scholarly journals III. Magnetical experiments and observations

1787 ◽  
Vol 77 ◽  
pp. 6-25
Keyword(s):  
Royal Society ◽  
Magnetic Needle

The Bakerian Lecture, which last year I had the honour to deliver to the Royal Society, contained the account of some magnetical experiments, particularly concerning the magnetism of brass, from which it appeared, that most brass becomes magnetic, so far as to attract the magnetic needle, by being hammered, and loses its magnetism by annealing or softening in the fire; but that there is some brass, which possesses no magnetism naturally, not acquires any by hammering.

Experiments on the influence of the aurora borealis on the magnetic needle. By the Rev. James Farquharson, F. R. S. Minister of Al­ford, Aberdeenshire. In letters addressed to Captain Edward Sa­bine, Sec. R. S

1833 ◽  
Vol 2 ◽  
pp. 391-392
Keyword(s):  
Royal Society ◽  
Magnetic Intensity ◽  
Aurora Borealis ◽  
Magnetic Declination ◽  
Stop Watch ◽  
The Mind ◽  
Magnetic Needle

In the first letter, dated from Alford, Dec. 15, 1829, the author gives a description of the instrument which was furnished to him by the Royal Society for measuring the variation of the magnetic needle, and also the magnetic intensity; and of his mode of using it. The needle was so delicately suspended as to render changes in the declination as small as 10'´ very sensible. In his experiments on the magnetic intensity, the intervals of time occupied in the needle’s performing 50 oscillations, commencing with an arc of 12°, were noted by a stop-watch, in which the stop, being applied on the ba­lance, is instantaneous in its operation. The watch is again released from the stop at the commencement of a new observation; thus com­pensating, on the principle of the repeating circle, for any inaccuracy in the reading off, or any inequality in the divisions of the dialplate. The observations made on an Aurora borealis which appeared on the night of the 14th of December, are particularly detailed. On that occasion, the disturbance of the magnetic declination was so great, and so frequently changing from east to west, and the reverse, as to leave no doubt in the mind of the author of the reality of this influence. The needle, however, was affected at those times only when the fringes of the aurora were in such a position as to include the needle in their planes. It appeared to him, also, that the side towards which the needle declined, was the quarter where the aurora gave out the most vivid light.

scholarly journals XXV. A letter from Mr. William Mountayne, F. R. S. to the Right Honourable James Earl of Morton, President of the Royal Society, containing some observations on the variation of the magnetic needle, made on board the Montagu Man of War, in the years 1760, 1761, and 1762, by Mr. David Ross, Surgeon

1766 ◽  
Vol 56 ◽  
pp. 216-223 ◽  
Keyword(s):  
Atlantic Ocean ◽  
Royal Society ◽  
The Earth ◽  
The Right ◽  
Magnetic Needle

My Lord, The following tables I have compared with the variation chart, published in the year 1756, and so find that they agree pretty well in general, making allowance for the time elapsed: it is true, that, in some few places in the Atlantic Ocean, they differ; yet this may probably arise, as is often the case, from an error in the Montagu's supposed longitude, where such observations were made. But the greatest difference (a greater than should arise, I think, according to common course) appears upon the coast of Portugal, Cape Saint Vincent, and about Gibraltar, near and within sight of land, where the observations are ascertained to the spot. Hence, if mine observed about the year 1756, and those of Mr. Ross's, were both near the truth, at the respective times when they were taken, I know not how to account for this considerable encrease, unless those late extraordinary convulsions, in the bowels of the earth, upon those several coasts, may be found, by further experiments, to have there influenced the directions of the magnetic needle.

