scholarly journals Magnetic declination at kew observatory, 1890-1900

1908 ◽  
Vol 80 (536) ◽  
pp. 113-113
Keyword(s):  
Diurnal Variation ◽  
Magnetic Declination ◽  
Large Disturbance

The paper deals with the phenomena exhibited by the magnetic declination at Kew from 1890 to 1900. The magnetograph curves have been measured on every day of this period, whether disturbed or undisturbed, and the data from days of the different species are contrasted. Diurnal inequalities are got out for ordinary days, excluding those of large disturbance, and separately for the highly disturbed days, and the differences between these, and the points wherein they differ from the corresponding inequalities from quiet days, are investigated. The disturbed days show a well-marked regular diurnal variation, which differs in many notable respects from that observed on ordinary days.

3. On the Lunar Diurnal Variation of Magnetic Declination at Trevandrum, near the Magnetic Equator

1872 ◽  
Vol 7 ◽  
pp. 756-758
Author(s):  
J. A. Broun
Keyword(s):  
Diurnal Variation ◽  
Diurnal Variations ◽  
Magnetic Equator ◽  
Magnetic Declination ◽  
The Law ◽  
The Times

The author gives the results derived from different discussions of nearly eighty thousand observations, made hourly during the eleven years 1854 to 1864. They are as follows:—1. That the lunar diurnal variation consists of a double maximum and minimum in each month of the year.2. That in December and January the maxima occur near the times of the moon's upper and lower passages of the meridian; while in June and July they occur six hours later, the minima then occurring near the times of the two passages.3. The change of the law for December and January to that for June and July does not happen, as in the case of the solar diurnal variations, by leaps in the course of a month (those of March and October), but more or less gradually for the different maxima and minima.

scholarly journals II. On the lunar diurnal variation of magnetic declination at the magnetic equator

1860 ◽  
Vol 10 ◽  
pp. 475-484
Keyword(s):  
Diurnal Variation ◽  
Careful Consideration ◽  
Magnetic Equator ◽  
Careful Examination ◽  
The Sun ◽  
The Moon ◽  
Magnetic Declination ◽  
The Law

This variation, first obtained by M. Kreil, next by myself, and afterwards by General Sabine, presents several anomalies which require careful consideration, and especially a careful examination of the methods employed to obtain the results. The law obtained seems to vary from place to place even in the same hemisphere and in the same latitude, and this to such an extent, that, for example, when the moon is on the inferior meridian at Toronto it produces a minimum of westerly declination; while for the moon on the inferior meridian of Prague and Makerstoun in Scotland it produces a maximum of westerly declination. No two places have as yet given exactly the same result; though the result for each place has been confirmed by the discussion of different periods. In order to obtain the lunar diurnal action, it has been usual to consider the magnetic declination at any time as depending on the sun’s and moon’s hour-angles and on irregular causes. Thus, if at conjunction, H 0 be the variation due to the sun on the meridian, and h 0 be that due to the moon on the meridian, H, the variation for the sun at 1 h , h 1 for the moon on the meridian of 1 h , and so on; it is supposed that we may represent the variations for a series of days by the following expressions, where the nearest values of h to the whole hour-angles are given:-

scholarly journals On the diurnal variation of the magnetic declination of St. Helena

1851 ◽  
Vol 5 ◽  
pp. 664-664
Keyword(s):  
Diurnal Variation ◽  
Northern Hemisphere ◽  
Opposite Direction ◽  
Diurnal Variations ◽  
The Sun ◽  
The Earth ◽  
Magnetic Declination ◽  
St Helena ◽  
Magnetic Needle

It has long been known that the diurnal variation of the magnetic needle is in an opposite direction in the southern, to what it is in the northern hemisphere; and it was therefore proposed as a pro­blem by Arago, Humboldt and others, to determine whether there exists any intermediate line of stations on the earth where those diurnal variations disappear. The results recorded in the present paper are founded on observations made at St. Helena during the five consecutive years, from 1841 to 1845 inclusive; and also on similar observations made at Singapore, in the years 1841 and 1842; and show that at these stations, which are intermediate between the northern and southern magnetic hemispheres, the diurnal variations still take place; but those peculiar to each hemisphere prevail at opposite seasons of the year, apparently in accordance with the position of the sun with relation to the earth’s equator.

scholarly journals Remarks on M. De la Rive’s theory for the physical explanation of the causes which produce the diurnal variation of the magnetic declination. In a letter to S. Hunter Christie, Esq., Sec. R. S., from Lieut.-Col. Sabine, For. Sec. R. S. Communicated by S. Hunter Christie, Esq

