XXVIII. On the annual variation of the magnetic declination, at different periods of the day

1851 ◽  
Vol 141 ◽  
pp. 635-641 ◽  
Keyword(s):  
Diurnal Variation ◽  
Annual Variation ◽  
Graphical Representation ◽  
Diurnal Variations ◽  
Horizontal Line ◽  
Annual Variations ◽  
The North ◽  
Magnetic Declination ◽  
Annual Range ◽  
The Mean

The interest which papers recently communicated to the Royal Society have excited in regard to the physical explanation of the Annual and Diurnal Variations of Terrestrial Magnetism, makes it extremely desirable that the facts which are to be explained should in the first instance be clearly and fully comprehended; and that for this purpose, the different classes of facts, which undergo much additional complication by being viewed together, should be distinguished apart, and that each class should be presented separately, combining at the same time, as far as circumstances may permit, facts of the same class obtained from different parts of the globe. Under this impression I have deemed that an acceptable service might be rendered, by arranging in a small compass and presenting together the Annual Variations which the Magnetic Declination undergoes at every hour of the day at the four Colonial Observatories established by the British Government at Toronto, Hobarton, the Cape of Good Hope and St. Helena;—stations selected, it may be remembered, with the express view (amongst others) of affording, as far as any four stations of equally convenient access might be expected to do, the means of generalizing the facts of the Annual and Diurnal Variations in different quarters of the globe. I have attempted to accomplish this object by a graphical representation (Plate XXVI.), in which the Annual Variation at every hour is shown by vertical lines varying in length according to the amount of the range of the Annual Variation at each hour; each line having also small cross lines marking the mean positions of the several months in the annual range. The scale is the same for all the stations, being one inch to one minute of declination. The declination is that of the north end of the magnet at all the stations; the upper end of the line is always the eastern extremity, and the lower end the western extremity, of the annual range. The broken horizontal line which crosses all the verticals at each station, marks for each of the observation hours the mean declination in the year at that particular hour, obtained by adding together the daily observations of the declination at that hour, and dividing the sum by the number of days of observation in the year. This line is consequently not a line of uniform declination-value throughout, because the mean declination varies at different hours, by quantities which constitute the mean Diurnal Variation: but it is the line, or curve as it is sometimes called, of mean Diurnal Variation projected as a straight line, for the parpose of viewing the phenomena of the Annual Variation at each hour, irrespective of the Diurnal Variation, or the changes which the mean declination undergoes at different hours. The hours are those of mean solar time at each station, the day commencing at noon, and being reckoned through the twenty-four hours; noon is therefore = 0 h . The fractional minutes are occasioned by the observations having been made at the exact hours of Göttingen time, which differ more or less at each station from exact hours of local time.

scholarly journals On the annual variation of the magnetic declination, at different periods of the day

1854 ◽  
Vol 6 ◽  
pp. 73-74
Keyword(s):  
Annual Variation ◽  
Graphical Representation ◽  
Horizontal Line ◽  
Annual Variations ◽  
Cape Of Good Hope ◽  
Magnetic Declination ◽  
Annual Range ◽  
The Hours ◽  
The Mean ◽  
St Helena

In this communication the author has arranged and presented together the Annual variations which the magnetic declination undergoes at every hour of the day at the four Colonial Observatories established by the British government, at Toronto, Hobarton, the Cape of Good Hope and St. Helena. This has been done by means of a graphical representation, in which the annual variations at every hour are shown by vertical lines varying in length according to the amount of the range of the annual variation at each hour; each line having also small cross lines marking the mean positions of the several months in the annual range. The mean declination in the year at the respective hours is marked by a horizontal line which crosses all the verticals at each station. The hours are those of mean solar time at each station, the day commencing at noon.

I. On the lunar variations of magnetic declination at Bombay

1872 ◽  
Vol 20 (130-138) ◽  
pp. 135-136
Keyword(s):  
Diurnal Variation ◽  
Relative Position ◽  
Diurnal Variations ◽  
The Sun ◽  
The Moon ◽  
Feature Correspondence ◽  
Magnetic Declination ◽  
Variation Curve ◽  
Ordinary Character ◽  
The Mean

This paper is in continuation of that “On the Solar Variations of Magnetic Declination at Bombay,” published in the Philosophical Transactions for 1869; but the discussion is confined to the observations of the years 1861 to 1863, which alone have as yet been reduced. The point of principal interest brought out in the discussion is that whilst the mean lunar-diurnal variation is of the ordinary character, having as its principal feature a double oscillation in the lunar day, its range is very small as compared with the several ranges of the lunar-diurnal variations when the sun and moon have several specific varieties of relative position; and moreover, although in those latter variations the double oscillation is generally preserved as a main feature, correspondence of phase in the representative curves is as generally absent; and in some cases the curves are, whilst systematic, altogether different in character from the mean lunar-diurnal variation curve. The semiannual inequality in the lunar-diurnal variation, whilst it is as definitely systematic, has twice the range of the mean lunar, diurnal variation; and it is also subject to remarkable modifications which accompany changes of phase of the moon.

