Page:Popular Science Monthly Volume 23.djvu/251

From Wikisource
Jump to navigation Jump to search
This page has been validated.
239
THE BOUNDARIES OF ASTRONOMY.

Come, a fraternal grasp, thou hand of stone!
The flesh that once was thine is now mine own.

V.

Sublime is life, though in beginnings base
At first enkindled. In this clod of mold
Beats with faint spirit-pulse the heart of gold
That warms the lily's cheek; its silent grace
Dwells unborn 'neath this sod. Fain would I trace
The potent mystery which, like Midas' hand,
Thrills the mean clay into refulgence grand;
For, gazing down the misty aisles of space
And time, upon my sight vast visions throng
Of the imperial destiny of man.
The life that throbbed in plant and beast ere long
Will break still wider orbits in its van—
A race of peace-robed conquerors and kings,
Achieving evermore diviner things.

From "Idyls of Norway."

 

THE BOUNDARIES OF ASTRONOMY.
II.

THE NEBULAR HYPOTHESIS.

By ROBERT S. BALL, F. R. S.,

ASTRONOMER-ROYAL OF IRELAND.

THE whole range of astronomy presents no speculations which have attracted more attention than the celebrated nebular hypotheses of Herschel and of Laplace. We shall first enunciate these speculations, and then we shall attempt to indicate how far they seem to be warranted by the actual state of scientific knowledge. In one of his most memorable papers, Sir William Herschel presents us with a summary of his observations on the nebulæ, arranged in such a manner as to suggest his theory of the gradual transmutation of nebulæ into stars. He first shows us that there are regions in the heavens where a faint diffused nebulosity is all that can be detected by the telescope. There are other nebulæ in which a nucleus can be just discerned; others again in which the nucleus is easily seen; and still others where the nucleus is a brilliant, star-like point. The transition from an object of this kind to a nebulous star is very natural, while the nebulous stars pass into the ordinary stars by a few graduated stages. It is thus possible to enumerate a series of objects, beginning at one end with the most diffused nebulosity, and ending at the other with an ordinary