These dates indicate a period of about 29-1/8 years. Thus: 901 to 930 1 period of 29.000 years. 930 to 1571 22 periods of 29.136 " 1571 to 1833 9 periods of 29.111 " 1833 to 1862 1 period of 29.000 " Meteors of October 16-20. Meteoric showers were observed from the 16th to the 20th of October in the years 288, 1436, 1439, 1743, and 1798. These dates render it somewhat probable that the period is about 27-1/2 years. Thus: A.D. 288 to 1439 42 periods of 27.405 years each. 1439 to 1743 11 " 27.636 " " 1743 to 1798 2 " 27.500 " " If these periods are correct, it is a remarkable coincidence that the aphelion distances of the meteoric rings of April 20, October 18, November 14, and December 12, as well as those of the comets 1866 I., and 1867 I., are all nearly equal to the mean distance of Uranus. The Meteors of April 30, May 1. Professor Schiaparelli, in his list of meteoric showers whose radiant points are derived from observations made in Italy during the years 1868, 1869, and 1870, describes one as occurring on April 30 and May 1; the radiant being in the Northern Crown. The same shower has also been recognized by R. P. Greg, F.R.S., of Manchester, England. This meteor-stream, it is now proposed to show, is probably derived from one much more conspicuous in ancient times. In Quetelet's "Physique du Globe" we find meteoric displays of the following dates. In each case the corresponding day for 1870 is also given,[28] in order to exhibit the close agreement of the epochs: 1. A.D. 401, April 9th; corresponding to April 29th, for 1870. 2. 538, " 6th; " April 25th, " 3. 839, " 17th; " May 1st, " 4. 927, " 17th; " April 30th, " 5. 934, " 18th; " May 1st, " 6. 1009, " 16th; " April 28th, " [28] Making proper allowance for the precession of the equinoxes. The epochs of 927 and 934 suggest as probable the short period of 7 years. It is found accordingly that the entire interval of 608 years--from 401 to 1009--is equal to 89 mean periods of 6.8315 years each. With this approximate value the six dates are all represented as follows: From A.D. 401 to A.D. 538, 20 periods of 6.85 years. 538 to 839, 44 " 6.84 " 839 to 927, 13 " 6.77 " 927 to 934, 1 " 7.00 " 934 to 1009, 11 " 6.82 "