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Page:Popular Science Monthly Volume 21.djvu/204

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THE POPULAR SCIENCE MONTHLY.

South by the great star-shower of 1833 have been so often described that the details need not here be repeated. I may, however, remark in passing that this shower was derived from the same meteoric swarm that produced the displays of 1202 and 1366, to which I have referred, and which returns at intervals of thirty-three years and three months.

In former ages comets were regarded as signs sent directly by the Diety to announce coming wars or fatal disasters. The degree of terror which they excited was proportioned to the size of the comet or the form and length of its train. A great comet, believed to have been that of Halley, appeared in April, a. d. 1066, the year in which William the Conqueror invaded England. This comet was looked upon as the forerunner of the conquest, and produced universal alarm. "The new star means a new king," was the common expression of the day. All writers of that period bear witness to the splendor of the comet of 1066.

But the accounts of all great comets in ancient times furnish similar instances of superstitious dread and consternation. Of a different nature was the alarm produced among the ill-informed in 1832 by the baseless expectation of the earth's collision with Biela's comet. It had been announced by astronomers that on a particular day a part of the earth's orbit would be included within the nebulosity of the comet. This statement was misunderstood by the general public, and a coming together of the earth and the comet was by many apprehended. Astronomers well knew, however, that our planet would be millions of miles from the intersection of the two orbits before that point could be reached by the comet.

The latest instance of supposed danger from a comet is that founded on a misapprehension of an article by the distinguished Mr. Proctor. In 1668 a large comet appeared and passed very near to the sun's surface—probably through the upper strata of its atmosphere. The great comet of 1843 moved so nearly in the same path that it was supposed by some astronomers to be a return of the same body; the period being one hundred and seventy-five years. But the path of the bright comet seen in the southern hemisphere in 1880 coincided still more nearly with that of the comet of 1843, and these dates would indicate a period of only thirty-seven years. Either, therefore, the period is becoming rapidly shorter, or the comets are separate bodies moving in orbits which, within the limits of the planetary system, are nearly co-incident. The latter alternative has, I think, the greater probability. The theory, however, that the comets of 1668, 1843, and 1880 were returns of the same body, and that its orbit is converging with great rapidity, has been defended as affording a plausible explanation of the similarity of elements. At a meeting of the Royal Astronomical Society of London, May 14, 1880, Mr. Marth, a well-known astronomer, remarked as follows:

"Supposing this comet of 1843 is the same as that of 1668, it would