Light Science for Leisure Hours: A series of familiar essays on scientific subjects, natural phenomena, &c. — John Shaqi
Light Science for Leisure Hours: A series of familiar essays on scientific subjects, natural phenomena, &c.Proctor, Richard A. (Richard Anthony)
Science
Light Science for Leisure Hours: A series of familiar essays on scientific subjects, natural phenomena, &c.
Proctor, Richard A. (Richard Anthony)
Science
On the 1st of September, 1859, Messrs. Carrington and Hodgson were
observing the sun, one at Oxford and the other in London. Their
scrutiny was directed to certain large spots which, at that time,
marked the sun’s face. Suddenly a bright light was seen by each
observer to break out on the sun’s surface, and to travel, slowly
in appearance, but in reality at the rate of about 7,000 miles in a
minute, across a part of the solar disc. Now it was found afterwards
that the self-registering magnetic instruments at Kew had made at
that very instant a strongly marked jerk. We learned, also, that at
that moment a magnetic storm prevailed at the West Indies, in South
America, and in Australia. The signalmen in the telegraph stations at
Washington and Philadelphia received strong electric shocks; the pen
of Bain’s telegraph was followed by a flame of fire; and in Norway the
telegraphic machinery was set on fire. At night great auroras were seen
in both hemispheres. It is impossible not to connect these startling
magnetic indications with the remarkable appearance observed upon the
sun’s disc.
But there is other evidence. Magnetic storms prevail more commonly in
some years than in others. In those years in which they occur most
frequently, it is found that the ordinary oscillations of the magnetic
needle are more extensive than usual. Now when these peculiarities had
been noticed for many years, it was found that there was an alternate
and systematic increase and diminution in the intensity of magnetic
action, and that the period of the variation was about eleven years.
But at the same time, a diligent observer had been recording the
appearance of the sun’s face from day to day and from year to year. He
had found that the solar spots are in some years more freely displayed
than in others. And he had determined the period in which the spots are
successively presented with maximum frequency to be about eleven years.
On a comparison of the two sets of observations, it was found (and has
now been placed beyond a doubt by many years of continued observation)
that magnetic perturbations are most energetic when the sun is most
spotted, and _vice versâ_.
For so remarkable a phenomenon as this, none but a cosmical cause can
suffice. We can neither say that the spots cause the magnetic storms
nor that the magnetic storms cause the spots. We must seek for a cause
producing at once both sets of phenomena. There is as yet no certainty
in this matter, but it seems as if philosophers would soon be able to
trace in the disturbing action of the planets upon the solar atmosphere
the cause as well of the marked period of eleven years as of other
less distinctly marked periods which a diligent observation of solar
phenomena is beginning to educe.
(From the _Cornhill Magazine_, June 1868.)
_OUR CHIEF TIME-PIECE LOSING TIME._
Public-domain text, read in full here on John Shaqi.
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