  We extend our earlier macrostatistical treatment of hydrodynamical
fluctuations about nonequilibrium steady states to viscous fluids. Since the
scale dependence of the Navier-Stokes equations precludes the applicability of
any infinite scale (hydrodynamical) limit, this has to be based on the generic
model of a large but finite system, rather than an infinite one. On this basis,
together with assumptions of Onsager's regression hypothesis and conditions of
local equilibrium and chaoticity, we show that the hydrodynamical fluctuations
of a reservoir driven fluid about a nonequilibrium steady state execute a
Gaussian Markov process that constitutes a mathematical structure for a
generalised version of Landau's fluctuating hydrodynamics and generically
carries long range spatial correlations.
