scholarly journals On irregularities observed in the direction of the compass needles of H. M. S. Isabella and Alexander, in their late voyage of discovery, and caused by the attraction of the iron contained in the ships

1833 ◽  
Vol 2 ◽  
pp. 109-109
Keyword(s):  
Magnetic Meridian ◽  
Magnetic Needle ◽  
Made In

In this paper Captain Sabine shows in what respect the effects of local attraction in the above-mentioned ships were conformable to observations made in previous voyages; and how far the errors found to take place on different courses, and under different dips of the magnetic needle, corresponded with those rules for calculating corrections recommended by Captain Flinders, who found that in every ship a compass would differ very materially from itself on being removed from one place to another, and this was found to be the case in the Isabella and Alexander. As the ships ascended Davis’s Straits, the binnacle compasses, in consequence of their construction, became nearly useless; accordingly, a standard compass was placed in the Isabella exactly amidship between the main and mizen mast, on a stout cross-beam, about nine feet above the deck; and in the Alexander amidship, on a box of sand five or six feet above deck. Captain Sabine next describes the methods by which the points of no error in these compasses were determined, and which were not in either ship coincident with the magnetic meridian.

scholarly journals The Bakerian Lecture. An account of experiments to determine the amount of the dip of the magnetic needle London, in August 1821; with remarks on the instruments which are usually employed in such determinations

1833 ◽  
Vol 2 ◽  
pp. 155-156
Keyword(s):  
Nursery Ground ◽  
The North ◽  
The Subject ◽  
The Difference ◽  
Regent's Park ◽  
The Times ◽  
Magnetic Meridian ◽  
Magnetic Needle ◽  
Source Of Error ◽  
Made In

After describing the imperfections of the instruments in general use for ascertaining the dip of the magnetic needle, and adverting to the consequent inaccuracy and insufficiency of the observations made with them, Captain Sabine gives an account of the form of dipping-needle which he preferred for his experiments, and which was con­structed for him by Mr. Dollond, upon principles laid down by Pro­fessor Meyer, of Gottingen. He then enters into minute details of the mode of pursuing and verifying his observations, the results of which, gained by three different methods, are as follows: viz. by 10 experiments with Meyer’s needle, 70° 2'.9; by the times of oscil­lation in the magnetic meridian, and in the plane perpendicular to it (mean by three needles), 70° 04'; by the times of vertical and hori­zontal oscillation, 7° 02'.6. So that 70° 03' may be considered as the mean dip of the needle towards the north, in August and Sep­tember 1821, within four hours of noon, being the limit within which all the experiments were made. Alluding to former observations for the purpose of determining the dip in London, the author observes that, independent of any im­perfection in the instruments, they were made in houses in close built parts of the metropolis, and, therefore, all subject to the in­fluence of local attraction; and, moreover, that the correction found by observing the difference of the dip on the outside of the house cannot be regarded as an effectual remedy, inasmuch as the needle may still have been attracted by iron in the adjoining houses, or in the neighbourhood. It is, indeed, only requisite to try needles in different situations in a city, to be convinced how little dependence should be placed in the accuracy of such results: the author thinks that it is rather owing to this cause than to instrumental error, that the dip at the Apartments of the Royal Society is stated in the Phi­losophical Transactions for the present year to be 71° 06'. To avoid this source of error, Captain Sabine conducted the observations which form the subject of this lecture in the nursery-ground in the Regent’s Park, a situation which he regards in all respects eligible, and far removed from the influence of iron.

scholarly journals Note on a simultaneous disturbance of the barometer and of the magnetic needle

1877 ◽  
Vol 25 (171-178) ◽  
pp. 90-91
Keyword(s):  
Terrestrial Magnetism ◽  
Magnetic Needle ◽  
Made In

As any question of the connexion between the different phenomena of nature may be of interest, I will venture to call attention to an observation made, in February last, in China, which tends to establish a fresh link between terrestrial magnetism and meteorology. From the curves that accompany this note (p. 91), it would seem that the same cause may be capable of producing a simultaneous perturbation of the barometer and of the suspended magnets.

scholarly journals I.—Account of some Experiments made in Different Parts of Europe, on Terrestrial Magnetic Intensity, particularly with reference to the Effect of Height

1839 ◽  
Vol 14 (1) ◽  
pp. 1-29 ◽  
Author(s):  
James D. Forbes
Keyword(s):  
Royal Society ◽  
Horizontal Plane ◽  
Magnetic Intensity ◽  
Magnetic Needle ◽  
Different Parts ◽  
Made In

