  The influence of the gravity acceleration on the regularized energy-momentum
tensor of the quantized electromagnetic field between two plane parallel
conducting plates is derived. We use Fermi coordinates and work to first order
in the constant acceleration parameter. A new simple formula for the trace
anomaly is found to first order in the constant acceleration, and a more
systematic derivation is therefore obtained of the theoretical prediction
according to which the Casimir device in a weak gravitational field will
experience a tiny push in the upwards direction.
