scholarly journals On periodical laws discoverable in the mean effects of the larger magnetic disturbances.―No. III

1857 ◽  
Vol 8 ◽  
pp. 40-40
Keyword(s):  
Magnetic Storms ◽  
The Other ◽  
Total Force ◽  
Magnetic Element ◽  
Similar Investigation ◽  
Magnetic Declination ◽  
Magnetic Elements ◽  
Minimum Variation ◽  
The Mean ◽  
Magnetic Disturbances

In two previous papers bearing the same title as the present (Phil. Trans. 1851, Art. V., and 1852, Art. V III.), the author showed, from the hourly observations of the magnetic Declination at Toronto and Hobarton, that the magnetic disturbances of large amount, and apparently irregular occurrence, commonly called magnetic storms , are found, when studied in their mean effects, to he governed by periodical laws of systematic order and regularity, and to exhibit periods whose duration is, respectively, 1, a solar day; 2, a solar year; and 3, a period of about ten of our solar years, corresponding both in duration and in the epochs of maximum and minimum variation, to the approximately decennial period discovered by Schwahe in the phsenomena of the solar spots. In the present paper the author communicates the results of a similar investigation into the laws of the disturbances of the two other magnetic elements at Toronto, namely, the Inclination and the Total Force, derived from the hourly observations of the horizontal and vertical Forces during the five years from July 1843 to June 1848; affording, as he states, a full confirmation of the existence of periodical laws regulating the disturbances of the Inclination and Total Force corresponding to those which he had previously deduced from the disturbances of the other magnetic Element, viz. the Declination.

scholarly journals VIII. On periodical laws discoverable in the mean effects of the larger magnetic disturbance.—No. II

1852 ◽  
Vol 142 ◽  
pp. 103-124 ◽  
Keyword(s):  
Royal Society ◽  
The Other ◽  
Present Moment ◽  
Total Force ◽  
Magnetic Disturbance ◽  
Common Cause ◽  
Similar Investigation ◽  
Magnetic Elements ◽  
The Mean ◽  
Periodical Variation

In a former paper presented to the Royal Society in January 1851, bearing the same title as the present, I submitted to the Society the evidence afforded by the principal disturbances of the Magnetic Declination at Toronto and Hobarton in the years 1843, 1844 and 1845, of the existence of periodical laws by which their occurrence and mean effects appeared to be regulated. At the close of that paper I expressed the intention of submitting, on some future occasion, the results of a similar investigation into the periodical laws which might be expected to show themselves in like manner in the disturbances of the other two magnetic elements, viz. the Inclination and the Total Force. Having since had occasion to examine the disturbances of the Declination at the same two stations in the three succeeding years 1846, 1847 and 1848, I have had the satisfaction of finding that the observations of these years confirm every deduction which I had ventured to make from the analysis of the disturbances of the former period; whilst new and important features have presented themselves in the compa­rison of the frequency and amount of the disturbances in different years , apparently indicating the existence of a periodical variation , which, either from a causal con­nection (meaning thereby their being possibly joint effects of a common cause), or by a singular coincidence, corresponds precisely both in period and epoch, with the variation in the frequency and magnitude of the solar spots, recently announced by M. Schwabe as the result of his systematic and long-continued observations. As facts and collocations of this description are of particular interest at the present moment, from their bearing on inquiries in which physical philosophers are engaged, I have deemed it better to communicate them at once, in the form of a second paper on the disturbances of the Declination, than to await the completion of the investiga­tion into the laws of the disturbances of the Inclination and of the Total Force, for which I have not yet been able to command the necessary leisure.

scholarly journals On periodical laws discoverable in the mean effects of the larger magnetic disturbances.—No. II

1854 ◽  
Vol 6 ◽  
pp. 174-178 ◽  
Keyword(s):  
Causal Connection ◽  
Magnetic Declination ◽  
The Mean ◽  
Magnetic Disturbances ◽  
Periodical Variation

From the discussion of the magnetic observations made at Toronto and Hobarton in the years 1843, 44, 45, the author in a former paper adduced evidence of the existence of periodical laws by which the principal disturbances of the magnetic declination appeared to be regulated. Having since had occasion to examine the disturbances of the Declination at the same two stations in the three succeeding years 1846, 47, 48, he states that he had the satisfaction of finding that the observations of these years confirm every deduction which he had ventured to make from the analysis of the disturbances of the former period; whilst new and important features have presented themselves in the comparison of the frequency and amount of the disturbances in different years , apparently indicating the existence of a periodical variation , which, either from a real or causal connection, or by a singular coincidence, corresponds precisely, both in period and epoch, with the variation in the frequency and magnitude of the solar spots, recently announced by M. Schwabe as the result of his systematic and long-continued observations.

