algorithms, and computation facilities have made it possible to solve many hydrologic problems. The emphasis on numerical solutions requires that the hydrologist have some basic knowledge of numerical methods, i.e., the calculus of finite differences. Flow of water in its various phases comprises a large part of hydrologic studies. These processes described by partial differential equations (generally nonlinear) require finite difference approximations for tractable computations. Considerations of convergence, order of approximation, and stability of these difference quotients again require some background in finite difference methods. Through brief discussions, several examples, and a list of references, this paper attempts to introduce some of the above considerations.
On the similitude of dispersion phenomena in homogeneous and isotropic porous mediums
Authors: Bachmat Y.
Published: February 2008

A procedure of simulating, by means of a physical model, the dispersion of a solute in ground water flowing through a homogeneous and isotropic aquifer is considered. Ground water is a solution of variable density and viscosity owing to variations of solute concentration. The model has a very restricted application owing to the required simultaneous invariancy of four nondimensional criteria of similitude: a macroscopic Reynolds number, a macroscopic Peclet number, the criterion of geometrical similarity of the medium, and the criterion of physicochemical similarity of the solution. However, at certain conditions, which are common in practice, some of those criteria can be waived, and the model becomes a useful device for the solution of field problems. These conditions occur in the range of validity of Darcy's law (small Reynolds numbers), at relatively high Peclet numbers, and at very small variations of relative solute concentration (ideal solute).
Water quality as affected by a Wyoming mountain bog
Authors: Sturges David L.
Published: February 2008

Waters collected July through October 1965 at a Wyoming mountain bog were analyzed for potability and seasonal changes in calcium, magnesium, potassium, iron, and silica. Four locations were sampled: effluent stream, fissure locations in the bog, peat locations in the bog, and ground water. The color and turbidity of peat water greatly exceeded that at other locations and the maximum levels established by the U. S. Public Health Service for drinking water. The dissolved mineral content of all waters was very low, and the waters were of excellent chemical quality. All waters contained coliform organisms, probably of a nonfecal origin in peat and fissure water. The concentration of minerals in peat water remained constant through the sampling period. Mineral concentrations in ground water increased in September, when the water table was at a seasonal minimum, but decreased in October following water table recharge. Silica levels were higher than other ions at all locations; the highest levels were in peat water.
Flow around a vertical sheetpile embedded in an inclined stratified medium
Authors: Krizek Raymond J. , Anand Vera B.
Published: February 2008

The steady‐state flow around a vertical sheetpile embedded in an inclined stratified porous medium underlain by an impervious boundary is studied experimentally. The porous medium is a synthetic ‘sandstone’ composed of alternating thin layers of two sand‐epoxy mixtures with coefficients of permeability differing by a factor of 18. The problem is subjected to a coordinate transformation based upon considering the layered system as homogeneous and anisotropic, and a graphical flow net solution is obtained for the streamlines, potential distribution, and flow quantity. By consideration of the porous medium as a semi‐infinite half‐space and use of the same coordinate transformation, complex variable theory and conformal mapping techniques are used to obtain an approximation for the flow quantity and exit gradient variation. Experimental results on streamlines, potential distribution, flow quantity, and exit gradient were obtained from a model study, and these results were found to exhibit some variations from the theoretically predicted results, especially with regard to the flow quantities. A systematic study of possible experimental errors suggests that these variations cannot be attributed wholly to experimental sources and leads to the implication that perhaps the effective permeability of a stratified porous medium cannot be determined by considering the system as homogeneous and anisotropic.
Gross alpha and beta radiation in waters at a Wyoming mountain bog
Authors: Sturges David L. , Sundin Robert E.
Published: February 2008

Waters collected between July and October 1965 from four locations at a mountain bog were analyzed for radiologic content. The gross alpha and beta content of waters was less than 5 and 10 pc/liter, respectively. Gross beta activity of filterable solids in ground water collected above the bog reached 400 pc/gram when the water table was at a seasonal minimum, but on other dates and at bog and stream locations, the gross beta activity of filterable solids was less than 100 pc/gram. Radiation levels in waters from snow, overland flow, and stream sources were measured in May, June, or October 1965. Snow water activity was less than 25 pc/liter, but filterable solids had a maximum gross alpha and beta activity of 243 and 1348 pc/gram, respectively. Standing vegetation, litter, and moss on the bog surface screened radionuclides from snowmelt water. Radionuclide filtration on watersheds is significant from a public health standpoint.
Water quality management and the time profile of benefits and costs
Authors: Parker Denny S. , Crutchfield James A.
Published: February 2008

Economists, in evaluating the long‐term benefits in public works projects, have traditionally held that long‐term benefits will contribute very little to the total present worth of the benefits accrued over the life of the project. It is shown, however, that the long‐term social cost resulting from projects that cause water pollution cannot be neglected or assumed away in the host of practical cases where ‘amenity’ demands for good water quality in a project's area of influence are significant.