Imatges de pÓgina
PDF
EPUB

swer.

years in the working of telegraph-lines, struments are enabled to work; but the witnessed anything like the extraordina- time, varying according to the rapidity ry effect of the aurora borealis, between of the vibrations of the auroral bands, is Quebec and Father Point, last night. only from one quarter of a minute to one The line was in most perfect order, and minute in duration. Therefore, whatever well-skilled operators worked incessantly business is done upon the wires during from eight o'clock last evening till one these displays has to be accomplished in o'clock this morning, to get over, in even brief intervals of from quarter to half a a tolerably intelligible form, about four minute in duration. hundred words of the steamer “Indian's" During one of these intervals, the Bosreport for the press ; but at the latter ton operator said to the one at Portland, hour, so completely were the wires under “ Please cut off your battery, and let the influence of the aurora borealis, that us see if we cannot work with the auroral it was found utterly impossible to com- current alone." municate between the telegraph-stations, The Portland operator replied,and the line was closed for the night.” “I will do so. Will you do the same?"

We have seen from the foregoing ex- “I have already done so," was the anamples that the aurora borealis produces “ We are working with the aid remarkable effects upon the telegraph- of the aurora alone. How do you relines during its entire manifestation. We ceive my writing?" have, however, to record yet more won- " Very well indeed,” responds the opderful effects of the aurora upon the erator at Portland ; “much better than wires, namely, the use of the auroral cur- when the batteries were on; the current rent for transmitting and receiving tele- is steadier and more reliable. Suppose graphic dispatches. This almost incred- we continue to work so until the aurora ible feat was accomplished in the fore- subsides?” noon of September 2, between the hours “ Agreed,” replied the Boston operator. of half past eight and eleven o'clock, on “ Are you ready for business ? ” the wires of the American Telegraph “ Yes; go ahead,” was the answer. Company between Boston and Portland, The Boston operator then commenced and upon the wires of the Old Colony sending private dispatches, which he was and Fall River Railroad Company be- able to do much more satisfactorily than tween South Braintree and Fall River. when the batteries were on, although, of

The auroral influence was observed course, not so well as he could have done upon all the lines running out of the with his own batteries without celestial oflice in Boston, at the hour of com- assistance. mencing business, (eight o'clock, A. M.,) The line was worked in this manner and it continued so strong up to half past more than two hours, when, the aurora eight as to prevent any business being having subsided, the batteries were redone; the ordinary current upon the sumed. While this remarkable phenomwires being at times neutralized by the enon was taking place upon the wires bemagnetism of the aurora, and at other tween Boston and Portland, the operator times so greatly auginented as to render at South Braintree informed me that he operations impracticable. At this junc- was working the wire between that stature it was suggested that the batteries tion and Fall River - a distance of about should be cut off, and the wires simply forty miles — with the current from the connected with the earth.

aurora alone. He continued to do so It is proper to remark here, that the for some time, the line working comparacurrent from the aurora coming in waves

tively well.

Since then I have visited of greater or less intensity, there are Fall River, and have the following actimes, both while the wave is approach- count from the intelligent operator in the ing and while it is receding, when the in- railroad office at that place. The office

[ocr errors]

at the station is about half a mile from the rent will be null, that is to say, each will regular office in the village. The bat- neutralize the other. Now the aurora, tery is kept at the latter place, but the in presenting its positive pole, we will operator at the station is provided with a say, increases the current upon the line switch by which he can throw the battery beyond the power of the magnet-keeperoff the line and put the wire in connec- spring to control it, and thus prevents tion with the earth at pleasure. The bat- the line from working, by surfeiting it tery at the other terminus of the line is with the electric current; until, presentat Boston; but the operator at South ly, the wave recedes and is followed by Braintree is furnished with a similar a negative current which neutralizes the switch, which enables him to dispense battery current, and prevents the line with its use at pleasure. There are no from working for want of power. It is intermediate batteries; consequently, if plain, therefore, that, if the batteries be the Fall River operator put his end of taken off, the positive current of the authe wire in connection with the earth, rora cannot increase nor the negative and the South Braintree operator do the decrease the working state of the line to same, the line is without battery, and the same extent as when the batteries are of course without an electrical current. connected ; but that, whichever pole is Such was the state of the line on the presented, the magnetism can be made 2d of September last, when for more use of by the operator for the ordinary than an hour they held communication duties of the line. over the wire with the aid of the celes- At Springfield, a gentleman who obtial batteries alone.

