Page:Percival Lowell - an afterglow.djvu/125

An Afterglow

We were up all night last night with Mars. Among other things we took six plates of the planet showing that morning frost is nearly half way round the longitudes. The fact that it was always there on the sunrise limb and never entered far on to the disc proves conclusively that it was morning frost that melted as the day advanced. It was perfectly white and more salient than the south polar cap.

I shall shortly send you an enlargement of our last night's work. 95