XV. On periodical laws discoverable in the mean effects of the larger magnetic disturbances.—No. III

1856 ◽  
Vol 146 ◽  
pp. 357-374 ◽  
Keyword(s):  
Royal Society ◽  
The State ◽  
Total Force ◽  
Vertical Force ◽  
Magnetic Forces ◽  
The Hours ◽  
The Mean ◽  
Magnetic Disturbances

Having at length completed the analysis of the larger disturbances of the horizontal and vertical magnetic forces at Toronto during five years of hourly observa­tion, with a view to the development of the periodical laws which regulate the occur­rence of the occasional disturbances of those elements, and of their theoretical equiva­lents, the Inclination and Total Force, I now propose to lay before the Royal Society a condensed view of the mode in which the investigation has been made, and of its results. The hourly observations of the Bifilar and Vertical Force Magnetometers during the five years terminating June 30, 1848, were received at Woolwich, from Toronto, precisely in the state in which they are printed in the second and third volumes of the 'Observations at the Toronto Observatory'; namely, the readings, uncorrected for temperature, at every hour of Göttingen time, arranged in Monthly tables, accom­panied by corresponding tables of the temperature of the magnets, shown by thermo­meters of which the balls were enclosed in the same case with the magnets, and which were read contemporaneously with the Bifilar and Vertical Force scales. The Monthly tables of the scale-readings and of the temperatures were summed before their transmission to Woolwich, both in vertical and horizontal columns, and means were taken of all the days in the month at the different hours, and of all the hours of the day on the different days, forming "hourly means” and "daily means.” In this state the observations were received at Woolwich and subsequently printed; they were, in fact, printed from the original manuscripts.

scholarly journals Some phenomena of magnetic disturbances at Kew

1910 ◽  
Vol 83 (566) ◽  
pp. 579-581
Keyword(s):  
The Other ◽  
Diurnal Changes ◽  
Vertical Force ◽  
Horizontal Force ◽  
Rapid Rise ◽  
Sunspot Maximum ◽  
Magnetic Elements ◽  
Early Afternoon ◽  
Phase Angles ◽  
Magnetic Disturbances

A recent paper discussed the diurnal inequality of Kew magnetic declination derived from 209 of the most highly disturbed days of the eleven years 1890 to 1900. The present paper discusses the corresponding phenomena for the same days in the other magnetic elements. The most prominent features of disturbed days are the irregular nature of magnetic changes, and the frequency of large oscillations. These more obvious features have hitherto engrossed attention. It is found, however, that the irregular changes on disturbed days are accompanied by large regular diurnal changes, which are specially striking in vertical force. In declination and horizontal force the range of the regular diurnal inequality on disturbed days is in the average month of the year about double that on quiet days, but in vertical force the former range is fully four times the latter. Disturbance affects the type as well as the range of the diurnal inequality. The former influence is comparatively small in horizontal force and the component to geographical north, larger in declination and the component to geographical west, and largest of all in vertical force. On quiet days the characteristic feature of the vertical force inequality is the fall in the forenoon to the minimum about 11 a. m. and the rapid rise in the early afternoon. Disturbed days, however, approach to a type in which there is a minimum about 4 a. m.— near the principal barometric minimum for the day—and a maximum at from 4 to 6 p. m. according to the season. The day rise and the night fall are about equally rapid. On disturbed days the shorter period Fourier “waves” in the diurnal inequality for V become of reduced importance relative to the 24-hour wave, and this wave has its phase some four hours earlier than on quiet days. Vertical force inequalities from the disturbed days of the four sunspot maximum years 1892—1895 show a considerably larger range than those from the whole 209 days, and their phase angles depart more from the phase angles for the quiet days of the eleven years.

scholarly journals I. On the laws of the phenomena of the larger disturbances of the magnetic declination in the Kew Observatory: with notices of the progress of our knowledge regarding the magnetic storms

1860 ◽  
Vol 10 ◽  
pp. 624-643
Keyword(s):  
Magnetic Storms ◽  
Vertical Column ◽  
First Approximation ◽  
Exact Measurement ◽  
Continuous Record ◽  
The Hours ◽  
British Colonial ◽  
The Mean ◽  
As Effects ◽  
Magnetic Disturbances

