Discussions on climate and cosmology / by James Croll.

  • James Croll
Date:
1885
Catalogue details

Licence: Public Domain Mark

Credit: Discussions on climate and cosmology / by James Croll. Source: Wellcome Collection.

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    nebular hypothesis, I cannot understand how we can consistently deny the existence o£ gaseous nebulae; for, according to the nebular hypothesis, the central nucleus which constitutes a sun or star, and which exhibits a continuous spectrum, was formed by condensation as surely as the planets or the satellites have been. Were we to go back sufficiently far in the past, we should come to a time when not only our globe but the sun himself consisted of gaseous matter only. If we admit this, then why not also admit that there may be nebulae at the present time in a condition similar to what our sun must formerly have been. The gaseous condition of the nebulae seems to follow as a consequence from Mr. Lockyer's theory. For, in order that the materials in the formation of a sun or star may arrange themselves according to their densities, dissociation is requisite; but there can be no dissociation except in the gaseous condition. Star - Clusters. — The wide - spread and irregular manner in which the materials would in many cases be distributed through space after collision, would prevent a nebula from condensing into a single mass. Sub- ordinate centres of attraction, as was long ago shown by Sir William Herschel (in his famous memoir on the formation of stars^), would be established, around which the gaseous particles would arrange themselves and gradually condense into separate stars, which would finally assume the condition of a cluster. Binary, Triple, and Multiple systems of stars will of course be accounted for in a similar manner. It is conceivable that it may sometimes happen that by the time the materials are broken up and dissipated into space, there may not be sufficient heat left to convert the fragments into vapour. In this case we * Phil. Trans. for 1811.