objects without optical aid. The two stars seem fused together into
one. In the telescope, however, the bodies may be discerned
separately, though they are frequently so close together that it
taxes the utmost power of the instrument to indicate the division
between them.

The appearance presented by a double star might arise from the
circumstance that the two stars, though really separated from each
other by prodigious distances, happened to lie nearly in the same
line of vision, as seen from our point of view. No doubt, many of
the so-called double stars could be accounted for on this
supposition. Indeed, in the early days when but few double stars
were known, and when telescopes were not powerful enough to exhibit
the numerous close doubles which have since been brought to light,
there seems to have been a tendency to regard all double stars as
merely such perspective effects. 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