Abstract
An attempt is made to test the accuracy of the block measurement method for the determination of positions from the Oxford Zone I of the Carte du Ciel catalog, and to determine the precise proper motions for all stars, down to the catalog's photographic limiting magnitude, in a 4.7 arcmin-diameter area which covers a large part of the cluster in Coma Berenices. The earliest epoch employed consists of nine fields of the Oxford Zone which were simultaneously reduced by means of block adjustment methods, while the latest epoch is based on plates taken with a Schmidt telescope. Intermediate epochs were taken from Heckmann (1929) and the AGK catalogs, with the latter serving as a reference system throughout.
