[6]It is not a little singular that the Chinese in bygone centuries have often alluded to comets under the name of vapours; _e.g._, the comet of 1618 is recorded as having been “a white vapour 20 cubits long.” APPENDIX.—TABLES OF THE SOLAR SYSTEM. THE SUN AND PLANETS. Name. Sidereal Mean Diameter. Surface. Volume. Mass. Density. Axial Force of Velocity period. distance Miles. Earth=1. Earth=1. Earth=1. Earth=1. Rotation. gravity. in orbit. from d. h. m. Fall: Miles per Sun. Ft. in 1 hour Millions sec. of miles. SUN ..... ..... 866,200 11,946 1,305,000 332,000 0.25 25 7 48 461 h. m. s. MERCURY 88 days. 36 3,008 0.144 0.055 0.066 1.26 24 5 30 7 107,000 VENUS 225 ″ 67 7,480 0.891 0.841 0.782 0.92 23 21 23 14 78,000 EARTH 365 ″ 93 7,926 1.000 1.000 1.000 1.00 23 56 4 16 66,000 MARS 687 ″ 141 5,000 0.398 0.251 0.107 0.45 24 37 23 4 53,000 Minor Planets Eros (433) 1.76 ..... 18 Eros is the nearest to the Sun of the Minor Planets, part years. of its orbit falling between the Earth and Mars. Vesta (4) 3.6 ″ 219 214 Vesta is the largest of the Minor Planets. Thule (279) 8.8 ″ 396 ..... Thule is the most distant from the Sun of the Minor Planets. JUPITER 11.8 ″ 483 88,439 124 1,389 317 0.23 9 55 21 41 29,000 SATURN 29.4 ″ 886 75,036 89 848 94 0.11 10 29 17 18 21,000 URANUS 84.0 ″ 1782 30,875 15 59 14 0.25 ? 13 15,000 NEPTUNE 164.6 ″ 2792 37,205 21 103 17 0.17 ? 12 12,000 SATELLITE OF THE EARTH.