Helen B. Sawyer A Bibliography of Individual Globular Clusters

384 Publications of the David Dunlap Observatory
no. 4). This paper gives a list of references to variable stars in these
clusters. (A second edition of this catalogue is in preparation at
present). But at the time this work was published it was felt that
a complete bibliography of individual clusters would be of great use
to an astronomer concerned with globular clusters. It is good for
an astronomer working on variables in a cluster, or radial velocities,
or space reddening, to be able to find out speedily what other data
about the cluster are known.
In the globular cluster literature of the present century little
attention is paid to the earlier references, that is, those up until the
later nineteenth century. References to globular clusters of a cen-
tury ago are buried beneath an enormous amount of literature on
all kinds of nebulous objects, and in nebular catalogues. There is
a confusion of numbering too, before the Xew General Catalogue,
so that each cluster may be referred to by any one of several
numbers.
As far as possible, the writer has read over this entire mass of
literature, back to the time of Hevelius and Halley, and segregated
all pertinent material from it. Over 800 individual references in
about 125 different serial publications have been listed and sur-
veyed. The bibliography is essentially complete up to the dis-
ruption of communications in Canada at the beginning of the last
war. Most literature published up to the end of 1938 was safely
reccived and has been included, together with as much as possible
of the literature of the past eight years. Disruption of foreign
communications occurred in Canada in 1939; some material was
received through the United States during the ensuing two years.
The substance of earlier bibliographies has been incorporated in
the present work, as well as many references not in any existing
bibliography. Of course the Astronomischer Jahresbericht has been
used for many years as a basis for references. For earlier biblio-
graphies some use has been made of the list of papers on nebulae
by Knobel, Monthly Xotices, vol. 36, p. 377, 1876. This list does
not give much clue to the character of many of the references, but
the subject was rediscussed by Holden, who published a very comprehensive
reference work, with comments, in Smithsonian Mis-
cellaneous Collections, no. 311, 1877 (from which our foreword is
taken). A more recent bibliography was published by Bigourdan in
1917. in Paris Annales, Observations 1907. A comprehensive biblio-