Date of this Version
The Cepheid DL Cas and the nonvariable supergiant Star A are confirmed as members of NGC 129, and both are found to be spectroscopic binaries with orbital periods of a few years. Periods and orbits are determined for both stars. Star A is apparently rotating; tidal interaction with its companion is discussed and then rejected as the probable cause of the rotation. The membership of other stars and the velocity of the cluster are redetermined.