Excerpt from Measures of Double Stars With the 40-Inch Refractor of the Yerkes Observatory in 1900 and 1901

The double-star measures recorded here were made principally in the years 1900 and 1901. The observations preceding this period were almost entirely of the B stars; and the mean results have been incorporated in the General Catalogue of 1290 Double Stars discovered by the writer from 1871 to 1899, and issued in 1900 as Vol. I of the Publications of the Yerkes Observatory. The detailed measures have not been printed, but, as the results have been given in connection with all the measures of these stars, arranged In chronological order, I have not thought it worth while to give the separate observations.

In making the working-list of objects for measurement, the purpose was to include no star likely to be observed elsewhere, and to confine it wholly to long-neglected and little-known pairs, and those which for the lack of sufficient measures, or the uncertainty of the early results, could not be classified as to motion or otherwise. These stars, so far as the early astronomers are concerned, come largely from the several catalogues of the two Herschels and South, with some of the rejected Struve pairs also catalogued and roughly measured by Herschel II. Many of these, and particularly those from Herschel I. And South, are wide pairs, and too widely separated to be considered by modern observers as double stars in the proper sense of the term; and, whenever change has been found in this class of objects, it is very probable that it is due to the proper motion of one or the other of the components. In the other class, where the distances are less, the changes, if confirmed by later observations, may point to physical systems, though, of course, the orbital movement would of necessity be slow. It seemed very desirable that these stars, among the oldest known so far as the literature of the subject is concerned, and observed by the most eminent astronomers who have ever lived, should receive sufficient attention from modern observers to show whether or not In this long interval there has been any relative motion. In many instances the measures now made do not satisfactorily determine this, since the apparent change may be accounted for by errors in the single observations made when the pair was first catalogued, and another series of measures at some later time may be necessary.

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