Page:The evolution of worlds - Lowell.djvu/95

Rh It takes place, as Schiaparelli found, in eighty-eight days, or the time of the planet's revolution round the Sun. The markings disclosed the fact, as Schiaparelli had also discovered, in a most interesting manner, for

the ellipticity of the planet's orbit stood reflected in the swing of the markings across the face of the disk, a definiteness in the proof of a really surprising kind. What this means we shall see in a subsequent chapter when we take up the mechanical problem of the tides. Another result that issued from the positions of the markings was the determination of the planet's pole. Except for the libration above noticed, the