re to the case of another star,
namely V Puppis, in which such evidence does already exist. I give an
account of it, because it presents a peculiarly interesting confirmation
of the correctness of the theory.

In 1895 Pickering announced in the "Harvard Circular" No. 14 that the
spectroscopic observations at Arequipa proved V Puppis to be a double
star with a period of 3d 2h 46m. Now when Roberts discussed its
light-curve he found that the period was 1d 10h 54m 27s, and on account
of this serious discrepancy he effected the reduction only on the simple
assumption that the two stars were spherical, and thus obtained a fairly
good representation of the light-curve. It appeared that the orbit was
circular and that the two spheres were not quite in contact. Obviously
if the stars had been assumed to be ellipsoids they would have been
found to overlap, as was the case for RR Centauri. ("Astrophysical
Journ." Vol. XIII. (1901), page 177.) The matter rested thus for some
months until the spectroscopic evidence was re-examined by Miss Cannon
on behalf of Professor Pickering, and we find in the notes on page
177 of Vol. XXVIII. of the "Annals of the Harvard Observatory" the
following: "A.G.C. 10534. This star, which is the Algol variable V
Puppis, has been found to be a spectroscopic binary. The period 1d.454
(i.e. 1d 10h 54m) satisfies the observations of the changes in light,
and of the varying separation of the lines of the spectrum. The spectrum
has been examined on 61 plates, on 23 of which the lines are double."
Thus we have valuable evidence in confirmation of the correctness of the
conclusions drawn from the light-curve. In the circumstances, however,
I have not thought it worth while to reproduce Dr Roberts's provisional
figure.

I now turn to the conclusions drawn a few years previously by another
observer, where we shall find the component stars not quite in contact.
This is the star Beta Lyrae which was observed by Goodricke, Argelander,
Belopolsky, Schur, Markwick and by many others. The spectroscopic method
has been successfully applied in this case, and the component stars are
proved to move in an orbit about one another. In 1897, Mr. G.W. Myers
applied the theory of eclipses to the light-curve, on the hypothesis
that the stars are elongated ellipsoids, and he obtained the interesting
results exhibited in Fig. 7. ("Astrophysical Journ." Vol. VII. (1898),
page 1.)

The period of Beta Lyrae is relatively long, be