  In order to study the small-scale structure of the hot interstellar gas, we
obtained Far Ultraviolet Spectroscopic Explorer interstellar O VI interstellar
absorption spectra of 4 four post-extreme horizontal branch stars in the
globular cluster NGC 6752 [(l,b) = (336.50,-25.63), d = 3.9 kpc, z= -1.7 kpc].
The good quality spectra of these stars allow us to measure both lines of the O
VI doublet at 1031.926 \AA and 1037.617 \AA. The close proximity of these stars
permits us to probe the hot interstellar gas over angular scale of only
$2\farcm2 - 8\farcm9$, corresponding to spatial scales $\la 2.5-10.1$ pc. On
these scales we detect no variations in the O VI column density and velocity
distribution. The average column density is log <N(O VI)> = 14.34 \pm 0.02 (log
<N_\perp(O VI)> = 13.98). The measured velocity dispersions of the O VI
absorption are also indistinguishable. Including the earlier results of Howk et
al., this study suggests that interstellar O VI is smooth on scales $\Delta
\theta \la 12\arcmin$, corresponding to a spatial scale of less than 10 pc, and
quite patchy at larger scales. Although such small scales are only probed in a
few directions, this suggests a characteristic size scale for the regions
producing collisionally-ionized O VI in the Galaxy.
