mperfections of the eye or the telescope. In 1871 Burnham
believed he had discovered that the companion was an exceedingly close
double star. No one except Burnham himself succeeded in dividing it, and
he could only do so at times. Afterward, when he was at Mount Hamilton,
he tried in vain to split it with the great thirty-six-inch telescope,
in 1889, 1890, and 1891. His want of success induced him to suggest that
the component stars were in rapid motion, and so, although he admitted
that it might not be double after all, he advised that it should be
watched for a few years longer. His confidence was justified, for in
1898 Aitken, with the Lick telescope, saw and measured the distance of
the extremely minute companion--distance 0.17", p. 177 deg..

[1] The angle of position measures the inclination to the meridian of a
line drawn between the principal star and its companion; in other words,
it shows in what direction from the primary we must look for the
companion. It is reckoned from 0 deg. up to 360 deg., beginning at the north
point and passing around by east through south and west to north again.
Thus, if the angle of position is 0 deg. or 360 deg., the companion is on the
north side of the primary; if the angle is 90 deg., the companion is to the
east; if 180 deg., to the south; if 270 deg., to the west, and so for
intermediate angles. It must be remembered, however, that in the field
of the telescope the top is south and the bottom north, unless a prism
is used, when directions become complicated. East and west can be
readily identified by noticing the motion of a star through the field;
it moves toward the west and from the east.

Rigel has been suspected of a slight degree of variability. It is
evidently a star of enormous actual magnitude, for its parallax escapes
trustworthy measurement. It can only be ranked among the very first of
the light-givers of the visible universe. Spectroscopically it belongs
to a peculiar type which has very few representatives among the bright
stars, and which has been thus described: "Spectra in which the hydrogen
lines and the few metallic lines all appear to be of equal breadth and
sharp definition." Rigel shows a line which some believe to represent
magnesium; but while it has iron lines in its spectrum, it exhibits no
evidence of the existence of any such cloud of volatilized iron as that
which helps to envelop the sun.

For another test of what the three-inch will do turn to