  The Sloan Digital Sky Survey has already doubled the number of
spectroscopically identified white dwarfs. However, there remains a wealth of
white dwarfs in the McCook & Sion catalog for which little or nothing is known.
We have thus undertaken a spectroscopic survey of all Northern hemisphere DA
white dwarfs from this catalog in order to (1) confirm the spectroscopic
classification, and (2) provide measurements of Teff and log g for each star.
As part of this project, we have also secured spectroscopic data for all DA
stars with high-speed photometric measurements available, in order to study the
purity of the ZZ Ceti instability strip, which has recently been challenged,
once again.
