In this paper we present new and improved data on 38 cool white dwarfs identified by ( ) ( OHDHS ) as candidate dark halo objects . Using the high-resolution spectra obtained with LRIS on Keck I , we measure precise radial velocities for 13 white dwarfs that show an { H } \alpha absorption line . We show that the knowledge of radial velocities on average decreases the UV -plane velocities by only 6 % . In two cases the radial velocities put original halo candidates below the OHDHS velocity cut . The radial velocity sample has a velocity dispersion in the direction perpendicular to the Galactic plane of \sigma _ { W } = 59 { km } { s } ^ { -1 } – in between the values typically associated with the thick disk and the stellar halo populations . We also see indications for the presence of two populations by analyzing the velocities in the UV plane . In addition , we present CCD photometry for half of the sample , and with it recalibrate the photographic photometry of the remaining white dwarfs . Using the new photometry in standard bands , and by applying the appropriate color-magnitude relations for hydrogen and helium atmospheres , we obtain new distance estimates . By recalibrating the distances of the white dwarfs that were not originally selected as halo candidates , we obtain 13 new candidates ( and lose 2 original ones ) . On average , new distances produce velocities in the UV plane that are larger by 10 % , with already fast objects gaining more . Using the new data , while applying the same UV -velocity cut ( 94 { km } { s } ^ { -1 } ) and methods of analysis as in OHDHS , we find a density of cool white dwarfs of 1.7 \times 10 ^ { -4 } { pc } ^ { -3 } , confirming the value of OHDHS . In addition , we derive the density as a function of the UV -velocity cutoff . The density ( corrected for losses due to higher UV -velocity cuts ) starts to flatten out at 150 { km } { s } ^ { -1 } ( 0.4 \times 10 ^ { -4 } { pc } ^ { -3 } ) , and is minimized ( thus minimizing a possible non-halo contamination ) at 190 { km } { s } ^ { -1 } ( 0.3 \times 10 ^ { -4 } { pc } ^ { -3 } ) . These densities are in a rough agreement with the estimates for the stellar halo white dwarfs , corresponding to a factor of 1.9 and 1.4 higher values .