For the Greeks there were seven planets: Mercury, Venus, Mars, Saturn, Jupiter, the sun and the moon; hence the lucky character of the number seven. Pythagoras, having found the vibration of two similar strings inversely proportional to their lengths, began to look for regularity in the planetary motions, When the motions were shown to be fairly regular "they seemed more respectable somehow." But so necessary was it to Plate and the Greeks who followed him that the heavenly bodies should move in perfect circles that it remained for Kepler in 1609 to show that the planets moved in ellipses, "not at a uniform speed, but with their radii sweeping out equal arcas in equal lengths of time."
Heavenly Timekeepers There are interesting comments on Time and the Calendar These three celestial clocks, the rotation of the earth on its axis, th:
revolution of the Earth around' the Sun, and the revolution of the Moon arotind the Earth, have formed the bases of time in our practical ever; day lives.
But the Precession of the Equinoxes is "the fourth of these great heavenly timekeepers." "The fifth, and the slowest, worth mentioning here, is the wheel-like rotation of the Milky Way." And of course the changes in the calendar are told, including the introduction of the Gregorian calendar in 1582 by the Church, Great Britain following suit long Afterward in 1752, when the mobs cried "Give us back our eleven days." There is reproof for Shakespeare's Puck for saying he would put a girdle round the earth in 40 seconds. "He was too slow. The electric current of the telegraph, telephone and radio threw that girde in much less than one second."
The King-Killer It must be evident that this is no dry treatise on the subjects it includes. There is Halley's Comet, appearing just before Duke William landed at Hastings to conquer England, and in the embroidered Bayeux Tapestry (see in your Encyclopædia Britannica, 11th edition, under this title) tHe comet is shown, with King Harold's men looking unhappily at the portent. There is the debt of Thales to the Babylonians who predicted eclipses from the series of their recurrences; but Thales went farther and assumed that all of mature's processes could be predicted if sufficiently studied, There are the discoveries of the planets Uranus, in 1781, Neptune in 1846, discovered just where the mathe-magicians "Adams and Leverrier had shown a planet ought to be found; and Pluto, discovered in 1930, the eighth of the planets. And we have not mentioned the asteroids, 44,000 in number. What becomes of the mystic number seven, from the seven planets? But far be it from us to discourage dice throwers who have trusted this number since the game was played by the Achaean soldiers before the walls of Troy.
As if to suggest the reason for the title of this book we shall close with a quotation from the last page:
ant htt unto night showing know: nto day uttering speech.
fedre, we have made some progress towards a reasonable explanation fne universe, What we have now come about only by generation:
men passing their Jearning to future generations, only by criticism ihe "old and hypothesis for the Pew. There are still more things in Reaven'and Barth than we, twentieth Genter reams of our philosophy.
Text read from the printed page and cleaned; old type leaves the occasional error.