Page:The evolution of worlds - Lowell.djvu/228

190 thus gaudily because the Sun was there to see by, as well as eyes to see. For without the Sun those unconscious horticulturists, the insects, could not have exercised their pictorial profession.

To the entering of the Sun upon the scene this wondrous revolution was due; and once entered, it became the dominant factor in the Earth's organic life. We are in the habit of apostrophizing the Sun as the source of all terrestrial existence. It is true enough to-day, and has been so since man entered on the scene. But it was not always thus. There was a time when the Sun played no part in the world's affairs.

As its heat is now all-important, it becomes an interesting matter to determine the laws governing its amount. That summer is hotter than winter we all know from experience, pleasurable or painful as the case may be. This is due to the fact that the Sun is above the horizon for a greater number of hours in summer and passes more directly overhead. But not so many people are aware that on midsummer day, so far as the Sun is concerned, the north pole should be the hottest place on earth. That Arctic explorers, who have got within speaking acquaintance of it, assure us it is not so, shows that something besides the direct rays of the Sun is involved. Indeed, we learn as much from the extensively advertised thermometers of winter resorts which, judiciously placed, beguile the stranger to