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There have been many attempts to formulate a theory of evolution for 
the earth, the solar system, and indeed the whole siderial universe. Un- 
fortunately, most of these were based on comparatively little scientific data 
and any actual proofs of reliability or truth were lacking. Most of them 
might better be called speculations, pure and simple, and were produced 
largely from analogy. For example, we have known for some three hundred 
years that the planets circulate about the sun in nearly the same plane, the 
ones near the sun moving faster than those farther away. The visible 
universe is apparently arranged more or less in one plane or at least is very 
much extended in the plane of the Milky Way, the solid figure that would 
enclose the solar system not being greatly different, except in size, from the 
one which would enclose all the stars. What would be more matural then 
than to suppose that the whole universe was built up on a large scale much 
as the planetary system, the sun being in revolution with many others 
about some distant center. These, in turn, perhaps, revolving about 
another center till the whole Universe is accounted for. Some such idea 
was advanced by Kant who had only the Law of Gravitation upon which 
to base his speculations. Unfortunately he knew nothing of the distances of 
the stars. At that time no one knew from actual observation that the 
stars had any real motions of their own through space. 
We know little enough of these things now, but a few facts have been 
established with certainty in the last hundred years, indeed most of our 
accurate knowledge of the stars being attained in much more modern times. 
It was not till 1839 that we knew the distance of a single star in the whole 
sky, and only in the last fifty years has it been possible to measure their 
motions in any very precise way. 
Following the above general theory it was supposed for a while that the 
central point about which the whole siderial system revolved had been lo- 
cated in Aleyone, the brightest of the Pleiades. It is sufficient to say that 
there is not a particle of evidence to sustain this conclusion, or the conclusion 
that the stars, as a whole, revolve about any center whatever. As far as 
we know the stars move in all sorts of directions and with all sorts of veloci- 
ties. We are lacking now as much as a thousand years ago any theory of the 
evolution of the system of the stars, which is based upon observed changes 
in the stars themselves. The theories and speculations regarding the origin 
and history of the planetary system are more numerous and in some cases as 
improbable and impossible as those regarding the universe, The best 