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 IV. A contribution to terrestrial magnetism; being the record of observations of the magnetic inclination, or dip, made during the voyage of H. M. S. ‘Iron Duke’ to China and Japan, &c., 1871-75

1877 ◽  
Vol 167 ◽  
pp. 137-147
Keyword(s):  
Royal Society ◽  
Terrestrial Magnetism ◽  
Magnetic Inclination ◽  
China And Japan ◽  
Magnetic Needle

In the following, paper I propose to place on record, and submit for the information of the Royal Society, the observations made by me for the determination of the magnetic inclination, or dip of the magnetic needle, during the recent voyages of H. M. S. 'Iron Duke’ in the Eastern Seas, when visiting China, Japan, and places adjacent, between October 1871 and April 1875. The instrument employed was a six-inch dip-circle by Robinson, furnished with two needles, and graduated to ten minutes, which was formerly the property of the late Capt. Francis P. Blackwood, R. N., and which was used by me during that officer’s survey of the N. E. coast of Australia in H. M. S. ‘Fly,’ 1842-46.

scholarly journals On the influence of the sun's rays on the oscillations of the magnetic needle. By William Snow Harris, Esq. F. R. S. In a letter addressed to Samuel Hunter Christie, Esq. M. A. F. R. S

1837 ◽  
Vol 3 ◽  
pp. 175-176
Keyword(s):  
Royal Society ◽  
Magnetic State ◽  
Surrounding Medium ◽  
Dense Medium ◽  
Series Of Experiments ◽  
Intense Light ◽  
Freely Suspended ◽  
Magnetic Needle ◽  
Source Of Error ◽  
Solar Rays

The apparatus employed by the author in the inquiries of which he gives the results in the present paper, is very similar to that he has already described in his former communications to the Royal Society. It allowed of his carrying on a long series of experiments with freely suspended magnets, oscillating in a medium either rare or dense, and either in the sunshine or in the shade. The source of error incident to experiments in sunshine, made under an air-tight receiver, arise from the increased temperature, producing, both in the rare and in the dense medium, an irregular expansion, and a constant circulation of currents of air, which interfere with the equable movements of the bar—a condensation of vapour on the interior of the receiver—an expansion of the bar itself, by which its length, as a pendulum, becomes changed—and, lastly, a derangement of the original magnetic state of the bar. These disturbing causes he endeavoured to avoid by observing the oscillations, first in the shade, under a close receiver, and next when a beam of sunshine was thrown into the receiver by means of a plane mirror j in which case the heat was inconsiderable. When the bar had been allowed to return to its former temperature, similar experiments were repeated, after exhausting the receiver. The results of a series of experiments conducted in this manner are given in several tables: and the author concludes from them that the influence of the solar rays on a magnetic bar, oscillating in air, is to increase its apparent rate of oscillation ; while in vacuo, that rate is diminished. The author seeks for an explanation of these phenomena in certain changes effected in the surrounding medium. Comparative experiments were instituted on a bar of copper of the same dimensions as the magnetic bar employed in the former series. The author concludes from these inquiries, that the phenomena in question are independent both of the magnetic state of the bar, and also of the influence of solar light. He tried the effect of exposure of the bar to the intense light evolved by lime, acted upon by the influence of the oxy-hydrogen blowpipe; but with the same negative result.

scholarly journals XLI. A letter to the Right Honourable the Earl of Macclesfield, President, the Coun­cil, and Fellows, of the Royal Society, concerning the variation of the magnetic needle ; with a sett of tables annexed, which exhibit the result of upwards of fifty thousand observations, in six perio­dic reviews, from the Year 1700 to the Year 1756, both inclusive; and are ad­apted to every five degrees of Latitude and Longitude in the more frequented oceans. By William Mountaine and James Dodson, Fellows of the Royal Soci

1757 ◽  
Vol 50 ◽  
pp. 329-349 ◽  
Keyword(s):  
Royal Society ◽  
Periodic Review ◽  
The Right ◽  
Magnetic Needle

Sirs, On the 20th of March 1755, We presented an address to this illus­trious Body, intituled, “ An Attempt to point out, “ in a concise manner, the Advantages which would “ accrue from a periodic Review of the Variation of “ the Magnetic Needle, throughout the known World; “ requesting contributions thereto, by communicat- “ ing such observations concerning it, as had then “ been lately made, or could be procured from cor- “ respondents in foreign parts.”

scholarly journals XXVI. Electrodynamic qualities of metals (continued from Phil. Trans. Vol. 146. Read Feb. 28, 1856). —Part VI. effects of stress on magnetization

