Vol. 6, 1920 INTERNATIONAL ASTRONOMICAL UNION 
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cause of its elasticity. The number once assigned is permanent and always 
places the star in its proper serial order in the catalogue. 
4. Ephemerides of variable stars. — Hitherto published annually in the 
Vierteljahrsschrift. Again a question of policy must be considered. In 
case this very desirable aid to the observer is to be prepared under the 
direction of the International Committee, the form of publication should 
be most carefully considered. 
5. Catalogue of variable stars. — Intimately related to (3) and (4). 
A complete catalogue, of carefully considered form, should be published; 
at intervals which may be determined by experience it should be com- 
pletely revised. In the interim annual supplements containing revisions 
and additions should be available. 
6. Systematic observation of variable stars. — To insure a proper distri- 
bution of effort and to avoid a needless duplication of results, there should 
be mutual agreement between observers as to the objects to be observed 
or at least an announcement as to objects under observation. A central 
committee, as a clearing house for the dissemination of information and the 
arrangement of details, would prove invaluable. Directive action on the 
part of the committee should be reduced to a minimum. The affiliation 
of associations of amateurs should be invited. 
Other questions might easily be added, but these we believe sufficient, 
to indicate the character of the organization required. 
Very respectfully submitted, 
F. H. Skares, Chairman, S. I. BaiIvBy, F. C. Jordan, J. A. Parkhurst, 
JoKiv St^bbins. 
REPORT OF THE COMMITTEE ON DOUBLE STARS 
I. CLASSIFICATION 
The term "double star" is still loosely used to describe any pair of stars 
which have been connected by micrometric measures. It seems desirable 
to agree, if possible, upon some more exact definition and to adopt some 
system of classification and of printing conventions which will enable us 
to distinguish between pairs of different character. To be of service, 
such a system must be adopted by common consent of astronomers and 
such consent can best be obtained by discussion and agreement at a meet- 
ing of the character of the proposed International Astronomical Union. 
As a basis for discussion, the Committee on Double Stars suggests: 
1. That in measuring and cataloging new pairs definite limits as to 
magnitude and angular separation be observed, such as those, for example, 
proposed in The Working Definition of a Double Star, published in A. N. 
188, 1911, (281). 
2. That double stars already cataloged be divided into four classes, 
as follows:^ 
^ The section requested the committee to devise a different mode of printing. 