The laws manifested by the mean effects of the larger magnetic disturbances (regarded commonly as effects of magnetic storms) have been investigated at several stations on the globe, being chiefly those of the British Colonial Observatories; but hitherto there has been no similar examination of the phenomena in the British Islands themselves. The object of the present paper is to supply this deficiency, as far as one element, namely the declination, is concerned, by a first approximation derived from the photographs in the years 1858 and 1859, of the self-recording declinometer of the observatory of the British Association at Kew; leaving it to the photographs of subsequent years to confirm, rectify, or render more precise the results now obtained by a first approximation. The method of investigation is simple, and may be briefly described as follows:— The photographs furnish a continuous record of the variations which take place in the direction of the declination-magnet, and admit of exact measurement in the two relations of time, and of the amount of departure from a zero line. From this automatic record, the direction of the magnet is measured at twenty-four equal intervals of time in every solar day, which thus become the equivalents of the “hourly observations” of the magnetometers in use at the Colonial Observatories. These measures, or hourly directions of the magnet, are entered in monthly tables, having the days of the month in successive horizontal lines, and the hours of the day m vertical columns. The “means” of the entries in each vertical column indicate the mean direction of the magnet at the different hours of the month to which the table belongs, and have received the name of “First Normals.” On inspecting any such monthly table, it is at once seen that a considerable portion of the entries in the several columns differ considerably from their respective means or first normals, and must be regarded as “disturbed observations” The laws of their relative frequency, and amount of disturbance, in different years, months and hours, are then sought out, by separating for that purpose a sufficient body of the most disturbed observations, computing the amount of departure in each case from the normal of the same month and hour, and arranging the amounts in annual, monthly, and hourly tables. In making these computations, the first normals require to be themselves corrected, by the omission in each vertical column of the entries noted as disturbed, and by taking fresh means, representing the normals of each month and hour after this omission, and therefore uninfluenced by the larger disturbances. These new means have received the name of “Final Normals,” and may be defined as being the mean directions of the magnet in every month and every hour, after the omission from the record of every entry which differed from the mean a certain amount either in excess or in defect.

II. On the lunar-diurnal variation of the magnetic declination with special regard to the Moon’s declination

1867 ◽  
Vol 15 ◽  
pp. 414-416
Keyword(s):  
Diurnal Variation ◽  
Magnetic Element ◽  
Special Regard ◽  
The North ◽  
Magnetic Declination ◽  
At Command ◽  
Magnetic Disturbances ◽  
North End

The hourly records of the magnetic declination systematically kept at the Flagstaff Observatory at Melbourne, Victoria, during the period from the 1st of May 1858 to the 28th of February 1863, have been discussed by the author, with a view to determine the lunar-diurnal variation to which that magnetic element is subject. The results arrived at in the course of, this discussion elicit, he believes, facts hitherto unnoticed, to which it seems desirable that the attention of scientific men should be directed. The process employed in reducing the observations was identical with at generally adopted in such cases. The disturbed observations were first eliminated, by rejecting all that differed from the final normal belonging to the same solar hour by more than a certain separating value, which ts taken at 3·61 minutes of arc. The elimination of the larger disturbances having been thus effected, from every remaining reading (R ) of the magnet’s direction the final normal (N ) belonging to that solar hour was subtracted, so that the residue R—N is devoid of the influence of the solar-diurnal variation. This residue is positive when the north end of the needle is to the east of its mean position, and negative in the contrary case. The number of observations at command amounted to 38,194, of which 4178 single observations were excluded from the discussion as being beyond the assumed limit used for separating the greater magnetic disturbances, leaving 34,016 available for the purpose of determining the lunar-diurnal variation.

scholarly journals II. On the simultaneity of magnetic variations at different places on occasions of magnetic disturbance, and on the relation between magnetic and earth current phenomena

1892 ◽  
Vol 51 (308-314) ◽  
pp. 445-446 ◽  
Keyword(s):  
Diurnal Variation ◽  
Magnetic Storms ◽  
Magnetic Disturbance ◽  
Progressive Change ◽  
Magnetic Elements ◽  
Sun Spots ◽  
Magnetic Disturbances

