Page:The Music of the Spheres.djvu/64

 Dipper? This strange phenomenon not only happened but happens regularly, for the earth "reels like a top" as well as "whirls," although the reeling motion is so much slower than the whirling motion that while it whirls once on its axis in a day, it reels around only once in 25,000 years. During this time the earth's axis describes a circle from Thuban, through the present Pole Star, around through Vega and back again. Vega may be easily located for it crosses the zenith in the late evenings of summer, a beautiful bluish-white star of the first magnitude. It will be about 11,500 years or about 13,500 before this blue star will again shine above the northern pole of our earth.

It was not an uncommon thing in olden times to build temples dedicated to the observation of certain stars. It is believed that the great pyramid of Cheops, built 4600 years ago, was so constructed that the light of Thuban, then the Pole Star, would shine down its great stone tube at the time the star was at its lower culmination. Olcott in "Starlore of All Ages" tells us that the idea was to conduct the ray of light from Thuban through the passage opening high up in the side of the pyramid, to the eye of a god hidden far down beneath its foundations. When viewed from the bottom of the tunnel, which ends in a room hollowed out of solid stone, it is said that the mouth appears but little larger than the moon's diameter. It is interesting to note that the pyramid of Cheops is the mightiest structure the world has ever seen. According to Herodotus, 100,000 men were employed constantly on this work for 20 years. But the rays of Thuban can no longer shine down the 380 feet of stone tube to light the eye of the god hidden in its depths, for the reeling of the earth has caused the tube to be out of the star's line of light. It may happen again in 21,000 years, however—if the pyramid is still there.

In China there is an observatory 4000 years old which Samuel G. Bayne in his little book the "Pith of Astronomy" speaks of visit-