New views of Mr. George H. Darwin's theory of the evolution of the Earth-Moon system : considered as to its bearing on the question of the duration of geological time / by Samuel Haughton.

  • Haughton, Samuel.
Date:
1882
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Licence: Public Domain Mark

Credit: New views of Mr. George H. Darwin's theory of the evolution of the Earth-Moon system : considered as to its bearing on the question of the duration of geological time / by Samuel Haughton. Source: Wellcome Collection.

Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.

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    stones moving around a solid or liquid nucleus, the difficulty re- specting their specific gravity would disappear. 3. Tlie recent researches connecting the November, tlie August, and other periodic swarms of shooting stars with comets tend in the direction of showing that comets, in cooling, break up into dis- crete solid particles (each no doubt having passed through the liquid condition) ; and that probably the solar nebula cooled in like manner into separate fiery tears, which soon solidified by ra- -diation into the cold of space. 4. Mr. Huggins’s recent comparisons of the spectroscopic ap- pearances of comets and incandescent portions of meteoric stones, showing the presence in both of hydrocarbon and nitrogen com- pounds, confirm the conclusions drawn from the identity of the paths of comets and meteoric periodic shooting stars. 5. Mr. H. A. Newton, in a remarkable paper read before the Sheffield Meeting of the British Association (1879), showed the possibility (if not probability) of the asteroids being extinct comets, captured and brought into the solar system by the attrac- tion of some one or other of the outer large planets, and perma- nently confined in the space between Mars and Jupiter, which is the only prison cell in the solar system large enough to hold per- manently such disorderly wanderers. In the same paper. Professor Newton threw out the idea that some of the satellites of the large planets might also be of com- etary origin. From all these and other considerations, it is therefore allowable to suppose that the earth and moon, when they separated from the solar nebula, did so as a swarm of solid meteoric stones, each of them having the temperature of interstellar space ; i. e., something not much warmer than 460° F. below the freezing point of water. Mr. George H. Darwin has shown, admirably, how the earth- moon system may have been developed from the time when the earth-moon formed one planet revolving on its axis in a few hours, to the present time, when the earth and moon (in conse- quence of tidal friction) have pushed each other asunder to a dis- tance of sixty times the radius of the earth.^ In his paper on the tidal friction of a planet^ (supposed viscous and under the influence of bodily tides caused in it b}' an external “Proceedings of Royal Society, 19th June, 1879. ■ s Phil. Trans., 1881, Part ii, p. 494.