1851 ◽  
Vol 5 ◽  
pp. 821-825
Keyword(s):  
Diurnal Variation ◽  
Royal Society ◽  
Exact Methods ◽  
Physical Explanation ◽  
Cape Of Good Hope ◽  
Magnetic Declination ◽  
St Helena ◽  
Physical Principles ◽  
Magnetic Observatories ◽  
Recent Establishment

My dear Sir, The Annales de Chimie et de Physique for March last contains a letter from M. De la Rive to M. Arago, in which a theory is proposed, professing to explain on physical principles the general phenomena of the diurnal variation of the magnetic declination, and, in particular, the phenomena observed at St. Helena and at the Cape of Good Hope, described in a paper communicated by me to the Royal Society in 1847, and which has been honoured with a place in the Philosophical Transactions. Although I doubt not that the inadequacy of the theory proposed by M. De la Rive for the solution of this interesting problem will be at once recognised by those who have carefully studied the facts which have become known to us by means of the exact methods of investigation adopted in the magnetic observatories of recent establishment, yet there is danger that the names of De la Rive and Arago, held in high and deserved estimation as authorities on such subjects, attached to a theory, which moreover claims reception on the ground of its accordance with “well-ascertained facts” and “with principles of physics positively established,” may operate prejudicially in checking the inquiries which may be in progress in other quarters into the causes which really occasion the phenomena in question; I have thought it desirable therefore to point out, in a very brief communication, some of the important particulars in which M. De la Rive’s theory fails to represent correctly the facts which it professes to explain, and others which appear to me to be altogether at variance with, and opposed to it.

scholarly journals II. On the law of disturbance and the range of the diurnal variation of magnetic declination near the magnetic equator, with reference to the moon’s hour-angle

1862 ◽  
Vol 11 ◽  
pp. 298-302
Keyword(s):  
Diurnal Variation ◽  
Magnetic Equator ◽  
Magnetic Declination ◽  
The Law

The discovery by Dr. Lamont of a "decennial” period in the range of the solar diurnal variation of magnetic declination, naturally leads to the question whether a similar law may not exist for the lunar diurnal variation; the question is also of importance in connexion with the theory of the cause of these variations.

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.

XXIV.—On the Lunar Diurnal Variation of Magnetic Declination at Trevandrum, near the Magnetic Equator, deduced from Observations made in the Observatory of His Highness the Maharajah of Travancore, G.C.S.I.

1872 ◽  
Vol 26 (4) ◽  
pp. 735-757
Author(s):  
J. A. Broun
Keyword(s):  
Diurnal Variation ◽  
Magnetic Force ◽  
Horizontal Component ◽  
Magnetic Equator ◽  
Horizontal Force ◽  
Magnetic Declination ◽  
Magnetic Needle ◽  
Made In

1. The lunar diurnal variation of magnetic declination as first discovered by Kreil, depended on too few observations to be free from the errors introduced by irregular disturbing causes. The independent discovery of the lunar action on the magnetic needle made afterwards by myself, was liable to the same criticism; but the agreement of the results obtained, both for the magnetic declination and the horizontal force, was sufficiently great to give a considerable value to the conclusion, that the magnetic needle obeys a diurnal law, depending on the moon's hour angle, both as to its direction and the force with which it is directed. This conclusion was farther confirmed in the discussion first made by myself, for the lunar diurnal variation of the vertical magnetic force, which gave, within an hour, the same epochs of maxima and minima as those obtained previously by me for the horizontal component.

III. On the lunar-diurnal variation of the magnetic declination obtained from the Kew photograms in the Years 1858, 1859, and 1860

1862 ◽  
Vol 11 ◽  
pp. 73-80
Keyword(s):  
Diurnal Variation ◽  
Royal Society ◽  
Magnetic Declination

Having communicated to the Royal Society in a recent paper an analysis of the disturbances of the declination in the years 1858 and 1859, shown by the photograms of the Kew Observatory, I propose in the present paper to submit the results of the lunar-diurnal variation of the declination in the years 1858, 1859, and 1860, obtained from the same source. The directions of the declination magnet at the instant of the commencement of every solar-hour having been tabulated from the photograms, and the final normals for each month and hour computed, after the omission from the record of all the hourly directions which deviated 3'·3 from their final normals,—the differences were taken between each of the remaining hourly directions and the final normal of the same month and hour, and were entered afresh in lunar monthly tables, having the lunar days in successive horizontal lines, and the twenty-four lunar hours in vertical columns, each difference being placed under the lunar hour to which it most nearly approximated.

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