The New Heavens

Abstract

IT is impossible not to be impressed by the wonderful story of astronomical achievement told by Prof. Hale in felicitous language in this little volume. Before the invention of the telescope not more than about six thousand stars had ever been seen by human eyes, and less than half this number at any one time. The small telescope, with an object-glass an inch or so in diameter, used by Galileo in 1610, brought within the range of vision stars down to magnitude 10.5, numbering about five hundred thousand. The 60-inch reflector of the Mount Wilson Observatory, Pasadena, of which Prof. Hale is director, reveals stars of the 18th magnitude, and the 100-inch carries the sounding-line still further, while with both instruments many stars can be photographed which the eye cannot see directly, the photographic limit with four or five hours' exposure being about the 20th magnitude.

The New Heavens.

By Prof. G. E. Hale. Pp. xv + 88. (New York and London: C. Scribner's Sons, 1922.) 7s. 6d. net.