In this paper the author refers to the ordinary variations of the magnetic elements as observed at Greenwich; the annual progressive change; the diurnal variation—large in summer, small in winter, and also larger when sun spots are numerous and smaller when sun spots are few; the irregular magnetic disturbances and magnetic storms, and the accompanying earth currents; phenomena which are generally similar at other places.

scholarly journals IV. On the variations of the daily range of the magnetic declination as recorded at the Kew observatory

1878 ◽  
Vol 26 (179-184) ◽  
pp. 102-121 ◽  
Keyword(s):  
Magnetic Activity ◽  
Mean Value ◽  
The Other ◽  
Daily Range ◽  
Magnetic Declination ◽  
Angular Change ◽  
The Mean

1. The daily range of the magnetic declination at any station may perhaps be regarded as a convenient representative of the magnetic activity of the place. For while a thorough discussion of the diurnal magnetic changes must embrace along with the declination the two components of the force, yet, as regards such daily ranges, the declination gives results which are not only more prominent but also more easily procurable and subject to fewer uncertainties than similar ones for the other two elements. In estimating the daily range of the magnetic declination, as recorded at the Kew Observatory, I have excluded the disturbed observations, conceiving that by so doing a better indication of the true magnetical activity of the place would be obtained than by including them, inasmuch as they follow a very different set of laws from that of the well-known diurnal declination-range. The disturbed observations have been separated by the method of Sir E. Sabine, those being rejected as disturbed for which the measurements on the photographic curve are 0⋅150 inch either above or below the mean value for that month and hour, one inch denoting 22′⋅04 of angular change. The daily ranges are here given in inches, and they denote the differences between the greatest and least values of each day’s hourly tabulations from the curve, disturbances being excluded. I am indebted to the kindness of the Kew Committee for giving me the daily ranges herein discussed, extending from the beginning of 1858 to the end of 1873, thus embracing in all sixteen years’ observations.

scholarly journals IV. On the variations of the diurnal range of the magnetic declination as recorded at the Prague observatory

1878 ◽  
Vol 27 (185-189) ◽  
pp. 389-402
Keyword(s):  
Mean Values ◽  
Magnetic Declination ◽  
Diurnal Range ◽  
The Hours ◽  
The Mean ◽  
The Difference ◽  
Magnetic Disturbances

1. The Prague magnetic observations began in July, 1839, and have been continued until the present date. The observation hours, 18h., 22h., 2h., 10h., are common to the whole series, except for the year 1853, during which observations were made only at the hours 8h., 2h., 10h. As far, however, as the estimation of the diurnal range of magnetic declination is concerned, these last three hours are practically as good as the former four, inasmuch as the observations at 22h. are hardly ever made use of in determining the diurnal range. In the determinations herein recorded, magnetic disturbances are included, and the range is a mean monthly one, obtained by comparing together the mean values of the magnetic declination, corresponding to the hours 18h., 22h., 2h., 10h., for any given month, and taking the difference between the highest and the lowest of these values as representing the mean range for that month. There is reason to believe that the ranges thus obtained are not greatly different from those which would have been obtained from an hourly series of observations.

scholarly journals On periodical laws discoverable in the mean effects of the larger magnetic disturbances

1854 ◽  
Vol 6 ◽  
pp. 30-32 ◽  
Keyword(s):  
Royal Society ◽  
Magnetic Storms ◽  
Long Duration ◽  
The Press ◽  
The Hours ◽  
Different Seasons ◽  
The Subject ◽  
The Mean ◽  
Magnetic Disturbances ◽  
Made In

In a discussion of the two-hourly observations of the magnetic declination, made in 1841 and 1842 at the observatories of Toronto and Hobarton, published in 1843 and 1845, the author expressed an opinion that themagneticdisturbances,of largeamountand apparently irregular occurrence, commonly called magnetic storms or shocks, would be found, when studied in their mean effects on the magnetic direction and force extending over a sufficient period of time, to be subject to periodical laws , connecting them with the seasons of the year and the hours of the day at the particular stations. In preparing for the press the hourly observations of the declination in the years 1843, 1844 and 1845, at the same two stations, the author found his previous opinions strongly confirmed; and believing that the evidence thus obtained of periodical laws is far too systematic, and rests on a series of too long duration to make it probable that it will be otherwise than confirmed by the continuation of the observations in subsequent years, he has been induced to make it the subject of a communication to the Royal Society; although it is probable that the exact periods, and the mean numerical values of the effects produced, or their proportions to each other in the different seasons and at the different hours, may hereafter receive modifications.

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