CHAPTER IX.

IN

A CATALOGUE OF VARIABLE STARS.

N the Astronomical Register for August 1864 I published a Catalogue of Variable Stars, based upon the latest information. accessible to me; this catalogue was copied into the Astronomische Nachrichten, the Wochenschrift für Astronomie und Meteorologie, and the Rev. W. A. Darby's Astronomical Observer. It afterwards appeared in a revised form in the Monthly Notices. The publicity thus attained had the important effect of drawing forth from various sources, including two distinguished foreign observatories, a considerable number of substantial additions and corrections.

As regards the catalogue itself, the headings of the columns are sufficiently explicit, and it is only necessary to state that the symbol signifies that the star's minimum magnitude fell below that given, but how much is unknown.

In the catalogue in its original form, following precedents set by previous writers, I included various stars strongly suspected to be variable, but which had never been proved so by anything like systematic and rigorous observation. At the suggestion of M. Schönfeld these stars have been detached from the main body, and (with others) have been formed into a sub-class by themselves; that this is a reasonable alteration will hardly, I think, be doubted; some of them probably will ere long have to be transferred back to the main catalogue.

Argelander's nomenclature has been followed, but it is manifest that it is a very crude and unsatisfactory one, and at no very distant period will have to give place to something more artistic. Perhaps, on the whole, simple cardinal numbers, representing the order of discovery, with the syllable "var." and the name of the

constellation appended, would be the most convenient and manageable system; e.g. " 154 var. Andromeda."

I must not close this introduction without acknowledging the important assistance derived from the communications of Mr. J. Baxendell, F.R.A.S., of Manchester, M. Schönfeld, of Mannheim, and Dr. Schjellerup, of Copenhagen.

PART I.-STARS KNOWN TO BE VARIABLE.

2. This is the celebrated temporary star observed by Tycho Brahe. D'Arrest has noticed a suspicious star close to this place.

4. J. F. Schmidt says he can detect not the least trace of variability, though he has kept watch on the star for many years.

5. Hind says: "Certainly variable from 9th mag. to below 12th mag.; generally of the 115 mag." Notwithstanding this clear and unequivocal testimony, both Schjellerup and Schönfeld oppose its admission into the list of recognised variables, and unreasonably, as I think.

12. Schmidt's latest period is 330 days exactly.

P P

23. This is Hind's celebrated "crimson star." It well deserves all that has been said of it, for it is a truly remarkable object. In 1855 Schmidt reported it to be gaining light and losing colour: when I last saw it, however, on Jan. 4, 1865, its colour was as deep a ruby as well could be; and, gauged by Dawes's method, its magnitude was 93.

26. See note to a Cassiopeia.

27. This is the well-known variable of Schmidt which is in combination with the nebula 2 H IV. (See Ast. Nach. 1302, April 6, 1861.)

41. See note to a Cassiopeia.

43. "A fine rich ruby star." (MS. Jan. 20, 1865.)

57. The declination in the Greenwich Observations for 1861 is greater by 10'. 72. Schönfeld objects to this designation on the ground that "it is by no means clear that the star belongs to the variables properly so called; much more does it seem to resemble in nature 11 Vulpeculæ, Hind's Nova in Ophiuchus, &c." I confess I do not think the objection tenable, more particularly as Schönfeld has included these two objects in his own Catalogue of Variables. (Ast. Nach. 1523, April 21, 1865.)

73. The exact position of this star does not appear to be determined with the fullest certainty.