The probability that these meteors are derived from a ring which intersects the earth's orbit, was first suggested by Arago in 1836. A comparison of dates led Herrick to designate 27 years as the probable period of the cluster. In the _Astronomische Nachrichten_, No. 1632, Dr. Weiss called attention to the fact that the orbit of the first comet of 1861 very nearly intersects that of the earth, in longitude 210°--the point passed by the latter at the epoch of the April meteoric shower. A relation between the meteors and the comet, indicating an approximate equality of periods, was thus suggested as probable. But the comet, according to Oppolzer, does not complete a revolution in less than 415 years. If, therefore, the meteoric period is nearly the same, the known dates of star-showers indicate a diffusion of meteoroids around one half of the orbit previous to the display of the year 15 B.C. No subsequent perturbation, then, of a particular _part_ could sensibly effect the general orbit of the stream. The infrequency of the display renders, therefore, the hypothesis of a long period extremely improbable. The entire interval between 687 B.C. and A.D. 1803 is 2490 years, or 92 periods of 27.0652 years; and the known dates are all satisfied by the following scheme: B.C. 687 to B.C. 15 .. 672 years = 25 periods of 26.8800 _y._ each. 15 to A.D. 582 .. 597 " = 22 " 27.1363 " A.D. 582 to 1095 .. 513 " = 19 " 27.0000 " 1095 to 1122 .. 27 " = 1 " 27.0000 " 1122 to 1803 .. 681 " = 25 " 27.2400 " With a period of 27 years, the perihelion being interior to the earth's orbit, the aphelion distance of the meteors would be very nearly equal to the distance of Uranus. The next shower, if the assumed period be correct, ought to occur about 1884. It is worthy of remark that near the time of the last (hypothetical) return Mr. Du Chaillu witnessed the meteors of this epoch, in considerable numbers, in the interior of Africa. The Meteors of December 12. Meteoric showers have occurred about the 12th of December in the following years: 1. A.D. 901. "The whole hemisphere was filled with those meteors called falling-stars from midnight till morning, to the great surprise of the beholders in Egypt." 2. In 930 a remarkable shower of falling stars was observed in China. 3. Extraordinary meteoric phenomena were observed at Zurich at the same epoch in 1571. 4. On the night of the 11th and 12th of December, 1833, a great number of shooting-stars were seen at Parma. At the maximum as many as ten were visible at the same time. 5. (Doubtful.) 1861, 1862, and 1863. Maximum probably in 1862. The meteors at this return were far from being comparable in numbers with the ancient displays. The shower, however, was distinctly observed. R. P. Greg, Esq., of Manchester, England, says the period of December 12, 1862, was "exceedingly well defined."