served the needle of the compass, during This seems almost too wonderful for the auroral display of August 28th, nobelief, and yet the proof is incontesta- ticed that it was deflected first to the ble. However, the fact being established west, and then to the east, while the that the currents from the aurora borea- waves of the aurora were in motion. lis do have a direct effect upon the tele- The electrotype plates at the office of graph-wires, and that the currents are the “ Republican” at that place were so of both kinds, positive and negative, so seriously affected by the aurora, that as I have shown in my remarks upon they could not be printed from during the aurora of 1852, which soinetimes left the continuance of the phenomenon. a dark line upon the prepared paper, The aurora borealis of August 28th and at other times bleached it, - it is a was surpassingly brilliant not only in the natural consequence that the wires should northern portion of this continent, but alwork better without batteries than with so as far south as the equator, - as well them, whenever a current from the au- as in Cuba, Jamaica, California, and the rora has sufficient intensity to neutralize greater portion of Europe. The London the current from the batteries.

newspapers of the 29th contain glowing I will try to make myself clear upon descriptions of it. A California journal this point. It makes no difference, in says:—“During the last ten years the working the Morse, or any other system aurora borealis was never seen in Caliof magnetic telegraph, whether we have fornia except on very rare occasions, and the positive or the negative pole to the then the light was very faint or barely line; but, whichever way we point, the visible; but on the 28th ult., it

appearsame direction must be continued with all ed in wonderful splendor, — the whole additional batteries we put upon the line. northern part of the sky being of a bright Now if we put a battery upon the line crimson ; and the same phenomenon, with at Boston, of, say, twenty-five cells, and equal magnificence, was repeated on the point the positive pole eastward, and the night of the first instant.” same number of cells at Portland, point- In Jamaica the aurora borealis was ing the positive pole westward, the cur- witnessed for the first time, perhaps, since

[ocr errors]

the discovery of this island by Colum- tained a small piece, which I preserv-
bus. So rare is the phenomenon in those ed."
latitudes, that it was taken for the glare It is due to Mr. Meriam, as well as to
of a fire, and was associated with the re- the scientific world, to say, that he stands
cent riots.

alone in his convictions with regard to the
Mr. E. B. Elliot of Boston, in an in- aurora, both in respect of the cause and
teresting article upon the recent aurora, the effect of the phenomenon.
points out the simultaneous occurrence
of the auroral display of February 19th, Having thus illustrated the effects of
1852, with the eruption of Mauna Loa, the aurora, let us now return to the dis-
-- the largest volcano in the world, situ- cussion of its causes.
ated on Hawaii, (one of the Sandwich The intimate and constant connection
Island
group,)-0

- on the 20th of February; between the phenomena of the aurora
on which occasion, the side of the moun- borealis and terrestrial magnetism led
tain gave way about two-thirds of the dis-

Humboldt to class under the head of
tance from the base, giving passage to a Magnetic Storms all disturbances in the
magnificent stream of lava, five hundred equilibrium of the earth's magnetic forces.
feet deep and seven hundred broad. The presence of such storms is indicated

Again, on the 17th of December, 1857, by the oscillations of the magnetized nee-
between the hours of one and four in the dle, the disturbance of the currents upon
morning, there occurred an aurora of un- the telegraph-wires, and the appearance
wonted magnificence. The first steam- of the aurora, of which these oscillations
er arriving from Europe after that date and disturbances are, as it were, the fore-
brought the following intelligence, which runners, and which itself puts an end to
is taken from one of the journals of the the storm, - as in electric storms the
day:-“ An earthquake took place on the phenomenon of lightning announces that
night of the 17th, throughout the whole the electrical equilibrium, temporarily dis-
kingdom of Naples, but its effects were turbed, is now restored.
most severe in the towns of Salerno, Po- The atmosphere is constantly charged
tenza, and Nola. At Salerno, the walls with positive electricity,- electricity fur-
of the houses were rent from top to bot- nished by the vapors that rise from the
tom. Numerous villages were half de- sea, especially in tropical regions, - and,
stroved."

