The first table gives him no information, the latter gives him a minimum at 8h.19m.

P.M.on August 30; hence of course there is a minimum at 11h.31m.

P.M.on August 27; and there are no other conveniently observable minima during the fortnight in question.
The cause of the remarkable variation in this star's brilliancy has been assigned by some astronomers to the presence of an opaque secondary, which transits Algol at regular intervals; others have adopted the view that Algol is a luminous secondary, revolving around an opaque primary.
Of these views the former seems the most natural and satisfactory.

It points to a secondary whose mass bears a far greater proportion to that of the primary, than the mass even of Jupiter bears to the sun; the shortness of the period is also remarkable.

It may be noticed that observation points to a gradual diminution in the period of Algol's variation, and the diminution seems to be proceeding more and more rapidly.