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.

4. Results of Makerstoun Observations, No. III. On the Solar and Lunar periods of the Magnetic Declination.

1851 ◽  
Vol 2 ◽  
pp. 144-145
Author(s):  
J. A. Broun
Keyword(s):  
The North ◽  
Magnetic Declination ◽  
The Mean ◽  
The Absolute ◽  
Annual Period ◽  
North End

The absolute westerly declination at Makerstoun, for the mean epoch, June 1844 = 25° 17′·12.The annual motion of the north end of the needle towards the east = 5′·67.The annual periodof magnetic declination consists of a double oscillation, having nearly the following epochs of maxima and minima.

I. On the solar-diurnal variation of the magnetic declination at Pekin

1860 ◽  
Vol 10 ◽  
pp. 360-374
Keyword(s):  
Diurnal Variation ◽  
First Year ◽  
Magnetic Observatory ◽  
Magnetic Element ◽  
Monthly Means ◽  
The North ◽  
The Hours ◽  
The Mean ◽  
The Times ◽  
North End

When the first year of hourly observations of the declination, January 1 to December 31st, 1841, was received at Woolwich from the Magnetic Observatory at Hobarton, and when means had been taken of the readings of the collimator-scale at the several hours in each month, and these monthly means had been collected into an­nual means, it was found that the mean daily motion of the declina­tion magnet at Hobarton presented, as one of its most conspicuous and well-marked features, a double progression in the twenty-four hours, moving twice from west to east, and twice from east to west; the phases of this diurnal variation were, that the north end of the magnet moved progressively from west to east in the hours of the forenoon, and from east to west in the hours of the afternoon ; and again from west to east during the early hours of the night, return­ing from east to west during the later hours of the night: the two easterly extremes were attained at nearly homonymous hours of the day and night, as were also the two westerly extremes; the ampli­tudes of the arcs traversed during the hours of the day were con­siderably greater than those traversed during the hours of the night. When, in like manner, the first year of hourly observations, July 1st, 1842, to June 30th, 1843, was received from the Toronto Ob­servatory, and the mean diurnal march of the declination magnet was examined, it was found to exhibit phenomena in striking corre­spondence with those at Hobarton. At Toronto also a double pro­gression presented itself, of which the easterly extremes were attained at nearly homonymous hours, as were also the westerly; whilst the hours of extreme elongation were nearly the same (solar) hours at the two stations, but with this distinction, that the hours at which the north end of the magnet reached its extreme easterly elongation at Hobarton were the same, or nearly the same, as those at which it reached its extreme westerly elongation at Toronto, and vice verâ Pursuing, therefore, the ordinary mode of designating the direction of the declination by the north end of the magnet in the southern as well as in the northern hemisphere, the diurnal motion of the magnet may be said to be in opposite directions at Hobarton and Toronto; but if (in correspondence with our mode of speaking in regard to another magnetic element, the Inclination) the south end of the magnet is employed to designate the direction of the motion in the southern hemisphere, and the north end in the northern hemisphere, the apparent contrariety disappears, and the directions, as well as the times of the turning hours, are approximately the same at both stations.

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.

PLASMA INSULIN AND GROWTH HORMONE IN DAIRY COWS; DIURNAL VARIATION AND RELATION TO FOOD INTAKE AND PLASMA SUGAR AND ACETOACETATE LEVELS

1973 ◽  
Vol 73 (2) ◽  
pp. 289-303 ◽  
Author(s):  
Knut Hove ◽  
Anne Kristine Blom
Keyword(s):  
Growth Hormone ◽  
Food Intake ◽  
Diurnal Variation ◽  
Dairy Cows ◽  
Plasma Levels ◽  
Plasma Insulin ◽  
Diurnal Variations ◽  
Plasma Growth Hormone ◽  
The Mean ◽  
Different Levels

