It was not at first suggested that
there could be any physical connection between the components of each
pair. The appearance presented was regarded as merely due to the
circumstance that the line joining the two bodies happened to pass
near the earth.
[PLATE: SIR JOHN HERSCHEL.]
In the early part of his career, Sir William Herschel seems to have
entertained the view then generally held by other astronomers with
regard to the nature of these stellar pairs. The great observer
thought that the double stars could therefore be made to afford a
means of solving that problem in which so many of the observers of
the skies had been engaged, namely, the determination of the
distances of the stars from the earth. Herschel saw that the
displacement of the earth in its annual movement round the sun would
produce an apparent shift in the place of the nearer of the two stars
relatively to the other, supposed to be much more remote. If this
shift could be measured, then the distance of the nearer of the stars
could be estimated with some degree of precision.
As has not unfrequently happened in the history of science, an effect
was perceived of a very different nature from that which had been
anticipated. If the relative places of the two stars had been
apparently deranged merely in consequence of the motion of the earth,
then the phenomenon would be an annual one.
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