Section Iii.—the Solar System.

Frontispiece—DONATI’S COMET 228

1.— PHOTOGRAPH OF A SUN-SPOT 243 2.— SUN-SPOTS AND MAGNETIC VARIATIONS 246 3.— CURVES SHOWING THE DEVELOPMENT OF SUN-SPOTS 257 4.— ERUPTIVE PROMINENCE 264 5.— THE SAME, 18 MINUTES LATER 265 6.— THE ECLIPSED SUN 267 7.— THE CORONA OF JANUARY 1, 1889 269 8.— MAP OF MERCURY 276 9.— VENUS, FROM A DRAWING BY MASCARI 280 10.— MAP OF THE MOON 291 11.— PHOTOGRAPH OF THE TOTALLY ECLIPSED MOON 296 12.— CHART OF MARS 300 13.— THE “EYE OF MARS” 302 14.— THE OASES OF MARS 304 15.— JUPITER, SHOWING THE RED SPOT 322 16.— PHOTOGRAPH OF JUPITER 328 17.— TRANSIT OF JUPITER’S FIRST SATELLITE 330 18.— SATURN AND HIS RINGS 335 19.— GREAT COMET OF SEPTEMBER, 1882 361 20.— DONATI’S COMET 363 21.— PHOTOGRAPH OF SWIFT’S COMET 374 22.— THE SAME, 24 HOURS LATER 375 23.— PHOTOGRAPH OF HOLMES’ COMET 378 24.— PHOTOGRAPH OF BROOKS’ COMET 381