  Ibata et al (1999) have recently discovered faint, moving objects in the
Hubble Deep Field. The quantity, magnitudes and proper motions of these objects
are consistent with old white dwarfs making up the Galactic dark halo. We
review a number of ground-based proper motion surveys in which nearby dark halo
white dwarfs might be present, if they have the colours and absolute magnitudes
proposed. No such objects have been found, whereas we argue here that several
times more would be expected than in the Hubble Deep Field. We conclude it is
unlikely that hydrogen atmosphere white dwarfs make up a significant fraction
of the halo dark matter. No limits can be placed yet on helium atmosphere
dwarfs from optical searches.
