his many
interesting discoveries was that of a minute companion to Alpha
Ursae Majoris (the first Pointer), which already gives unmistakable signs
of orbital movement round the shining orb it is attached to. Another
pair, Kappa Pegasi, detected in 1880, was found in 1892 to have
more than completed a circuit in the interim.[1593] Its period of a
little over eleven years is the shortest attributable to a _visible_
binary system, except that of Delta Equulei, provisionally
determined by Professor Hussey in 1900 at 5.7 years,[1594] and indicated
by spectroscopic evidence to be of uncommon brevity.[1595] Burnham's
Catalogue of 1,290 Double Stars, discovered by him from 1871 to
1899,[1596] is a record of unprecedented interest. Nearly all the 690
pairs included in it, 2" or less than 2" apart, must be physically
connected; and they offer a practically unlimited field for
investigation; while the notes, diagrams, and orbits appended profusely
to the various entries, are eminently helpful to students and computers.
The author is continuing his researches at the Yerkes Observatory,
having quitted the Lick establishment in 1892. The first complete
enrolment of southern double stars was made by Mr. R. T. A. Innes in
1899.[1597] The couples enumerated, twenty-one per cent. of which are
separated by less than one second of arc, are 2,140 in number. They
include 305 discovered by himself. Dr. See gathered a rich harvest of
nearly 500 new southern pairs with the Lowell 24-inch refractor in
1897.[1598] Professor Hough's discoveries in more northerly zones amount
to 623;[1599] Hussey's at Lick to 350; and Aitken's already to over 300.

There is as yet no certainty that the stars of 61 Cygni form a true
binary combination. Mr. Burnham, indeed, holds them to be in course of
definitive separation; and Professor Hall's observations at Washington,
1879 to 1891, although favouring their physical connection, are far from
decisive on the point.[1600] Dr. Wilsing, from certain anomalous
displacements of their photographed images, concluded in 1893[1601] the
presence of an invisible third member of the system, revolving in a
period of twenty-two months; but the effects noticed by him were
probably illusory.

Important series of double-star observations were made by Perrotin at
Nice in 1883-4;[1602] by Hall, with the 26-inch Washington equatoreal,
1874 to 1891;[1603] by Schiaparelli from 1875 onward; by Glasenapp, O.
Stone, Leavenworth, Seabrok