1907-8.] The Problem of a Spherical Gaseous Nebula. 
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XVI. — The Problem of a Spherical Gaseous Nebula. 
By Lord Kelvin. 
(MS. received March 9, 1908.) 
This paper was begun about the close of 1906, in order to fulfil a promise 
given at the end of the paper “ On the convective equilibrium of a 
gas under its own gravitation only,” published in the Philosophical 
Magazine , 1887 ; and part of it was communicated by Lord Kelvin to the 
Royal Society of Edinburgh at its meeting on 21st January 1907. Since 
then, however, important additions have been made to it, and the subject 
has been dealt with more fully than was originally intended. Unfortunately 
the manuscript was left incomplete at Lord Kelvin’s death. It ended 
with § 35. 
However, from information which I received from Lord Kelvin while 
carrying out the earlier work connected with the paper, I have been able 
to write the sections from § 36 to the end. These complete all that 
Lord Kelvin desired to include in this communication ; and they express, 
I believe, the views he held while writing the earlier sections. 
The statement of mathematical solutions and numerical results separately, 
as an Appendix to the paper, under my own name, is in accordance with 
Lord Kelvin’s wishes. 
George Green, 
Secretary. 
§ 1.* If a fluid globe were given with any arbitrary distribution of 
temperature, subject only to the condition that it is uniform throughout 
every spherical surface concentric with the boundary, the cooling, and 
consequent augmentation of density of the fluid at its boundary, by 
radiation into space, would immediately give rise to an instability according 
to which some parts of the outermost portions of the globe would sink, and 
upward currents would consequently be developed in other portions. In 
any real fluid, whether gaseous or liquid, this kind of automatic stirring 
would tend to go on until a condition of approximate equilibrium is reached, 
in which any portion of the fluid descending or ascending would, by the 
thermodynamic action involved in change of pressure, always take the 
* § 1 is extracted from “On Homer Lane’s Problem of a Spherical Gaseous Nebula,” 
Nature, Feb. 14, 1907. 
