We present measurements of the column densities of interstellar D I and O I made with the Far Ultraviolet Spectroscopic Explorer ( FUSE ) , and of H I made with the International Ultraviolet Explorer ( IUE ) toward the sdOB star Feige 110 [ ( l , b ) = ( 74 \fdg 09 , -59 \fdg 07 ) ; d = 179 ^ { +265 } _ { -67 } pc ; z = -154 ^ { +57 } _ { -227 } pc ] .
Our determination of the D I column density made use of curve of growth fitting and profile fitting analyses , while our O I column density determination used only curve of growth techniques .
The H I column density was estimated by fitting the damping wings of the interstellar Ly \alpha profile .
We find log N ( D I ) = 15.47 \pm 0.06 , log N ( O I ) = 16.73 \pm 0.10 , and log N ( H I ) = 20.14 ^ { +0.13 } _ { -0.20 } ( all errors 2 \sigma ) .
This implies D/H = ( 2.14 \pm 0.82 ) \times 10 ^ { -5 } , D/O = ( 5.50 ^ { +1.64 } _ { -1.33 } ) \times 10 ^ { -2 } , and O/H = ( 3.89 \pm 1.67 ) \times 10 ^ { -4 } .
Taken with the FUSE results reported in companion papers ( Moos et al .
2001 ) and previous measurements of the local interstellar medium , this suggests the possibility of spatial variability in D/H for sight lines exceeding \sim 100 pc .
This result may constrain models which characterize the mixing time and length scales of material in the local interstellar medium .