ABSTRACT Marked diurnal variations were found in plasma growth hormone (GH), insulin, acetoacetate (AcAc) and sugar in two herds (U and A) of dairy cows kept at two different levels of feeding. Seven animals from each herd were tested. The main diurnal variations were related to food intake, a significant increase in plasma insulin, and a significant decrease in plasma sugar being found. The acetoacetate level rose significantly during feeding in herd U (moderately underfed), while no significant increase was found in herd A (adequately fed). Plasma growth hormone was found to decrease (P < 0.01) only during feeding in herd U, while no change in the GH level could be detected in herd A. The mean level of GH in herd U was found to be twice the value found in herd A. There were no significant differences between the herds in plasma insulin and sugar. Significant differences in plasma levels of GH, insulin and sugar were found between animals when analysed within the herds. Variations in the levels of insulin and acetoacetate were very small during the night. This is contrary to GH, which shows the least variation during food intake. The correlation coefficient between the plasma components was low, although in many cases significant.

scholarly journals On the meteorological observations made at the apartments of the Royal Society, during the year 1827, 1828, and 1829

1837 ◽  
Vol 3 ◽  
pp. 42-43
Keyword(s):  
Royal Society ◽  
Limited Range ◽  
Diurnal Variations ◽  
The Moon ◽  
French Academy ◽  
Annual Variations ◽  
The Mean ◽  
Meteorological Observations ◽  
Academy Of Sciences

The author first inquires into the annual and diurnal variations of the barometer and thermometer, for the determination of which he takes the mean of the observations in each month made at the Apartments of the Royal Society, during the years 1827,1828, and 1829; and also that deduced from Mr. Bouvard’s observations, published in the Memoirs of the French Academy of Sciences. From the table given it would appear that the annual variations are independent of the diurnal variations. A much greater number of observations than we possess at present, made frequently and at stated times each day, are requisite before any very satisfactory conclusion can be deduced as to the influence of the moon on the fluctuations of the barometer. The author, however, has attempted the inquiry, as far as the limited range of the present records will allow, by classifying all the observed heights, corresponding to a particular age of the moon, as defined by her transit taking place within a given half hour of the day; and thence deducing mean results, which are exhibited in tables. The results afforded by the observations at Somerset House differ widely from those obtained from corresponding observations made at the Paris Observatory. According to the former, the barometer is highest at new and full moons, and lowest at the quadratures the extent of the fluctuations being 0.08 of an inch: according to the lottery the controly is the esse, and the extent is only 0.05 of an inch.

scholarly journals Diurnal and annual variations of meteor rates at the Arctic circle

2004 ◽  
Vol 4 (1) ◽  
pp. 1-20 ◽  
Author(s):  
W. Singer ◽  
J. Weiß ◽  
U. von Zahn
Keyword(s):  
Diurnal Variations ◽  
The Arctic ◽  
Noctilucent Cloud ◽  
Arctic Circle ◽  
Annual Cycles ◽  
Annual Variations ◽  
The North ◽  
Radar Antenna ◽  
Metal Layers ◽  
Antenna Field

Abstract. Meteors are an important source for (a) the metal atoms of the upper atmosphere metal layers and (b) for condensation nuclei, the existence of which are a prerequisite for the formation of noctilucent cloud particles in the polar mesopause region. For a better understanding of these phenomena, it would be helpful to know accurately the annual and diurnal variations of meteor rates. So far, these rates have been little studied at polar latitudes. Therefore we have used the 33 MHz meteor radar of the ALOMAR observatory at 69° N to measure the meteor rates at this location for two full annual cycles. This site, being within 3° of the Arctic circle, offers in addition an interesting capability: The axis of its antenna field points (almost) towards the North ecliptic pole once each day of the year. In this particular viewing direction, the radar monitors the meteoroid influx from (almost) the entire ecliptic Northern hemisphere. We report on the observed diurnal variations (averaged over one month) of meteor rates and their significant alterations throughout the year. The ratio of maximum over minimum meteor rates throughout one diurnal cycle is in January and February about 5, from April through December 2.3±0.3. If compared with similar measurements at mid-latitudes, our expectation, that the amplitude of the diurnal variation is to decrease towards the North pole, is not really borne out. Observations with the antenna axis pointing towards the North ecliptic pole showed that the rate of deposition of meteoric dust is substantially larger during the Arctic NLC season than the annual mean deposition rate. The daylight meteor showers of the Arietids, Zeta Perseids, and Beta Taurids supposedly contribute considerably to the June maximum of meteor rates. We note, though, that with the radar antenna pointing as described above, all three meteor radiants are close to the local horizon. This radiant location should cause most of these shower meteors to occur above 100 km altitude. In our observations, the June maximum in meteor rate is produced, however, almost exclusively by meteors below 100 km altitude.

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.

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