1904-5.] Mr Romanes on the Formation of the Moon. 
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A Possible Explanation of the Formation of the Moon. 
By George Romanes, C.E. 
(Read November 21, 1904.) 
The subject of the moon’s development has been dealt with by 
Professor G. H. Darwin by means of a highly abstruse mathe- 
matical analysis, which the present writer cannot pretend to be 
able to discuss. He wishes to point out, however, that Professor 
Darwin’s theory requires the assumption that earth and moon 
formed, at one time, a single highly -heated fluid mass ; the theory 
being that the moon was thrown off by centrifugal force aided by 
the sun’s tidal influence and synchronous vibratory motion of the 
fluid mass. 
There is another possible explanation of the formation of the 
moon, that gets over many difficulties in explaining its features. 
It is to suppose that earth and moon were separately formed out 
of different parts of the same nebula, or crowd of small parts which 
were at one time circulating round their common centre of mass 
at great varieties of distances, in every plane and with every 
degree of eccentricity, the whole having a balance of moment in 
the plane and direction in which earth and moon are now revolv- 
ing. The portions near the centre would tend to collect there to 
form the earth, while the outer portions gradually collected into 
larger and larger masses to form the moon, and in doing so built up 
its mass in such a way as to leave a record, which it is the purpose 
of this paper to endeavour to interpret. 
Before considering the markings on the moon’s surface, the 
writer wishes to show, as clearly as he can, how such a result as 
the building up of the moon in this way is possible. All bodies 
circulating round the earth are subject not only to the influence of 
the earth, but also that of the sun and of each other ; which must 
have caused great irregularities in their motions, and increased the 
chances of collisions among each other, and thus gradually reduced 
