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THE INNER PLANETS
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dark streak stretching thence well down the disk, he convinced himself that no such period as twenty-four hours could possibly be correct, inasmuch as whenever he looked, the markings were always there. His notes read, "Same appearance as yesterday," day after day, until he would really have saved ink and penmanship had he had the phrase cut into a die and stamped. He concluded that the rotation was at least six months long, and was probably synchronous with the planet's time of revolution. This was in 1889. In 1895 he became still more sure, and showed how the older observations were really compatible with what he had found.

In 1896 the subject was taken up at Flagstaff. Very soon it became evident there that markings existed on the disk, most noticeable as fingerlike streaks pointing in from the terminator, faint but unmistakable from the identity of their successive presentation. Schroeter's projection near the south cusp was also clearly discernible as well as two others, one in mid-terminator, one near the northern cusp. Schiaparelli's dark markings also came out, developing into a sort of collar round the southern pole. Other spots and streaks also were discernible, and all proved permanent in place. By watching them assiduously it was possible to note that no change in position occurred in them, first through an interval of five hours, then