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LXIY. On Certain Questions connected with Astronomical 

 ■ Physics. By S. Tolvee Peeston, Ph.D. * 



1XHE Philosophical Magazine for March 1 847 contains a 

 paper under the title " The Form of the Earth no Proof 

 of Original Fluidity," by Herbert Spencer. A remote date 

 to any publication may tend to its being overlooked, and some 

 of the conclusions in this article appear to be worthy of 

 notice. 



The implication of course is that in the case of our earth t, 

 gravitational pressure by itself alone would demonstrably 

 suffice to have effected the compacted" flow " of solid substance 

 into globular form, -without the necessity for any preceding- 

 state of fluidity or of high temperature. 



In the '' flow of solids " (metals particularly) by the mere 

 action of pressure, without any application of heat, subse- 

 quently demonstrated experimentally by Tresca, we may see 

 a parallel effect actually produced and illustrative of the 

 above theoretical view. 



As a fact of general application, we may also notice that, 

 provided the accumulation of aggregated material were 

 assumed sufficiently gradual, or spread over an epoch of 

 adequate duration, there might be time for any heat to dissi- 

 pate; and so it appears there need be no real accumulation of 

 heat from this cause, but rather a gradual yielding of materials 

 under gravitational stress, somewhat comparable [say]" to 

 metals "flowing'''' under a very gradually augmented pressure. 

 The sphere is then regarded as the natural J form assumed 

 under gravitation, even if there were no fluidity produced 

 by heat. 



But it would seem as if one fact had been overlooked by 

 Herbert Spencer. For while, at the surface of the globe, 



* Communicated by the Author. 



t Since our earth in the remote past is generally held to have rotated 

 more quickly about its axis than now, any quantitative inference as to 

 its shape, if grounded on the present rate of axial rotation, would appear 

 to be open to question. 



J The pressure at the centre of our globe is calculated by Prof. 

 T. J. J. See as equivalent to that of a column of mercury 2383-152 

 kilometres high — a pressure " so enormous that Prof. See attempts to 

 render it more comprehensible by suggesting that it is 7838 times as 

 great as that of a mercurial column equal in height to the Eiffel Tower " 

 (' Nature,' March 2,. 1905, p. 424). Curiously enough, this Tower is 

 reputed to contain a mercurial manometer equal to its height [300 

 metres]. 