1876 ◽  
Vol 166 ◽  
pp. 693-713 ◽  
Keyword(s):  
Royal Society ◽  
Sudden Change ◽  
The Other ◽  
Thermo Electric ◽  
Iron And Steel ◽  
Steel Wires ◽  
Other Hand ◽  
Ballistic Method ◽  
Effects Of Stress ◽  
Magnetic Needle

178. In Parts III. and IV. of my first series of papers under this title (Transactions of the Royal Society for February 1856), I described experiments discovering effects of stress on the thermo-electric quality and the electric resistances of metals. About the time those experiments were made I also made several nugatory attempts to discover the effects of stress on magnetization; and eighteen years have passed before I have been able to resume the investigation. Early in the year 1874 I made arrangements to experiment on the magnetization of iron and steel wires in two different ways—one by observing the deflections of a suspended magnetic needle produced by the magnetization to be tested, the other by observing the throw of a galvanometer-needle, due to the momentary current induced by each sudden change of magnetism. The second method, which for brevity I shall call the ballistic method, was invented by Weber, and has been used with excellent effect by Thalén, Roland, and others. It has great advantages in respect of convenience, and the ease with which accurate results may be obtained by it; but it is not adapted to show slow changes of magnetism, and is therefore not fit for certain important parts of the investigation. On this account I am continuing arrangements for carrying out the first method, although hitherto I have obtained no good results by it. 179. On the other hand, I have found the ballistic method very easy and perfectly satisfactory in every respect, except that it does not show the slow changes of magnetization. It was by it that all the results which I am now going to describe were obtained. The apparatus, which is very simple, is represented in the accompanying sketch (fig. 1).

scholarly journals X. Observations on the dip and variation of the magnetic needle, and on the intensity of the magnetic force; made during the late voyage in search of a North West Passage

1819 ◽  
Vol 109 ◽  
pp. 132-144 ◽  
Keyword(s):  
Royal Society ◽  
Magnetic Force ◽  
North West ◽  
The Cross ◽  
Magnetic Needle

The dipping needle used in these observations is the property of Henry Browne, Esq.; it was made by Messrs. Nairne and Blunt, and is similar in construction to one made by the same artists, and described by the Hon. Henry Cavendish in the 66th volume of the Philosophical Transactions, as used in the house of the Royal Society. Previously to delivering it into my charge, Mr. Browne had adjusted the balance of the needle by means of the screws on the cross of wires attached to its axis ; so that no alteration took place in the indication of the dip, on reversing the poles.

XX. Observations on the variation, and on the dip of the magnetic needle, made at the apartments of the Royal Society, between the years 1786 and 1805 inclusive

1806 ◽  
Vol 96 ◽  
pp. 385-419 ◽  
Keyword(s):  
Royal Society ◽  
The Sun ◽  
The South ◽  
South Side ◽  
Meeting Room ◽  
Vertical Circle ◽  
Magnetic Needle ◽  
Made In

The variation compass used in making the following obser­vations is the same instrument used in former observations of the variation, and published by the Society in several volumes of their Transactions: and as a particular and accurate descrip­tion of its construction was given by Henry Cavendish, Esq. F. R. S. in the LXVIth volume, it will not be necessary to say any thing here on that subject. But these observations being the first that have been communicated since the compass was put up in the Society's apartments in Somerset Place, it may not be amiss to point out its situation in the house at the time of observation, and the method pursued to attain such allow­ances as were proper to be made in deducing the results here given. 1. The compass in the house, at the time of observation, was placed in the middle window, on the south side of the Society's meeting-room, upon a strong mahogany board 1½ inch thick. Against the opposite building the dial-plate of a watch is fixed, making an angle with the true meridian of 31° 8', 8 to the eastward, as a mark to which the telescope of the compass was adjusted. To obtain the angle that this mark made with the true meridian, I fixed a transit-instru­ment on the mahogany board above mentioned, precisely in the same place where the compass had been placed, and having adjusted its telescope to the said mark, the transits of the sun and stars over a vertical circle passing through the zenith and this mark, were observed; and the angle contained between the said mark and the true meridian, was found by computation to be 31° 8', 8 as above.

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