Address to the British Association for the Advancement of Science / delivered by the President, William Robert Grove ... in the Theatre, Nottingham, August 22, 1866.

  • William Robert Grove
Date:
1866
Catalogue details

Licence: Public Domain Mark

Credit: Address to the British Association for the Advancement of Science / delivered by the President, William Robert Grove ... in the Theatre, Nottingham, August 22, 1866. Source: Wellcome Collection.

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    similarly though not identically constituted, stars differing from each other and from our system, and nebulae more remote in space and differing more in their characters and constitution. While we thus can to some extent investigate the physical constitution of the most remote visible substances, may wo not hope that some further insight as to the constitation of the nearest, viz. our own satellite, may be given us by this class of researches ? The question whether the moon possesses any atmosphere may still be regarded as unsolved. If there be any, it must be exceedingly small in quantity and highly attenuated. Calculations, made from occultation of stars, on the apparent differences of the somidiameter of the bright and dark moon give an amount of difference which might indicate a minute atmosphere, but which Mr. Airy attributes to irradiation. Supposing the moon to be constituted of similar materials to the earth, it must be, to say the least, doubtful whether there is oxygen enough to oxidate the metals of Avhich she is composed; and if not, the surface which we see must be metallic, or nearly so. The appearance of her craters is not unlike tliat seen on the surface of some metals, such as bismuth, or, according to Professor Phillips, silver, when cooling from fusion and just previous to solidifying ; and it might be a fair subject of inquiry whether, if there be any coating of oxide on the surface, it may not be so thin as not to disguise the form of the con¬ gealed metallic masses, as they may have set in cooling from igneous fusion. M. Chacornac’s recent observations lead him to suppose that many of the lunar craters were the result of a single explosion, which raised the surface as a bubble and deposited its debris around the orifice of eruption. The eruptions on the surface of the moon clearly did not take place at one period only, for at many parts of the disk craters may be seen encroachiug on and disfiguring more ancient craters, sometimes to the extent of three or four successive displacements ; two important questions might, it seems to me^ bo solved by an attentive examination of such portions of the moon. Py ob¬ serving carefully with the most powerful telescopes the character of the ridges thus successively formed, the successive states of the lunar surface at different epochs might be elucidated; and secondly, as on the earth we should look for actual volcanic action at those points where recent eruptions have taken place, so on the moon the more recently active points being ascertained by the suc¬ cessive displacement of anterior formations, it is these points which should be examined for existing disruptive disturbances. Metius and Pabricius might be cited as points of tliis character, having been found by M. Chacornac to present successive displacements and to be perforated by numerous channels or cavities. M. Chacornac considers that the seas, as they are called, or smoother portions of the lunar surface have at some time made inroads on
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