on the other hand, the earth is nega-
Were these coincidences of extraor- tively electrized. The recomposition or
dinary auroras with extraordinary com- neutralization of the two opposite elec-
motions in the physical condition of our tricities of the atmosphere and of the
globe merely accidental? or are these terrestrial globe is brought about by
phenomena due to a common cause ? means of the moisture with which the
The latter supposition is not improbable,

lower strata of the air are more or less but the question can be fully settled on- charged. But it is especially in the poly by further observations.

lar regions, where the eternal ice that Mr. Meriam, “ the sage of Brooklyn," reigns there constantly condenses the as the daily journals denominate him, aqueous vapors under the form of haze, considers the aurora as the result of that this recomposition must be brought earthquakes or volcanic eruptions. He the more so, as the positive vaalso says:—" The auroral light sometimes pors are carried thither and accumulated is composed of threads, like the silken by the tropical current, which, setting warp of a web; these sometimes become out from the equatorial regions, where broken and fall to the earth, and possess it occupies the most elevated regions of exquisite softness and a silvery lustre, the atmosphere, descends as it advances and I denominate them the products towards the higher latitudes, until it comes f the silkery of the skies. I once ob- in contact with the earth in the neighbor

about ;

1

!

а

hood of the poles. It is there, then, of the circumference only of this surchiefly, that the equilibrium between the face, so as to form around it a continupositive electricity of the vapors and the ous luminous ring. This ring possesses negative electricity of the earth must be a movement of rotation around the magaccomplished by means of a discharge, netized cylinder, sometimes in one direcwhich, when of sufficient intensity, will tion, sometimes in another, according to be accompanied with light, if, as is al- the direction of the discharge and of the most always the case near the poles, and magnetization. Finally, some more brilsometimes in the higher parts of the at- liant jets seem to come out from this lumosphere, it take place among those minous circumference without being conextremely small icy particles which con- founded with the rest of the group. Now stitute the hazes and the very elevated the magnetic pole exercises over the luclouds.

minous haze which we have mentioned There can be no doubt that the oc- as always present during an aurora precurrence of the phenomenon is mate- cisely the same action which the pole of rially dependent on the presence in the electro-magnet exercises in the exthe atmosphere of these particles of ice, periment just described; and what takes forming a kind of thin haze, which, be- place on the small scale of the expericoming luminous by the transmission of ment is precisely what takes place on the electricity, must appear simply as an il- large scale of the phenomenon of the auluminated surface of greater or less ex

rora borealis. tent, and more or less cut up. The phe- The arc of the aurora borealis is a pornomenon actually takes place in this man- tion of a luminous ring, the different points ner in the parts of the atmosphere that of which are sensibly at equal distances are the most distant from the earth. We from the earth, and which centres upon perceive what are termed auroral plates the boreal magnetic pole, so as to cut at of a purple or reddish-violet color, more right angles all the magnetic meridians or less extended, according as this spe- that converge towards this pole. Such a cies of veil, formed by icy particles, ex- ring, seen by an observer placed at the tends to a greater or less distance from surface of the earth, evidently presents the poles. The tenuity of this veil is to him the known arc of the aurora; and such that it admits of our seeing the its apparent summit is always necessastars through the auroral plates. Ofrily situated in the magnetic meridian of its existence, independently of indirect

the place. proofs, we have a direct demonstration The diameter of the luminous ring is in the observation of MM. Bixio and greater in proportion as the magnetic Baral, who, being raised in a balloon to pole is more distant from the surface of a great height, found themselves, on a the earth, since this pole must be situatsudden, although the sky was entirely ed upon the intersection of the plane of serene and the atmosphere cloudless, in the ring with the axis of the terrestrial the midst of a perfectly transparent veil, globe ; if we could determine rigorously formed by a multitude of little icy nee- the position of the aurora borealis, we dles, so fine that they were scarcely vis- should then have the means of knowing ible.