1. The Council of the Royal Society of Edinburgh having, on my application in 1832, entrusted me with Hansteen's Magnetic Intensity Apparatus, in their possession, I feel it to be my duty to communicate to the Society the results then and subsequently obtained with it.2. The instrument consists of a mahogany box 5 inches long, 4 broad, and 2 deep, with sides and top of glass, having also a wooden tube, screwing into the top, for containing a silk-worm's fibre about 5 inches long, by which the magnetic needle is suspended so as to place itself horizontally, and after being caused to deviate from its point of rest, the time of any given number of oscillations in a horizontal plane is measured,—whilst a graduated circle in the bottom of the box indicates its arc of vibration.

scholarly journals Theory of the diurnal variation of the magnetic needle, illustrated by experiments

1833 ◽  
Vol 2 ◽  
pp. 321-323
Keyword(s):  
Diurnal Variation ◽  
Small Scale ◽  
The Sun ◽  
Partial Heating ◽  
Similar Idea ◽  
Magnetic Meridian ◽  
Magnetic Needle ◽  
Magnetic Phenomena

Mr. Christie having been led to doubt the validity of the explanation of the moving easterly variation adopted by Canton, but at the same time having observed that the changes in deviation and intensity appear always to have reference to the position of the sun with regard to the magnetic meridian, was led to connect these phenomena with Professor Seebeck’s discovery of thermo-magnetism, and Professor Cumming’s subsequent experiments; and to refer the phenomena of diurnal variation to the effect of partial heating, modified, perhaps, by that of rotation, and by peculiar influence in the sun’s rays. In support of this opinion, he cites passages from papers by Professor Cumming and Dr. Traill, whom a similar idea appears also to have impressed. But in place of looking to the stony strata, of which the earth’s surface consists, as the elements of the thermo-magnetic apparatus which this doctrine requires, the author regards them as rather consisting of the atmosphere and the surfaces of land and water with which it is in contact. Thermo-magnetic phenomena, he remarks, have hitherto only been observed in metallic combinations, but this may be owing merely to the small scale on which our experiments are conducted.

On the position of the north magnetic pole

1837 ◽  
Vol 3 ◽  
pp. 254-254 ◽  
Keyword(s):  
Vertical Position ◽  
Magnetic Pole ◽  
The North ◽  
The Earth ◽  
North Magnetic Pole ◽  
To Come ◽  
Magnetic Poles ◽  
Magnetic Needle ◽  
Made In

The author remarks that the discordances in former observations made with a view to determine the position of the magnetic pole, have arisen partly from the irregularity of distribution in the earth of the substances which exert magnetic power, and partly from the great distances from the magnetic poles at which these observations have been made. The latter cause of uncertainty has been now, in a great measure, removed, by the numerous and accurate observations made during the late arctic expeditions. The object of the present paper is to put on record those which were made in the last voyage of Captain Ross, in which a spot was reached corresponding to the true north magnetic pole on the surface of the earth. The nature of the instruments, and the difficulties encountered in their practical employment, under the circumstances of the expedition, are fully stated. Having arrived, on the 1st of June, at north latitude 70° 5' 17", and west longitude 96° 45' 48", the horizontal magnetic needle exhibited no determinate directive tendency, and the dipping needle was within a minute of the vertical position, a quantity which may be supposed to come within the limits of the errors of observation; hence the author concludes that this spot may be considered as the true magnetic pole, or as a very near approximation to it, as far, at least, as could be ascertained with the limited means of determination of which he was then in possession. A table of the observations, including those on the intensity of the magnetic force at various stations, is subjoined.

scholarly journals XXI. Theory of the diurnal variation of the magnetic needle, illustrated by experiments

1827 ◽  
Vol 117 ◽  
pp. 308-354 ◽  
Keyword(s):  
Diurnal Variation ◽  
Considerable Effect ◽  
Subsequent Paper ◽  
The Sun ◽  
Influence Of Temperature ◽  
Terrestrial Magnetism ◽  
The Subject ◽  
Magnetic Meridian ◽  
Magnetic Needle

In a Paper published in the Transactions for 1823, I stated my opinion, that the diurnal variation of the needle was probably due to the influence of temperature, but that the principle adopted by Canton would not account for the morning easterly variation. In a subsequent paper, I pointed out that the changes in direction and intensity appeared always to have a reference to the position of the sun with regard to the magnetic meridian ; the direction of the needle being undisturbed nearly at the time the sun passed that meridian; and the horizontal intensity being the least at the same time. Having taken this view of the subject previously to my being aware of Dr. Seebeck's discovery, that magnetical phenomena will arise from a disturbance in the equilibrium of temperature, my knowledge of that discovery and of subsequent experiments, particularly those of Professor Cumming, confirmed me in the opinion, that temperature must have a considerable effect in producing some of the phenomena of terrestrial magnetism, although I considered that this influence might be modified by the effects produced by rotation, or by peculiar influence in the sun's rays.

