Page:Popular Science Monthly Volume 23.djvu/176

164 seen from the center of the stream, away from the glare of the streetlamps. A decently-dressed and not unintelligent-looking man asked me, with a troubled look, and pointing to the heavens:

"What is that?"

"It's the aurora borealis," I replied.

He seemed relieved to find some one who could give it a name, and who did not appear to be alarmed.

"I thought it might be the comet the papers are talking about," he said, "and I didn't know what was going to happen."

I know that this man's vague fears were shared by others.

Everybody who had anything to do with telegraphs will remember the effects of the aurora. The wires played strange freaks. In some places they were disconnected from the batteries and worked by means of the current furnished by the magnetic storm; in other places they refused to work at all. The Atlantic cable was crippled, and at intervals, for several days thereafter, there was considerable delay of all telegraphic business. Subsequently it was learned that the auroral storm had raged, simultaneously, not only in the United States and Canada, but in Great Britain, on the Continent of Europe, and in Asia, extending clear across to the shores of China.

The next day, when I turned my telescope upon the sun, I was astonished at the changes that had taken place. The smaller spot, which I had seen increasing in magnitude on the previous day, had swollen to between five and six times its former size, so that now it was about half as large as the larger spot, and both were clearly visible to the unassisted eye, shaded with a dark glass.

I find by reference to the exact measurements of these spots, made at the Greenwich Observatory, that, whereas on the 16th the area of the smaller spot was to that of the larger about as 1 to 13·6, on the 17th the relative magnitudes were about as 1 to 2·2.

For three or four days afterward there were magnetic disturbances and occasional auroral displays at night, and during this time the activity of the solar forces continued.

On the 19th there was another magnetic storm, and coincidently with it the smaller spot suddenly increased in size again, until it was nearly as large as the other, and on the 21st it actually surpassed its neighbor in magnitude. After that both groups rapidly waned, the one which had undergone the remarkable development I have described fading much faster than the other one.

The next great display of sun-spots accompanied by auroras and magnetic disturbances—if we except one or two of minor importance and a somewhat remarkable one seen in Europe, which will be described hereafter—occurred in November last, culminating on the 17th of that month in one of the greatest magnetic storms on record, which crippled the telegraphs almost all over the civilized world. In Europe fine auroras were observed on the 12th, 13th, 14th, 15th, 16th,