exactly that of the pole itself. If we place the pole of an electro- Each observer sees the summit of the magnet over the jets of electric light auroral arc at his magnetic meridian; it that are made to converge in extremely is, therefore, only those who are on the rarefied air, we shall see that the elec- same magnetic meridian who see the same tric light, instead of coming out indif- summit, and who are able by simultaneous ferently from all points of the upper observations to take its height. surface, as had taken place before the If the summit of the arc pass beyond magnetization, comes out from the points the zenith of the observer, the latter is

47

VOL. IV.

every clear

surrounded by the matter of the aurora able. This conviction is in accordance borealis. This matter is nothing else than with the very careful observations which aqueous vapors traversed by the dischar- have now been made for four years in ges, and which are in general luminous the northern hemisphere. It appears, only at a certain height from the ground, as the result of these, that the aurora either because the air is there more rare- borealis is visible almost fied, or because they are themselves con- night, but it does not show itself at all gealed, and more capable, consequently, the stations at the same time. From Ocof liberating their electric light. Then tober to March there is scarcely a night it is, that, from being nearer to the spot in which it may not be seen; but it is in where the phenomenon is taking place, February that it is most brilliant. In the observer hears the crepitation, or 1850 it was observed two hundred and whizzing, of which we have spoken, espe- sixty-one nights, and during 1851 two cially if he be in an open country and hundred and seven. The proportion of in a quiet place. But if the arc do not nights in which the aurora is seen is attain to his zenith, he is situated beyond much greater the nearer we are to the the region in which the meeting of the magnetic pole. electric currents takes place; he sees on

De la Rive, from whose admirable trealy an are a little more elevated to the tise upon Electricity we have borrowed north or the south, according as he is situ- our general views, and whose theory we ated in one hemisphere or the other; and have attempted to illustrate in this pahe hears no noise, on account of his too per, concludes that the aurora borealis great distance. The crepitation is the re- is a phenomenon which has its seat in sult of the action of a powerful magnetic the atmosphere, and consists in the propole upon luminous electric jets in its im- duction of a luminous ring of greater or mediate neighborhood. With regard to less diameter, having for its centre the the sulphurous odor which some observ- magnetic pole. Experiment shows, as ers have perceived, it arises, as does that we have seen, that, on bringing about in which accompanies the fall of lightning, rarefied air the reunion of the two elecfrom the conversion into ozone of the tricities, near the pole of a powerful artioxygen of the air, by the passage of elec- ficial magnet, a small luminous ring is tric discharges.

produced, similar to that which constiGisler says, that on the high moun- tutes the aurora borealis, and animated tains of Sweden the traveller is some- by a similar movement of rotation. The times suddenly enveloped in a very trans

aurora borealis would be due, consequentparent fog, of a whitish-gray color inclin- ly, to electric discharges taking place in ing a little to green, which rises from the the polar regions between the positive ground, and is transformed into an auro- electricity of the atmosphere and the negra borealis. The cirro-cumulus and the ative electricity of the earth. These elechazes become luminous when they are tric discharges taking place constantly, traversed by sufficiently energetic dis- but with intensities varying according to charges of electricity, and when the light the state of the atmosphere, the aurora of day is no longer present to overcome borealis should be a daily phenomenon, their more feeble light. Dr. Usher de- more or less intense, consequently visiscribes an aurora borealis seen in the ble at greater or less distances, but only open day, at noon, May 24, 1778. when the nights are clear,—which is per

MM. Cornulier and Verdier are con- fectly in accordance with observation. vinced, after carefully studying the sub- The aurora australis presents precisely ject, that there are almost always auro- the same phenomena as the aurora bo ræ boreales in the high polar latitudes, realis, and is explained, consequently, in and that their brilliancy alone is vari- the same manner.

« AnteriorContinua »