scholarly journals VIII. On irregularities observed in the direction of the compass needles of H. M. S. Isabella and Alexander, in their late voyage of discovery, and caused by the attraction of the iron contained in the ships

1819 ◽  
Vol 109 ◽  
pp. 112-122 ◽  
Keyword(s):  
Magnetic Needle ◽  
Made In

It is proposed in this paper to show in what respects the effects of local attraction, in the above mentioned ships, were conformable to the observations which had been made in preceding voyages; and how far the errors, which were found to take place on different courses, and under different dips of the magnetic needle, corresponded with the rules for calculating corrections, which Captain Flinders had found useful in his own experience, and which he had recommended for a more extensive trial. It may be desirable to premise, that the irregularities here alluded to, are not those accidental disturbances which may be caused by iron placed inadvertently too near the compasses ; but the permanent, and constant effect of the mass of iron contained in a ship, affecting its compasses at all times, and in a greater or less degree, according as its influence is more or less powerful, in comparison to the directive force of the earth's magnetism. That errors have always existed from this cause, may be inferred, from the uncertainty which ex­perience has attached to the results of azimuths observed in ships. The cause, however, appears to have been very long unsuspected, whilst its effects had produced a general impres­sion, that the azimuth compass was in itself an imperfect instrument, and only to be relied on within certain undefined and variable limits.

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.

scholarly journals III. On the annual variation of the magnetic declination

1874 ◽  
Vol 22 (148-155) ◽  
pp. 254-258
Keyword(s):  
Annual Variation ◽  
Modern Times ◽  
Magnetic Declination ◽  
The World ◽  
The Mean ◽  
Magnetic Needle ◽  
Different Parts ◽  
Made In

The first observations which seemed to show that the mean position of the declination-needle followed an annual law were those of Cassini, made, more than eighty years ago, in the hall of the Paris Observatory and in the caves below it (90 feet under ground). It cannot be said, however, that Cassini’s result has been confirmed by subsequent observations, either as regards the direction or amounts of movement from month to month. The extensive series of observations made in different parts of the world in modern times have given results so different that we must conclude either that the magnetic needle obeys different annual laws at each place, or that the differences are due to instrumental errors. The consequence has been that, after long, laborious, and expensive researches, it is still a question whether the magnetic needle obeys an annual law or not.

Concerning the differences in the magnetic needle, on board the investigator, arising from an alteration in the direction of the ship’s head. By Matthew Flinders, Esq. Commander of His Majesty’s Ship Investigator. In a letter to the Right Hon. Sir Joseph Banks, K. B. P. R. S

1832 ◽  
Vol 1 ◽  
pp. 187-188 ◽  
Keyword(s):  
South Coast ◽  
The South ◽  
The West ◽  
Magnetic Meridian ◽  
The Right ◽  
Magnetic Needle ◽  
Contrary Direction

In the years 1801 and 1802, while Capt. Flinders, on board the Investigator, was surveying the south coast of New Holland, he observed a difference in the direction of the magnetic needle, for which there appeared no other cause than that of the ship’s head being in a different direction. The compasses made use of on board the above mentioned ship were of Walker’s construction, one excepted, which was made by Adams; and it appears, from a table of observations given by Capt. Flinders, that some of the variations here treated of were 4° less, and others 4° greater than the truth. It also appears, that when this error was to the west, the ship’s head was to the east, or nearly so; when the error was eastward, the ship’s head was in a contrary direction; and when the observations agree best with those taken on shore, which may be considered as having the true variation, the ship’s head was nearly north or south. A minute inspection of the table seems to favour the opinion, that the excess or diminution of the variation was generally in proportion to the inclination of the ship’s head, from the magnetic meridian, on either side. Capt. Flinders, having ascertained the certainty of a difference in the compass, arising from an alteration in the point steered, thought it necessary, when he wanted a set of bearings from a point where the ship tacked, to take one set just before and another immediately after that operation. Several specimens of the manner in which these bearings were taken are given; also a specimen of the plan he followed in protracting such bearings: these specimens are in the form of tables, and are not of a nature to be abridged.

Sign in / Sign up

Export Citation Format

Share Document