54 H. A. Newton on November Star-Showers. 
expect a shower. The two showers in A.D. 1832, and 18338, 
indicate that the latter was toward the close of one short period. 
n like manner, the two showers in A. D. 902 934, being 
only 32 years apart, belong evidently, the Sinoae toward the 
close of the period, and the latter toward its beginning. The 
two years A. 2, and A.D. , occupy then, approxi- 
mately, corresponding places in the cycle. The interval, divided 
by, 28, gives 33°25 years for the length of one cycle. 
Various facts respecting these showers are shown by the 
following table. The first column contains the number of the 
display as given in the earlier part of this article, the second the 
year, and the third the day and hour of what I consider the his- 
toric date of the shower. The hour is somewhat arbitrary. I 
have assumed that the maxima of the displays recorded in the 
European annals were 5 o'clock, A.M., Paris time, or 17 hours 
from the preceding noon. This of course may involve an error 
of some hours, which is to be borne in mind in considering the 
remainders in another column. For the showers taken from the 
Chinese records, seven hours are subtracted from the seventeen 
to allow for the difference of longitude; and for the two Ameri- 
can showers, four and five hours are added. No. 8 was observed 
both in Europe and China, and No. 6 at Baghdad. Hence, three 
hours are taken from each date. The shower of 1832 was 
mainly east of Paris, and one hour is therefore subtracted. | 
In the fourth column is the earth’s longitude at each date, 
eomputed by Le Verrier’s tables (Annales de I Observatoire, iv, 
102-206). Thess longitudes are approximately represented b 
the formula a — nt, where a is 51° 177, n is 1711, and ¢ is the 
number of years from the time of tre shower to Jan. Ist, A. 
1850. ‘Ihese values of a—nt are given in the fifth column. 
Subtracting them from the corresponding longitudes in the fourth 
column, gives the remainders in the sixth column, 
We may suppose a cycle to begin midway between the dis- 
plays of Sireubey 1832, and November, 1833. If the begin- 
ning of a year be ‘reckoned from the day of the ‘shower, “the 
beginning of the cycle may be written 183250. Subtracting 
now from this date multiples of 33°25 years, we have the num- 
bers in the seventh column for the dates of the beginning of the 
cycles. Subtracting now these from the years given in the sec- 
ond column, and we have the remainders in the eighth column. 
Each remainder represents evidently the number of years from 
the Ms ges of Sinaia) eycle to the time of the shower. 
oy ae co column contains the sum of the perturbations of the 
earth’s distance from the sun, ase by the moon and planets, 
compute Pel “the tables of Le V. The unit is the seventh 
of the sun’s mean distance, << represents about 9°5 
